NASA FIFE Project

Description

An inventory of NASA's airborne and field campaigns for Earth Science

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The Fifteen Minute Stream Flow Data from the USGS Data Set contains 15 minute stream flow data from the USGS station located 2.9 miles upstream from the mouth of Kings Creek. The record extends from April 1, 1979 through September 2, 1988. The purpose of this data set was to provide accurate measurements of the stream flow from Kings Creek so that a water budget analysis for the northwest quadrant of the FIFE study area could be performed. The stilling pipe installed at the USGS station operates on the principle that the water level in a standpipe at a specific location within a stream bed can be converted to a volume of water in the stream bed. The tracking of the change in stream height with time then enables the calculation of stream flow.

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The FIFE Thirty Minute Rainfall Data Data Set contains data from thirty rain gauges located in the Kings Creek basin in the northwest corner of the FIFE study area during 1987. Reliability of the gauges were such that at any particular time, data from approximately 20 were recovered. The high temperatures and humidity, plus software problems in the loggers, resulted in data losses. The collected data were of high quality and sufficiently many gauges were working that the structure of the raincells can be observed from the gauge data.

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The purpose of this study was to develop alternatives to ground-based measurements in order to obtain information required to predict the effects of soil and land use on the fluxes of greenhouse gases, the surface energy balance, and the water balance. Satellite-based algorithms have been developed via flux measurements from an aircraft to estimate vegetation and soil conditions on a regional scale. The purpose of the Twin Otter FIFE flights was to make measurements in the boundary layer of the fluxes of sensible and latent heat, momentum, and carbon dioxide, plus supporting meteorological parameters such as temperature, humidity, wind speed, and direction. Aircraft position, heading, and altitude were also recorded, as were several radiometric observations for use in interpretation of these data. The Twin Otter aircraft allows steady flight trajectories at low airspeed (50-60 [m][sec^-1]) down to levels less than 10 m above the ground. The aircraft is instrumented to measure the contribution of flux densities of momentum, sensible, and latent heat, and CO2 over a frequency range of 0 to 5 Hz (MacPherson et al., 1981). All the flux measurements were obtained with the eddy-correlation method, wherein the aircraft is equipped with an inertial platform, accelerometers, and a gust probe for measurement of earth-relative gusts in the x, y, and z directions. Gusts in these dimensions are then correlated with each other for momentum fluxes and with fluctuations in other variables to obtain the various scalar fluxes, such as temperature (for sensible heat flux) and water vapor mixing ratio (for latent heat flux). The fluctuations in all variables were calculated with three different methods (the arithmetic means removed, the linear trends removed, or filtered with a high-pass recursive filter) prior to the eddy correlation calculations. This data set contains the linearly detrended data. Through this research, it is hoped that techniques can be developed to utilize satellite data for global monitoring of crop health and climate change.

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The University of Wyoming (UW) King Air atmospheric boundary layer measurement missions were flown in 1987 during IFCs 3 and 4. This Boundary Layer Fluxes data set contains parameters that describe the environment in which the flux data were collected and the flux data itself . The fluctuations in all variables were calculated with three different methods (the arithmetic means removed, the linear trends removed, or filtered with a high-pass recursive filter) prior to the eddy correlation calculations. This data set contains the linearly detrended data. All the flux measurements were obtained with the eddy-correlation method, wherein the aircraft is equipped with an inertial platform, accelerometers, and a gust probe for measurement of earth-relative gusts in the x, y, and z directions. Gusts in these dimensions are then correlated with each other for momentum fluxes and with fluctuations in other variables to obtain the various scalar fluxes, such as temperature (for sensible heat flux) and water vapor mixing ratio (for latent heat flux). The summary of data calculated from each aircraft pass includes various statistics, correlations, and fluxes calculated after the time series for each variable with the linear trends removed.

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The NCAR King Air participation in FIFE-1987 and FIFE-1989 was part of a coordinated atmospheric boundary layer component which included other aircraft, surface measurements, balloon-borne profiles, SODAR, and lidar remote sensing. The chief objective of the boundary layer component was to describe the structure of the atmospheric boundary layer over the FIFE study area, increase knowledge of the physical processes active in the daytime boundary layer, and explore the relationship of surface properties to the time and spatial variation in the structure of the boundary layer. The phenomena studied were the daytime convective boundary layer structure and physical processes. This study used airborne measurement of vertical and horizontal wind gusts, humidity, potential temperature, mean horizontal wind speed, and horizontal linear trends of temperature, humidity, radiation. Fluxes of sensible heat, moisture, and momentum were estimated from fast response wind gust, temperature, and humidity measurements; these fluxes were evaluated from data whose linear trend and mean were removed. In addition several radiation parameters were also measured.. Several radiation parameters were also measured (e.g., global short and longwave, upwelling, and downwelling). Altitude of the aircraft was measured by radar and pressure; radar was more accurate but was only valid below about 930 m. Geographical position was measured by an inertial navigation system. All level legs of a flight mission were flown at a constant pressure altitude, thus the altitude of the aircraft over the surface varied. In general, the detrended data set is of excellent overall quality with very little loss of data. Vertical winds were sampled at an effective rate of 5 samples per second instead of the customary 10 samples per second; this had negligible effect on the fluxes but could compromise estimates of turbulence dissipation. Fluxes were estimated using raw, detrended and high-pass filtered data. From extensive analysis the FIFE Boundary Layer Group recommends using the detrended data.

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The NCAR King Air participation in FIFE-1987 and FIFE-1989 was part of a coordinated atmospheric boundary layer component which included other aircraft, surface measurements, balloon-borne profiles, and SODAR and lidar remote sensing. The chief objective of the boundary layer component was to describe the structure of the atmospheric boundary layer over the FIFE study area, increase knowledge of the physical processes active in the daytime boundary layer, and explore the relationship of surface properties to the time and spatial variation in the structure of the boundary layer. The phenomena studied were the daytime convective boundary layer structure and physical processes. This study used airborne measurement of vertical and horizontal wind gusts, humidity, potential temperature, mean horizontal wind speed, and horizontal linear trends of temperature, humidity, radiation. Fluxes of sensible heat, moisture, and momentum were estimated from fast response wind gust, temperature, and humidity measurements; these fluxes were evaluated from data which had been high pass filtered with a third order algorithm with a break point set at 0.012 Hz (5 km wavelength). Several radiation parameters were also measured (e.g., global short and longwave, upwelling, and downwelling). Altitude of the aircraft was measured by radar and pressure; radar was more accurate but was only valid below about 930 m. Geographical position was measured by an inertial navigation system. All level legs of a flight mission were flown at a constant pressure altitude, thus the altitude of the aircraft over the surface varied. In general, the data set is of excellent overall quality with very little loss of data. Vertical winds were sampled at an effective rate of 5 samples per second instead of the customary 10 samples per second; this had negligible effect on the fluxes but could compromise estimates of turbulence dissipation. From extensive analysis the FIFE Boundary Layer Group recommends using the detrended data rather than the filtered data.

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The University of Wyoming (UW) King Air atmospheric boundary layer measurement missions were flown in 1987 during IFCs 3 and 4. This Raw Boundary Layer Fluxes data set contains parameters that describe the environment in which the flux data were collected and the flux data itself. The fluctuations in all variables were calculated with three different methods (the arithmetic means removed, the linear trends removed, or filtered with a high-pass recursive filter) prior to the eddy correlation calculations. This data set contains the data with the arithmetic means removed (i.e., RAW). All the flux measurements were obtained with the eddy-correlation method, wherein the aircraft is equipped with an inertial platform, accelerometers, and a gust probe for measurement of earth-relative gusts in the x, y, and z directions. Gusts in these dimensions are then correlated with each other for momentum fluxes and with fluctuations in other variables to obtain the various scalar fluxes, such as temperature (for sensible heat flux) and water vapor mixing ratio (for latent heat flux). The summary of data calculated from each aircraft pass includes various statistics, correlations, and fluxes calculated after the time series for each variable with the arithmetic means removed.

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As part of the FIFE staff science data collection effort, the FIFE Information System (FIS) processed and archived 5 minute, near-surface radiometric and meteorological information collected by the Automated Meteorological Stations (AMS) distributed over the FIFE study area. The FIFE AMS Data Set contains the two output products created. The level-1 product contains unpacked 5 minute data. The level-1a product contains 30 minute averages of these data. All AMS stations were equipped to measure air temperature, humidity, wind speed, soil temperature, reflected solar radiation, net radiation, surface temperature, and precipitation. Two stations were augmented with extra radiation sensors to become super-AMS (SAMS). These stations measured total radiation, direct solar radiation, diffuse solar radiation, photosynthetically active radiation, and downward longwave radiation.

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The NOAA Radiosonde Observations - 1989 (NCDC) Data Set contains radiosonde data obtained from the National Climatic Data Center (NCDC). These 396 days of data cover 13 months from October 1988 through October 1989. These data were collected using sondes released in Dodge City and Topeka Kansas, 337 km and 68 km, respectively, from the FIFE study area. Radiosonde observations were made to determine the pressure, temperature, and humidity from the surface to the point where the sounding was terminated. It is assumed that the use of these data is applicable to the FIFE study because these meteorological data are relatively stable in the horizontal domain. These data may be used as input to numerical models, as well as verification data for simulation studies.

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The FIFE Standard Pressure Level Radiosonde Data Set provides a set of standard level profiles (i.e., 5 mb pressure intervals) from over 450 radiosonde balloon flights, which occurred every one to three hours (daylight hours) during the FIFE IFCs. This derived profile data were computed to 5 mb pressure intervals through simple linear interpolation means. An assumption exists that a linear interpolation scheme may be used with sufficient accuracy to assign meteorological values at 5 mb pressure levels. Some errors are introduced using this method. Several new variables were computed from the original FIFE Radiosonde Data and are included in this derived data set. U (east-west) and V (north-south) winds have been computed from wind speed and direction, and potential temperature has been computed from pressure and temperature. These new parameters are desirable for initial conditions in numerical models as well as forcing functions in models, or as verification and comparison of numerical model's results.

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The FIFE Radiosonde Data Set contains temperatures, wind speed, and temperature profiles in the atmospheric boundary layer measured by means of radiosondes that were analyzed in the framework of Monin-Obukhov similarity theory, with the objective of determining the regional surface heat flux. Profiles of temperature, humidity and wind velocity in the atmosphere were measured by means of intensive radiosoundings conducted approximately between 900 and 1800 CDST in northeastern Kansas during the five FIFE Intensive Field Campaigns in spring, summer and fall of 1987, and in the late summer of 1989. Some 445 radiosondes were released to generate the measurements needed to obtain profiles of wind velocity dry-bulb and wet-bulb temperature. The launch site was located near the northern edge of the experimental area to ensure that these profiles reflect surface conditions over the fetch of the experimental area in the general direction of the prevailing southerly wind. The raw radiosonde data described here have been corrected for sensor delays (see the FIFE Temperature and Humidity Profiles) and algorithm inconsistencies, (see the FIFE Radiosonde Wind Profiles) and have been interpolated to a set of standard pressure levels (see the FIFE Standard Pressure Level Radiosonde Data). These derived data sets are described separately.

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The TOVS data were acquired from NOAA/NESDIS to monitor atmospheric conditions that occurred over the FIFE study area during 1987. The TOVS data were obtained from NESDIS in the standard TOVS sounding product format containing atmospheric sounding data for NOAA-9 and NOAA-10 satellites over the FIFE study area. The TOVS sounding products information is derived from three sensors which measure the intensity of upwelling radiation in the various spectral intervals that occur at maxima over broad layers and depths of the atmosphere. These radiance measurements are processed into Earth-located, calibrated radiance values, "clear" radiances (radiances corrected for cloud effects and angle-of-view), estimates of water vapor in three atmospheric layers (converted to precipitable water in these layers), mean temperatures for selected atmospheric layers, tropopause height and temperature estimates, and geopotential thickness of selected atmospheric layers.

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The Volume Imaging LIDAR (VIL) system of the University of Wisconsin, operated during FIFE and all LIDAR return signals measured at a 90 degree elevation angle were averaged and stored in a file. From plots of those profiles, clouds up to 15 km AGL can be identified. By choosing appropriate reflectivity levels, the data from the University of Wisconsin LIDAR have been used to derive unique 2-D and 3-D views of the Atmospheric Boundary Layer (ABL) structure and the variations in that structure with time. Some of these views are available in the GRAB BAG directory on FIFE CD-ROM Volume 1. Color videos were also produced and are available from the Archive listed in Section 13.1. These views and videos provide important insights into many problems facing investigators in all aspects of FIFE, including scaling and the representativeness of point and line samples.

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The acoustic sounder (SODAR) maps the amplitude of backscattered acoustic energy associated with temperature fluctuations and thus thermal inversions in the atmosphere. The aim of the SODAR measurements was to provide estimates of the height of the mixed layer and the vertical dimensions of inversions within the lower kilometer of the atmosphere. A single, vertically pointing, conventional SODAR was operated at an acoustic frequency near 1500 Hz to detect the amplitude of backscattered acoustic energy. The thickness of an elevated inversion as seen by the SODAR is often smaller than the difference between the heights of the inversion top and bottom, because of oscillations in the heights that occur. The heights were estimated only for the inversions that were clearly associated with the active mixed layer. These data were collected at one location in the northwest quadrant of the FIFE study area during the first three Intensive Field Campaigns held in 1987.

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Surface flux measurements were made at selected sites within the FIFE area. Each surface flux station was capable of measuring the fluxes of net radiation, sensible heat, and latent heat. The Bowen ratio stations measured the soil heat flux as well. The surface flux and micrometeorological measurements available in this data set were collected from 15 locations within the FIFE study area between 1987 and 1989. Six automatic surface energy and radiation balance systems were operated continuously for 144 days from May 16 to October 16, 1987. Variables including net radiation, air temperature, vapor pressure and wind speed, were quite similar for the sites even though the sites were as much as 10 km apart and represented the four cardinal slopes and a top. The Bowen ratio was low during most of the season, increasing sharply toward the end of the season after a long dry spell. The average Bowen ratio was 0.35. About 72% of the available energy was converted into latent heat flux density. Since the data systems and instrumentation used were of similar design, the variability in results can be ascribed to treatment and locations. These results can be used to estimate the number of stations needed to represent a rolling prairie topography.

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The Bowen Ratio Surface Flux Observations (GSFC) Data Set contains data collected using the Bowen Ratio Techniques. The major data collection effort was conducted in 1987 when 16 stationary sites were equipped with Bowen ratio equipment by different groups. Surface flux measurements were made at selected sites within the FIFE area. All measurements are from a single upland site that was grazed. This station measured the fluxes of net radiation, sensible heat, and latent heat and several micrometeorological parameters.

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The Bowen Ratio Surface Flux Observations (KSU) Data Set contains surface flux measurements made at selected sites within the FIFE area. The sites were equipped with Bowen ratio equipment that was operated by several different groups. Each surface flux station was capable of measuring the fluxes of net radiation, latent heat and sensible heat. The Bowen ratio stations measured the soil heat flux as well. The components of the energy balance were determined with the Bowen Ratio Energy Balance (BREB) method. The BREB is a combination of the transport and the energy balance equations. The surface flux and micrometeorological measurements available in this data set were collected from 23 locations with 27 site identifiers from 1987 through 1989. Thirteen of these locations were instrumented with stationary bowen ratio systems which collected daily measurements for months. These systems were all located in the northwest quadrant of the FIFE study area within the Konza Prairie Natural Research Area. Ten locations were instrumented in 1987 for a few days at a time with a portable Bowen ratio system. This roving system visited all but the southeast quadrant of the FIFE study area.

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The Bowen Ratio Surface Flux Observations (Smith) Data Set contains surface flux measurements made at selected sites within the FIFE area. The collection effort was conducted in 1987, 1988, and 1989 from sites equipped with Bowen ratio equipment operated by several different groups. Each surface flux station was capable of measuring the fluxes of net radiation, sensible heat, and latent heat using. The Bowen ratio stations measured the soil heat flux as well. The surface flux and micrometeorological measurements available in this data set were collected from 2 locations within the FIFE study area. One of these sites was located at the bottom of a valley while the other was on the top of a ridge. During the IFC's data were collected daily.

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The Bowen Ratio Surface Flux Observations (UNL) Data Set contains surface flux and micrometeorolgical measurements collected at one location located in a flat area of uniform surface vegetation approximately in the center of the FIFE study area. The data collection effort was during the four Intensive Field Campaigns in the spring, summer, and fall of 1987 (May 28 - Oct 17). The Bowen ratio system that collected these data was designed to retrieve all major components of the surface energy budget along with a large set of measured and derived parameters describing the dynamical, thermodynamical, hydrological, and radiative properties of the ground surface and atmosphere surface layer.

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The Bowen Ratio Surface Flux Observations (USGS) Data Set contains surface flux and micrometeorological collected from one location within the Northwest quadrant of the FIFE study area. Data were collected daily at this location only during the IFC's during the period from late May through mid-October, 1987. Each Bowen ratio station was capable of measuring the fluxes of net radiation, sensible heat, and latent heat. The Bowen ratio stations measured the soil heat flux as well.

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The Canopy Photosynthesis Data Set data were collected from five sites within the FIFE study area during July 1, 1987 through October 12, 1987. The objectives of the study were to estimate canopy photosynthetic rates, respiration rates, and bulk stomatal resistance. Photosynthesis was measured by monitoring the net exchange of CO2 from the canopy to the atmosphere while the canopy is enclosed in a Plexiglas chamber equipped with a LI-COR CO2 gas analyzer. The rate of CO2 concentration change over intervals of 10 - 20 seconds is measured. This CO2 concentration rate of change is used along with other factors (e.g., the amount of canopy area enclosed, the volume of the enclosure, and temperature) to estimate the net photosynthesis rate. The stomatal resistance and conductance is calculated from the total leaf resistance (i.e., calculated via the transpiration rate along with the leaf and air temperatures) minus the boundary layer resistance. Stomatal resistance of selected species of the grass used to estimate the total canopy resistance were measured independently using a leaf diffusion porometer. The results showed that estimated values of net CO2 flux varied between about 0.25 and 1.0 [mg][m^-2][sec^-1] during IFC-2 and IFC-3, and around zero during IFC-4. Resistances ranged from 80 [sec][m^-1] to 300 [sec] [m^-1] during IFC-2 and IFC-3, rising to very high values (greater than 1000 [sec][m^-1]) during IFC-4.

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The FIFE Cloud Camera Data Data Set was collected to document distribution of clouds during FIFE, evaluate algorithms for identifying presence of thin cirrus, and popcorn cumulus clouds, and evaluate the impact of these clouds on retrieval of surface fluxes from satellite data. Clouds could be remotely sensed from both the surface and from satellites. Unlike surface properties, cloud parameters are incompletely retrieved from above or below; there is no ground truth for cloud retrieval algorithms. A camera fitted with a whole-sky ("fish-eye") lens and positioned so that it points directly upwards can capture a full horizon-to-horizon image of the sky dome. Careful film and filter combinations permit differentiation of cloud types. The mathematical mapping of a spherical surface onto a flat surface uses nomenclature from the cartographic community, where the development of techniques for mapping the surface of the earth has a long history. Cartographic projections are precise, mathematically defined 'mappings' and, as a consequence, this nomenclature has been adopted in describing whole-sky camera photographs (Herbert 1986; McGuffie and Henderson-Sellers 1989). Analysis of the camera data showed considerable temporal variability indicating that synoptic observation of cloud was not adequate. There is indication that the NOAA station report convention (clear, scattered, broken, and overcast) from the nearest synoptic NOAA surface stations (Manhattan Airport, and Fort Riley airfield) were used instead of true okta cloud observations, in the NOAA data.

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The FIFE Daily Rainfall Data Set contains daily precipitation values for 42 rain gauge stations within the Konza LTER portion of the FIFE site (i.e., Northwest quadrant). The data set is a composite of data collected by the LTER staff and the Princeton University group. The LTER staff collected daily precipitation data from 12 of the 42 rain gauge stations within this area with the Princeton University group collecting 30 minute precipitation data from the remaining 30 stations. LTER data was collected from April 1982 through December 1989. Data collected by the LTER staff was year round for some stations and from April 1 to October 31 for others. The Princeton University group collected data from May 1987 to October 1987. The Princeton University 30 minute precipitation data was converted to daily precipitation data by the FIS staff. At any particular time, data from approximately 20 of the 30 Princeton University stations were recovered. High temperatures and humidity, plus software problems in the rainfall data loggers, resulted in these data losses. The collected data were of high quality and enough gauges were working at all times so that rain cells could be observed using these data.

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The Eddy Correlation Surface Flux Observations (Argonne) Data Set contains surface flux measurements made at selected sites within the FIFE study area. The surface area and aerological data described here were located at 2 sites in the northwest quadrant of the study area within the Konza Prairie Natural Research area. Both sites were located on hill tops that were burnt on a regular cycle. These data were collected daily only during the five Intensive Field Campaigns which were held during the growing season of 1987 and the projected summer dry down in 1989. Data were also collected using a portable eddy correlation system that moved to a variety of locations within the FIFE study area. These data were collected for a day or two at each location sometime between June 1, 1987 and October 13, 1987. Argonne National Laboratory did not measure radiation but concentrated on observations of turbulence quantities, primarily covariances and standard deviations of winds, temperature, water vapor, and other quantities. The surface fluxes and standard deviations of carbon dioxide and ozone were measured by Argonne so that the fluxes of mass could be related to each other, surface biophysical conditions, vegetative parameters, and the optical characteristics of the surface that could be detected by remote sensing.

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The Eddy Correlations Surface Flux Observations (GSFC) Data Set contains surface flux measurements made at selected sites within the FIFE study area. The surface flux and micrometeorological measurements in this data set were collected from a single location located in the southwest quadrant on a upland, grazed area. The data set contains data collected daily from June 26 - October 17, 1987 during the three Intensive Field Campaigns. No data is available between the campaigns. Micrometeorological techniques of eddy correlation and Bowen ratio were used in determining the fluxes of sensible heat, latent heat, and carbon dioxide in FIFE. Eddy correlation is a well-established technique that has the primary advantage of measuring turbulent diffusive fluxes directly across a near-horizontal plane above the surface. It requires a rigid platform unencumbered by significant aerodynamic obstacles. The fluxes of sensible and latent heat are computed as covariances of the fluctuations of vertical wind velocity with fluctuations of temperature and vapor density at the same point and time.

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Surface flux measurements were made at selected sites within the FIFE study area. Each surface flux station was capable of measuring the fluxes of net radiation, sensible heat, and latent heat. The Eddy Correlation Surface Flux Observations (UK) Data Set contains surface flux and micrometeorological measurements collected from one location in the southwest quadrant of the FIFE study area. This location was grazed and had a gentle downhill slope to the southwest. Data were collected daily from May 14 - October 18, 1987, and from July 21 - August 16, 1989. The output from the Hydra sensors is sampled at 10 Hz and processed in real time to give hourly averages of sensible and latent heat flux and the friction velocity. The hourly mean values of net radiation, temperature, and of vapor pressure, provided in this data are a synthesis of the best measurements available for this site. The temperature measurement provided here is the preferred value for this site. This temperature was used to calculate the fluxes and some standard deviations. This is necessary because the sonic anemometer has a slightly temperature dependent calibration. The average soil heat flux measured at 5 mm depth is a weighted average value over three sample positions with dense, medium and sparse vegetation. A vegetation survey was made to assign weights to these three classes at this site. The spatial variability in this measurement at this (over) grazed site is particularly high and the three individual sensors commonly measure soil heat fluxes differing by factors of two or three. Some evidence suggests these data are providing a measurement of this component of the energy budget for this site which is biased low. Presumably this is because the limited number of sensors inadequately samples the points with low canopy density for this sparse crop cover.

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Surface flux and micrometeorological measurements were collected at one site within the northwest quadrant near the center of the FIFE study area during all five of the Intensive Field Campaigns (four in 1987 and one in 1989). This site had historically been ungrazed but had recently been exposed to grazing. The station was capable of measuring the fluxes of net radiation, sensible heat and latent heat using an eddy correlation system. In addition, measurements of soil heat flux and several micrometeorological parameters were made.

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This data set provides aircraft-based NS001 Thematic Mapper Simulator (TMS) images of the study area associated with The First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE) project conducted on the Konza Prairie in Kansas. The images were acquired during June 1987 to August 1989. The images in this data set were originally provided on the FIFE CD-ROM Volume 3.

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Airborne soil moisture measurement is based on the difference between natural terrestrial gamma radiation flux measured for comparatively wet and dry soils. The presence of moisture in the soil causes an effective increase in the soil density resulting in an increased attenuation of the gamma flux for relatively wet soil and a correspondingly lower flux at the ground surface. As part of the FIFE experiment, natural terrestrial gamma radiation data over a network of 24 flight lines were collected. The data acquisition procedure was designed to accumulate and store spectral radiation data along a flight line from which estimates of soil moisture could be computed. Ground-based soil moisture measurements were used to make a one-time calibration of the natural terrestrial radioisotope signal over the flight line network. A time-series of airborne soil moisture measurements (to a depth of 20 cm) was compared to an extensive, independent data set of ground-based soil moisture measurements. Estimates for flight line segments were found to have an average RMS error of approximately 2.5 % soil moisture (Peck et al., 1990).

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During the 1989 Intensive Field Campaign a Russian spectroradiometer, the Gemma, was used to collect visible and near infrared spectra of a variety of FIFE sites from a helicopter. Gemma measurements of selected study sites and laboratory measurements of a portable calibration light sphere were made. The helicopter missions were designed to provide characterizations of each FIFE site while providing FIFE study area coverage, and to provide an intermediate scale of sampling between that of the surface measurements and the higher altitude aircraft and spacecraft multispectral imaging devices. The Gemma spectroradiometer was mounted on the helicopter to allow a comparison between it and the SE-590 spectroradiometer and Modular Multiband Radiometer (MMR) over a number of sites.

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The FIFE Historic Daily Meteorology Data Data Set is one of the historical data sets used for the FIFE project. The data set contains data back to January, 1900. This data set was prepared for input into models, therefore, no leap days (February 29) are included. Daily weather observations of air temperature and precipitation were made by Kansas State University. The observations are made according to the procedures outlined by the National Weather Service (Anonymous 1989).

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The FIFE Historic Monthly Meteorology Data Data Set is one of the historical data sets used for the FIFE project. This data set provides monthly precipitation values from January 1858 to December 1989 for Manhattan, Kansas adjacent to the FIFE study area. Daily weather observations of precipitation were made according to the procedures outlined by the National Weather Service by Kansas State University. The daily precipitation data were then summed to produce monthly precipitation.

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The purpose of the Leaf Area Index and PAR Determined from KSU Light Bar Measurements study was to collect extensive non-destructive measurements of Leaf Area Index (LAI) at the flux sites during IFC-5 (August 1989). These data were collected at thirteen locations which were coincident with the surface flux measurements within the FIFE study area from July 3, 1989 through August 18, 1989. The various fractions of the Photosynthetically Active Radiation (PAR) (i.e., diffuse, reflected, transmitted and total) were measured using a Line Quantum meter from LI-COR Inc. From these fractions the ratio of reflected to total incoming PAR was computed. LAI can be estimated from light bar measurements of PAR transmittance from measurements above and below a vegetation canopy. The use of the light bar allows rapid, multiple, and repeatable measurements of LAI at the FIFE sites. This type of measurements could not be done using destructive measurements of LAI.

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The Leaf Area Index and PAR Determined from the UNL Light Bar Data were collected in 1987, 1988, and 1989. Incoming, reflected, and transmitted photosynthetically active radiation (PAR) was measured with a LI-COR LI-191SA line quantum sensor. Absorbed and intercepted PAR calculated from these measurements. The objectives of this research were to characterize bi-directional reflectance factor distributions, estimate surface albedo, determine the variability of reflected and emitted fluxes in selected spectral wavebands as a function of topography, vegetative community and management practice, determine the influence of plant water status on surface reflectance factors, and determine sun angle affects on radiation fluxes.

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The prairie is inherently variable and large numbers of samples are needed to obtain reliable estimates of the prairie agronomic characteristics. For the Indirect Leaf Area Index Obtained from the KSU Light Wand Study a limited number of destructive samples were supplemented by large numbers of rapid non-destructive estimates. For the non-destructive measurements the LI-COR Inc. LAI-2000 Plant Canopy Analyzer (light-wand) was used. This instrument measures transmittance of the canopy in the blue region of the spectrum, at five different zenith angles. These measurements were inverted to provide estimates of leaf area index, and mean inclination angle of the leaves to the zenith. Verification studies conducted by LI-COR Inc. indicated that the LAI-2000 Canopy Analyzer measurements were generally within 15% of values obtained by destructive sampling and measurement with a leaf area meter. As a rough guess even the destructive measurements are accurate only to within about 25% of the true sample leaf area value. In the opinion of the study team, the non-destructive measurements with the LAI-2000 are as good as the destructive measurements, and provide a better estimate of the site mean, because many more non-destructive measurement can be made.

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The Leaf Angle Data Data Set contains leaf angle distributions (LAD) obtained during the 1987 growing season for ten types of plant canopies, from the Konza Long-Term Ecological Research (LTER) area. These data were collected using a direct measurement technique (i.e., a Spatial Coordinate Apparatus (SCA)). The species selected were major species common on the prairie with the leaves were of sufficient size to allow SCA measurement. The objective of this study was to obtain detailed LAD information on the major canopy species of the tallgrass prairie and selected agricultural crops. The LAD information for specific canopies can be used as input for a canopy radiation model. Canopy leaf orientation is an important parameter for plant growth modeling. Four categories of zenith angle distributions were found among the 14 species. These were planophile, plagiophile, erectophile, and uniform. Some canopies were found to have non-uniform leaf azimuth angle distribution. Also there were deferences between the upper and lower parts of the canopies for some species.

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The objective of the Leaf Photosynthesis study was to measure the response of leaf photosynthesis and stomatal conductance to light, temperature, vapor pressure deficit, carbon dioxide and water potential for the most abundant C4 species at the FIFE study area. To this end, photosynthesis measurements were made on 6 days in June, July and August of 1987 at three different locations in the northwest quadrant of the FIFE study area. Leaf photosynthetic rate is measured by enclosing a leaf in a closed, transparent chamber and measuring the decrease in carbon dioxide concentration as a function of time. Light flux density is measured outside of the chamber and must be corrected for the chamber transmittance, which is 0.9. These data can be fit to various models of leaf photosynthesis and stomatal conductance by providing the responses to light, temperature leaf water potential, and carbon dioxide under field conditions on intact plants.

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The Incoming Longwave Radiation Data from UNL Data Set was collected as part of a study of thermal radiant energy from vegetative canopies. These data were collected during the growing season of 1987 and 1989. The data measurements were made at 13 stations within 12 sitegrids scattered throughout the FIFE study area. Values for incoming longwave radiation were calculated using the radiometer chopper or detector temperature as a measure of air temperature. When determining surface temperatures from infrared thermometer measurements of the surface, the surface emissivity and the reflected component must be taken into account. The reflected component is dependent on the surface emissivity and the incoming longwave radiation.

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The MMR Calibration Data Set contains radiance data collected in the summer of 1987 and in July and August of 1989 via a Modular Multiband Radiometer (MMR) instrument. The MMR instrument monitored a nearly lambertian calibration panel stationed near the center of the FIFE study area. The radiances recorded from this instrument can be used to monitor solar insolation and clouds. In some cases, these data were also used to calculate the reflectance factor for reflective radiances measured over vegetation using other MMR instruments located at other FIFE sites or mounted on a helicopter.

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Surface reflectance factors, radiances, and temperatures were measured with a Mast-borne Modular Multiband Radiometer (MMR), predominantly in the solar principal plane, with nadir and off-nadir, view-zenith angles. The MMR was mounted on a portable mast in order to achieve a spatial sampling at a variety of sites as well as within each site. The portable mast alignment varied from the solar principal plane, to the azimuthal plane aligned perpendicular to the principal plane and aligned with the satellite azimuthal plane. Measurements were periodically collected with the MMR over a barium sulfate reference panel. Measurements were typically coordinated with aircraft and/or satellite overpasses. Solar radiation data at or near the specific site should be used to screen possible times of variable cloud cover.

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The Surface Reflectance Measured with a Helicopter-borne MMR Data Set contains surface reflectance measurements in Landsat-TM bands at low to intermediate altitudes. The helicopter operated during all Intensive Field Campaigns (IFCs) and was available to support all satellite overpasses. The average flight time was 2 hours, during which an average of 11 FIFE sites plus one special target were covered. The helicopter missions were designed to provide a rapid means of intensively spectrally characterizing each FIFE site while providing FIFE study area coverage, and to provide an intermediate scale of sampling between that of the surface measurements and the higher altitude aircraft and spacecraft multispectral imaging devices. The Modular Multiband Radiometer (MMR) instrumentation was chosen to provide compatibility with surface-based radiometers and TM spacecraft sensors. Off-nadir measurements were made as a means of providing more accurate estimates of hemispherical reflectance and for use with bi-directional reflectance models.

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The Leaf Optical Properties from UNL Data Set contains leaf-level spectral observations acquired in situ with the Nebraska Multiband Leaf Radiometer (NMLR) coupled with a LiCor LI-1800-12 integrating sphere. The NMLR measured leaf reflectance and transmittance in the seven MMR bands. Data were collected in 1987, 1988, and 1989. During 1987, measurements were always made on the most recently expanded leaf of the selected plant. Measurements were made on a variety of forbs and grasses. During 1988, measurements were made on the most recently expanded leaf of the selected plant unless specified. Measurements were also made of older green, yellow and brown leaves on a plant. Measurements were usually made on grasses (i.e., Indian grass, Switch grass and Big bluestem). A few forbs were measured. The same leaf was sometimes measured throughout the day. During 1989, measurements were usually made on the most recently expanded leaf of the selected plant unless specified. Typically, leaves of the dominant grass species at a site were measured. At least two samples of each species were measured. Typically, during all collections (i.e., 1987 - 1989) an external light source with a restricted beam spot (slitted illuminator) was used to restrict the illumination spot on narrow grass leaves so that only leaf material was illuminated.

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The Mowing Experiment Biophysical Measurements data set was collected to quantify the effects of grazing and nitrogen fertilization on primary productivity and plant chemistry. The data in this data set quantified the effects of foliage removal on plant net primary productivity (NPP), plant nutrient content and the effects of grazing pressure as simulated by mowing. Mean values and their variances are reported. Standing crop values reflect treatment effects of removing biomass periodically, but the productivity levels show the inverse effects, suggesting plant compensatory growth mechanisms. Grazing intensity was defined as the amount of leaf area remaining following defoliation. The latter was manipulated experimentally by mowing at several heights. Grazing frequency was defined as the number of times foliage removal occurred in each year and included grazing and mowing history as well as current mowing frequency.

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Light radiation striking a vegetative canopy interacts with individual phyto-elements (i.e., leaves, stems, branches) and the underlying substrate. The interaction depends on light quality, radiative form (direct or diffuse), illumination incidence angle, vegetative component optical properties and canopy architecture. Radiation is reflected, transmitted or absorbed. Mowing, grazing, and fertilization can affect the canopy architecture or optical properties of vegetation, thus changing the canopy reflectance. This study examined the response of spectral reflectance characteristics (using an Exotech radiometer) to canopies that were manipulated using simulated grazing and fertilization of plots. The spectral reflectance data set supports the original hypothesis of a curvilinear relationship between productivity and grazing intensity. Reflectances for the four MSS bands and the standard error for each are reported. These data were collected at two locations within the northwest quadrant of the FIFE study area during the growing season of 1987. Reflected radiation measurements were converted to radiances and reflectance factor. The reflectance factor is the ratio of the target reflected radiant flux to an ideal radiant flux reflected by an ideal Lambertian standard surface irradiated in exactly the same way as the target.

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The Upper Air Derivative Data from NMC Data Set was derived from National Meteorological Center global upper air models. These models use a 6 hours intermittent assimilation method. In this method, the objective analysis is performed every 6 hours using a 6 hours forecast as an initial guess (Kanamitsu 1989). The National Meteorological Center (NMC) gridded upper air data was extracted from the NOAA operational analysis system and transmitted to the FIS. This contained spatially interpolated NMC upper air data calculated for four grid points of 381 km polar-stereograph over the FIFE area. FIS considers this a derived data set (i.e., not from original measurements).

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The FIFE Staff Science effort included the acquisition, processing and archiving of meteorological parameters of the atmosphere above the FIFE study area, which would furnish surface meteorological parameters from hourly reporting network for the FIFE area, and provide input data and/or verification data for numerical simulation models. Though the measurements presented in this data set were not taken precisely at the FIFE site, it is hypothesized that they present a representative horizontal cross-section of meteorological variables and sky conditions in and around the site. It is also realized that many of the variables presented in this data set are somewhat subjective and dependent on the skill (and biases) of the observer, such as estimates of cloud amount and height. The NOAA regional surface reports were extracted from the NOAA operational analysis system and transmitted to the FIS. This contained hourly surface meteorological data from selected stations as received from NESDIS for FIFE.

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As part of the FIFE staff science data processing effort, the FIFE Information System (FIS) extracted site average radiances from the level-1 NS001-TMS products. Data were collected by the NS001 during each of the FIFE IFC's. Selected flights were processed to level-1. The site averages were extracted from these processed images. Therefore, this data set contains a small number of observation dates for each site, but at the multiple angles provided by the grid pattern used during each flight. The data set can be used for canopy reflectance modeling studies. The site average radiances extracted from the NS001 imagery are instrument-corrected spectral radiances for each of the eight spectral bands. Geographic location and viewing and solar angles for each of 39 FIFE ground measurement sites are also included for each observation. The sensor calibrated radiance values were corrected using atmospheric aerosol optical thickness and gaseous absorption profile measurements, when available. The atmospheric correction algorithm of Fraser et al. (1989) was used to calculate reflectance in the visible and infrared channels. The thermal data are corrected using parameters derived from the Lowtran7 atmospheric path radiance model (Kneizys et al., 1988).

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The objective of the Optical Thickness Calibration study was to compare aerosol optical thickness measurements derived from three different groups. These groups measured atmospheric transmission, in particular, the aerosol optical thickness, using at least three different instruments (e.g., a solar transmissometer SXM-2, a Reagan sunphotometer, and an airborne tracking sunphotometer) and three different analysis procedures.

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The NIPS and Reagan Sunphotometer Optical Thickness study compared various ground and image-based techniques used to characterize the atmosphere. These data are used to remove atmospheric absorption and scattering from remote sensing scenes so that surface parameters can be retrieved. An evaluation of the effects of uncorrected atmospheric absorption and scattering on various vegetation indices and subsequent biophysical parameter estimations was also undertaken. These data can also be used to derive aerosol size distribution (King et al., 1978) and thereby estimate the phase function. Aerosol optical depths were recorded at various locations within the FIFE site. A Normal Incident Pyrheliometer (NIP) and a Reagan sunphotometer was used to collect data during the IFCs. These data showed that daily averages span a range of 0.05 to 0.28 in the mid-visible wavelength (Bruegge et al., 1992a). Diurnal variations were recorded. The afternoon optical depths are greater than those of the morning by as much as 0.07. These data are analyzed using the Langley technique. Rayleigh optical depth is subtracted, and aerosol, ozone, and water vapor abundance's simultaneously measured. In retrieving ozone, a Junge aerosol model is assumed, thus, the natural log of aerosol optical depth is linear with wavelength (Bruegge et al., 1992a). This contrasts with other experimental approaches used by investigators in which an ozone abundance is assumed (Halthore and Markham 1992). This approach allows measurement of aerosol, but is limited by the accuracy of the ozone data.

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The data in the Sunphotometer Optical Thickness Data from C130 Aircraft data set were collected in June, July and August 1987, and in August 1989. The data was collected at selected locations within the FIFE study area. Atmospheric optical depths derived from measurements of solar radiation by the airborne suntracking sunphotometer are available in this data set. These data are necessary for atmospheric correction of data from Earth viewing airborne and satellite sensors in the visible and near infrared regions of the electromagnetic spectrum. The data show that atmospheric optical depth changes significantly both spatially and temporally. Variability in atmospheric optical properties and substantial differences in atmospheric optical properties during the data collection, emphasize the need to make quantitative measurements of atmospheric optical properties at the time of remote sensing data acquisition.

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The Solar Transmissometer Aerosol Optical Thickness Data Set contains optical thickness data that provide a measure of the effect of aerosols on the attenuation of radiation through the atmosphere at 8 discrete wavelength bands throughout the visible and near IR portion of the electromagnetic spectrum. These data were collected using a ground-based solar transmissometer in June and July of 1987, and July and August of 1989, at two stations in the FIFE study area. These data are used to provide atmospheric correction of remotely sensed data using radiative transfer models and to study aerosol particle size distribution (see Halthore and Markham 1992; King et al. 1978). These data are also used to infer the optical clarity of the atmosphere.

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Aerosol optical thickness in conjunction with an atmospheric model can provide estimates of atmospheric effects on transmitted and reflected solar radiation. These effects can then be used to correct aircraft and satellite radiometric data. In FIFE, three sunphotometers were used to track the sun through a range of airmasses during the period of February 6, 1987 through October 31, 1989. The Aerosol Optical Thickness from GSFC Data Set were analyzed using the Langley technique. Rayleigh optical depth was subtracted, and aerosol, ozone, and water vapor abundance's simultaneously measured. In retrieving ozone a Junge aerosol model was assumed, thus the natural log of aerosol optical depth was linear with wavelength (Bruegge et al. 1992). This approach allows measurement of aerosol, but is limited by the accuracy of the ozone data.

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The Surface Reflectances Measured by the PARABOLA Data Set contains measurements from the Portable Apparatus or Rapid Acquisitions of Bi-directional Observations of Land and Atmosphere (PARABOLA) instrument. The focus of this research was to characterize the variation in vegetation reflectance as a function of solar and sensor viewing geometry, wavelength, and plant canopy biophysical characteristics. An understanding of these relationships is necessary for meaningful biophysical and ecological interpretations of measurements acquired from airborne and satellite sensors. The PARABOLA is able to measure these variations in reflectance because it measures at different viewing angles and at 3 spectral bands. The data are averaged reflectance factors of the Konza Prairie at different view angles and at 3 wavelength bands throughout the day. PARABOLA measurements were made during each of the 5 FIFE Intensive Field Campaigns from five locations within the FIFE study area.

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The focus of this study was to quantify the effects of foliage removal by cattle on plant net primary productivity (NPP). The Vegetation Biomass, Production and Consumption at Selected Sites Data Set contains mean values and their variances. During the growing season of 1987, portable cattle exclosures were used to quantify above-ground plant biomass dynamics at each of four sites. All sites had been grazed each year and burned frequently during the preceding 10 years. Biomass was measured inside portable exclosures, outside exclosures (in unprotected vegetation), and inside permanent exclosures. Exclosures were moved to previously unsampled locations within a distance of 10 m after samples were obtained, and these remained in place until the next sampling date.

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The Surface Radiant Temperature Measured with a Helicopter-borne Infrared Thermometer Data Set were collected for six days during July and August of 1989 to provide the radiant temperature of the FIFE sites and as a check of the thermal band on the MMR. The average and standard deviation of radiant temperature were measured with an Everest infrared thermometer. The Everest Series 4000 Infrared Thermometer (IRT) was mounted on the NASA Bell UH-1B helicopter in conjunction with the Barnes Multiband Modular Radiometer (MMR) and the Spectron Engineering SE590 Spectroradiometer for the 1989 field campaign. The IRT collected radiant temperature data as the helicopter hovered over individual sites within the FIFE study area.

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The Surface Temperatures Measured at Multiple Angles Data Set was collected at two locations within the northwest quadrant of the FIFE study area during July and August 1989. The data set contains hemispherical surface temperature, surface temperatures measured at several view zenith angles, and surface temperatures and at-view azimuth increments of 45 degrees. These data were collected using the Everest multiplexed infrared thermometers (IRT) Model 4000 and an Eppley Precision Infrared Radiometer Model PIR. Periodically measurements of the surface emissivity and incoming longwave radiation were also made. The purpose of this study was to characterize bi-directional reflectance factor distributions, estimate surface albedo from bi-directional reflectance factor and radiance data, determine the variability of reflected and emitted fluxes in selected spectral wavebands as a function of topography, vegetative community and management practice, determine the influence of plant water status on surface reflectance factors, and determine sun angle affects on radiation fluxes.

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The Surface Temperatures from UNL Data Set contains surface temperatures collected between July 15 and August 11, 1989 at three FIFE area sites. These surface temperatures were measured with an Everest multiplexed infrared thermometer (IRT) Model 4000 predominantly in the solar principal plane, with nadir and off-nadir, view-zenith angles (mounted on the portable mast with the Barnes Model 12-1000 Modular Multiband Radiometer (MMR)). The purpose of this study was to determine the variability of emitted fluxes as a function of topography, vegetative community and management practice. Spatial and temporal sampling at sites 906 (2133-EVN), 916 (4439-EVN), and 966 (2437-EVN) was achieved. Measurements were typically coordinated with aircraft and/or satellite overpasses.

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The NOAA Radiosonde Observations Data Set contains data that were extracted from the NOAA operational analysis system and transmitted to the FIS. Data are available from July 1985 to October 1988, there are 1123 days of data during this period with data at twelve hour intervals. These data were collected using sondes released in Dodge City and Topeka, Kansas, 337 km and 68 km, respectively, from the FIFE site. Radiosonde observations were made to determine the pressure, temperature, and humidity from the surface to the point where the sounding was terminated.

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The FIFE Root Biomass data were collected from 16 locations within the FIFE study area during the 1987 growing season. They provide a measure of the below-ground biomass for the study area. Biomass reported as grams per square m assumes that the depth of the core samples is sufficient to include all root biomass under the surface to an infinite depth. Prairie vegetation does possess roots deeper than the 20 cm coring, however, the fraction of total root biomass below 20 cm is minuscule and safely ignored in a study of biomass.

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The atmospheric effects on the transmitted and reflected solar radiation should be factored into the estimation of geophysical and biophysical parameters from remotely-sensed data, so that appropriate correction schemes can be employed to infer reflectivity of the ground from satellite radiometric data. Some of the correction techniques require derived coefficients as inputs in the algorithms that perform the atmospheric correction. As part of the FIFE staff science data collection effort, the FIFE Information System (FIS) utilized atmospheric correction and related algorithms to generate coefficients for deriving corrected values from the FIFE level-1 image products. These coefficients were used by FIFE staff in calculating site reflectances from pixel values extracted from the level-1 imagery. The Fraser (Fraser et al., 1992) and LOWTRAN 7 (Kneizys et al., 1988) models were used for computation of coefficients used to correct radiances of scattered radiation measured by aircraft and/or satellite during FIFE. The Fraser algorithm is designed to compute the surface reflectance for a given measured radiance, or alternatively, the upward radiance at an arbitrary height when the surface reflectance is given. LOWTRAN 7 is a low-resolution propagation model and computer code for predicting atmospheric transmittance and background radiance from 0 to 50,000 [cm^-1] at a resolution of 20 [cm^-1].

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The Advanced Very High Resolution Radiometer (AVHRR) is a four- or five-channel scanning radiometer capable of providing global daytime and nighttime sea-surface temperature and information about ice, snow, and clouds. The sensor measures emitted and reflected radiation in five channels (bands) of the electromagnetic spectrum. The Site Average Reflectances Extracted from AVHRR-LAC Imagery Data Set consists of averages of pixel extracts from AVHRR-LAC (1 km resolution) scenes that overlay the FIFE site. Average radiances for dates are available for the five sensor wavebands and average reflectance and exoatmospheric reflectances are available for wavebands 1 and 2. Site averages are clustered in 1987 and during the summer of 1989. Some data are also available for early 1988. The AVHRR is capable of operating in both real-time or recorded modes. Direct readout data were transmitted to ground stations of the automatic picture transmission (APT) class at low-resolution (4x4 km) and to ground stations of the high-resolution picture transmission (HRPT) class at high resolution (1x1 km). Data recorded on board were available for processing in the NOAA Central Computer Facility. They included local area coverage (LAC) data which were from selected portions of each orbit with a 1x1 km resolution. The precision of satellite remote sensing estimates of surface reflectance (Hall et al., 1992), calibrated and corrected for atmospheric effects, was no worse than about 1 percent absolute.

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The Thematic Mapper sensor system was used to collect the original data between February 1987 and October 1989 from which this data set was produced. Landsat TM extract data contains the average instrument corrected spectral radiances for each of the seven spectral bands. In addition, the associated view and solar angles are available for each of 39 FIFE ground measurement sites. The Site Reflectances Extracted from Landsat TM Imagery Data Set also contains reflectance values and exoatmospheric reflectance values for these seven spectral bands. These reflectances were derived using the sensor calibrated radiances which were corrected for exoatmospheric effects using atmospheric aerosol optical thickness and gaseous absorption profile measurements, when available. The atmospheric correction algorithm of Fraser et al. (1989) was used to calculate reflectance in the visible and infrared channels. The thermal data were corrected using parameters derived from the Lowtran-7 atmospheric path radiance model (Kneizys et al. 1988).

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The Site Reflectances Extracted from SPOT HRV Imagery Data Set contains the average instrument corrected spectral radiances for each of the spectral bands (3 in XS and 1 in PAN) collected during the growing seasons of 1987, 1988, and 1989. In addition, the associated view angles and solar angles are available for each of 39 FIFE ground measurement sites. The data set also contains reflectances and exoatmospheric reflectances for these spectral bands. These reflectances were derived using the sensor calibrated radiance values corrected using atmospheric aerosol optical thickness and gaseous absorption profile measurements, when available. The atmospheric correction algorithm of Fraser et al. (1989) was used to calculate reflectance in the visible and infrared channels.

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The SE-590 Spectroradiometer Reflectance Factors from GSFC Data Set contains spectral data collected with the Spectron SE-590 Spectral Radiometer at selected FIFE sites located primarily on the Konza Prairie. These measurements were acquired in conjunction with the Surface Reflectances measured by the PARABOLA bi-directional measurements. Ground SE-590 data were acquired in all four 1987 Intensive Field Campaigns and in the 1989 Intensive Field Campaign. The ground SE-590 data were collected at approximately every 10 degree change in solar zenith angle (SZA) to characterize diurnal variations and/or simultaneous observations acquired by helicopter, airplane, or satellite over flights. The data were collected as wavelength intensity values which were converted to spectral radiances with instrument and campaign-specific calibration coefficients.

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The SE-590 Reflectance Factors and Radiances from UNL Data Set contains surface reflectance and viewing angle data that was collected at three sites within the FIFE study area via a SE590 mounted on a portable mast. All measurements were made on eleven days between July 15 and August 11, 1989. Measurements were typically coordinated with aircraft and/or satellite overpasses. On days when measurements were not made the bare soil was covered with a plastic mulch that allowed moisture to penetrate the surface but hindered the regrowth of the vegetation. Solar radiation data at or near the specific site should be used to screen possible times of variable cloud cover. Canopy, illumination, and viewing geometry are critical in determining the amount of reflected radiation received at the sensor. The measurements were predominantly made in the solar principal plane since the greatest variation in observed reflected radiation is expected to occur in that plane due to extremes in sunlit and shaded portions of the canopy (Norman and Walthall 1985). Reflected radiation measurements were converted to radiances and reflectance factor. Reflected radiation from a field reference panel corrected for non-perfect reflectance and sun angle was used as an estimate of the ideal Lambertian standard surface (Walter-Shea and Biehl 1990).

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The SE-590 Leaf Level Spectral Observations from GSFC Data Set were acquired in situ with a Spectron SE590 spectroradiometer fitted with the 1 degree IFOV lens, and coupled with a LI-COR integrating sphere. The purpose in collecting SE590 leaf reflectance and transmittance data was to characterize the optical properties of the canopy components to gain a better understanding of how these optical properties contribute to canopy reflection and absorption of radiation. To measure the reflectance and transmittance of leaf surfaces an integrating sphere was used. The integrating sphere collected all of the radiation reflected from or transmitted through a surface. These data are the average spectral optical properties (i.e., reflectance, transmittance) and the standard deviations for the three dominant species found on each of three sites: 916 (i.e., Big Bluestem, Indiangrass, and Switchgrass), 906 (i.e., Big Bluestem, Indiangrass, and Switchgrass), and 26 (i.e., Big Bluestem, Lovegrass and Dropseed) during late July and early August, 1989. The average spectral reflectance and transmittance represent the mean values for the adaxial (top) and abaxial (bottom) sides of 4 - 10 leaves for wavelengths between 400 - 1050 nm at approximately 3 nm intervals.

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The SE-590 Reflectance Factors and Radiances Measured from a Helicopter Data Set were collected using the helicopter-borne SE-590 during Intensive Field Campaign 5 (IFC-5) in 1989. These data were collected at 17 different grid locations within the FIFE study area. Data were collected on 6 days from July 28, 1989 through August 8, 1989, when sky conditions were clear. The helicopter missions were designed to provide a means of spectrally characterizing each FIFE site and provide an intermediate scale of sampling between that of the surface measurements and the higher altitude aircraft and spacecraft multispectral imaging devices. The SE-590 instrumentation was chosen to provide compatibility with surface-based radiometers and TM spacecraft sensors. Off-nadir measurements were made as a means of providing more accurate estimates of hemispherical reflectance and for use with bi-directional reflectance models.

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The Site Averaged AMS Data: 1987 (Betts) Data Set contains the site averaged product of the Portable Automatic Meteorological Station (AMS) data acquired during the 1987-1989 FIFE experiment. Data are in 30 minute time intervals in 1987.

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The Site Averaged AMS Data: 1987 - 1989 (Betts) Data Set contains the site averaged product of the Portable Automatic Meteorological Station (AMS) data acquired during the 1987-1989 FIFE experiment. Data are in 30 minute time intervals in 1987.

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The Site Averaged AMS Data: 1988 (Betts) Data Set contains the site averaged product of the Portable Automatic Meteorological Station (AMS) data acquired during the 1987-1989 FIFE experiment. Data are in 30 minute time intervals in 1988.

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The Site Averaged AMS Data: 1989 (Betts) Data Set contains the site averaged product of the Portable Automatic Meteorological Station (AMS) data acquired during the 1987-1989 FIFE experiment. Data are in 30 minute time intervals in 1989.

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The Site Averaged Flux Data: 1987 (Betts) Data Set contains the site averaged product data collected by many PIs during the 1987-1989 FIFE experiment. This data set is a time series of 30-minute average variables for the periods May 27, 1987 - Oct 16, 1987.

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The Site Averaged Flux Data: 1987 (Betts) Data Set contains the site averaged product data collected by many PIs during the 1987-1989 FIFE experiment. Data are in 30 minute time intervals in 1987 and include the entire period 1987-1989.

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The Site Averaged Flux Data: 1988 (Betts) Data Set contains the site averaged product data collected by many PIs during the 1987-1989 FIFE experiment. Data are in 30 minute time intervals and include data only for 1988.

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The Site Averaged Flux Data: 1987 (Betts) Data Set contains the site averaged product data collected by many PIs during the 1987-1989 FIFE experiment. Data are in 30 minute time intervals and include data only for 1989.

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The Site Averaged Gravimetric Soil Moisture Data: 1987 (Betts) Data Set contains the site averaged product data collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged for each day. This data set includes only 1987 data.

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The Site Averaged Gravimetric Soil Moisture Data: 1987 - 1989 (Betts) Data Set contains the site averaged product data collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged for each day. This data set includes data from May 20, 1987 through August 12, 1989.

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The Site Averaged Gravimetric Soil Moisture Data: 1988 (Betts) Data Set contains the site averaged product data collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged for each day. This data set includes only 1988 data.

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The Site Averaged Neutron Soil Moisture Data: 1987 (Betts) Data Set contains the site averaged product data of the neutron probe soil moisture collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged for each day. This data set includes only 1987 data.

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The Site Averaged Neutron Soil Moisture Data: 1987 - 1989 (Betts) Data Set contains the site averaged product data of the neutron probe soil moisture collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged for each day. This data set includes the 1987 - 1989 data.

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The Site Averaged Neutron Soil Moisture Data: 1988 (Betts) Data Set contains the site averaged product data of the neutron probe soil moisture collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged for each day. This data set includes only 1988 data.

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The Site Averaged Neutron Soil Moisture Data: 1989 (Betts) Data Set contains the site averaged product data of the neutron probe soil moisture collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged for each day. This data set includes only 1989 data.

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Soil bulk density is defined as the ratio of the mass of dry solids to the bulk volume of the soil occupied by those dry solids. Bulk density of the soil is an important site characterization parameter since it changes for a given soil. It varies with structural condition of the soil, particularly that related to packing. The Soil Bulk Density Data Set contains bulk density of the soil based on dry weight at two depths, 0-10 cm and 10-20 cm. Samples were collected at 31 different locations within the FIFE study area during the growing season of 1987. Samples were collected primarily in the northwest quadrant of the study area but at least one sitegrid is located in each of the quadrants of the study area.

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In the Soil Carbon Dioxide Flux study, a prototype gas exchange system and sensor were used to determine the soil surface flux of CO2 and associated parameters at the three FIFE supersites. The goal of this investigation was to characterize fluxes of carbon dioxide from the surface of the soil for a representative portion of the FIFE study area. These measurements are required to understand the carbon budget of the prairie and necessary for comparing vegetation models of photosynthesis with CO2 flux measurements by micrometeorological methods. The flux of the carbon dioxide from the surface of the soil is an important component of the carbon budget of a prairie ecosystem. The results from this study indicate that a soil chamber can be used to obtain reasonable estimates of soil surface carbon dioxide fluxes when operated in a closed system that is ported to the free atmosphere. Further, the flux of carbon dioxide from the soil surface of a grassland can be a large part of the carbon budget and should never be assumed to be negligible. Both soil temperature and soil water content are critical parameters for predicting soil surface CO2 flux, and leaf area index is a surrogate for the plant contribution through root respiration.

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Nitrogen gas fluxes are important to ecosystem productivity and atmospheric chemistry. Scaling of these microscale fluxes to landscape and regional scales relevant to ecosystem and atmosphere-biosphere exchange questions is difficult. For FIFE, two approaches were explored to accomplish scaling. First the relationships between hourly and daily gas fluxes and soil moisture were established and then large area estimates of soil moisture from simulation models or a push broom microwave radiometer were used to scale data from experimental sites to larger areas. The second approach was to establish relationships between annual gas fluxes and plant productivity and then use large area data on plant productivity derived from SPOT images as a scaling tool. Both approaches were based on hypotheses and previous studies that established strong relationships between soil moisture and plant productivity and gas fluxes. FIFE Soil Gas Fluxes Using Soil Cores Data Set contains the daily flux rates of denitrification, nitrous oxide flux and carbon dioxide flux obtained from 10 sites at four sampling dates during 1987. Soil gas fluxes were measured using an intact extracted core technique. The data set includes estimates of in situ fluxes as well as denitrification fluxes measured in cores amended with either water or water plus nitrate. Analysis of relationships between daily flux rates and soil moisture and between annual fluxes and plant productivity are reported elsewhere (Groffman and Turner submitted to Ecology, Groffman and Wood in preparation). Analysis of the denitrification data, and evaluation of denitrification fluxes in the context of the ecosystem ecology of the FIFE study area are presented in Groffman et al. (1992).

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The Soil Hydraulic Conductivity Data Set contains soil hydraulic conductivity, matric flux potential, and soil depth data collected during the 1989 FIFE soil properties investigation. The purpose of the 1989 FIFE soil properties investigation was to obtain more points on the soil moisture release curves for the soils at the FIFE stations, and provide values for the saturated hydraulic conductivity for the long-term water balance studies. In-situ measurements of field-saturated hydraulic conductivity were made using the constant well head permeameter method. These measurements were made at five sites, each representing a different soil series. The constant well head method for hydraulic conductivity involves augering a hole to the desired depth and measuring the steady state flow rate of water into the hole while maintaining a constant head of water inside the hole. Six measurements were made at each of the two soil depths at each site. The hydraulic conductivity measurements were made at the same depths and close to (less than 1 m away from) the location where samples for moisture release measurements were taken.

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The purpose of this research was to characterize the soil moisture distribution in the FIFE study area. Daily measurements of the soil dielectric properties were obtained at five locations throughout the FIFE study area during the 1987 Intensive Field Campaigns (IFC). Calculated soil volumetric water contents were compared with gravimetric soil moisture measurements collected at the same locations by the FIFE staff science team. Examination of the data revealed that the impedance probe is a more consistent source of time series information than traditional measurements, and is potentially more closely linked to the physical parameters. The dielectric constant of soil is a potentially sensitive indicator of soil moisture. Since, the magnetic permeability of all naturally occurring soils is near that of free space, dielectric measurements serve to fully characterize the electromagnetic response of soils. Many of the indirect methods of soil moisture measurement permit frequent or continuous measurements in the same place with only small expenditure of time. Thus, changes in water content with time can be approximated. The soil impedance is sensitive to the moisture content of the soil and can be used to calculate the volumetric water content of the soil. Soil impedence techniques using probes have been demonstrated to show small-scale diurnal variations that would be completely missed by small-scale spatial variations in the gravimetric sampling scheme. Furthermore, the basically non-destructive nature of the fixed probes minimize the impact of the sampling technique on the dynamic behavior of the region under study.

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Water content measurements by gravimetric methods involve weighing a wet sample, removing the water via drying in an oven, and reweighing the sample to determine the amount of water removed. Water content then is obtained by dividing the difference between wet and dry masses by the mass of the dry sample to obtain the ratio of the mass of water to the mass of dry soil. When multiplied by 100, this becomes the percentage of water in the sample on a dry-mass (or, as often expressed, on a dry-weight) basis. Soil moisture determined using the gravimetric method was measured at 800 sites along 24 transects. These transects were over flown by the airborne Gamma Radiation System used to measure soil moisture. These data are useful for comparison of airborne and ground soil moisture data. This analysis for the airborne Gamma Radiation System, using completely independent soil moisture data showed that the root mean square error of 97 flights was 3.02 percent soil moisture, with a bias of less than 0.5 percent soil moisture (Carroll et al., 1988).

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The gravimetrical soil moisture data were collected from many stations spread over the FIFE study area. These data were collected to characterize the spatial and temporal patterns of moisture content of the soils over this area during and between the FIFE Intensive Field Campaigns. The aim of the FIFE soil moisture work was to characterize spatial and temporal patterns of soil moisture at the FIFE site, to validate and calibrate remote sensing measurements of soil water, and to evaluate alternative methods of measuring soil moisture both from the air and on the ground. A further goal was to develop techniques for comparing point and spatially continuous measurements of soil moisture. The FIFE soil moisture research was designed to advance the technology for characterizing soil moisture and contribute useful data to other FIFE investigations.

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The neutron-probe data present a series of measurements of volumetric water content in the soil profile compiled using the neutron method. These data were collected from throughout the FIFE study area from May 1987 through August 1989. The neutron method of measuring soil water content uses the principle of neutron thermalization. When both hydrogen and oxygen are considered, water has a marked effect on slowing or thermalizing neutrons. Thermal neutron density is easily measured with a detector, if the capture cross-section remains constant then the thermal neutron density may be calibrated against water concentration on a volume basis.

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This data product was created based on the hypothesis that a variety of ground truth observations of soil moisture could be combined to estimate equal soil moisture contours across a large area (e.g., the FIFE area). A second stage required interpolating from these contours, using the methods of spatial statistics, to average soil moisture values at the nodes of a uniform grid. The grid node values in this product represent the average soil moisture of a 0.5 km x 0.5 km area centered at the node location. The correlation area method (CAM) was used to combine in situ measurements and airborne gamma remote sensing estimates to obtain areal averages of soil moisture. Information on biomass and the spatial distribution of vegetation in a model was also used to estimate soil moisture from PBMR measurements. Another simple method, using only ground soil moisture data, was also used to compute soil moisture from the PBMR measurements. All soil moisture data collected from the aircraft platforms and ground measurements were entered into the ARC/INFO GIS along with the UTM coordinates of each observation. All available and usable measurements of soil moisture were considered in an analysis that produced isolines of soil moisture.

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The aim of the FIFE soil moisture transect work was to characterize spatial and temporal patterns of soil moisture along selected transects at the FIFE study area. Two levels of ground data were collected to support the passive microwave (PBMR) flights over the Konza experimental area. The water content measurements were collected using gravimetric methods. Soil moisture measured along a transect is necessary to calibrate airborne moisture instruments or compare data obtained from them. Soil units in a landscape are inherently heterogeneous, which leads to variations in moisture content along an aircraft flight path on the ground. In order to reduce errors, values on the flight path were sampled at close intervals.

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Soil reflectance properties are an important factor in determining landscape reflectance characteristics. No soil reflectance data were collected as part of the FIFE experiment. Therefore, the FIS staff choose spectra from soils similar to those in the FIFE study area from the atlas of soil reflectance properties (Stoner et al., 1980). The atlas represents a wide range of soil types, and FIS staff choose spectra from soils similar to those in the FIFE study area. The selection of spectra was based on soil particle size, organic carbon content, taxonomic classification, and geography of soils found in the FIFE study area. All measurements were made on uniformly moist, sieved soils, which were equilibrated for 24 hours at a one-tenth bar moisture tension. Soil reflectance was measured using an Exotech Model 20 C spectroradiometer adapted for indoor use with a reflectometer equipped with an artificial illumination source, transfer optics, and sample stage. Spectral readings were taken in 0.01 micrometer increments over the 0.52 to 2.32 micrometer wavelength range.

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The objectives of this study were to collect soil survey information from the FIFE study area, determine the soil types at the FIFE sites, and characterize the physical and chemical properties of the soils. The Soil Properties Reference Information Data Set provide a description of the soils and their properties at the FIFE study sites as described by the U.S. Soil Conservation Service. Five stations representative of the Clime, Benfield, Dwight, Florence, and Tully soil types were selected, and a detailed description of the soil profile at each of these five sites was made. Soil samples from the surface down to bedrock were collected from the horizons and analyzed for bulk density, particle size distribution, moisture retention at 1/3 and 15 bar suctions, cation exchange capacity, and other chemical and physical properties, using standard procedures (Soil Survey Staff 1984).

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The purpose of the 1989 FIFE soil properties investigation was to obtain a description of the thermal properties of the soils within the FIFE study area. Soil thermal conductivity measurements describe the soil properties which govern the flow of heat through the soil. The thermal conductivity is defined as the quantity of heat that flows through a unit area in a unit time under a unit temperature gradient. These measurements were made using a hot wire probe in situ at two depths at twenty six FIFE sites during October 1987. The measurements were taken using a long electrically heated wire enclosed in a cylindrical probe . The probe is placed in the soil, the wire is heated by running a current through it, and the temperature rise is measured with a thermocouple placed next to the wire. A plot of temperature versus the log of time can be used to derive the thermal conductivity. The results may require a correction factor to account for the dimensions of the probe.

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During the 1989 FIFE field campaign, measurements were made of soil moisture release parameters and hydraulic conductivity. Bulk density and soil moisture release data were collected at five FIFE sites representing the major soil types in the FIFE study area. These data were used to model the porosity, saturated water potential, and the b-factor (the exponent of the power curve function) following the method of Clapp and Hormberger (1978). These soil moisture characteristics can be used to describe plant-available water and water movement through soils.

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The FIFE Standing Crop and Nitrogen Content Data Set contains biomass and nitrogen concentration data for live and dead above-ground plant material collected along transects in watersheds within the FIFE study area. The transects were in watersheds that had undergone burning and grazing treatments. Point physical descriptors (elevation, slope, and soil depth) are also included in the data set. Substantial variation in biomass, and N accumulation occurred over time, with topography, and as a result of grazing and previous burning (Schimel et al. 1991a, Kittel et al. 1990, Turner et al. 1992, Davis et al. 1992).

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The Daily Stream Flow Amounts Data Set contains daily measurements of stream flow for the four LTER stations and for the USGS stream-flow station located on tributaries to Kings Creek. This data set contains measurements from April 1979 to September 1988 for the USGS station, and from June 1985 to December 1987 for the 4 LTER stations. Five stream-flow gauges were placed across creeks in the Long-Term Ecological Research (LTER) section of the FIFE study area. Four of these five stations were maintained and monitored by the LTER staff while the fifth was part of the USGS network of stream flow gauges. The V-throated flume and standpipes used at the LTER weirs operated on the principle that the height of the water level in a standpipe at a specific location within a weir of known dimensions can be converted to volume of water in the stream. The change of this instantaneous volume with time could then be used to compute volumetric stream flow. The stilling pipe installation at the USGS stations operates on the principle that the height of the water level in a standpipe at a specific location within a streambed can be converted to volume of water in the stream. The tracking of the change in stream height with time then enables the calculation of stream flow.

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The Storm Event Stream Flow Data Set were collected during storm events from five treatment areas within the Konza Prairie Long-Term Ecological Research (LTER) site located within the northwest quadrant of the FIFE study area. These data were recorded so that the hydrology of the streams draining the tallgrass prairie could be studied. Moreover, these data were collected to determine the effect of burn frequency of a watershed upon runoff. Data are available from June 14, 1985 through December 31, 1987. The V-throated flume and standpipes used at the LTER weirs operated on the principle that the height of the water level in the standpipe at a specific location within a weir of known dimensions can be converted to volume of water in the stream. The change of this instantaneous volume with time could then be used to compute volumetric stream flow. The V-notch, sharp-crested weir used in watershed 1D operated on the principle that water flowing past a point of known dimensions per unit time could be converted through standard equations to volumetric flow.

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The FIFE Surface Flux Baseline 92 Derived Data Set was compiled from the original surface flux data collected during FIFE (i.e., no measurements were made specifically for this data set). This data set contains data collected from mid-May through mid-October, 1987 at 21 stations located within 19 sitegrids spread throughout the FIFE study area. For a description of the theory behind the original surface flux measurements see the documentation for each of the original surface flux data sets. Surface heat flux data routinely have erroneous jumps (i.e., spikes) in the latent and sensible heat flux time series in the early morning and evening hours due to small gradients in the measured data. A series of tests were developed to identify these spikes and flag them. Flux data obtained from Bowen ratio sites are also checked for energy imbalances. These data were also compared to model results. The consistency between these two methods is indicated in this data set.

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The NOAA Regional Surface Data - 1989 (NCDC) Data Set contains hourly surface meteorological data for the FIFE area. Though the measurements presented in this data set were not taken precisely at the FIFE study area, it is hypothesized that they present a representative horizontal cross-section of meteorological variables and sky conditions in and around the site. It is also realized that many of the variables presented in this data set are somewhat subjective and dependent on the skill (and biases) of the observer, such as estimates of cloud amount and height. This data may be used as input data and/or verification data for numerical simulation models.

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The Surface Temperatures, Reflected and Emitted Radiation, and PAR from UNL Data Set contains surface temperatures at different view zenith and azimuth angles, net radiation, incoming and reflected photosynthetically active radiation, incoming and reflected shortwave radiation, and reflected and emitted longwave radiation. Surface temperatures were measured at a 30 degree view zenith angle with an Everest infrared thermometer (IRT) Model 112C and at approximately a 60 degree view zenith angle with a Scheduler Plant Stress Monitor at 4 view azimuths (predominantly 90 degree increments from the solar azimuth). The Scheduler also measured air temperature, relative humidity, and vapor pressure deficit. Net radiation was measured with a Radiation and Energy Balance Systems (REBS) net radiometer Model Q*3. Incoming shortwave radiation was measured with a horizontally mounted Eppley Precision Pyranometer Model PSP. Reflected shortwave radiation was measured with two (2) Eppley Precision pyranometers Model PSP usually mounted horizontally (at site 966 (2437-PSP) one PSP was mounted horizontally and the other was inclined parallel to the slope). Reflected and emitted longwave radiation were measured with a horizontally mounted Eppley Precision Infrared Radiometer Model PIR.

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The temperature profile data included in this data set was derived from the FIFE radiosonde data collected during the summer and fall of 1987 and the late summer of 1989 by Dr. Wilfred H. Brutsaert. These intensive radiosonde flights allowed the measurement of the atmospheric profiles of potential temperature and specific humidity. These data have been corrected for sensor delays, algorithm inconsistencies and have been interpolated to a set of standard pressure levels.

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The Total Leaf Tissue Water Potential Data Set was collected during the summer months of 1988 and 1989. The objective of this study was to determine the influence of plant water status on surface reflectance factors. Measurements were made at six stations on Indian grass, switch grass, Big bluestem, little bluestem, and tall dropseed. Leaf water potential measurements were usually made on the same leaf that optical measurements were made and on leaves of surrounding plants. Measurements were made on the most recently expanded leaf of the selected plant unless specified. Measurements were also made of older green and yellow leaves on a plant. Leaf water potential measurements can be linked with the leaf optical properties data if the plant number in both sets of data are known. Plant water potential values measured just before dawn will provide the highest plant water potential (smallest negative value) during the day and also provides a reasonable estimate of the soil water potential. It is hypothesized that as the leaf water potential decreases (large negative value) that there may be some change in the internal structure of the leaf that would be detectable in one or more of the Nebraska Multiband Leaf Radiometer (NMLR - instrument used during leaf optical measurements) wavebands. It is also hypothesized that the amounts of water in a leaf will be lowest at low water potential and that this might also be detectable with the NMLR especially in the mid-IR wavebands.

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The Biophysical Properties of the Vegetation Data Set were collected as part of the larger FIFE Science effort to characterize the physical and biological properties of the sites within the FIFE study area over the life of the field experiment. These data were collected at 43 locations scattered throughout the FIFE study area between May 1987 and August 1989. The measurements of leaf area were based on an optical technique in which the area of the light beam obscured by the material under the beam is a measure of the surface area of that material relative to the total surface area that the beam covers. The resulting Leaf Area Indices (LAI) provide a relative measure of leaf area. These indices, when compared between plant samples provide an indirect and relative measure of plant biomass.

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The Vegetation Species and Cover Abundance Data Set documents the species present at the FIFE staff data measurement sites. Percent cover is estimated for each species at approximately the time of the IFC's. Disturbances occur over a variety of spatial and temporal scales in North American grasslands, and interactions of these different disturbances affect community structure. Two types of disturbance commonly occur over large spatial scales in grasslands, namely, fire and grazing. Analysis of percent cover of dominant species indicated that composition and heterogeneity was significantly affected by grazing intensity and burning. The effects of disturbances on community structure are not additive, and may not be extrapolated from studies of single factors. The interpretation of patterns in natural communities is clearly scale dependent, and processes may act differently when viewed from different spatial or temporal scales. The effects of scale may not always be predictable; therefore, an understanding of pattern and process at one hierarchical level may not provide useful information about pattern and process at a different hierarchical level.

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The Konza Natural Research Area is a tallgrass prairie in a biologically heterogeneous environment that is rich in native plant species. Species composition is extremely variable over sites because of the effects of both natural and anthropological factors. The FIFE Vegetation Species Reference Data Set is used to associate the plant species found on the Konza Prairie with both their common and Latin names, and to translate the species codes found in the FIFE vegetation data sets to their Latin and common names.

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The aim of this wind profile study was to derive wind profiles and momentum fluxes from the National Oceanic and Atmospheric Administration (NOAA)/Wave Propagation Laboratory (WPL) Doppler LIDAR, and compare LIDAR and airborne measurements of mean wind, turbulent structure, momentum flux, and heat flux. Another objective was to compare profiles of mean wind and temperature obtained from aircraft, balloon sondes, and wind LIDAR. These data were collected at one location near the center of the FIFE study area but in the northwest quadrant. Data were acquired for a two week period during June and July 1987. Pulsed Doppler LIDAR measures the radial (along-beam) velocity as a function of range using light-scattering particles in the air as tracers. When the LIDAR beam is directed straight upward and the backscattered return as a function of height is recorded, vertical aerosol profiles may be determined. Various pointing and scanning schemes permit measurement of a variety of mean and turbulent quantities based on assumptions about the flow. The remote-sensing character of LIDAR offers the ability to measure flow parameters simultaneously at all the heights in a profile. The winds were obtained with the VAD (Velocity Azimuth Display) technique. The LIDAR only operates above 500 m, therefore the wind profile begins above the ground surface. Data in the planetary boundary layer are usually continuous, but gaps appear occasionally in profiles extending to several kilometers. Profiles were unsmoothed, and the LIDAR's short pulse made adjacent data points almost independent.

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The wind profile data described in this document were derived from the raw radiosonde data collected during FIFE by Dr. Wilfred H. Brutsaert during the summer and fall of 1987 and the late summer of 1989 The objective of this study was to calculate wind velocity and wind direction from successive horizontal positions of a radiosonde. These data have allowed the measurement of the atmospheric profiles of wind velocity and direction. The raw data have also been corrected for sensor delays and have been interpolated to a set of standard pressure levels. Successive horizontal positions of the radiosonde balloon in relation to its release point was used to calculate average wind speed and direction. The variables used to make these calculations were obtained from the FIFE Radiosonde Data. The balloon height was calculated by adding 10 m (i.e., the length of the string) to the height of the sonde. The horizontal distance of the sonde, together with the measured azimuth angle (also obtained from the FIFE Radiosonde Data), produced the horizontal position of the sonde. Finally, successive horizontal positions allowed the calculation of average wind velocity and direction over the interval. Note, as a result of the addition of 10 m for most flights, the height of the wind measurements in this data set is 10 meters higher than the companion values in the original FIFE Radiosonde Data.

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NASA FIFE Project was accessed on DATE from https://registry.opendata.aws/nasa-fife.