NASA Fluxnet Project

Description

CO2 and water vapor fluxes and ecosystem characteristics were measured at 24 sites along a 317-km transect from the Arctic coast to the latitudinal treeline in Alaska during the growing seasons of 1994-1996. The sites were stratified to sample the ranges of climate, physiography, soil moisture, and vegetation type within the region. Our main objective was to understand what factors control variations in CO2 and water vapor exchange across the region. We therefore developed a spatially extensive approach of documenting fluxes for 1-2 weeks at each of the sites in order to study as many sites as possible during the middle of the short arctic growing season, when plant phenology is most comparable among different vegetation types and climatic regions. This allowed us to compare, with some replication, a given vegetation type across different provinces and climatic zones, as well as multiple vegetation types within a given geographic area.

FLUXNET_Canada_1335

FLUXNET Canada is a Fluxnet research network comprised of the Fluxnet-Canada Research Network (FCRN) and the Canadian Carbon Program (CCP) operating from 1993 through 2014. It was a national research network of university and government scientists studying the influence of climate and disturbance on carbon cycling along an east-west transect of Canadian forest and peat land ecosystems. The data provided are measured and modeled results as obtained from the site investigators. They were not standardized and quality-controlled. Data include: atmospheric carbon dioxide (CO2) and water vapor fluxes and many ancillary meteorological variables; soil CO2 efflux and soil moisture; stable carbon isotopes; site soil and vegetation characteristics, plus documentation and descriptions for the 32 tower sites across 12 flux research stations. The time period is from 1993 - 2014; most reported data for a site does not cover the entire period.

gap_filled_marconi_811

Fluxes of carbon dioxide, water vapor, and energy exchange have been measured at 38 forest, grassland, and crop sites as part of the EUROFLUX and AmeriFlux projects. A total of 97 site-years of data were compiled, primarily between 1996 and 1998 but also for 1992-1995 and 1999-2000. Half-hour flux and meteorology measurements are included plus the gap-filled half-hour estimates and aggregations to day and night, weekly, monthly, and annual periods. The FLUXNET 2000 Synthesis Workshop was held at the Marconi Conference Center, Marshall, California, June 11-14, 2000. The Marconi Flux Data Collection was compiled to aid in exploring the interactions between the terrestrial biosphere and the overlying atmosphere through carbon, water, and energy exchanges. The workshop resulted in several studies to synthesize and interpret differences and similarities in long-term measurements of carbon dioxide, water vapor, and energy exchanges between vegetation and the atmosphere for a spectrum of ecosystems. A series of synthesis papers based on these data and studies was published in a special issue of the Agriculture and Forest Meteorology, Volume 113, 2002. The papers are listed in the reference section. This data product is being archived as a record of the data used the AFM special issue. Updates and revisions to the data are available at the FLUXNET web site.The eddy covariance technique is used for long-term continuous measurements of mass and energy fluxes to capture seasonal dynamics and allow for a meaningful scaling with respect to time. The equipment and methodology were standardized among sites by using common software and instrumentation. Comparisons of ecosystem fluxes among sites are usually performed on annual or monthly sums calculated on complete data records; however, the average site data coverage during a year was only 65%. Therefore, development and application of robust and consistent data gap-filling methods was required before fluxes could be calculated. One of the outcomes of the FLUXNET project was computer applications to process the data into complete, consistent, quality assured, and documented data sets (Falge et al. 2001a,b). Gap-filled flux data from four different filling methods are reported. Selected meteorological parameters were also gap filled to support flux estimating methods and are reported along with non-filled meteorological data. Note that the measured/estimated CO2 fluxes and storage fluxes were summed into net ecosystem exchange (NEE), and ONLY NEE data are reported.

Fluxnet_site_DB_1530

FLUXNET is a global network of micrometeorological tower sites that use eddy covariance methods to measure the exchanges of carbon dioxide, water vapor, and energy between terrestrial ecosystems and the atmosphere. This dataset provides information from the ORNL DAAC-hosted FLUXNET site database which was discontinued in 2016. The files provided contain a list of investigators associated with each tower site, site locations and environmental data, and a bibliography of papers that used FLUXNET data. For more up to date information on FLUXNET sites, see http://fluxnet.fluxdata.org/.

Fluxnet_website_archive_copy_1549

This dataset contains an archived copy of the fluxnet.ornl.gov website as of September 2017. This archived website is provided for informational purposes only. The last updates to the website and the underlying database were made in October 2016. Support for the Fluxnet project and website was transitioned to http://fluxnet.fluxdata.org in September 2017. Please see http://fluxnet.fluxdata.org/ for information on site locations, data availability, and to add or update a flux tower site.

net_carbon_flux_662

The variability of net surface carbon assimilation (Asmax), net ecosystem surface respiration (Rsmax), and net surface evapotranspiration (Etsmax) among and within vegetation types was examined based on a review of studies performed in either a micrometeorological setting or an enclosure setting. The majority of studies involved forests and C3 crops, particularly in the northern hemisphere; however, studies on tropical forests, C4 grasslands or wetlands were included. Data are presented for 133 published studies, although individual studies may not have measure all variables of interest.Despite large variations within a vegetation type, enclosure studies tended to give highest Asmax rates compared to micrometeorological techniques (Buchmann and Schulze 1999). Excluding enclosure studies, the investigators tested the effect of stand age and leaf area index (LAI) on net ecosystem gas exchange. The results from these analyses illustrate where gaps in scientific knowledge exist and how ecosystem properties affect the capacity of net ecosystem gas exchange.The information was collected from papers with publication dates from 1969-1998. Mean maximum flux rates for the period chosen by the authors were used instead of absolute maximum values for flux rates. Positive values stand for CO2 uptake by the vegetation and negative values represent CO2 release from the ecosystem. More information about the compilation can be found in Buchmann and Schultze (1999) or the individual studies cited in the data table.

Data Discovery

Explore this data using NASA's Earthdata Search, a comprehensive tool for discovering and visualizing Earth science datasets.

Data Access

Access requires an Earthdata Login account. Read our guide on obtaining AWS credentials to retrieve this data from AWS.

Update Frequency

Varies by dataset

License

Creative Commons BY 4.0

Documentation

https://earthdata.nasa.gov/

Managed By

See all datasets managed by NASA.

Contact

https://earthdata.nasa.gov/contact

How to Cite

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