The FT-ESDR is a NASA MEaSUREs (Making Earth System Data Records for Use in Research Environments) funded effort to provide a consistent long-term global data record of land surface freeze/thaw (FT) state dynamics for all vegetated regions where low temperatures are a major constraint to ecosystem processes. The FT measurement is derived from temporal change classification of global satellite microwave remote sensing time series, including passive microwave radiometry from the Special Sensor Microwave Imager (SSM/I) and Advanced Microwave Scanning Radiometer for EOS (AMSR-E), and radar scatterometry from SeaWinds-on-QuikSCAT. The ecological significance and basis of the FT measurement from satellite microwave remote sensing is summarized in the literature (e.g., see "Relevant Publications" section below). The FT-ESDR is designed to:
Entekhabi, D., E. Njoku, P. Houser, M. Spencer, T. Doiron, J. Smith, R. Girard, S. Belair, W. Crow, T. Jackson, Y. Kerr, J. Kimball, R. Koster, K. McDonald, P. O'Neill, T. Pultz, S. Running, J.C. Shi, E. Wood, and J. Van Zyl, 2004. The Hydrosphere State (HYDROS) mission concept: An Earth System Pathfinder for global mapping of soil moisture and land freeze/thaw. Transactions in Geoscience and Remote Sensing 42, 10, 2184-2195.
Kimball, J.S., K.C. McDonald, and M. Zhao, 2006. Spring thaw and its effect on terrestrial vegetation productivity in the western Arctic observed from satellite microwave and optical remote sensing. Earth Interactions 10(21), 1-22.
Kimball, J.S., K.C. McDonald, S.W. Running, and S. Frolking, 2004. Satellite radar remote sensing of seasonal growing seasons for boreal and subalpine evergreen forests. Remote Sensing of Environment 90, 243-258.
McDonald, K.C, and J.S. Kimball, 2005. Hydrological application of remote sensing: Freeze-thaw states using both active and passive microwave sensors. Encyclopedia of Hydrological Sciences. Part 5. Remote Sensing. M.G. Anderson and J.J. McDonnell (Eds.), John Wiley & Sons Ltd. DOI: 10.1002/0470848944.hsa059a.
McDonald, K.C., J.S. Kimball, E. Njoku, R. Zimmermann, and M. Zhao, 2004. Variability in springtime thaw in the terrestrial high latitudes: Monitoring a major control on the biospheric assimilation of atmospheric CO2 with spaceborne microwave remote sensing. Earth Interactions 8(20), 1-23
This global database contains a satellite passive microwave remote sensing based land parameter retrievals generated from the Advanced Microwave Scanning Radiometer on EOS Aqua (AMSR-E), with funding from the NASA. The daily land parameter retrievals extend from 2002 and include daily air temperature minima and maxima (ta; ~2 m height), fractional cover of open water on land (fw), vegetation canopy microwave transmittance (tc), surface soil moisture (mv; ≤ 2 cm soil depth) and integrated water vapor content of the intervening atmosphere (V; total column). The global retrievals are derived over land for non-precipitating, non-snow, and non-ice covered conditions. The primary inputs for these retrievals are daily AMSR-E dual polarized multi-frequency, ascending and descending overpass brightness temperature (Tb) data (version 3). The AMSR-E brightness temperature data were obtained in global 25-km EASE grid format from the National Snow and Ice Data Center (NSIDC). The resulting land parameter data are internally consistent and are being used for a range of global ecological and hydrological studies, including vegetation biomass and phenology mapping, soil moisture and surface water and energy balance studies. These data are archived at both NTSG and NSIDC.
Jones, L.A., and J.S. Kimball, 2010. Daily Global Land Surface Parameters Derived from AMSR-E. Boulder Colorado USA: National Snow and Ice Data Center. Digital media (http://nsidc.org/data/nsidc-0451.html).
Jones, L.A., J.S. Kimball, E. Podest, K.C. McDonald, S.K. Chan, and E.G. Njoku, 2009. A method for deriving land surface moisture, vegetation optical depth and open water fraction from AMSR-E. Proceedings of the IEEE Int. Geosci. Rem. Sens. Symp. (IGARSS ‘09), Cape Town, South Africa, 916-919.
Jones, L.A., C.R. Ferguson, J.S. Kimball, K. Zhang, S.K. Chan, K.C. McDonald, E.G. Njoku, and E.F. Wood, 2010. Satellite microwave remote sensing of daily land surface air temperature minima and maxima from AMSR-E. IEEE Journal of Selected Topics in Earth Observations and Remote Sensing (JSTARS) 3(1), 111-123.
Jones, M.O., J.S. Kimball, K.C. McDonald, and L.A. Jones, 2010. Utilizing satellite passive microwave remote sensing for monitoring global land surface phenology. Remote Sensing of Environment (in press).
An Earth System Data Record for Global Monitoring of Wetlands Extant and Dynamics
Wetlands exert major impacts on global biogeochemistry, hydrology, and biological diversity. The extent and seasonal, interannual, and decadal variation of inundated wetland areas play key roles in ecosystem dynamics. Despite the importance of theseenvironments in the global cycling of carbon and water and to current and future climate, the extent and dynamics of global wetlands remain poorly characterized and modeled, primarily because of the scarcity of suitable regional-to-global remote sensing data for characterizing their distribution and dynamics.
The NASA Earth science project's main objective is the construction of a global-scale Earth System Data Record (ESDR) of inundated wetlands to facilitate investigations on their role in climate, biogeochemistry, hydrology, and biodiversity. The ESDR is comprised of two complementary components. The first component consists of fine-resolution, 100 meter, maps of wetland extent, vegetation type, and seasonal inundation dynamics, derived from Synthetic Aperture Radar (SAR) for continental-scale areas covering crucial wetland regions. The contemporary-era mapping will use newly available data (HH/HV) from the Phase Array L-Band SAR (PALSAR) sensor mounted on the Advanced Land Observing Satellite (ALOS). The second component is comprised of global monthly mappings of inundation extent at ~25 km resolution. These products will be derived from multiple satellite remote sensing observations including coarse resolution passive and active microwave sensors and optical data sets (e.g. ERS and SeaWindson-QuikSCAT scatterometers, AVHRR, MODIS) optimized specifically for inundation detection.
This ESDR will provide the first accurate, consistent and comprehensive global-scale data set of wetland inundation and vegetation, including continental-scale multi-temporal and multi-year monthly inundation dynamics at varying scales.
Seasonal vegetation dynamics significantly impact the carbon cycle and weather (surface energy balance, transpiration vapor fluxes). These impacts are related to growing season length for evergreen ecosystems, to timing of leaf flush and senescence for drought- or cold-deciduous systems, and to seasonal and annual variability in canopy biomass. Spaceborne remote sensing is the only practical tool for monitoring seasonal vegetation dynamics globally with high temporal repeat and moderate spatial resolution.
We are working to establish a satellite radar and microwave remote sensing-based methodology and associated product time series for global assessment and monitoring of vegetation phenology, capitalizing on the systematic, multi-year (1999 onward) measurement series provided by the SeaWinds scatterometers and AMSR-E radiometer. We exploit the high temporal repeat, all-weather capabilities of satellite radar and microwave and dynamic radar backscatter sensitivity to both vegetation structure and water status to develop a comprehensive phenology measure that is synergistic with existing satellite optical-IR based approaches that are primarily sensitive to effective (sunlit) leaf area and photosynthetic biomass.
Image is estimated Length of the Growing Season derived from the AMSR-E Vegetation Optical Depth (VOD) Land Surface Parameter. VOD is part of a suite of land surface parameters calculated at NTSG/FLBS and is available via our ftp site.
Jones, M.O., Kimball, J.S., McDonald, K.C., Jones, L.A. Utilizing Satellite Passive Microwave Remote Sensing for Monitoring Global Land Surface Phenology – recently submitted
Jones, L.A., Ferguson, C.R., Kimball, J.S., Zhang, K., Chan, S.K., McDonald, K.C., Njoku, E.G., & Wood, E.F. (2010). Satellite Microwave Remote Sensing of Daily Land Surface Air Temperature Minima and Maxima from AMSR-E. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Jones, L.A., Kimball, J.S., McDonald, K.C., Chan, S.K., & Njoku, E.G. (2009). A method for deriving northern hemisphere vegetation phenology, land surface wetness, and open water fraction from AMSRE. In, IGARSS Symposium. Cape Town, South Africa
Approximately 68-80 percent of the North American region experiences seasonal freezing and thawing with the relative influence of these processes on terrestrial carbon budgets generally increasing at higher latitudes and elevations. The timing and duration of surface and soil freeze-thaw state is closely linked to vegetation phenology and growing season dynamics in northern temperate, sub-alpine, boreal and arctic biomes. Variability in these environmental variables also has been shown to have dramatic impacts on spatial patterns, seasonal to interannual variability and long-term trends in terrestrial carbon budgets and surface-atmosphere trace gas exchange primarily through biophysical controls on both photosynthesis and respiration. These processes are strongly influenced by land cover and soil properties, as well as the timing and condition of regional snow cover.
We are applying daily time series radar backscatter information from the SeaWinds Ku-band scatterometer to quantify spatial patterns and daily, seasonal and interannual variability in landscape freeze-thaw status in support of the North American Carbon Program (NACP). We are investigating synergistic relationships and trade-offs in relative sensitivity, spatial scale and temporal monitoring capabilities between SeaWinds freeze-thaw and MODIS land surface temperature (LST) products for quantifying landscape freeze-thaw state and thermal and moisture controls to vegetation gross primary production (GPP) and net primary production (NPP). We are quantifying the spatial and temporal patterns of these variables and determining their relative importance in determining seasonal patterns and annual variability in vegetation productivity using a modified form of the MODIS Production Efficiency Model (MOD17). We are also investigating relations between the microwave based freeze-thaw signal and surface biophysical network measures of the surface energy budget and associated linkages to soil respiration and land-atmosphere CO2 exchange dynamics. These results are being integrated within the larger NACP project to provide a comprehensive assessment of the North American carbon budget.
Map of the relative impact of low temperature on vegetation productivity for the North American study domain derived from the MODIS MOD17 time series. Darker blue regions denote areas where cold temperatures are a significant limitation to GPP, as determined from the MODIS LAI and FPAR time series (2000-2004) and MOD17 algorithm. Areas in white include non-vegetated surfaces and areas where low temperature is not a significant constraint to plant growth. Vegetation productivity over approximately 33% of Earth’s global vegetated surface is limited by cold temperatures and water in its frozen state. This investigation is characterizing the relative control of freeze-thaw state on the annual carbon budget of the North American domain.
McDonald, K.C., J.S. Kimball, E. Njoku, R. Zimmermann, and M. Zhao, 2004. Variability in springtime thaw in the terrestrial high latitudes: Monitoring a major control on the biospheric assimilation of atmospheric CO2 with spaceborne microwave remote sensing. Earth Interactions 8(20), 1-23.
We are developing a new satellite-based approach for regional assessment and monitoring of terrestrial net carbon exchange (NEE) for the pan-Arctic; NEE quantifies the magnitude and direction of land-atmosphere net CO2 exchange and is a fundamental measure of the balance between carbon uptake by vegetation net primary production (NPP) and carbon loss through soil heterotrophic respiration (Rh). We are using satellite microwave remote sensing to extract surface soil wetness and temperature information with existing satellite-based measurements of vegetation structure (LAI, FPAR) and productivity (GPP, NPP) from Aqua/Terra MODIS sensors to derive spatially explicit estimates of NEE for the pan-Arctic at weekly and annual intervals. Calibration and validation activities involve multiscale comparisons with tundra CO2 eddy-flux tower and biophysical measurement networks, detailed hydroecological process model simulations and low altitude flux aircraft overflights along regional moisture and temperature gradients across Alaska. This project provides the first-ever operational satellite-based approach for regional assessment and monitoring of NEE, the primary measure of carbon exchange between the land and atmosphere. These data also provide a valuable new tool for assessing regional patterns, temporal variability and environmental controls on pan-Arctic terrestrial sources and sinks for atmospheric CO2 and advances our understanding of the extent to which the Arctic is being affected by recent warming trends and reinforcing global change.
Prototype application of a new MODIS-AMSR-E sensor based remote sensing algorithm for daily mapping of land-atmosphere net CO2 exchange (NEE) for the pan-Arctic.
Heinsch, F.A., M. Zhao, S.W. Running, J.S. Kimball, R.R. Nemani, et al., 2006. Evaluation of remote sensing based terrestrial productivity from MODIS using regional tower eddy flux network observations. IEEE Transactions in Geoscience and Remote Sensing 44(7), 1908-1925.
Jones, L.A., J.S. Kimball, K.C. McDonald, E.G. Njoku, W.C. Oechel. Satellite microwave remote sensing of arctic and boreal soil temperatures from AMSR-E. IEEE Trans. Geosci. Rem. Sens. (in press).
Kimball, J.S., L.A. Jones, K.C. McDonald, E.G. Njoku, and W.C. Oechel, 2006. A satellite remote sensing approach for mapping soil respiration and terrestrial carbon exchange for boreal and arctic biomes using MODIS and AMSR-E. Eos Transactions of the American Geophysical Union Meeting. B43-A-0242.
Zhang, K., J.S. Kimball, M. Zhao, W.C. Oechel, J. Cassano, and S.W. Running, 2006. Sensitivity of pan-Arctic terrestrial net primary productivity simulations to daily surface meteorology from NCEP/NCAR and ERA-40 Reanalyses. J. Geophys. Res. - Biogeosciences 112, G01011, 1-14, doi:10.1029/2006JG000249.
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