1_IGARSS11_2069_ONeill.pptx
- 1. Utilization of Ancillary Data Sets for SMAP AlgorithmDevelopment and Product GenerationPeggy E. O’Neill, NASA GSFCErika Podest, JPLEni G. Njoku, JPL IGARSS’11, Vancouver, BCJuly 27, 2011http://smap.jpl.nasa.govNational Aeronautics and Space Administration
- 2. BACKGROUNDSMAP is a planned NASA Earth Science Decadal Survey Mission
- 3. Launch currently scheduled for October 2014 into a 6 am / 6 pm sun-synchronous orbit Will use an L-band radar & radiometer to measure global soil moisture & freeze/thaw every 2-3 days Baseline SMAP data products include:-- radar-derived F/T at 3 km resolution-- radiometer-only SM at 40 km resolution-- combined radar/radiometer SM at 9 km resolution-- value-added products (root zone SM, carbon NEE) at 9 km All SMAP products output on nested 1, 3, 9, 36 km EASE gridsSMAP Data Products
- 4. Algorithm Needs All baseline SMAP products have associated algorithm(s) which require a variety of ancillary data to meet retrieval accuracies:-- 0.04 cm3/cm3 for soil moisture within SMAP land mask -- 80% classification accuracy for binary F/T in boreal latitudes Areas of snow/ice, frozen ground, mountainous topography, open water, urban areas, and dense vegetation (> 5 kg/m2) are excluded from SM accuracy statistics Static ancillary data do not change during mission -- permanent masks (land/water/forest/urban/mountain), DEM, soilsDynamic ancillary data require periodic updates ranging from daily to seasonally -- soil T, precipitation, vegetation, surface roughness, land cover
- 5. Ancillary ParametersTable 1. Ancillary Parameters 14 ancillary data parameters identified as needed by one or more SMAP algorithms choice of source of each parameter driven by:-- availability-- ease of use-- inherent error-- latency-- temporal & spatial resolution-- global coverage-- positive impact on SMAP retrieval accuracies-- compatibility with SMOS choices choices documented in a SMAP Ancillary Data Report for each parameter
- 6. data from each primary source will be used now in pre-launch simulations
- 7. choices will be revisited as new information becomes availableSoil TemperatureSMAP 6 am descending orbit SMAP soil moisture products will be retrieved using data from the 6 am descending orbits the 6 am 0-5 cm TS is the most dynamic ancillary parameter needed -- it is updated every orbit for each location SMAP error budgets currently carry 2 K as the error in ancillary TS data from the Oklahoma Mesonet indicates that at the 6 am overpass time, all NWP TS products have errors just below 2 K initial global estimates of NWP TS error against in situ point measurements are less optimistic, more in the range of 2.5 – 3.0 K; analysis on global TS error is continuingAccuracy of synchronized NWP forecast surface soil temperature compared against in situ temperatures for the Oklahoma Mesonet for 2004 and 2009.
- 8. Vegetation Water ContentsnowAnnual climatology of NDVI for Walnut Creek, IAa new 10-year (2000-2010) MODIS NDVI climatology has been created at 1 km resolutionglobally VWC calculated using NDVI-based water contributions from both foliage and stem components, adjusted for IGBP land cover classesVWC (kg/m2) over the continental U.S. for the month of July on a 1-km EASE grid asconstructed from a 10-year MODIS NDVI climatology and land cover products.
- 9. Soil TextureGlobal sand fraction at 0.01 degree resolution based on a composite of FAO, HWSD, STATSGO, NSDC, and ASRIS datasets using best available source for a given region. soil sand & clay fraction needed by dielectric models used in SM retrieval
- 10. best available source used for any given region
- 11. resulting global map a combination of different data sets
- 12. potential for discontinuities at data set boundaries (e.g., US / Canada)Urban AreasGlobal Rural-Urban Mapping Project GRUMP urban data (Columbia U.) gridded to SMAP 9 km EASE grid
- 15. however, urban flag likely to be set much lower since TB cannot be corrected for presence of urban areas
- 16. Open Water FractionOpen water (both permanent & transient)in a SMAP footprint is a potential large error source for SMAP retrieval algorithms if its presence is not detected & corrected for Partial UAVSAR ratio image of Mono Lake. ~7% detection error use SMAP HiRes radar to determine open water fraction
- 17. a 3 dB threshold is applied to HH to VV ratio to distinguish water from land
- 18. this SMAP parameter can be supplemented by static permanent water body data sets like MODIS MOD44W and JERS-1/PALSAR (for boreal latitudes) the water fraction is then used to correct TB for a mix of land & water in the grid cell
- 19. Input Data Set:US SRTMSRTMGTOPOAlaska DEMCanada DEMCoverage:United States56 °S to 60 °NGlobalAlaskaCanadaSource:NASA-JPLNASA-JPLUSGSUSGSGeoBaseResolution:1 arc-second3 arc-seconds30 arc-seconds2 arc-seconds3x6 arc-secondsHorz. Datum:WGS84WGS84WGS84NAD27NAD83Vertical Datum:EGM96EGM96EGM96NAVD29CVGD28Projection:GeographicGeographicGeographicGeographicGeographicAcquisition Date:February 2000February 2000Late 19961925 - 1999--Topography / DEMJPL Global DEM-- compiled from different sources-- 1 arc-secondresolution -- GMTED2010 will eventually replace GTOPO30-- above will be useful in assessing any discontinuities between existing data sets-- elevation and slope variance (TBC) could be used to set topography flag
- 20. Error Analysis Errors in ancillary data are factored into the SMAP soil moisture retrieval algorithm error budgetL2_SM_P Error AnalysisSimulated error performance of candidate retrieval algorithms for the radiometer-derived soil moisture product using one year of simulated SMAP H- and V-pol TB with indicated errors in model and ancillary parameters.
- 21. Ancillary Parameter Choices Anticipated Primary Sources of Ancillary Parameters
- 22. SummaryAll ancillary data will be resampled to the SMAP EASE grids at 1, 3, 9, 36 km
- 23. Preliminary choices have been made for primary source of each ancillary parameter-- these choices will be used pre-launch for SMAP simulations and algorithm development-- choices will be re-examined as new information becomes available-- will leverage SMOS data and experience -- SMOS / SMAP consistency desirableChoices documented in SMAP Ancillary Data Reports
- 24. Wise choices in ancillary data will help SMAP to provide accurate global measurements of SM & F/T