2026-07-26T04:25:08Zhttp://nsidc.org/api/dataset/metadata/oaioai:nsidc.org/SPL4SMAU.0022026-03-31T20:16:37Zcumulusretirednasa_nsidc_daac
SPL4SMAU.002SMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis UpdateReichle, R., De Lannoy, G., Koster, R. D., Crow, W. T. & Kimball, J. S.SMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update2016-04-29Boulder, Colorado USANASA NSIDC DAAC: NASA National Snow and Ice Data Center Distributed Active Archive Center2false10.5067/JJY2V0GJNFRZhttps://nsidc.org/sites/default/files/multi_spl4smau-v002-userguide.pdfSPL4SMAUTechnical ContactNSIDCUser Servicesnsidc@nsidc.org1-303-492-61991-303-492-2468CIRES, 449 UCBUniversity of ColoradoBoulderCO80309-0449USAEARTH SCIENCELAND SURFACESOILSSOIL MOISTURE/WATER CONTENTROOT ZONE SOIL MOISTURE EARTH SCIENCELAND SURFACESOILSSOIL MOISTURE/WATER CONTENTSURFACE SOIL MOISTURE Climatology/Meteorology/AtmosphereGeoscientific InformationEASE-Grid Other-projectMODELSRADIOMETERSMAP-projectSoil MoistureSoil Moisture Active PassiveSMAP L-BAND RADARSMAP L-Band RadarSMAPSoil Moisture Active and Passive Observatory2015-03-312017-07-15deprecated-85.04485.044-180180GEOGRAPHIC REGIONGLOBAL LAND9 km9 km3 hourSMAP products provide multiple means to assess quality. Uncertainty measures and file-level metadata that provide quality information are provided within each product. For details, refer to the Data Fields and Metadata Fields documents.
Each HDF5 file contains file-level metadata. A separate metadata file with an .xml file extension is also delivered to NSIDC DAAC with the HDF5 file; it contains essentially the same information as the file-level metadata. In addition, a Quality Assessment (QA) file with a .qa file extension is provided for every HDF5 file. QA files contain spatial statistics across the SMAP Level-4 soil moisture products, such as the global minimum, mean, and maximum of each data field.
Level-4 surface and root zone soil moisture estimates are validated to a Root Mean Square Error (RMSE) requirement of 0.04 m3 m-3 after removal of the long-term mean bias. This accuracy requirement is identical to Level-2 soil moisture product validation and excludes regions with snow and ice cover, frozen ground, mountainous topography, open water, urban areas, and vegetation with water content greater than 5 kg m-2. Research outputs (not validated) include the surface meteorological forcing fields, land surface fluxes, soil temperature and snow states, runoff, and error estimates that are derived from the ensemble.These data have been retired and are no longer accessible, though a more recent version of these data may be available.These data have been retired and are no longer available for use, though a more recent version of these data may be available. Cite any prior or planned use of these data according to the recommended citation at https://nsidc.org/about/data-use-and-copyright. For more information on the NASA ESDIS Data Use Guidance, see https://www.earthdata.nasa.gov/engage/open-data-services-software-policies/data-use-guidance.EnglishNASA/GSFC/SED/ESD/GMAONASA NSIDC DAACNASA National Snow and Ice Data Center Distributed Active Archive Centerhttps://nsidc.org/daacData Center ContactNSIDCUser Servicesnsidc@nsidc.org1-303-492-6199National Snow and Ice Data CenterCIRES, 449 UCBUniversity of ColoradoBoulderCO80309-0449USAFTP1.5 GBHDF5HTTPS1.5 GBHDF5Brodzik, M. J., B. Billingsley, T. Haran, B. Raup, and M. H. Savoie. 2012. EASE-Grid 2.0: Incremental but Significant Improvements for Earth-Gridded Data Sets. ISPRS Int. J. Geo-Inf. 1(1):32-45. http://dx.doi.org/10.3390/ijgi1010032.
Brodzik, M. J., B. Billingsley, T. Haran, B. Raup, and M. H. Savoie. 2014. Correction: Brodzik, M. J. et al. EASE-Grid 2.0: Incremental but Significant Improvements for Earth-Gridded Data Sets. ISPRS Int. J. Geo-Inf 2012. 1(1):32-45 ISPRS Int. J. Geo-Inf. 3(3):1154-1156. http://dx.doi.org/10.3390/ijgi3031154.
Entekhabi, D. et al. 2014. SMAP Handbook–Soil Moisture Active Passive: Mapping Soil Moisture and Freeze/Thaw from Space. Pasadena, CA USA: SMAP Project, JPL CL#14-2285, Jet Propulsion Laboratory.
Entekhabi, D., R. H. Reichle, R. D. Koster, and W. T. Crow. 2010. Performance Metrics for Soil Moisture Retrievals and Application Requirements. Journal of Hydrometeorology. 11:832–840. http://dx.doi.org/10.1175/2010JHM1223.1.
Reichle, R. et al. 2015. Soil Moisture Active Passive (SMAP) Mission Level 4 Surface and Root Zone Soil Moisture (L4_SM) Product Specification Document. SMAP Project, Global Modeling and Assimilation Office, Goddard Space Flight Center, Greenbelt, MD, USA. (http://nsidc.org/data/docs/daac/smap/sp_l4_sm/pdfs/SMAP_L4_SM_PSD_v1.4_beta-release.pdf, 1.7 MB)
Reichle, R. et al. 2014. SMAP Algorithm Theoretical Basis Document: L4 Surface and Root-Zone Soil Moisture Product. SMAP Project, JPL D-66483, Jet Propulsion Laboratory, Pasadena, CA, USA. (http://nsidc.org/data/docs/daac/smap/sp_l4_sm/pdfs/272_L4_SM_RevA_web.pdf, 1.4 MB)
Reichle, R., G. J. M. De Lannoy, Q. Liu, J. V. Ardizzone, F. Chen, A. Colliander, A. Conaty, W. Crow, T. Jackson, J. Kimball, R. D. Koster, and E. Brent Smith. 2016. Soil Moisture Active Passive Mission L4_SM Data Product Assessment (Version 2 Validated Release). GMAO Office Note No. 12 (Version 1.0), 55 pp, NASA Goddard Space Flight Center, Greenbelt, MD, USA. Available from http://gmao.gsfc.nasa.gov/pubs/office_notes.
Reichle, R., G. De Lannoy, Q. Liu, A. Colliander, A. Conaty, T. Jackson, J. Kimball, and R. Koster. 2015. Soil Moisture Active Passive (SMAP) Project Assessment Report for the Beta- Release L4_SM Data Product. Global Modeling and Assimilation Office, Goddard Space Flight Center, Greenbelt, MD, USA. NASA/TM-2015-104606, Vol. 40. (http://nsidc.org/data/docs/daac/smap/sp_l4_sm/pdfs/SMAP_L4_SM_Beta-Release_Assessment_Report_V40.pdf, 5.7 MB)
Reichle, R. H., and Q. Liu. 2014. Observation-Corrected Precipitation Estimates in GEOS-5. SMAP Project, Global Modeling and Assimilation Office, Goddard Space Flight Center, Greenbelt, MD, USA. NASA/TM–2014-104606, Vol. 35. (http://gmao.gsfc.nasa.gov/pubs/docs/Reichle734.pdf, 495 KB).SMAP Level-4 (L4) surface and root zone soil moisture data are provided in three products: (1) SMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data (SPL4SMGP). (2) SMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update (SPL4SMAU). (3) SMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants (SPL4SMLM). For each product, SMAP L-band brightness temperature data from descending and ascending half-orbit satellite passes (approximately 6:00 a.m. and 6:00 p.m. local solar time, respectively) are assimilated into a land surface model that is gridded using an Earth-fixed, global, cylindrical 9 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0) projection.VIEW RELATED INFORMATIONhttps://nsidc.org/sites/default/files/multi_spl4smau-v002-userguide.pdfSMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update, Version 2 User GuideVIEW RELATED INFORMATIONhttp://nsidc.org/data/smap/index.htmlSMAP Data at NASA NSIDC DAACVIEW RELATED INFORMATIONhttp://nsidc.org/data/smap/validation/val-data.htmlSMAP Validation Data at NASA NSIDC DAACPROJECT HOME PAGEhttp://smap.jpl.nasa.gov/SMAP Web Site at the Jet Propulsion LaboratoryVIEW RELATED INFORMATIONhttps://www.asf.alaska.edu/smap/SMAP Data at NASA ASF DAACVIEW RELATED INFORMATIONhttp://nsidc.org/data/docs/daac/smap/sp_l4_sm/pdfs/272_L4_SM_RevA_web.pdfAlgorithm Theoretical Basis Document (ATBD)CEOS IDN DIFVERSION 9.92016-04-292026-03-31NSIDCVersion SummaryChanges to this version include: (1) Transitioned to Validated-Stage 2. (2) Using updated SPL1CTB V3 Validated data as input. (3) Minor bug fixes.NSIDCMinor VersionVv2010Changed with Version 2 update. 2015-03-312016-12-071Vv2030No science change. CRID incremented to coincide with the release of the following: enhanced products, including SPL1CTB_E, SPL2SMP_E, SPL3SMP_E, SPL3FTP_E (Version 1); SPL3FTP (Version 1); and SPL2SMP, SPL3SMP (Version 4).2015-03-312017-07-152NSIDCLevel of ServiceNo Data AccessNSIDCFull Dataset CitationReichle, R., De Lannoy, G., Koster, R. D., Crow, W. T. & Kimball, J. S. (2016). <i>SMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update</i>. (SPL4SMAU, Version 2). [Data Set]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. <a href="https://doi.org/10.5067/JJY2V0GJNFRZ">https://doi.org/10.5067/JJY2V0GJNFRZ</a>. [<i><describe subset used if applicable></i>].NSIDCRetiredtrue