2026-08-18T15:47:57Zhttp://nsidc.org/api/dataset/metadata/oaioai:nsidc.org/SPL3SMP.0052026-03-30T20:16:37Zcumulusretirednasa_nsidc_daac
SPL3SMP.005SMAP L3 Radiometer Global Daily 36 km EASE-Grid Soil MoistureO'Neill, P. E., Chan, S., Njoku, E. G., Jackson, T. & Bindlish, R.SMAP L3 Radiometer Global Daily 36 km EASE-Grid Soil Moisture2018-06-06Boulder, Colorado USANASA NSIDC DAAC: NASA National Snow and Ice Data Center Distributed Active Archive Center5false10.5067/ZX7YX2Y2LHEBhttps://nsidc.org/sites/default/files/documents/user-guide/spl3smp-v005-userguide.pdfSPL3SMPTechnical ContactNSIDCUser Servicesnsidc@nsidc.org1-303-492-61991-303-492-2468CIRES, 449 UCBUniversity of ColoradoBoulderCO80309-0449USAEARTH SCIENCESPECTRAL/ENGINEERINGMICROWAVEBRIGHTNESS TEMPERATURE EARTH SCIENCELAND SURFACESOILSSOIL MOISTURE/WATER CONTENT Climatology/Meteorology/AtmosphereGeoscientific InformationEASE-Grid SM-projectSMAP-projectSMAP-project-L3SMAP L-BAND RADIOMETERSMAP L-Band RadiometerSMAPSoil Moisture Active and Passive Observatory2015-03-312019-08-12deprecated-85.04485.044-180180GEOGRAPHIC REGIONGLOBAL LAND36 km36 km1 daySMAP products provide multiple means to assess quality. Each product contains bit flags, uncertainty measures, and file-level metadata that provide quality information. For information regarding the specific bit flags, uncertainty measures, and file-level metadata contained in this product, refer to the Data Fields and Metadata Fields documents.
Each HDF5 file contains metadata with Quality Assessment (QA) metadata flags that are set by the Science Data Processing System (SDS) at the JPL prior to delivery to NSIDC. A separate metadata file with an .xml file extension is also delivered to NSIDC with the HDF5 file; it contains the same information as the file-level metadata.
A separate QA file with a .qa file extension is also associated with each data file. QA files are ASCII text files that contain statistical information in order to help users better assess the quality of the associated data file.
If a product does not fail QA, it is ready to be used for higher-level processing, browse generation, active science QA, archive, and distribution. If a product fails QA, it is never delivered to NSIDC DAAC.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/JPL/SMAPNASA 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 ColoradoBoulderCO80309-0449USAHTTPS24 MBHDF5Brodzik, 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. https://dx.doi.org/10.3390/ijgi3031154.
Brodzik, 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. https://dx.doi.org/10.3390/ijgi1010032.
Chan, S., R. Bindlish, P. O'Neill, E. Njoku, T. Jackson, A. Colliander, F. Chen, M. Mariko, S. Dunbar, J. Piepmeier, S. Yueh, D. Entekhabi, M. Cosh, T. Caldwell, J. Walker, X. Wu, A. Berg, T. Rowlandson, A. Pacheco, H. McNairn, M. Thibeault, J. Martinez-Fernandez, A. Gonzalez-Zamora, M. Seyfried, D. Bosch, P. Starks, D. Goodrich, J. Prueger, M. Palecki, E. Small, M. Zreda, J. Calvet, W. Crow, and Y. Kerr. 2016. Assessment of the SMAP Passive Soil Moisture Product. IEEE Trans. Geosci. Remote Sens. 54(8):4994-5007. https://dx.doi.org/10.1109/TGRS.2016.2561938.
Chan, S. K., R. Bindlish, P. O'Neill, T. Jackson, E. Njoku, S. Dunbar, J. Chaubell, J. Piepmeier, S. Yueh, D. Entekhabi, A. Colliander, F. Chen, M. H. Cosh, T. Caldwell, J. Walker, A. Berg, H. McNairn, M. Thibeault, J. Martiinez-Fernandez, F. Uldall, M. Seyfried, D. Bosch, P. Starks, C. Holifield Collins, J. Prueger, R. van der Velde, J. Asanuma, M. Palecki, E. E. Small, M. Zreda, J. Calvet, W. T. Crow, Y. Kerr, 2018. Development and assessment of the SMAP enhanced passive soil moisture product, Remote Sensing of Environment, 204: 931-941. https://doi.org/10.1016/j.rse.2017.08.025.
Jet Propulsion Laboratory (JPL). "SMAP Instrument." JPL SMAP Soil Moisture Active Passive. https://smap.jpl.nasa.gov/observatory/instrument/ [20 August 2015].
NASA EOSDIS Land Processes DAAC. 2015. Land Water Mask Derived from MODIS and SRTM L3 Global 250m SIN Grid. Version 005. NASA EOSDIS Land Processes DAAC, USGS Earth Resources Observation and Science (EROS) Center, Sioux Falls, SD. (https://lpdaac.usgs.gov/dataset_discovery/modis/modis_products_table/mod44w), [20 August 2015].
O'Neill, P. E., E. G. Njoku, T. J. Jackson, S. Chan, and R. Bindlish. 2016. SMAP Algorithm Theoretical Basis Document: Level 2 & 3 Soil Moisture (Passive) Data Products. SMAP Project, JPL D-66480, Jet Propulsion Laboratory, Pasadena, CA. (PDF, 3.3 MB; see Technical References)
Owe, M., De Jeu, R. A. M., and Walker, J. P. 2015. A Methodology for Surface Soil Moisture and Vegetation Optical Depth Retrieval Using the Microwave Polarization Difference Index. IEEE Transactions on Geoscience and Remote Sensing, 39(8):1643–1654, 2001.
Piepmeier, J. R., D. G. Long, and E. G. Njoku. 2008. Stokes Antenna Temperatures. IEEE Trans. Geosci. Remote Sens. 46(2):516-527.
This Level-3 (L3) soil moisture product provides a composite of daily estimates of global land surface conditions retrieved by the Soil Moisture Active Passive (SMAP) passive microwave radiometer. SMAP L-band soil moisture data are resampled to a global, cylindrical 36 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0).VIEW RELATED INFORMATIONhttps://nsidc.org/sites/default/files/documents/user-guide/spl3smp-v005-userguide.pdfSMAP L3 Radiometer Global Daily 36 km EASE-Grid Soil Moisture, Version 5 User GuideCEOS IDN DIFVERSION 9.92018-06-062026-03-30NSIDCVersion SummaryChanges to this version include: (1) Level-1B water-corrected brightness temperatures are used in passive soil moisture retrieval. This procedure corrects for anomalous soil moisture values seen near coastlines in the previous version and should result in less rejected data due to waterbody contamination. Five new data fields accommodate this correction: grid_surface_status, surface_water_fraction_mb_h, surface_water_fraction_mb_v, tb_h_uncorrected, and tb_v_uncorrected. (2) Improved depth correction for effective soil temperature used in passive soil moisture retrieval; new results are captured in the surface_temperature data field. This correction reduces the dry bias seen when comparing SMAP data to in situ data from the core validation sites. (3) Frozen ground flag updated to reflect improved freeze/thaw detection algorithm, providing better accuracy; new results are captured in bit 7 of surface_flag.NSIDCMinor VersionR16000Changed with Version 5 update. Changes include: (1) Level-1B water-corrected brightness temperatures are used in passive soil moisture retrieval. This procedure corrects for anomalous soil moisture values seen near coastlines in the previous version and should result in less rejected data due to waterbody contamination. Five new data fields accommodate this correction: grid_surface_status, surface_water_fraction_mb_h, surface_water_fraction_mb_v, tb_h_uncorrected, and tb_v_uncorrected. (2) Improved depth correction for effective soil temperature used in passive soil moisture retrieval; new results are captured in the surface_temperature data field. This correction reduces the dry bias seen when comparing SMAP data to in situ data from the core validation sites. (3) Frozen ground flag updated to reflect improved freeze/thaw detection algorithm, providing better accuracy; new results are captured in bit 7 of the surface_flag.2015-03-312018-06-131R16010No science change. CRID incremented to coincide with updates to L1-L3 radiometer products.2015-03-312018-11-062R16020Changes to this version constitute a bug fix. The surface-uncorrected horizontally polarized brightness temperature data value was inadvertently assigned to the surface-uncorrected vertically polarized brightness temperature data field. This has been corrected.2015-03-312018-12-313R16022No science change. CRID incremented to coincide with an update to the radiometer reflector ancillary file for January through December 2019.2018-12-312019-08-124NSIDCSpatial Reference SystemsEPSG:6933WGS 84 / NSIDC EASE-Grid 2.0 GlobalNSIDCLevel of ServiceNo Data AccessNSIDCFull Dataset CitationO'Neill, P. E., Chan, S., Njoku, E. G., Jackson, T. & Bindlish, R. (2018). <i>SMAP L3 Radiometer Global Daily 36 km EASE-Grid Soil Moisture</i>. (SPL3SMP, Version 5). [Data Set]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. <a href="https://doi.org/10.5067/ZX7YX2Y2LHEB">https://doi.org/10.5067/ZX7YX2Y2LHEB</a>. [<i><describe subset used if applicable></i>].NSIDCRetiredtrue