JPL SMAP Level 3 CAP Sea Surface Salinity Standard Mapped Image 8-Day Running Mean V4.2 Validated Dataset

JPL SMAP Level 3 CAP Sea Surface Salinity Standard Mapped Image 8-Day Running Mean V4.2 Validated Dataset
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DescriptionThis is the PI-produced JPL SMAP-SSS V4.2 CAP, 8-day running mean, level 3 mapped, sea surface salinity (SSS) product from the NASA Soil Moisture Active Passive (SMAP) observatory. It is based on the Combined Active-Passive (CAP) retrieval algorithm developed at JPL originally in the context of Aquarius/SAC-D and now extended to SMAP. SMAP-SSS V4.2 is a complete reprocessing of the entire mission series following on from the reprocessing of the source L1B-TB data by the SMAP mission on 6/4/2018. Updates in v4.2 include: improvement in the brightness temperature (TB) calibration using an adjusted reflector emissivity, inclusion of a Sea Surface Temperature (SST) dependent flat surface emissivity model, use of updated land correction tables, and inclusion of averaged ice concentration ancillary data in the v4.2 product. Daily data files for this L3 product are based on SSS averages spanning an 8-day moving time window. Associated file variables include: derived SSS with associated uncertainties and wind speed data from SMAP, ancillary ice concentration and HYCOM surface salinity data. SMAP data begins on April 1, 2015 and is ongoing, with a 7-day latency in processing and availability. L3 products are global in extent and gridded at 0.25degree x 0.25degree with an approximate spatial resolution of 60km. The SMAP satellite is in a near-polar orbit at an inclination of 98 degrees and an altitude of 685 km. It has an ascending node time of 6 pm and is sun-synchronous. With its 1000km swath, SMAP achieves global coverage in approximately 3 days, but has an exact orbit repeat cycle of 8 days. On board instruments include a highly sensitive L-band radiometer operating at 1.41GHz and an L-band 1.26GHz radar sensor providing complementary active and passive sensing capabilities. Malfunction of the SMAP scatterometer on 7 July, 2015, has necessitated the use of collocated wind speed for the surface roughness correction required for the surface salinity retrieval.
Dataset TypeOPEN
MeasurementOceans > Ocean Winds > Surface Winds
Oceans > Salinity/Density > Salinity > None
Processing Level3
CoverageRegion: Global
Northernmost Latitude: 90 degrees
Southernmost Latitude: -90 degrees
Westernmost Longitude: -180 degrees
Easternmost Longitude: 180 degrees
Time Span: 2015-Mar-31 to Present
ResolutionSpatial Resolution: 0.6 degrees (Latitude) x 0.6 degrees (Longitude)
Temporal Resolution: 8 Day
ProjectionType: Gridded
Ellipsoid: WGS 84
Latency192 hours
Name: NASA Soil Moisture Active Passive (SMAP) (SMAP)
Orbit Period: 98.5 minutes
Inclination Angle: 98 degrees
Ascending Node: 1970-Jan-01 00:00:00
Name: SMAP L-Band Radiometer (SMAP_RADIOMETER)
Swath Width: 1000 km
Description: L-Band 1.41 GHz Radiometer aboard the NASA SMAP (Soil Moisture Active Passive) satellite observatory

ProjectSoil Moisture Active Passive (SMAP) Sea Surface Salinity (SSS) (SMAP-SSS)
Data ProviderCreator: JPL Climate Oceans and Solid Earth group
Release Place: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA91109, USA
Release Date: 2019-Jan-24
Keyword(s)JPLSMAPSSSV42, L3, Level 3, 8 day running mean, SMAP, SMAP-SSS, Soil Moisture Active, Passive, salinity, polar, sun-synchronous, sss, sea surface, salinity, psu, NASA, project, mission, JPL, CAP, combined active/passive
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User's Guide
Users Guide
JPL CAP SMAP-SSS V4.0 Technical Guide (ATBD, Validation Analysis, Product Format Specification)
Project Materials
JPL CAP SMAP-SSS v4.2 Documentation Package
ATBD, Validation Analysis, Product Specifications, etc
Additional Sites
PO.DAAC SMAP-SSS Mission page
SMAP-SSS Project and Instrument Overview
SMAP Mission Website
NASA SMAP Mission Website
Citation JPL Climate Oceans and Solid Earth group. 2019. JPL SMAP Level 3 CAP Sea Surface Salinity Standard Mapped Image 8-Day Running Mean V4.2 Validated Dataset. Ver. 4.2. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at

For more information see Data Citations and Acknowledgments.

Journal Reference Fore,A.G, S.H. Yueh, W. Tang, B.W. Stiles, and A.K. Hayashi (2016). Combined Active/Passive Retrievals of Ocean Vector Wind and Sea Surface Salinity With SMAP. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 54, NO. 12. p.7396-7404. DOI: 10.1109/TGRS.2016.2601486