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Description

This is the PI-produced JPL SMAP-SSS V5.0, level 2B NRT CAP, validated sea surface salinity (SSS) and extreme winds orbital/swath product from the NASA Soil Moisture Active Passive (SMAP) observatory available in near real-time with a latency of about 6 hours. 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. JPL SMAP V5.0 SSS is based on the newly released SMAP V5 Level-1 Brightness Temperatures (TB). An enhanced calibration methodology has been applied to the brightness temperatures, which improves absolute radiometric calibration and reduces the biases between ascending and descending passes. The improved SMAP TB Level 1 TB will enhance the use of SMAP Level-1 data for other applications, such as sea surface salinity and winds. The JPL SMAP-SSS L2B CAP NRT product includes data for a range of parameters: derived SMAP sea surface salinity, SSS uncertainty and wind speed/direction data for extreme winds, brightness temperatures for each radiometer polarization, ancillary reference surface salinity, ice concentration, wind and wave height data, quality flags, and navigation data. Each data file covers one 98-minute orbit (15 files per day). Data begins on April 1,2015 and is ongoing, with a 6 hour latency in processing and availability. Observations are global in extent and provided at 25km swath grid with an approximate spatial resolution of 60 km.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.

Product Summary

Platforms
SMAP
Instruments
SMAP L-BAND RADIOMETER
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Spatial Resolution
25000 Meters x 25000 Meters
Geographic Region
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2015-04-01
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C2208418228-POCLOUD
Data State
ACTIVE
Number of Files/Granules
50931
Processing Level
2
Published
Updated
Science Keywords
Salinity

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

NASA/JPL. (2020). JPL SMAP Level 2B Near Real-time CAP Sea Surface Salinity V5.0 Validated Dataset [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/SMP50-2NOCS Date Accessed: 2025-12-14

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
anc_dir NCEP wind direction (oceanographic convention) Degrees float -9999 -180 to 180 1
anc_spd 10 meter NCEP wind speed (scaled by 1.03) Meters/second float -9999 0 to 100 1
anc_sss HYCOM salinity PSU float -9999 0 to 45 1
anc_sst NOAA Optimum Interpolation sea surface temperature Degrees kelvin float -9999 0 to 340 1
anc_swh NOAA WaveWatch III significant wave height Meters float -9999 0 to 25 1
antazi_aft Antenna azimuth angle aft look Degrees float -9999 0 to 360 1
antazi_fore Antenna azimuth angle fore look Degrees float -9999 0 to 360 1
azi_aft Cell azimuth angle aft look Degrees float -9999 -180 to 180 1
azi_fore Cell azimuth angle fore look Degrees float -9999 -180 to 180 1
ice_concentration Ice concentration N/A float -9999 0 to 1 1
inc_aft Cell incidence angle aft look Degrees float -9999 0 to 90 1
inc_fore Cell incidence angle fore look Degrees float -9999 0 to 90 1
land_fraction_aft Average land fraction for aft look N/A float -9999 0 to 1 1
land_fraction_fore Average land fraction for fore look N/A float -9999 0 to 1 1
lat latitude Degrees float -9999 -90 to 90 1
lon longitude Degrees float -9999 -180 to 180 1
nedt_h_aft Aggregated noise equivilent Delta T for H-pol aft look Degrees kelvin float -9999 0 to 3 1
nedt_h_fore Aggregated noise equivilent Delta T for H-pol fore look Degrees kelvin float -9999 0 to 3 1
nedt_v_aft Aggregated noise equivilent Delta T for V-pol aft look Degrees kelvin float -9999 0 to 3 1
nedt_v_fore Aggregated noise equivilent Delta T for V-pol fore look Degrees kelvin float -9999 0 to 3 1
num_ambiguities Number of wind vector ambiguties N/A ubyte 0 N/A 1
n_h_aft Number of L1B TBs aggregated into H-pol aft look N/A ubyte 0 N/A 1
n_h_fore Number of L1B TBs aggregated into H-pol fore look N/A ubyte 0 N/A 1
n_v_aft Number of L1B TBs aggregated into V-pol aft look N/A ubyte 0 N/A 1
n_v_fore Number of L1B TBs aggregated into V-pol fore look N/A ubyte 0 N/A 1
quality_flag Quality flag N/A ushort 65535 N/A 1
row_time Approximate observation time for each row UTC seconds of day float N/A 0 to 86400 1
smap_ambiguity_dir SMAP ambiguity wind direction using ancillary SSS Degrees float -9999 -180 to 180 1
smap_ambiguity_spd SMAP ambiguity wind speed using ancillary SSS Meters/second float -9999 0 to 100 1
smap_high_dir SMAP wind direction using ancillary SSS Degrees float -9999 -180 to 180 1
smap_high_dir_smooth SMAP wind direction using ancillary SSS and DIRTH smoothing Degrees float -9999 -180 to 180 1
smap_high_spd SMAP wind speed using ancillary SSS Meters/second float -9999 0 to 100 1
smap_spd SMAP wind speed Meters/second float -9999 0 to 100 1
smap_sss SMAP sea surface salinity PSU float -9999 0 to 45 1
smap_sss_uncertainty SMAP sea surface salinity uncertainty PSU float -9999 0 to 50 1
tb_h_aft Average brightness temperature for all H-pol aft looks Degrees kelvin float -9999 0 to 340 1
tb_h_bias_adj Brightness temperature bias adjustment for H-pol Degrees kelvin float -9999 -3 to 3 1
tb_h_fore Average brightness temperature for all H-pol fore looks Degrees kelvin float -9999 0 to 340 1
tb_v_aft Average brightness temperature for all V-pol aft looks Degrees kelvin float -9999 0 to 340 1
tb_v_bias_adj Brightness temperature bias adjustment for V-pol Degrees kelvin float -9999 -3 to 3 1
tb_v_fore Average brightness temperature for all V-pol fore looks Degrees kelvin float -9999 0 to 340 1
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