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Full catalog/SMAP_JPL_L3_SSS_CAP_8DAY-RUNNINGMEAN_V5
SMAP_JPL_L3_SSS_CAP_8DAY-RUNNINGMEAN_V5·v5.0·dataset

How salty the sea surface is (SMAP, 8-day average)

JPL SMAP Level 3 CAP Sea Surface Salinity Standard Mapped Image 8-Day Running Mean V5.0 Validated Dataset
ocean NASA POCLOUD Level 3 netCDF-4
In plain English

What it measures. Maps of how salty the ocean surface is worldwide, smoothed over an 8-day window, along with related wind speed and uncertainty estimates. Grid cells are about 60 kilometers across.

How it's made. Produced from the SMAP satellite's microwave brightness-temperature readings using a JPL retrieval method, then averaged over rolling 8-day periods onto a global grid.

How & where you'd use it. Salinity shapes ocean currents and the water cycle, so this product supports climate research, ocean circulation studies, and tracking freshwater patterns at sea.

What's measured

OCEANS › SALINITY/DENSITY › SALINITY › NONEOCEANS › OCEAN WINDS › SURFACE WINDS

Coverage & cadence

  • Time span2015-04-30 → ongoing
  • Measured bySMAP (SMAP L-BAND RADIOMETER)
  • Processing levelLevel 3
  • Spatial extent-180, -90, 180, 90
  • FormatsnetCDF-4
  • StatusACTIVE

What you can do with it

  • Watch sea-surface temperature and marine heatwaves
  • Spot algal blooms and ocean-colour shifts
  • Support fisheries and coastal monitoring
Official description

This is the PI-produced JPL SMAP-SSS V5.0 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. 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. 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.

Get the data

smap_jpl_l3_sss_cap_8day-runningmean_v5_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="SMAP_JPL_L3_SSS_CAP_8DAY-RUNNINGMEAN_V5",
    version="5.0",
    bounding_box=(-122.5, 37.2, -121.8, 37.9),  # your area (W,S,E,N)
    temporal=("2024-01-01", "2024-12-31"),       # your dates
)
files = earthaccess.open(results)   # stream straight from POCLOUD
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.