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Full catalog/SMAP_JPL_L3_SSS_CAP_MONTHLY_V5
SMAP_JPL_L3_SSS_CAP_MONTHLY_V5·v5.0·dataset

How salty the sea surface is, monthly (SMAP, JPL version)

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

What it measures. Monthly maps of how salty the ocean surface is, worldwide, along with how uncertain each value is and the wind speed at the surface.

How it's made. Made from the NASA SMAP satellite's radio measurements of the sea surface, combined using JPL's active-passive method and blended with an ocean model, then averaged into a gridded monthly map.

How & where you'd use it. Useful for tracking how rainfall, evaporation, river flow, and melting ice change ocean saltiness over time, which in turn shapes ocean currents and climate patterns like El Nino.

What's measured

OCEANS › OCEAN WINDS › SURFACE WINDSOCEANS › SALINITY/DENSITY › SALINITY › NONE

Coverage & cadence

  • Time span2015-04-01 → 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, level 3, monthly 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. L3 monthly product file variables include: derived SSS with associated uncertainties and wind speed from SMAP and ancillary surface salinity from HYCOM. SMAP data begins on April 1, 2015 and is ongoing, with a 1 month 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 for the surface roughness correction required for the surface salinity retrieval.

Get the data

smap_jpl_l3_sss_cap_monthly_v5_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="SMAP_JPL_L3_SSS_CAP_MONTHLY_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.