SMAP V6.0: 8-Day Running Mean Global Sea Surface Salinity

NASA's SMAP satellite, launched January 31, 2015, provides global sea surface salinity measurements with a 40km resolution and an 8-day repeat cycle. The Version 6.0 validated dataset applies corrections for radar operation biases, look-angle dependencies, and high-latitude salinity errors. Each netCDF-4 file contains an 8-day running mean of salinity, its uncertainty, rain-filtered data, collocated wind speed, and HYCOM model reference salinity.

Use Cases

• Monitoring large-scale salinity patterns and freshwater fluxes into oceans based on global 40km resolution SSS maps.
• Validating and assimilating satellite-derived salinity into ocean circulation models using the ancillary HYCOM reference data.
• Analyzing the impact of rainfall and wind on surface salinity retrievals using the rain-filtered SSS and collocated wind speed variables.
• Investigating long-term trends in ocean salinity for climate change studies, leveraging the continuous record from April 2015 onward.
• Correcting for sun-glint effects in salinity retrievals using the revised flagging methodology in Version 6.0.

Strengths

• Provides a continuous, ongoing global time series starting on April 1, 2015.
• Version 6.0 includes specific corrections for early mission biases, look-angle dependencies, and high-latitude errors.
• Data has a known latency of about 7 days after the end of each 8-day averaging period.
• Cross-platform presence on NASA Earthdata and Data.gov signals its importance as a validated, authoritative product.

Limitations

• Spatial resolution is approximate (40km), which may limit fine-scale coastal or mesoscale studies.
• The scatterometer malfunction on July 7, 2015, necessitates reliance on collocated wind speed data from other sources like WindSat.
• Column names and precise data volume (rows/size) are not provided in the available metadata.

Provenance

Source

Remote Sensing Systems (RSS), sponsored by the NASA Ocean Salinity Science Team.

Collection Method

Derived from the NASA Soil Moisture Active Passive (SMAP) satellite mission's L-band radiometer.

Time Range

April 1, 2015 to present (ongoing).

Freshness

Last updated metadata date is 2026-04-09 22:25:41.126228.

Geography

Global ocean coverage.