RSS SMAP L3 Sea Surface Salinity 8-Day Running Mean

RSS SMAP Level-3 Sea Surface Salinity Standard Mapped Image 8-Day Running Mean V6.0 (product ID SMAP_RSS_L3_SSS_SMI_8DAY-RUNNINGMEAN_V6, DOI 10.5067/SMP60-3SPCS) provides daily-updated global sea surface salinity composites from the SMAP Radiometer (L-band 1.41 GHz) on the SMAP mission, covering 2015-04-01 to present.^[1][2] Each file is an 8-day running mean advancing one day at a time, with approximately 7-day latency after the end of the averaging window. The product is mapped to a 0.25-degree equal-angle grid, with an effective spatial resolution of approximately 70 km after smoothing; an experimental 40 km version (sss_smap_40km) is included as a supplemental variable.^[1][3] Key variables include sss_smap (sea surface salinity in psu), sss_ref (HYCOM reference model salinity), ancillary wind speed, SSS uncertainty, and rain rate. The retrieval algorithm is RSS V6.0, released and validated in March 2024, using HYCOM SSS as a first-guess field and rain filtering.^[3] The product is produced by Remote Sensing Systems (RSS) and distributed open access by NASA PO.DAAC in netCDF-4 (CF/ACDD) format.