The version 2.0 70km SMAP-SSS, level 2C product is the second release of the validated sea surface salinity orbital/swath data from the NASA Soil Moisture Active Passive (SMAP) observatory produced operationally by Remote Sensing Systems (RSS). There are no changes to the salinity retrieval algorithm with this release, just an increase in the spatial resolution of the data from 40km to 70km to reduce some of the observed noise. The SMAP-SSS L2C product includes data for a range of parameters: derived sea surface salinity (SSS), brightness temperatures for each radiometer polarization, antenna temperatures, collocated wind speed, data and ancillary reference surface salinity data from HYCOM, rain rate, 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 one-month latency in processing and availability. Observations are global in extent and provided at a 0.25 degree x 0.25 degree grid with an approximate spatial resolution of 70km.

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, primarily from WindSat, for the surface roughness correction required for the surface salinity retrieval.