This product contains average 10 days & monthly salinity field corrected from land-sea contamination and latitudinal bias, based on L2Q products, mixing ascending and descending orbits.

NOAA STAR produces two lines of gridded 0.02deg super-collated L3S LEO datasets from Low Earth Orbiting (LEO) satellites, one from the NOAA afternoon JPSS (L3S_LEO_PM) and the other from the EUMETSAT mid-morning Metop-FG (L3S_LEO_AM). The L3S_LEO_PM is derived from JPSS satellites (in v2.80, NPP and N20) with VIIRS sensor onboard (0.75km/nadir). The L3S_LEO_PM dataset is produced by aggregating L3U datasets from two JPSS satellites ( https://doi.org/10.5067/GHVRS-3UO28 and https://doi.org/10.5067/GHV20-3UO28 ) and covers from Feb 2012-present. The L3S-LEO-PM data are reported in two files per 24hr interval, one daytime and one nighttime (nominal JPSS local equator crossing times around 01:30/13:30). Data is in NetCDF4 format, compliant with the GHRSST Data Specification version 2 (GDS2). The Near-Real Time (NRT) L3S-LEO data are archived at PO.DAAC with approximately 6 hours latency and then replaced by the Delayed Mode files about 2 months later, with identical file names. In addition to SST, the L3S-LEO files report the location and intensity of thermal fronts. The NRT/DM data are seamlessly stitched with the full-mission Reanalysis (RAN). The ACSPO L3S products are monitored and validated against in situ data in the NOAA iQuam system ( https://www.star.nesdis.noaa.gov/socd/sst/iquam ) in the NOAA SQUAM system ( https://www.star.nesdis.noaa.gov/socd/sst/squam ). Quality of SST imagery, clear-sky mask and thermal fronts is evaluated in the NOAA ARMS system ( https://www.star.nesdis.noaa.gov/socd/sst/arms ). NOAA plans to include data from other afternoon platforms and sensors, such as N21 and Aqua MODIS, into the future releases of the L3S_LEO_PM.

A Group for High Resolution Sea Surface Temperature (GHRSST) gap-free (L4) Sea Surface Temperature (SST) analysis produced daily on an operational basis by the Danish Meteorological Institute (DMI) using an optimal interpolation (OI) approach on a global 0.05 degree grid. Whereas along swath observation data essentially represent the skin or sub-skin SST, the L4 SST product is defined to represent the foundation (SSTfnd). SSTfnd is defined within GHRSST as the temperature at the base of the diurnal thermocline. It is so named because it represents the foundation temperature on which the diurnal thermocline develops during the day. SSTfnd changes only gradually along with the upper layer of the ocean, and by definition it is independent of skin SST fluctuations due to wind- and radiation-dependent diurnal stratification or skin layer response. SSTfnd corresponds to the temperature of the upper mixed layer which is the part of the ocean represented by the top-most layer of grid cells in most numerical ocean models. It is never observed directly by satellites, but it comes closest to being detected by infrared and microwave radiometers during the night, when the previous day's diurnal stratification can be assumed to have decayed. The processing combines night-time GHRSST L2P skin and subskin SST observations from several satellites. The data is inter-calibrated and bias corrected before being merged and interpolated using an optimal interpolation scheme to provide daily gap-free fields. The optimal interpolation scheme uses the previous days analysis as a background field. An ice field from the EUMETSAT OSI-SAF is used to mask out areas with ice.