Thursday, February 22, 2018

The PO.DAAC is pleased to announce the availability of the PI-produced JPL V4.0 SMAP Sea Surface Salinity (SSS) and extreme winds data.  This release includes Level-2B and Level 3 products based on the JPL Combined Active-Passive (CAP) algorithm applied to data from the NASA Soil Moisture Active Passive (SMAP) observatory. Data begins April 1, 2015 and is ongoing. Improvements with this version include: addition of estimated SSS uncertainty fields, improvement of TB correction for high latitudes, modification of the land correction range to 1000 km from coast, change of the ancillary wind source from NCEP GDAS to NCEP GFS resulting in significant improvements in SSS retrievals near storms, extension of the range of SSS retrievals to 45 PSU, and SSS retrievals also for large inland seas.

Data sets comprising this release include the Level 2B (L2B) orbital data and two Level 3 (L3) mapped salinity products: an 8-day running mean product based on the repeat orbit of the SMAP mission, along with a monthly average product.  Both are global in extent, and the L2B is provided on a 25 km swath grid while the L3s are gridded at 0.25o x 0.25o. The spatial resolution of all three products is approximately at 60 km.  The L2B product is in HDF5 format, and the L3 products are in netCDF4 file format.  All products are CF/ACDD metadata standards compliant.

The JPL SMAP-SSS CAP V4.0 data sets are described and discoverable via the PO.DAAC data portal.   Access to these data is via PO.DAAC’s public FTP site ftp//  The data can also be accessed via OPeNDAP, and PODAAC-WS, and are also be accessible via THREDDS and LAS.

The SMAP Algorithm Theoretical Basis Document (ATBD), validation analysis and file specification document together with other primary technical documentation, are available from the FTP site together with reader software.  General information regarding the SMAP mission is available from the mission website and also via PO.DAAC’s SMAP  and salinity webpages.

Should you have any questions, please contact us at: