The PO.DAAC is pleased to announce the availability of the PI-produced JPL V4.3 SMAP Sea Surface Salinity (SSS) and extreme winds data, which includes Level-2B (L2B) and Level 3 (L3) standard datasets based on the JPL Combined Active-Passive (CAP) algorithm applied to data from the NASA Soil Moisture Active Passive (SMAP) observatory. An associated near real-time L2B dataset is also available as a rolling store with a latency of about 4.3 hours. For science applications, use of the standard products is strongly advised. We also recommend the use of the V4.3 forward stream data over the prior version, which is deprecated and will be retired within the next 6 months.
Improvements with V4.3 include: 1) New residual TB calibration which removes the ascending/descending bias issue observed for version 4.2; 2) Slightly modified criteria for aggregation from L2B to L3 based on TB for V-pol minus TB for H-pol. Data begins on 1 April 2015 and is ongoing. Datasets comprising this release include the L2B orbital data and two L3 mapped, global coverage salinity datasets: an 8-day running mean dataset based on the repeat orbit of the SMAP mission, along with a monthly average dataset. The L2B data are provided on a 25 km swath grid with the L3 data are gridded at 0.25o x 0.25o. The spatial feature resolution of all four datasets is approximately 60 km. The L2B dataset is in HDF5 format, and the L3 datasets are in netCDF4 file format. All datasets are CF/ACDD metadata standards compliant, and include estimated SSS uncertainty fields.
The JPL SMAP-SSS CAP V4.3 datasets are described, discoverable, and accessible via the PO.DAAC data portal, as are the associated technical documentation. General information regarding the SMAP mission is available from the mission website and also via PO.DAAC’s SMAP and salinity webpages.
Fore, A.G, S.H. Yueh, W. Tang, B.W. Stiles, and A.K. Hayashi (2016). Combined Active/Passive Retrievals of Ocean Vector Wind and Sea Surface Salinity With SMAP. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 54, NO. 12. p.7396-7404. DOI: 10.1109/TGRS.2016.2601486
Fore, A., S. Yueh, W. Tanh, A. Hayashi, 2020: JPL SMAP Ocean Surface Salinity Products [Level 2B, Level 3 Running 8-day, Level 3 Monthly], Version 4.3 validated release. Jet Propulsion Laboratory, Pasadena, CA, USA.