Friday, June 7, 2024

The PO.DAAC is pleased to announce the availability of the version 5.3 SMAP Sea Surface Salinity (SSS) evaluation datasets from Remote Sensing Systems (RSS) and sponsored by the NASA Ocean Salinity Science Team. The SMAP satellite was launched on 31 January 2015 with 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 1000 km swath, SMAP achieves global coverage in approximately 3 days, but has an exact orbit repeat cycle of 8 days.

The evaluated Version 5.3 is identical to the Version 6.0 validated release with the exception that Version 5.3 uses the Version 5 L1B antenna temperatures (TA) as input. The V6 L1B TA uses a lower TA threshold for RFI exclusion, thus excluding more potential RFI contamination. Until the full back-processing of V6.0 is complete, the evaluation Version 5.3 can and should be used instead. Version 5.3 has been processed from the beginning of the SMAP mission to the end of 2023.

This release includes level 2C, level 3 mapped monthly and 8-day running mean datasets. All products are in the netCDF-4 file format and are CF/ACDD metadata conventions compliant. Similar to prior releases, the standard product is the smoothed salinity product with a spatial resolution of approximately 70 km, and the 40-km fields are included for experimental purposes. For most open ocean applications, the standard fields are the best used since they have significantly lower noise than the 40-km data. Please note that no SMAP salinity data are available from 08/09/2022 – 10/06/2022 and 06/19/2019 – 07/23/2019, as SMAP was not in science mode or flying in its nominal orbit during that time.

The SMAP RSS datasets and the associated technical documentation are described, discoverable, and accessible via the PO.DAAC data portal. Users are recommended to download the data using the podaac-data-subscriber. We also encourage users to visit PO.DAAC Cloud Data Page for detailed information about how to access the data from NASA Earthdata Cloud. General information regarding the SMAP mission is available from the mission website.



Meissner, T., F.J. Wentz, and D.M. Le Vine, 2018, The Salinity Retrieval Algorithms for the NASA Aquarius Version 5 and SMAP Version 3 Releases, Remote Sensing 10, 1121, doi:10.3390/rs10071121.

Technical Report:

NASA/RSS SMAP Salinity: Version 6.0 Validated Release


T. Meissner, F. J. Wentz, A. Manaster, R. Lindsley, M. Brewer, M. Densberger, 2024: Remote Sensing Systems SMAP Ocean Surface Salinities [Level 2C, Level 2C NRT, Level 3 Running 8-day, Level 3 Monthly], Version 6.0 validated release. Remote Sensing Systems, Santa Rosa, CA, USA. doi: 10.5067/SMP60-2SOCS,10.5067/SMP60-2SNRT,10.5067/SMP60-3SPCS,10.5067/SMP60-3SMCS.

Comments/Questions? Please contact or visit the PO.DAAC on Earthdata Forum.