User Notice: SMAP Level-1, -2, -3, and -4 data sets at NSIDC DAAC

Newly re-processed SMAP Level-1, -2, -3, and -4 data sets, accessible through the NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC), contain antenna scan angle (ASA) errors. ASA errors affected a large number of data files between 05 Oct and 23 Nov 2019, as well as a handful of dates within 2020 (04 and 05 Feb, 09 Apr, 30 May, and 18 Jun). These bad data are not currently identified by data quality flags. The ASA errors disrupt the proper geolocation of half-orbits, which may be off by as much as 99 km in the along scan direction. The affected half-orbits are in the Version 5 SPL1BTB product (specifically half-orbits 24977.5 – 25691, 26765 – 26781, 27709 – 27713, 28458~28459, and 28733.5 – 28739.5), but the most recent versions of all upstream products are similarly impacted. The cause of the ASA errors has been identified and all affected products will be reprocessed beginning in March, 2021. Current reprocessing of the Level-4 data sets will pause until the ASA errors have been corrected in downstream products.

Access to the data and documentation is provided on the data set web page at the NSIDC DAAC: https://nsidc.org/data/smap/smap-data.html

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