The SMAP Project performs annual reprocessing of all its science data products based on improvements in the algorithms and supporting information. As part of this routine reprocessing, the SMAP Science Data System (SDS) has now released new versions of the following four Level-4 data products, accessible through the NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC):
SMAP L4 Global 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants, Version 6
SMAP L4 Global Daily 9 km EASE-Grid Carbon Net Ecosystem Exchange, Version 6
For all Level-4 data products, data from the entire time series (31 March 2015 to present) are now available.
The main changes in the Level-4 soil moisture data products are:
- The rescaling of all L4_SM precipitation forcing units is now based on the climatology of the NASA IMERG-0FINAL (Version 06B) product. Where this climatology is not available (primarily poleward of 60ºN latitude), the Global Precipitation Climatology Project (GPCP) v2.3 product is used instead.
- The L4_SM precipitation forcing outside North America and the high latitudes is now corrected to match the daily totals from the NASA IMERG (Version 06B) product.
- A minor change in a parameter related to the multiplicative, lognormal precipitation perturbations and shortwave radiation forcing, to reduce minor bias between perturbed and unperturbed forcing.
- The brightness temperature scaling parameters in the updated Level-4 soil moisture algorithm are based on six years of SMAP observations (April 2015 – March 2021).
Changes to the Level-4 carbon net exchange data product primarily reflect Biome Properties Look-up Table (BPLUT) recalibration and soil organic carbon (SOC) re-initialization in response to updates to the upstream input datasets.
Data set DOIs:
https://doi.org/10.5067/MWAFPGI1KMMH
https://doi.org/10.5067/08S1A6811J0U