The SMOS Level-4 SMAP Compatible Brightness Temperatures (BT) product provides an unbiased version of the SMOS Level-3 BT with respect to the SMAP Enhanced Level-3 BT. This data set is self-sufficient but it can also be used along with the SMAP Level-3 Enhanced BT for applications for which spatial coverage and revisit frequency of the BT measurements are essentials.

The drought index (DI) is computed using SMOS derived root zone soil moisture (RZSM) monthly fields. The concept is to consider 13 years of SMOS data (2010-2022). The RZSM monthly mean and max over the period is iused to compute a soil water deficit to remove seasonal variability. from teh soil water deficit a soil moisture drought index is computed .The range of values for SMDI lies between -4 to +4, with -4 representing extreme dry conditions and +4 representing extreme wet conditions.