The Microwave Integrated Drought Index over pan-tropics

The MIDI is a reliable index in monitoring short-term drought by integrating the precipitation condition index (PCI), soil moisture condition index (SMCI), and temperature condition index (TCI), which are linearly scaled between 0 and 1 using the absolute maximum and minimum values for the same month based on microwave-derived precipitation, soil moisture, and land surface temperature (LST), respectively. The data used include the precipitation datasets of IMERGM (2000 to 2020) and TMPA (1998 to 2019), soil moisture and land surface temperature datasets derived by the Land Parameter Retrieval Model (LPRM) from microwave sensor of TMI (1998 to 2015) and AMSR 2 (2012 to 2020). Here, the PCI, SMCI, and TCI are calculated based on the anomalies of precipitation, soil moisture, and land surface temperature from different sensors. Taken the calculation of precipitation anomalies as an example, the monthly anomalies of the TMPA are obtained from 1998 to 2019, and the monthly anomalies of IMERGM are calculated from 2000 to 2020. Finally, the averaged precipitation anomalies that covered the entire time span from 1998 to 2020 are derived.