Evaluating satellite-based precipitation products for spatiotemporal drought analysis

A region's ecosystem, economics, and agriculture are severely harmed by drought. This study investigates meteorological droughts and their assessment through drought indices. We compared the suitability of satellite precipitation data from GPM-IMERG and TRMM with ground-based observations from 17 locations. To assess the severity and to identify the best index for the spatiotemporal analysis of the drought we employed two indices: the Standard Precipitation Index (SPI) and a new satellite-based index the Drought Exceedance Probability Index (DEPI). A thorough analysis of the dry periods identified by DEPI was carried out and later compared with two established metrics for analyzing rainfall patterns: the persistence of monthly rainfall and the correlation of monthly rainfall patterns with one-month auto lag. Evaluation and robust statistical analysis (R, r, RMSE & RSR) were performed for quantitative measure of drought indices performances. Additionally, an assessment of the regularity of drought episodes recorded using the DEPI and SPI reveals a considerable difference in terms of regular dry and mild wet occurrences. Following IMERG-GPM and gauge data comparison analysis between DEPI and SPI, DEPI offered superior agreement with gauge data. The outcomes of this analysis offer valuable insights for selecting the best satellite product for spatiotemporal drought analysis.