Drought Assessment over India using RCMs with Standardized Precipitation Evapotranspiration Index

Regional Climate Models (RCMs) work at finer resolution over a limited region and are presumed to perform better at regional scales. RCMs need thorough evaluation before being used for any climate change impact assessment study due to the biases associated with the observed data. While few studies used RCM outputs for understanding the spatio-temporal variability of precipitation and temperature over India, application of RCMs in drought assessment has been overlooked. Here, the study aims to perform drought analysis using RCMs over India with Standardized Precipitation Evapotranspiration Index (SPEI) as the drought index. About 10 RCMs from the Coordinated Regional Climate Downscaling Experiment program (CORDEX) have been considered in the analysis. To remove the systematic biases, a Quantile based bias correction method has been used. The study evaluated the performance of bias-corrected RCMs to simulate rainfall over India for each grid using the statistical measures such as correlation and Nash-Sutcliffe Efficiency coefficients. The monthly precipitation for all over India was best represented by the experiment LMDz-IITMRegCM4 (Regional Climatic Model version 4). Based on the performance evaluation in the study, ICHEC-EC-EARTH-SMHI-RCA4 and MPI-CSC-REMO2009 were used along with LMDz-IITMRegCM4 for drought assessment over India. The results reveal that for West and North-East zones, the drought frequencies and intensities increase for the periods of 2001-2050 and 2051-2100 with Representative Concentration Pathways (RCP) 4.5 for all three considered RCMs. All over India, the average drought intensities were observed to be increasing for ICHEC-EC-EARTH-SMHI-RCA4 and LMDz-IITMRegCM4 while there is no change for MPI-CSC-REMO2009.