Drought Assessment over India using RCMs with Standardized Precipitation
Evapotranspiration Index
Abstract
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.