Past and future trends of hydroclimatic intensity over the Indian monsoon region

Abstract

AbstractThe hydroclimatic intensity index (HY‐INT) is a single index that quantitatively combines measures of precipitation intensity and dry spell length, thus providing an integrated response of the hydrological cycle to global warming. The HY‐INT index is a product of the precipitation intensity (PINT, intensity during wet days) and dry spell length (DSL). Using the observed gridded rainfall data sets of 1951–2010 period, the changes in HY‐INT, PINT, and DSL over the Indian monsoon region have been examined in addition to changes in maximum consecutive dry days (MCD). We have also considered 10 Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models for examining the changes in these indices during the present‐day and future climate change scenarios. For climate change projections, the Representative Concentration Pathway (RCP) 4.5 scenario was considered. The analysis of observational data during the period 1951–2010 suggested an increase in DSL and MCD over most of central India. Further, statistically significant (95% level) increase in HY‐INT is also noted during the period of 1951–2010, which is mainly caused due to significant increase in precipitation intensity. The CMIP5 model projections of future climate also suggest a statistically significant increase in HY‐INT over the Indian region. Out of the 10 models considered, seven models suggest a consistent increase in HY‐INT during the period of 2010–2100 under the RCP4.5 scenario. However, the projected increase in HY‐INT is mainly due to increase in the precipitation intensity, while dry spell length (DSL) showed little changes in the future climate.