Spatial distribution of precipitation extremes over Rajasthan using CORDEX data

Abstract

ABSTRACT Rainfall is one of the key climatic variables that affect the spatial and temporal patterns of water availability. One of the challenges posed by climate change is identification and quantification of extreme precipitation events. This study aims to analyse the extreme precipitation events for historical (1971–2000), near-future (NF) (2021–2050) and far-future (FF) (2070–2099) over Rajasthan. Non-parametric tests (Mann–Kendall [MK] test, modified MK and Sen’s slope estimator) are used for trend analysis. The precipitation extreme indices R50, R25, R99p and R95p were used to calculate the extreme events based on historical and future outputs of regional climate models (RCMs) REMO 2009 (driving global climate model [GCM] ‘MPI-ESM-LR’) and RegCM4 (driving GCM ‘CCCma-CanESM2’) from Coordinated Regional Downscaling Experiment (CORDEX). The performances of both RCMs were evaluated against observed (Indian Meteorological Department [IMD]) daily precipitation data. The observed historical (IMD) data show that R99p threshold values are slightly overestimated by REMO 2009 and underestimated by RegCM4. The indices R25 and R95p simulated by REMO 2009 show a significant decreasing trend in FF of RCP8.5 scenario. Overall REMO 2009 performed better in simulating the key features of the spatial distribution of R95p (R99p) threshold and annual average frequency of R25 (R50) in historical period as compared to RegCM4. Abbreviations: NF: Near-future; FF: Far-future; MK: Mann-Kendall; RCM: Regional climate model; GCM: Global climate model; EPT: Extreme precipitation threshold; IMD: Indian Meteorological Department; CORDEX: Coordinated Regional Climate Downscaling Experiment