Drought projection in the Indochina Region based on the optimal ensemble subset of CMIP5 models

We explore future changes of temperature, precipitation, and drought characteristics in the Indochina Region (ICR) based on the optimal ensemble subset of global climate models (GCMs) of the Couple Model Intercomparison Project Phase 5 (CMIP5). The optimal ensemble subset is selected from 34 GCMs using an ensemble selection method by focusing on precipitation over ICR. Bias correction procedures for the optimal ensemble subset are examined for drought analysis in ICR. Based on the bias-corrected optimal ensemble subset, mean temperature in ICR is projected to increase around 1.1 °C (0.99 °C) in near future (2011–2040), 2.5 °C (1.8 °C) in mid future (2041–2070), and 4.3 °C (2.2 °C) in far future (2071–2100) time frames under representative concentration pathway 8.5 (RCP8.5) (RCP4.5) scenario. Mean precipitation decreases in the dry season and increases in the wet season. The 3-month Standardized Precipitation Evapotranspiration Index (SPEI-3) projects larger changes of drought characteristics than those of the 3-month Standardized Precipitation Index (SPI-3), especially quite large increases of drought duration, severity, and peak. Based on SPEI-3, the potential increase of severe drought hazard is expected in ICR in the far future period under both scenarios. The most drought-prone areas are detected over Thailand and Cambodia in which the drought characteristics are projected to expand to cover most parts of ICR in the mid and far future. The potentially dry condition over ICR is clearly depicted based on SPEI-3 with more reliable estimation after selecting the optimal ensemble subset and bias correction procedure.