Evaluation and projection of northeast monsoon precipitation over India under higher warming scenario: a multimodel assessment of CMIP6

An effort is made to investigate future changes in the northeast monsoon rainfall over the Indian region. Before examining the projections, we evaluate the performance of 23 Global Climate Models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6) over a long-term mean during the period (1950-2014). The CMIP6 GCMs successfully capture the regions of low and high precipitation. However, they exhibit varying skills with large spreads. Thus, the ensemble mean of the best five models is adapted to examine their projections of twenty-first-century precipitation changes. The changes are computed for two major time domains, namely, Near Future (NF; 2040-2059) and Far future (FF; 2080-2099) relative to the reference period (HIST; 1995-2014) under the Shared Socioeconomic Pathways (SSP-8.5). The projected precipitation is found to experience continuous changes over most parts of the northeast monsoon regions under the SSP8.5 scenario for all months of the northeast monsoon (NEM) season. However, magnitude and the nature change considerably from month to month variability. A 10-18% increase is noticed in October and November during NF while a similar to 20% decrease is in December. The changes are intensified by two-fold in October and December, while three-fold intensification is noticed in November. The physical basis of the projected change in North East precipitation is investigated. It was found that lower level circulation is found to have a minimal contribution to change in the precipitation. An intensified subtropical westerly jet and its southward shifting lead to enhanced precipitation over southern India.