Dynamic Regional Climate Models (RCMs) work at fine resolution for a limited region and hence they are presumed to simulate regional climate better than General Circulation Models (GCMs). Simulations by RCMs are used for impacts assessment, often without any evaluation. There is a growing debate on the added value made by the regional models to the projections of GCMs specifically for the regions like, United States and Europe. Evaluation of RCMs for Indian Summer Monsoon Rainfall (ISMR) has been overlooked in literature, though there are few disjoint studies on Indian monsoon extremes and biases. Here we present a comprehensive study on the evaluations of RCMs for the ISMR with all its important characteristics such as, seasonal rainfall patterns, onset and intra-seasonal oscillations,. We evaluate nine regional simulations from Coordinated Regional Climate Downscaling Experiment (CORDEX) and compare them with their host Coupled Model Intercomparison Project-5 (CMIP5) GCM projections. We do not find any consistent improvement in the RCM simulations with respect to their host GCMs for any of the characteristics of Indian monsoon. We also find that the simulations of the ISMR characteristics by a good number of RCMs, are worse than those of their host GCMs. These results highlight the need for proper evaluation before utilizing regional models for impacts assessment and subsequent policy making for sustainable climate change adaptation.

Reference: Singh, S., Ghosh S., Sahana, A. S., Vittal, H. and Karmakar, S. (2016), Do Dynamic Regional Models add Value to the Global Model Projections of Indian Monsoon?, Climate Dynamics, doi:10.1007/s00382-016-3147-y.

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