Assessment of two versions of regional climate model in simulating the Indian Summer Monsoon over South Asia CORDEX domain

• Published in: Climate dynamics Vol. 50; no. 7-8; pp. 3049 - 3061
• Main Authors: Pattnayak, K. C., Panda, S. K., Saraswat, Vaishali, Dash, S. K.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2018; Springer; Springer Nature B.V
• Subjects: Analysis; Annual rainfall; Annual variations; Climate change; Climate models; Climatology; Computer simulation; Earth and Environmental Science; Earth Sciences; Fluctuations; Flux; Future climates; Geophysics/Geodesy; Irradiance; Moisture; Moisture flux; Monsoon circulation; Monsoon onset; Monsoon rainfall; Monsoons; Oceanography; Performance assessment; Precipitation variability; Rain; Rainfall; Regional analysis; Regional climates; Solar constant; Solar irradiance; Somali Jet; Stratosphere; Summer; Summer circulation; Summer monsoon; Tropical climate; Tropical easterly jet; Weather forecasting; Wind; India; South Asia; Moisture flux; Surface net downward shortwave flux; CORDEX; RegCM4.2; Indian summer monsoon; RegCM4.3; Rainfall homogenous zones
• ISSN: 0930-7575; 1432-0894
• DOI: 10.1007/s00382-017-3792-9

This study assess the performance of two versions of Regional Climate Model (RegCM) in simulating the Indian summer monsoon over South Asia for the period 1998 to 2003 with an aim of conducting future climate change simulations. Two sets of experiments were carried out with two different versions of RegCM (viz. RegCM4.2 and RegCM4.3) with the lateral boundary forcings provided from European Center for Medium Range Weather Forecast Reanalysis (ERA-interim) at 50 km horizontal resolution. The major updates in RegCM4.3 in comparison to the older version RegCM4.2 are the inclusion of measured solar irradiance in place of hardcoded solar constant and additional layers in the stratosphere. The analysis shows that the Indian summer monsoon rainfall, moisture flux and surface net downward shortwave flux are better represented in RegCM4.3 than that in the RegCM4.2 simulations. Excessive moisture flux in the RegCM4.2 simulation over the northern Arabian Sea and Peninsular India resulted in an overestimation of rainfall over the Western Ghats, Peninsular region as a result of which the all India rainfall has been overestimated. RegCM4.3 has performed well over India as a whole as well as its four rainfall homogenous zones in reproducing the mean monsoon rainfall and inter-annual variation of rainfall. Further, the monsoon onset, low-level Somali Jet and the upper level tropical easterly jet are better represented in the RegCM4.3 than RegCM4.2. Thus, RegCM4.3 has performed better in simulating the mean summer monsoon circulation over the South Asia. Hence, RegCM4.3 may be used to study the future climate change over the South Asia.