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

K C Pattnayak,S K Dash,S K Panda,Vaishali Saraswat

doi:10.1007/s00382-017-3792-9

K C Pattnayak, S K Dash + Show 2 more

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https://doi.org/10.1007/s00382-017-3792-9

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Journal: Climate dynamics	Publication Date: Jul 19, 2017
Citations: 37	License type: open-access

Affiliation: Indian Institute of Technology Delhi

Abstract

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.

Highlights

Temperature and precipitation over Indian landmass exhibits considerable spatial and temporal variation
RegCM4.2 simulated rainfall has been overestimated by about 4–5 mm/day in July and August while RegCM4.3 simulated rainfall is much closer to the India Meteorological Department (IMD) observation
RegCM4.3 has overestimated the rainfall in be inferred that the RegCM4.3 has performed better in simulating rainfall during summer monsoon months than RegCM4.2

Summary

Introduction

Temperature and precipitation over Indian landmass exhibits considerable spatial and temporal variation. The most important seasonal variation over the course of a year is associated with the rainfall. The mean rainfall pattern and its seasonal variation have an important consequence in the sectors of agriculture and water availability in the country. It is well known that the summer monsoon is predominant in India, in which about 80% of the total annual precipitation is received over a large part of the country (Parthasarathy et al 1995; Guhathakurta and Rajeevan 2006). Many scientific communities are progressively making use of various regional models to study Indian summer monsoon. The regional models are tuned to represent the current climate as realistic as possible so as to build confidence for its subsequent use for addressing future projections under different climate change scenarios.

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