Response of Sensitivity Experiment over South China Sea on the Monsoon Variability using a RegCM3 Model

Abstract

Purpose of this paper is to establish teleconnections between the convection changes of the South China Sea (SCS) and the rainfall anomalies over India particularly over northeast and east coast of India. It has been observed in the present study that negative (positive) AMJ (April, May, June) Sea Surface Temperature (SST) anomalies over east end of the positive Tropical Indian Ocean dipole events induced an enhanced cyclonic (anti-cyclonic) circulation over the SCS and this not only cools (warms) SST, but also decreases (increases) Outgoing Longwave Radiation (OLR) anomalies in the SCS. This produced significant impact over Indian summer monsoon rainfall (ISMR) particularly over the northeast and east coast. The correlation of OLR between two regions, Equatorial Eastern South Indian Ocean (EQ.ESIO) and SCS are opposite during this event. The anomalous surface divergence in the eastern tropical Indian Ocean is liable to accelerate the deep convection over SCS. The observed results are verified with the RegCM3 model in its sensitivity experiment. The enforced perturbation in SST over the SCS by +0.50C throughout the summer monsoon season is generated and the simulated summer monsoon circulation at 850 hPa and ISMR are analyzed. The simulated vertical Water Vapour Mixing Ratio (WVMR) centered at 650E and 77.50 E longitudes in the warm SCS are also studied to examine the moisture availability over the Indian subcontinent and adjoining seas.