Improvement of simulated monsoon precipitation over South-Asia with a regionally coupled model ROM
A regional coupled atmosphere–ocean model is developed to study the monsoon climate over South Asia. Most of the climate models (both GCM and RCM) underestimate precipitation over South Asia, but overestimate precipitation over the Bay of Bengal and the equatorial Indian Ocean. These systematic differences between the models may be related to a fundamental problem of atmospheric models: the inability to simulate intraseasonal variability. The intraseasonal oscillations of the South Asian monsoon play a major role in influencing the seasonal mean monsoon characteristics and their interannual variability (Goswami and Mohan, 2001). Several GCM studies with focus on the South Asian monsoonal region have concluded that GCMs have difficulties in simulatingthe mean monsoon climate (Turner and Annamalai, 2012). RCMs do simulate better orographic induced precipitation, but also show limited ability to simulate the land precipitation (Lucas-Picher et al., 2011; Kumar et al., 2013). For this study, differences in coupled and uncoupled simulations are analyzed to investigate the effect of coupling on the simulated climate, especially precipitation spatial patterns.