Numerical Simulation of Indian Summer Monsoon Using MPAS-A: A Sensitivity Study

Many national and international agencies use presently available state-of-art global as well as regional models for the prediction of Indian Summer Monsoon (ISM) rainfall. Coupled Atmosphere-Land-Ocean model is also used at many centers for predicting ISM rainfall. ISM circulation is a major feature of atmospheric model, which arises primarily from a meridional land-sea thermal contrast between the Indian Ocean and elevated Tibetan Plateau during the boreal summer. The accurate prediction of ISM rainfall depends heavily on the ability of atmospheric models to realistically capture the interactions among different scales of regional circulation. Generally, a high resolution AGCMs are required to successfully predict orographic precipitation during the monsoon season.

In this study, the performance of MPAS (Model for Predictions Across Scales) will be evaluated for simulating the Indian summer monsoon (ISM) features. The grid refinement capability of MPAS-A model is used to achieve high grid resolution over study area. MPAS-A is integrated for three ISM periods (June to September) starting from the year 2010 to 2012 and the results are compared to observations and atmospheric reanalysis data. The ISM mean features like mean circulations, spatio-temporal rainfall distributions and intra-seasonal oscillations are analyzed. Initial results show that the June-September (JJAS) rainfall is sensitive to the radiation physics as well as microphysics schemes used in MPAS-A. We would like to present these results at the meeting.