To understand the dynamical processes of this BSISO event, coupled numerical simulations of one full BSISO life cycle are conducted to explore multiscale interaction in the atmosphere and air-sea interaction. The coupled modeling system inherited from Chen et al. (2013) is configured to couple the Weather Research and Forecasting Model (WRF) model and the Hybrid Coordinate Ocean Model (HYCOM). It is shown that the 2 month long coupled simulations reasonably capture large-scale northward propagation of this BSISO event, as well as prominent diurnal variations of precipitation at the large islands in this region. Simulation biases over ocean and land will be discussed. Coupled simulations with altered air-sea interaction and uncoupled simulations with prescribed sea surface temperature are further conducted. Results from these experiments indicate that air-sea interaction plays important roles in determining BSISO amplitude and propagation speed.