[A-AS03] Extreme Events and Mesoscale Weather: Observations and Modeling

[AAS03-P12] Intraseasonal Variability of Sea Surface Temperature in the Arabian Sea impacts on the Summer Monsoon Precipitation over the Bay of Bengal

*Jingyuan Xi¹ (1.Second Institute of Oceanography, Ministry of Natural Resources)

Keywords:Intraseasonal Variability, Monsoon Precipitation, Bay of Bengal, Arabian Sea

Summer monsoon precipitation over the Bay of Bengal (BoB) has pronounced intraseasonal variability (ISV), which has a close relationship to the local intraseasonal sea surface temperature (SST). Before heavy precipitation, intraseasonal SST in the BoB often has a warm anomaly and propagates northward, which drives the atmosphere and tends to trigger the convection. Besides the local air-sea interaction, the ISV of SST in the Arabian Sea (AS) also has an effect on the precipitation over the BoB. Results show that a prominent heavy precipitation usually occurs when the warm intraseasonal SST anomaly emerges early in the AS and moves northward ahead of that appearing in the BoB. The warm SST anomaly in the AS directly affects the south-north pressure contrast over the north Indian Ocean and then triggers a southwesterly wind anomaly along the climatological axis of the monsoon low-level jet (MLLJ). This wind anomaly promotes the wind convergence moving northward from the southern tip of Indian peninsula to the north India and the northern BoB, which influences the vertical and horizontal moisture advection and finally regulates the ISV of precipitation over the BoB. Understanding this process will be helpful to improve the predictive skill of the ISVs during the Indian Summer Monsoon.