Contribution of the winter salinity barrier layer to summer ocean-atmosphere variability in the Bay of Bengal  

作　　者：Shanshan Pang Xidong Wang Gregory R.Foltz Kaigui Fan 

机构地区：[1]College of Oceanography,Hohai University,Nanjing 210098,China [2]Laboratory for Regional Oceanography and Numerical Modeling,Qingdao Marine Science and Technology Center,Qingdao 266061,China [3]Atlantic Oceanographic and Meteorological Laboratory,Miami 33149,USA

出　　处：《Acta Oceanologica Sinica》2024年第9期35-53,共19页海洋学报（英文版）

基　　金：The Postgraduate Research and Practice Innovation Program of Jiangsu Province under contract No.KYCX22_0587;the Fundamental Research Funds for the Central Universities under contract No.B230205012.

摘　　要：It is found that the winter(December-February)barrier layer(BL)in the Bay of Bengal(BoB)acts as a dynamical thermostat,modulating the subsequent summer BoB sea surface temperature(SST)variability and potentially affecting the Indian summer monsoon(ISM)onset and associated rainfall variability.In the years when the prior winter BL is anomalously thick,anomalous sea surface cooling caused by intensified latent heat flux loss appears in the BoB starting in October and persists into the following year by positive cloud-SST feedback.During January-March,the vertical entrainment of warmer subsurface water induced by the anomalously thick BL acts to damp excessive cooling of the sea surface caused by atmospheric forcing and favors the development of deep atmospheric convection over the BoB.During March-May,the thinner mixed layer linked to the anomalously thick BL allows more shortwave radiation to penetrate below the mixed layer.This tends to maintain existing cold SST anomalies,advancing the onset of ISM and enhancing June ISM precipitation through an increase in the land-sea tropospheric thermal contrast.We also find that most of the coupled model intercomparison project phase 5(CMIP5)models fail to reproduce the observed relationship between June ISM rainfall and the prior winter BL thickness.This may be attributable to their difficulties in realistically simulating the winter BL in the BoB and ISM precipitation.The present results indicate that it is important to realistically capture the winter BL of the BoB in climate models for improving the simulation and prediction of ISM.

关 键 词：Bay of Bengal barrier layer Indian summer monsoon RAINFALL CMIP5 

分 类 号：P732.6[天文地球—海洋科学]