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Meridional and Zonal Eddy‐Induced Heat and Salt Transport in the Bay of Bengal and Their Seasonal Modulation
Author(s) -
Gonaduwage Lasitha Perera,
Chen Gengxin,
McPhaden Michael J.,
Priyadarshana Tilak,
Huang Ke,
Wang Dongxiao
Publication year - 2019
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2019jc015124
Subject(s) - baroclinity , bay , zonal and meridional , barotropic fluid , eddy , geology , eddy diffusion , climatology , mesoscale meteorology , stratification (seeds) , instability , monsoon , advection , atmospheric sciences , oceanography , turbulence , meteorology , geography , physics , mechanics , seed dormancy , botany , germination , dormancy , biology , thermodynamics
This study investigates basin and regional‐scale eddy (turbulent)‐induced heat and salt transport associated with mesoscale eddies of the Bay of Bengal (BOB). A high level of eddy‐induced transport is found in four subregions: the western boundary of the northern BOB (NB), the western BOB (WB), the southwestern BOB near Sri Lanka (SWB), and the southeastern BOB (SEB). The main seasons for eddy‐induced heat transport in the NB and SWB are identified as the presummer (March to April) and summer monsoon (May to September) seasons, whereas the postsummer monsoon season (October to November) is the main season for the WB and SEB. It is found that not only meridional but also zonal eddy‐induced transport is significant, due to the semienclosed nature of the BOB, which restricts poleward transport in the northern part of the bay. An analysis of upper‐layer eddy energetics reveals that the main contributor to the increased eddy kinetic energy and thus the transport is baroclinic instability in the NB, SWB, and WB, while both barotropic and baroclinic instability are important in the SEB. Using a 2.5‐layer reduced gravity model, baroclinic instability in the NB, SWB, and SEB is further investigated. The results reveal that strong vertical velocity shear and weak stratification are essential for generating baroclinic instability, which enhances the seasonal eddy‐induced transport in the respective subregions.