Origins of Eddy Kinetic Energy in the Bay of Bengal

By analyzing satellite observational data and ocean general circulation model experiments, this study investigates the key processes that determine the spatial distribution and seasonality of intraseasonal eddy kinetic energy (EKE) within the Bay of Bengal (BOB). It is revealed that a complicated me...

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Bibliographic Details
Published in:Journal of Geophysical Research: Oceans
Main Authors: Chen, Gengxin, Li, Yuanlong, Xie, Qiang, Wang, Dongxiao
Format: Report
Language:English
Published: AMER GEOPHYSICAL UNION 2018
Subjects:
Oceanography
eddy kinetic energy
ocean internal instability
remote equatorial wind
local wind
Bay of Bengal
EQUATORIAL INDIAN-OCEAN
PACIFIC SUBTROPICAL COUNTERCURRENT
SEA-SURFACE HEIGHT
INTRASEASONAL VARIABILITY
INTERANNUAL VARIABILITY
COASTAL CURRENT
SALINITY STRATIFICATION
TROPICAL PACIFIC
SST VARIABILITY
NORTH-ATLANTIC
Indian
Pacific
North Atlantic
Online Access:http://ir.gig.ac.cn/handle/344008/38093
https://doi.org/10.1002/2017JC013455
Description
Summary:By analyzing satellite observational data and ocean general circulation model experiments, this study investigates the key processes that determine the spatial distribution and seasonality of intraseasonal eddy kinetic energy (EKE) within the Bay of Bengal (BOB). It is revealed that a complicated mechanism involving both local and remote wind forcing and ocean internal instability is responsible for the generation and modulation of EKE in this region. High-level EKE mainly resides in four regions: east of Sri Lanka (Region 1), the western BOB (Region 2), northwest of Sumatra (Region 3), and the coastal rim of the BOB (Region 4). The high EKE levels in Regions 1 and 2 are predominantly produced by ocean internal instability, which contributes 90% and 79%, respectively. Prominent seasonality is also observed in these two regions, with higher EKE levels in boreal spring and fall due to enhanced instability of the East Indian Coast Current and the Southwest Monsoon Current, respectively. In contrast, ocean internal instability contributes 49% and 52% of the total EKE in Regions 3 and 4, respectively, whereas the atmospheric forcing of intraseasonal oscillations (ISOs) also plays an important role. ISOs produce EKE mainly through wind stress, involving both the remote effect of equatorial winds and the local effect of monsoonal winds. Equatorial-origin wave signals significantly enhance the EKE levels in Regions 3 and 4, in the form of reflected Rossby waves and coastal Kelvin waves, respectively. The local wind forcing effect through Ekman pumping also has a significant contribution in Regions 3 and 4 (24% and 22%, respectively).

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