Bay of Bengal Intraseasonal Oscillations and the Upper Ocean Mesoscale

Lead PI: Professor Arnold L. Gordon

Unit Affiliation: Ocean and Climate Physics, Lamont-Doherty Earth Observatory (LDEO)

April 2017 - March 2020
Indian Ocean ; Bay of Bengal
Project Type: Research

DESCRIPTION: The project addresses the complex oceanography of the Bay of Bengal (BoB) and its linkage with the tropical Indian Ocean. Using the 2003-2019 Argo profiles and surface drifter data, as well as the ASIRI and Miso-BoB ship based, glider and mooring data, along with reanalysis data and satellite based observations, the specific research objectives are:

1. Isopycnal Mixing: detail the monthly climatology and anomalies of the temperature and salinity patterns on isopycnals within the upper 400 m of the BoB and to assess the relative importance of isopycnal stirring in achieving the balance of freshwater relative to that accomplished by vertical diapycnal mixing across the Barrier Layer.

2. Freckled Face of BoB: To investigate the relationship of the ocean mesoscale to air-sea fluxes within the Bay of Bengal (BoB). More specifically: to assess if the varied stratification (pycnocline T/S induced intensity and depth) of the upper ~250 m within the broad range of the BoB mesoscale 'eddy' features induces a variable barrier layer that impacts the air-sea flux (buoyancy and momentum) ability to entrain cooler subsurface water into the surface layer, thus affecting sea surface temperature (SST) with feedback to the air-sea flux. The atmosphere 'sees' not a smooth regional climatology but rather a mesoscale pattern presenting a unique freckled ‘marine face’ to tropical atmosphere. The freckled SST signal could potentially affect atmospheric features, as tropical cyclones and intraseasonal oscillations, as well as induce Intrathermocline eddies within the pycnocline.

3. Andaman Sea water and Intrathermocline Eddies (ITE): tracking the westward spreading of low salinity, tidally mixed slabs of Andaman Sea water within the thermocline of the BoB region.


Office of Naval Research




V.Hormann, L. Centurioni, A.L. Gordon (2019) Freshwater Export Pathways from the Bay of Bengal. Deep Sea Research II, special issue on the Bay of Bengal.

E. Shroyer, A. L. Gordon, G. S. Jaeger, M. Freilich, A. Waterhouse, J. T. Farrar, VSS Sarma Vedula, R. Venkatesan, R. Weller, J.Moum, A. Mahadevan (2019) Upper Layer Thermohaline Structure of the Bay of Bengal during the 2013 Northeast Monsoon. Deep Sea Research II, special issue on the Bay of Bengal.

Gordon, A. L., E. Shroyer, V.S.N. Murty (2017) An Intrathermocline Eddy and a tropical cyclone in the Bay of Bengal. Sci. Rep. 7, 46218; doi: 10.1038/srep46218.


intraseasonal mesoscale oscillations