Collaborative observations of upper ocean circulation, air-sea interaction, and monsoon variability in the Bay of Bengal

Hemantha W Wijesekera1,2, Ewa Jarosz3, David W Wang2, Conrad A Luecke4, Tommy G Jensen5, Adam Rydbeck6, Maria K. Flatau7, Jerome Schmidt8, Jaynise Pérez Valentín9, Iossif Lozovatsky10, Harindra J.S. Fernando11, Sinhalage Udaya Priyantha Jinadasa, Jagath Rajapakshapa13, Udeshika Wimalasari14, William Teague15 and Zack Hallock15, (1)John C. Stennis Space Center, Stennis Space Center, MS, United States, (2)U.S. Naval Research Laboratory, Ocean Sciences, Stennis Space Center, United States, (3)Naval Research Lab Stennis Space Center, Stennis Space Center, MS, United States, (4)NRC Postdoctoral Fellow at Naval Research Laboratory, Stennis Space Center, MS, United States, (5)US Naval Research Laboratory, Ocean Sciences Division, Stennis Space Center, MS, United States, (6)U.S. Naval Research Laboratory, Ocean Sciences, Stennis Space Center, MS, United States, (7)Naval Research Laboratory, Monterey, CA, United States, (8)NRL, CA, United States, (9)University of Notre Dame, Department of Civil and Environmental Engineering and Earth Sciences, Notre Dame, United States, (10)University of Notre Dame, Notre Dame, IN, United States, (11)University of Notre Dame, Notre Dame, United States, (12)Ocean University, Colombo, Sri Lanka, (13)National Aquatic Research and Resorce Development Agency, Colombo, Sri Lanka, (14)SRR International, Inc., Riviera Beach, United States
Abstract:
Upper-ocean circulation, mixing, air-sea interaction, and monsoon variability have been studied in the Bay of Bengal as a part of U.S. (Office of Naval Research and Naval Research Laboratory) sponsored programs in collaboration with India and Sri Lanka. The Monsoon Intra- Seasonal Oscillations in the Bay of Bengal (MISOBOB) is an ongoing study to examine the ocean’s role on regional atmospheric phenomena, monsoon intraseasonal oscillations. The study is aimed at understanding and quantifying upper-ocean processes and coupled atmosphere-ocean dynamics of the Bay of Bengal with relevance to the MISO. As part of the MISOBOB, observations of ocean currents and hydrographic fields in the upper 1000 m of the water column were collected from five deep moorings in the Bay of Bengal from July 2018 to June 2019. In addition, coupled ocean-atmosphere model simulations were made using the NRL-COAMPS model. Ship-based surveys of the upper-ocean and atmospheric boundary layer, and upper-atmosphere were also conducted during the mooring deployment and recovery cruises. Here, we describe major features of the circulation and the evolution the upper-ocean heat content and thermohaline fields from combined shipboard and moored observations. The impacts of north-south and east-west temperature gradients in the upper ocean, cooling due to coastal upwelling south and southwest of the Sri Lankan coast, and open-ocean upwelling within the Sri Lanka Dome on air-sea interaction are discussed.
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