Monsoon Intra-seasonal oscillations in the Bay of Bengal

Amit Tandon, University of Massachusetts, Dartmouth, Mechanical Engineering, Dartmouth, MA, United States, Emily Shroyer, Oregon State University, Corvallis, OR, United States, Debasis Sengupta, Indian Institute of Science, Centre for Atmospheric and Oceanic Sciences, Bangalore, India, Hemantha W Wijesekera, Naval Research Laboratory, Ocean Sciences, Stennis Space Center, MS, United States, Harindra J.S. Fernando, University of Notre Dame, Notre Dame, IN, United States, Andrew J. Lucas, University of California San Diego, Scripps Institution of Oceanography, La Jolla, CA, United States, Eric A D'Asaro, Applied Physics Lab, Univ of Washington, Seattle, WA, United States, J. Thomas Farrar, Woods Hole Oceanographic Inst, Department of Physical Oceanography, Woods Hole, MA, United States, Jennifer A MacKinnon, Scripps Institution of Oceanography, La Jolla, CA, United States and Amala Mahadevan, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
Monsoon rains are the economic lifeline for countries in the South Asian region. The wet and dry spells, or active-break cycles of the Asian summer monsoon are governed by two distinct modes of intraseasonal variability - a low-frequency 30-60 day mode that moves northward over the Indian subcontinent and the Bay of Bengal at 1 degree per day, and a 10-25 day quasi-biweekly mode that moves westward at 4-5 degrees per day. There are multiple hypotheses on the influence of air-sea interaction and the ocean mixed layer on the propagation of Monsoon Intra-seasonal Oscillations (MISO), but the multi-scale nature of atmosphere-ocean coupling is not well understood. Multi-country collaborative initiatives MISOBOB, RIO-MISO and OMM have led to a combination of ocean observations, atmospheric observations and associated modeling to study this phenomenon. This talk presents an overview of the various hypotheses explored in these programs through intensive process observations in the Bay of Bengal during the 2018 and 2019 summer (or southwest) monsoons.