Each summer, the southwest monsoon arrives over the Indian subcontinent, bringing cool relief, steady winds, and heavy rains. Can we predict how much rain will fall a couple of months, or even a couple of weeks into the future, during this crucial wet season? The answer is not yet.
But it would be of great value if, for example, authorities managing water resources knew that heavier-than-average downpours would arrive in two weeks time, or if farmers knew the upcoming planting season would be drier than usual.
This quest of sub-seasonal to seasonal rainfall forecasts is propelling scientists to investigate the dynamics of the South Asian monsoon climate, and especially its intimate connections with the Indian Ocean.
My PhD ('19) research was motivated by that goal: to better understand how energy and water are exchanged across the vast expanses of ocean and atmosphere, affecting currents, winds, and rains.
Working with my advisor Dr. Amala Mahadevan (Lab: Ocean and Environmental Processes) as part of an international collaboration funded by the U.S. Office of Naval Research, the project brought me to the Bay of Bengal. Comparable in size to the Mediterranean Sea, the “Bay” of Bengal is no average bay. It is (together with the adjacent Andaman Sea) the freshest region of the tropical oceans, fed by gargantuan flows of freshwater pouring out of the Ganges, Brahmaputra, and Irrawaddy rivers.
Embarking on 3 to 5 week-long expeditions aboard research vessels, we deployed weather balloons, drifting instruments, moored weather stations, and autonomous underwater drones, and collected a wealth of data from our ship in the middle of monsoon storms. Back home, I analyzed hydrographic, atmospheric, and satellite climate data, and created computer simulations of the fluid dynamics at play in the coupled ocean-atmosphere system.
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Our findings revealed that the fingerprint of the river's discharge extends much further across the surface of the Bay of Bengal, in thinner and more stable layers of freshwater than previously expected. We also discovered that complex currents, internal waves, and turbulent dynamics play a leading role in controlling the surface layer's temperature and thickness, and thus heat and moisture fueling the monsoon - dynamics that need to be accounted for in long-range ocean-coupled weather forecasting models.
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​First- and co-authored publications on the topic:
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Oceanus, 2019: Can we improve monsoon forecasts?
MIT Doctoral Thesis, 2019: Stratified and stirred: monsoon freshwater in the Bay of Bengal
Journal of Physical Oceanography, 2020: How spice is stirred in the Bay of Bengal
Deep Sea Research II, 2020: Formation of interleaving layers in the Bay of Bengal
Deep Sea Research II, 2020: Upper layer thermohaline structure of the Bay of Bengal during the 2013 northeast monsoon
Science Advances, 2018: Submesoscale-selective compensation of fronts in a salinity-stratified ocean
Current Biology, 2018: Newly discovered deep-branching marine plastid lineages are numerically rare but globally distributed
Oceanography, 2016: Freshwater in the Bay of Bengal: Its fate and role in air-sea heat exchange
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Miscellaneous undergraduate research at UCSB:
Worked in the Jayich Lab on sensing at the nanoscale.
Researched pulsars via gamma ray and radio observations with Carl Gwinn, contributing to:
The Astrophysical Journal Letters, 2013: Excess Optical Enhancement Observed with ARCONS for Early Crab Giant Pulses
