Distribution of Nitrate, Oxygen and Chlorophyll in the Bay of Bengal: Physical Constraints and Mechanisms for Vertical Transport 

Amala Mahadevan1, Melissa M Omand2, Mara Freilich3, Emily Shroyer4, Sarma V5, Andrew Lucas6 and Robert A Weller1, (1)Woods Hole Oceanographic Institution, Woods Hole, MA, United States, (2)University of Rhode Island, Graduate School of Oceanography, Narragansett, RI, United States, (3)MIT- Woods Hole Oceanographic Institution, Joint Program in Oceanography, Woods Hole, MA, United States, (4)Oregon State Univ, Corvallis, OR, United States, (5)National Institute of Oceanography Vizag, Regional Centre, Visakhapatnam, India, (6)Scripps Institution of Oceanography, La Jolla, CA, United States
Abstract:
Surface waters in the Bay of Bengal are highly oligotrophic and subsurface waters are highly anoxic. Both nitrate and oxygen exhibit abrupt transitions in the vertical between 50 and 100 m depth. The strong density stratification resulting from surface freshwater in the Bay of Bengal inhibits the vertical transport of nitrate and oxygen, creating strong vertical gradients in their profiles. We analyze the distribution of nitrate, oxygen and chlorophyll in the context of density from measurements made during 2013-15 using several platforms. By examining the relationships of nitrate and oxygen to density, and the gradients of these properties, we infer physical mechanisms that facilitate the vertical transport of oxygen and nitrate in this strongly stratified ocean.
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