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Abstract Submission No. | ABS-2022-04-0304 |
Title of Abstract | Seasonal variability of chlorophyll and nitrate in the northeastern Arabian Sea. |
Authors | V. R. Sherin*, M. S. Girishkumar, N. Sureshkumar, T. V. S. Uday Bhaskar, E. P. Rama Rao |
Organisation | INCOIS, Hyderabad |
Address | Project Scientis B, OON division, ESSO - INCOIS Hyderabad, Telengana, India Pincode: 500090 Mobile: 9496389597 E-mail: sherinraju.v@incois.gov.in |
Country | India |
Presentation | Oral |
Abstract | The Arabian Sea is one of the most productive regions in the tropical oceans. Hence to understand the modulation of physical parameters and its consequent impact on biogeochemical variability in the region is of utmost importance. In this context, INCOIS deployed a biogeochemical float equipped with chlorophyll, nitrate, dissolved oxygen, optical backscatter, temperature, salinity, and depth sensors in the northeastern Arabian Sea. The float collects data in the upper 2000 m of the water column once every 5-day. The simultaneous availability of physical and biogeochemical parameters, especially chlorophyll and nitrate along with satellite data products provide an unprecedented opportunity to examine the evolution of chlorophyll in various temporal scales, from seasonal to short intense weather events such as a tropical cyclone. In this study, we analyzed data since May 2019. We observed a subsurface chlorophyll maximum between 40 to 80m depth. Our analysis shows two episodes of enhancement of chlorophyll one during August 2019 and the other in November 2019. During November, enhancement of nutrients (~ 6 M) in the near-surface layer due to increase in wind-induced vertical mixing associated with the tropical cyclone Kyaar lead to an enhancement of chlorophyll (>1.5 mg m-3) with a lag of 10 days. Though a similar magnitude of enhancement of chlorophyll was observed during August 2019, the nutrients in the near-surface layer were negligibly small. We speculate that the advection of chlorophyll to the float location might be a plausible explanation for this. |