International Indian Ocean Science Conference(IIOSC)-2022

Dona Paula, Goa, India.
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iiosc2020[at]nio[dot]org

Summary of Abstract Submission

Abstract Submission No.	ABS-2022-05-0227
Title of Abstract	A BGC-Argo perspective of sub-surface chlorophyll variability in Arabian Sea and Bay of Bengal
Authors	V S Udaya Bhaskar^*, Chiranjivi Jayaram
Organisation	INCOIS, MoES
Address	INCOIS, Pragathinagar Hyderabad, Telangana, India Pincode: 500090 Mobile: 9441920018 E-mail: uday@incois.gov.in
Country	India
Presentation	Oral
Abstract	The Arabian Sea (AS) and the Bay of Bengal (BoB) forms integral part of the northern Indian Ocean, exhibiting different characteristics despite falling in same latitudinal region. The present study is aimed at assessing the surface and sub-surface chlorophyll-a (chl-a) structure of the AS and BoB. For the first time, due to the BGC-Argo programme, simultaneous data from AS and BoB is measured for studying the factors responsible for differences in the chl-a structure and its variability, in these basins. A Pair of floats in the AS (WMO ID: 2902093 & 2902118) and BoB (WMO ID: 2902086 and 2902114) were used to study the variability of surface and sub-surface chl-a. The factory supplied BGC-Argo gain factor and offset were corrected and data from this corrected profile were used for assessing the spatio-temporal variability. From this study, the existence of a permanent deep chlorophyll maximum (DCM) is observed in both the basins. DCM is observed to vary at an annual mode in BoB and at a quasi-semiannual mode in the AS region. Strong correlation between DCM and depth of 26°C isotherm is observed in both AS and BoB. However, no concrete role of barrier layer is observed with DCM in either of the basins. The existence of sub-surface blooms in the pre-monsoon season in the upper 200m of the AS region is observed to be shoal during winter season, while shoaling in BoB happened only during passage of cyclones and eddies. The time-series data from BGC-Argo floats revealed the bio-optical mechanisms and their relationship with the physical processes.