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| Abstract Submission No. | ABS-2022-04-0251 |
| Title of Abstract | Quantification of various oceanic processes on the variability of sea surface temperature in the northern Bay of Bengal using seaglider and mooring observations |
| Authors | V. P. THANGAPRAKASH*, M. S. GIRISHKUMAR, J. SREELEKHA, N. SURESHKUMAR, M. RAVICHANDRAN, S. SHIVAPRASAD, D. SENGUPTA, E. PATTABHI RAMA RAO, TOM FARRAR, S.S.V.S.RAMAKRISHNA |
| Organisation | INDIAN NATIONAL CENTRE FOR OCEAN INFORMATION SERVICES (INCOIS) |
| Address | INDIAN NATIONAL CENTRE FOR OCEAN INFORMATION SERVICES (INCOIS) HYDERABAD, TELANGANA, India Pincode: 500090 Mobile: 8125448584 E-mail: thangaprakash.vp@incois.gov.in |
| Country | India |
| Presentation | Oral |
| Abstract | Concurrent availability of temperature and salinity measurements from a combination of seaglider and a mooring along with near-surface meteorological parameters during 06 September-12 December 2015 and 20 August-25 November 2018 are utilized to understand the sub-seasonal variability of mixed layer (ML) temperature (MLT) in the northern Bay of Bengal (nBoB). During this time period, seaglider captured five freshening episodes (3 and 2 events during 2015 and 2018) with vertically extending upto 3-4 m depths. During these events, the drop in sea surface salinity (SSS) varied between 2-6 psu with ~0.3-1.4 oC cooling in SST. Further, Our analysis indicates that variability in the mixed layer heat budget are mainly dominated by effective surface heat flux (Qeff) where the penetrative component of shortwave radiation (Qpen) dominates whenever ML becomes shallow (<10 m) while, horizontal advection and vertical processes are mainly governing the variability in the mixed layer salinity where local fresh water flux (evaporation-precipitation) are not much significant. The contribution from horizontal advection is significant during the later part of 2015 and 2018 while it warms the ML. The barrier layer (BL) and TI are strong during the winter of 2015 compared to the winter of 2018, and the magnitude of TI during 2015 was two times greater than that during 2018. Vertical processes shows warming (cooling) of ML by the entrainment of warm (cool) subsurface water into ML due to the presence of strong (weak) barrier layer (BL) and temperature inversion (TI) during winter (summer/fall). Moreover, BL temperature (BLT) warms during shallow ML and contributes later to MLT when ML deepens. Our BLT budget analysis indicates both the BL horizontal and vertical advection plays a significant role in BLT tendency. In general, the residual term is small during both study periods of 2015 and 2018 except on some occasions. |