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| Abstract Submission No. | ABS-2022-04-0438 |
| Title of Abstract | Seasonal Variability of the Mixed Layer Heat and Salt Budget in the Northern Bay of Bengal using Argo observations |
| Authors | Abhijit Shee*, Sourav Sil |
| Organisation | IIT Bhubaneswar |
| Address | IIT Bhubaneswar, Argul Campus Jatni, Khurda, Odisha, India Pincode: 752050 Mobile: 7750894869 E-mail: as29@iitbbs.ac.in |
| Country | India |
| Presentation | Oral |
| Abstract | Northern Bay of Bengal (NBoB) is well known for its unique features such as seasonally reversing monsoon winds, less saline surface layer due to huge precipitation over evaporation, strong temperature inversions, more buoyancy, high stratification etc. which independently or combinedly maintain and hold the seasonal variation of surface layer temperature and salinity. This study investigates the seasonal variation of mixed layer (ML) heat and salt budget in the NBOB using Argo observations. Dominated processes in the mixed layer heat budget are net surface heat flux (NSHF), horizontal advection, vertical entrainment, and vertical diffusion. During winter, NSHF leads to cooling while vertical processes show a warming tendency and overall temperature tendency results a low mixed layer temperature (MLT, 26 - 27oC) with in ML. During spring, the penetrative shortwave radiation flux (Qpen, ~35 W/m2) and the NSHF (~180 W/m2) both increase to maximum value. On the other hand, vertical processes show a strong cooling tendency and overall temperature tendency shows the heat gain. Due to presence of cloud, during summer the shortwave radiation decreases and NSHF varies between -50 and 150 W/m2. During fall, net shortwave radiation and Qpen again increase and a warming temperature tendency is observed. Presence of strong temperature inversions with thick barrier layer during fall and winter season have a significant role on MLT variation. In the mixed layer salt budget, dominated processes are net freshwater flux (NFF), horizontal advection, vertical entrainment, and vertical diffusion. During summer, huge precipitation over evaporation helps to decrease the surface salinity and to form a strong oceanic salinity stratification (OSS). In this period horizontal advection show a negative tendency. During fall the OSS reaches to maximum value. In this period vertical entrainment show a strong negative tendency and overall salinity tendency results the lowest salinity (~27 - 29 psu) within mixed layer. During winter, NFF shows a weak positive tendency due to increase in evaporation over precipitation, OSS gradually decreases and salinity within ML increases. During spring, OSS reaches to minimum value. Vertical processes shows a positive tendency and overall salinity tendency shows the salt gain. In this time salinity within mixed layer increases to maximum value (~34 psu). |