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| Abstract Submission No. | ABS-2022-05-0012 |
| Title of Abstract | Characteristics of vertical distribution of chlorophyll-a in the Southern Bay of Bengal during the BoBBLE field program |
| Authors | Prasanth R*, V Vijith, P. N. Vinayachandran |
| Organisation | Cochin university of Science and Technology |
| Address | Dept. of Physical Oceanography, Cochin University of Science and Technology Cochin, Kerala, India Pincode: 682016 Mobile: 9961354509 E-mail: prasanth.rajendran6@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | During the Bay of Bengal Boundary Layer Experiment (BoBBLE) field program, that was conducted in the southern Bay of Bengal, 11-day-long high-resolution time series of temperature, salinity and chlorophyll were measured at 8N, 89E from 4 to 14 July 2016. A strong barrier layer (BL) was observed during most of the observation period associated with low-saline surface water (< 34.0 psu). A prominent subsurface chlorophyll maximum (SCM) is observed within the BL (30 - 70 m), and it has a diurnal amplitude of 0.1 to 0.2 mg m-3. During 6 - 9 July, the mixed layer depth (MLD) deepened (30 - 60 m), and the BL eroded. The deepening of MLD was accompanied by a sharp increase in surface chlorophyll (0.5 mg m-3), an increase in sea surface salinity (0.5 psu) and a decrease in sea surface temperature (1oC). Diurnal variability in the surface chlorophyll is evident during this phase of the observation when the BL is absent. A coupled physical-biogeochemical one-dimensional water-column model is used to describe the diurnal variability of chlorophyll at the observation location. The model reproduced the diurnally-filtered variability of the chlorophyll, surface temperature and mixed layer depth. Experiments conducted using the model show that co-limitation of light and nutrients determine the position of SCM in the southern bay. Further, low wind speed and BL promote strong SCM, and the diurnal variability in shortwave radiation determines the diurnal variation of SCM. |