EGU21-14983
https://doi.org/10.5194/egusphere-egu21-14983
EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Vertical Analysis of Mesoscale Eddies in the Northern Bay of Bengal

Abhijit Shee1, Saikat Pramanik2, Sourav Sil3, and Sudeep Das4
Abhijit Shee et al.
  • 1Ocean Analysis and Modeling Laboratory, School of Earth Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha-752050, India (as29@iitbbs.ac.in)
  • 2Ocean Analysis and Modeling Laboratory, School of Earth Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha-752050, India (sp22@iitbbs.ac.in)
  • 3Ocean Analysis and Modeling Laboratory, School of Earth Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha-752050, India (souravsil@iitbbs.ac.in)
  • 4Ocean Analysis and Modeling Laboratory, School of Earth Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha-752050, India (sd64@iitbbs.ac.in)

Mesoscale eddies, coherent rotating structure with typical horizontal scale of ~100 km and temporal scales of a month, play a significant role in ocean energy and mass transports. Here both mesoscale cyclonic and anticyclonic eddies moving towards south in the northern Bay of Bengal during 20th March 2017 to 20th May 2017 are observed using a high resolution (~5 km) nitrogen-based nutrient, phytoplankton, zooplankton, and detritus (NPZD) ecological model embedded with Regional Ocean Modeling System (ROMS). Spatial maps of sea surface height anomaly (SSHA) from satellite-derived Archiving Validation, and Interpretation of Satellite Oceanographic (AVISO), and model are well matched. The centers and effective radii of both kind of eddies are identified using SSHA to proceed for their three-dimensional analysis. The extreme intensities of cyclonic and anticyclonic eddy centers are observed on 8th April 2017 at 86.40°E, 18.19°N and 84.80°E, 16.52°N respectively. Both kind of eddies are vertically extended upto 800 m and have radius ~100 km at surface. At these two locations, time-depth variations of zonal and meridional currents, and other physical (temperature and salinity) and bio-physical (chlorophyll-a, phytoplankton, zooplankton, detritus nutrient, dissolved oxygen and NO3 nutrient) parameters are studied particularly from 8th March 2017 to 8th May 2017. Further vertical distribution of zonal and meridional currents, and other parameters are studied along the eddy diameters at their extreme intensity. In the vertical structure of both current components, an opposite sense between cyclonic and anticyclonic eddies are clearly captured, while other variables show strong upwelling and downwelling nature around the cyclonic and anticyclonic eddy centers respectively. Abundances (scarcities) of chlorophyll-a, phytoplankton, zooplankton and detritus nutrient are observed at 50 – 150 m depth of the cyclonic (anticyclonic) eddy center. The concentration of chlorophyll-a, phytoplankton, zooplankton and detritus nutrient reach to maximum of 1 mg/m3, 0.35 mMol/m3, 0.22 mMol/m3 and 0.14 mMol/m3 at ~80 m depth for the cyclonic eddy, while these are absent for the anticyclonic eddy.

How to cite: Shee, A., Pramanik, S., Sil, S., and Das, S.: Vertical Analysis of Mesoscale Eddies in the Northern Bay of Bengal, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14983, https://doi.org/10.5194/egusphere-egu21-14983, 2021.