The Mechanism of the 20°C Isotherm Depth Oscillations for the Bay of Bengal

Abstract

The monthly variation of thermocline depth in terms of 20°C isotherm depth (Z20) in the Bay of Bengal has been studied using SODA and ARGO datasets. During a southwest monsoon, the Bay of Bengal is deepest in the western basin and shallowest in the eastern basin while it is the opposite during northeast monsoon. The Z20 oscillation is not only affected by semiannual reversing wind forcing but also influenced by coastal Kelvin waves from the eastern coast and remote effect from the Northern Indian Ocean and Malacca Strait. A linear relationship between SSHA and Z20 has been found from both SODA and observational studies.

Keywords:

• Bay of Bengal
• thermocline
• Z20
• ARGO
• upwelling

Acknowledgements

This study is supported by the INDOMOD research project (POM, PR2007) of INCOIS under the Ministry of Earth Science, Government of India, the OCEANSAT-II utilization project (BBC, PR2008) of SAC, ISRO. We are thankful to Prof. P. C. Pandey, Emeritus Professor CORAL, and Prof. D. Sen, Head CORAL, for scientific discussions and encouragement. We acknowledge the Indian National Centre for Ocean Information Services (INCOIS) for providing the ARGO dataset and Asia Pacific Data Research Centre (http://apdrc.soest.hawaii.edu/) for providing the access to the datasets for scientific research. We are also grateful to the anonymous reviewers for their valuable comments and suggestions to ameliorate this revised version of the paper.