Anomalous circulation around the southern Indian peninsula observed during winter, 2009; and the generation mechanisms

摘要

In the present study we have analysed the currents data collected on board INS Sagardhwani using Vessel-Mounted Acoustic Doppler Current Profiler (VM-ADCP) along the southern Indian peninsula and Sri Lanka during December 2009. The observed currents deviated from climatological circulation pattern except around Sri Lanka. The southeastern region of peninsular India has evidenced the most anomalous currents from in-situ observations, with a northward flowing east India coastal current which is often southward (climatologically). The ROMS model is unable to simulate the observed anomalous currents, whereas the high-resolution (1/12 degree) HYCOM ocean model had reasonably well simulated these currents. From HYCOM simulations, we have found that small scale eddies (which are not captured or resolved by altimeter) are responsible for the observed anomalous behaviour of currents (east India coastal current) over southeastern India. This work further emphasizes the need of high-resolution ocean modelling for proper representation of key physical process and associated circulation systems.