Impact of shamal winds and swells on the coastal currents along the west coast of India

Wind, wave and current data collected at/off Ratnagiri, west coast of India were analysed to study the wind-wave-current interaction along the west coast of India (WCI) during shamal events. Shamal winds which originate in the Persian Gulf region during winter (November-March) generate swells in the northwestern Arabian Sea, and these swells propagate towards the west coast of India with distinct wave direction (northwest) and increase in wave heights. It is observed that during these events, the de-tided current data present a distinct change in the current direction and increase in current speeds (approximately from 0.08 m/s to 0.15 m/s). It can be inferred from the analysis that the waves which propagate from NW and the currents which flow towards north oppose each other, resulting in intensification of currents off Ratnagiri. In order to understand the intensity of shamal effect on the existing current system, we have also analysed winds and currents before, during and after the events.