Recent Studies on Wind Seas and Swells in the Indian Ocean: A Review

Winds and waves data measured at a few locations along the west coast of India as well as wave model results were analysed to study the wave characteristics in the deep as well as nearshore regions during different seasons. During fair weather season, we can observe distinct and systematic diurnal variation in wave height and wave period, especially, simultaneous increase in wave height and decrease in wave period with increase in local wind speed. This is due to superimposition of wind seas generated by the sea breeze system with the pre-existing swells. The swells observed in the Arabian Sea are from SW direction during SW monsoon season and from SW/SSW and NW directions during both pre-monsoon and post-monsoon seasons. The NW swells which occur during Shamal events show distinct characteristics such as an increase in wave height, decrease in swell period and a common propagation direction (northwest) for wind seas and swells. Also the swells generated at 400 S, propagate in the north Indian Ocean, and enter the Bay of Bengal without affecting the Arabian Sea. Fine resolution winds (say, MM5 or WRF) are necessary to understand the effect of land-sea breeze system on wind-sea generation in the coastal regions. Here, we review the recent work on wind seas and swells in the Indian Ocean and coastal regions that we have carried out using measured wave data and model results.