Surface wave dynamics off Mumbai coast, north-eastern Arabian Sea

Abstract

Directional wave data collected in the coastal area at 10-m water depth for a period of 1 year is used to describe the surface wave dynamics off Mumbai coast. Partitioning of the wave spectrum into locally generated waves and remotely generated swells indicates that annually 57% of the surface height variance in the study area is a result of wind-seas and the remainder is swells from the southwest. More energetic waves are dominantly young swells and are observed during Indian summer monsoon (June–September), often generated by Somali jet. The waves are also occasionally influenced by the stronger winds over the south Indian Ocean and the Southern Ocean. The wave data indicate that the north-eastern Arabian Sea has two predominant wave regimes; (i) swells with peak wave period > 10 s from the southwest and (ii) wind-seas with peak wave period < 8 s from the northwest. In the pre-monsoon (February–May), the spectral density of the sea surface height variance of the wind-seas is higher than that of the swells. The direction of wind-seas and swells differs by 37 to 79° during the non-monsoon period, whereas it is less than 23° during the summer monsoon.