Surface wave dynamics off Mumbai coast, north-eastern Arabian Sea
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.
KeywordsMulti-peaked spectra Wind-seas Swells Wind waves Indian summer monsoon Ocean sciences
We thank Dr. T. M. Balakrishnan Nair, Head of the Ocean Science & Information Services Group, INCOIS, Hyderabad. We thank Mr. Arun Nherakkol, a scientist with INCOIS and Mr. Jai Singh, technical assistant at CSIR-NIO, for the help during data collection. We thank the reviewer and the Editor for the suggestions which improved the scientific content of this paper. This is NIO contribution No. 6301. ERA5 data is downloaded from the ECMWF website. The measured data used in this study is available at INCOIS (http://www.incois.gov.in/Incois/info_insitu.jsp).
This research was financially supported by the Council of Scientific & Industrial Research, New Delhi and Earth System Science Organization, Ministry of Earth Sciences, Government of India.
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