Superimposition of wind seas on pre-existing swells off Goa coast

Abstract

An analysis of wind and wave data collected in the coastal region of Goa, west coast of India, during fair weather season reveals a distinct and systematic diurnal variation in wind speed, wave height and wave period, especially simultaneous increase in wave height and decrease in wave period with increase in local wind speeds due to sea breeze system. During a typical daily cycle, the wave height reaches its peak early in the afternoon, then it decays progressively back to the swell conditions within 5 or 6 h. Measured wave spectra distinctly bring out salient features of deep water swell and wind seas generated by the local sea breeze. Numerical simulations reproduce the characteristics of this daily cycle. The exposure of Goa coast to long distant swells from the southwest and to the local wind seas from the northwest leads to complex cross-sea conditions.