Ocean wave dynamics in the coastal area of the central west coast of India and its variability

Abstract

Examined the spatial and temporal changes in the wave spectra using waves measured in the coastal area at two locations for three years. Long-term variability is examined with ERA5 reanalysis data. The annual average wave spectra have a significant wave height (Hs) of ~1m at both locations. During the Asian monsoon (June–September), the highest wave spectra resulted in Hs of 5.1m. Frequently, the wave pattern is with Hs of 0.4–0.8m and mean period of 3–8s. Annually, ~67% of the time, spectra consists of waves from 210 to 230°, 250–260°, and 300–310° with high waves (Hs > 4m) from southwest (250–260°). Due to the presence of significant wind-seas and swells, energy at the secondary spectral peak is ~38% of energy at the principal peak. During February–May, the sea state is dominated (~50% of time) by locally generated waves and young swells, while in monsoon, the swells are large (66–75%). Principal component (PC) of spectral energy density shows that monsoon and cyclonic storms are resulting in a large variability (~90%) in the first mode. Even though the wave characteristics are similar within 125 km distance, some metrological events cause significant changes in the waves and it resulted in different 100-year return period values at these locations.