Seasonal and interannual changes of significant wave height in shelf seas around India during 1998–2012 based on wave hindcast

Present study examines the interannual changes of significant wave height (H_s) in shelf seas around Indian mainland based on the 15-year (1998–2012) wave hindcast data obtained from numerical model. Validation of the hindcast data with buoy-measured data shows that hindcast H_s is reasonably in good agreement with the observation (Pearson correlation coefficient values of 0.92–0.97). Annual average H_s varied from 0.9 to 1.4 m and the wave heights are higher (∼20%) in western shelf seas compared to eastern shelf seas. The analysis reveals seasonal fluctuations of wave climate, with a strong influence of Asian summer monsoon in the western shelf seas compared to the eastern shelf seas of India. Maximum H_s varied from 3.65 to 7.36 m and these maximum values were during the tropical cyclones. During 1998 to 2012, a statistically significant positive trend of 0.8–1.4 cm yr⁻¹ in annual mean H_s is observed and the increasing trend is higher (∼0.7–2.5 cm yr⁻¹) during the Asian summer monsoon period (June–September). The average trend of annual mean wind speed is also positive and is higher (∼1.67 cm s⁻¹ yr⁻¹) for the western shelf seas than that for eastern shelf seas (∼0.93 cm s⁻¹ yr⁻¹).