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 (similar to 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 (similar to 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 (similar to 1.67 cm s(-1) yr(-1)) for the western shelf seas than that for eastern shelf seas (similar to 0.93 cm s(-1) yr(-1)).