Monsoon and cyclone induced wave climate over the near shore waters off Puduchery, south western Bay of Bengal

Seasonal and annual variations in wave characteristics are studied based on measurements during 2009-2011 using wave rider buoy. Presence of swells generated by the south Indian Ocean cyclones are found over the south western Bay of Bengal during pre-monsoon season. Maximum significant wave height is measured 6 m during Thane cyclone in December, 2011. Long period waves are observed mostly during the summer (SW) monsoon and are negligible in the winter (NE) monsoon period. Short period waves dominate (63%) the wave climate during the NE monsoon. Wave spectra during the SW monsoon are multi peaked whereas during the post monsoon season single peaked spectra are found. Single peaked spectra observed during SW monsoon of 2011 coincides with the presence of positive Indian Ocean Dipole. Waves during the pre monsoon and SW monsoon season are influenced by sea breeze. Analysis indicates that directional width is minimum for waves from the NE since they are wind waves and maximum for waves from SE since they are swells. Study indicates that wave climate of the south western Bay of Bengal is in contrast to that in eastern Arabian Sea during the SW monsoon.