Identification of wave systems in the multimodal sea state along the Indian shelf seas

Abstract

The coexistence of multiple wave systems generated locally and by remote storms is common in the ocean and its quantification is required in the design of marine facilities. This study identifies the multimodal sea states at six locations in the shelf seas of India based on partitioned wave output data from numerical model WAVEWATCH-III for 26 years (1990 to 2015). The different systems are identified by the propagation direction and frequencies with a relatively high probability of occurrence of spectral partitions. Four to seven types of distinct clusters of wave systems are present among the study locations. The occurrence of these systems and co-occurrence of this with other systems are examined. The southernmost location experiences the effect of seven wave systems. At all locations, two wave systems from the south with relatively low partial significant wave height (Hs) are present for more than 71% of the time and co-occurred with other systems during 2–67%. The most energetic systems are observed 23% (system 5 at station 3) to 60% (system 4 at station 4) of the time with maximum mean partial Hs values of 1 to 3 m during summer monsoon months. The southernmost location (3) experienced maximum opposing (18%) and crossing (78%) sea states.