Wave systems in the Arabian Sea and their spatial and seasonal variationsWave systems in the Arabian Sea and their spatial and seasonal variationsK K Sivakrishnan, V Sanil Kumar

This study identifies the wave patterns of the Arabian Sea (AS) by analyzing the monthly averaged directional wave spectra and its inter-annual variability. The focus is on three primary wave types, each exhibiting unique seasonal patterns and intensity variations across the region. During non-monsoon months, local wind-driven, shorter-period waves are prevalent. However, with the onset of the southwest monsoon, intermediate-period swells (swell 1) become dominant. This transition marks distinct seasonal patterns: in April, swells primarily originate from the west-northwest; by August, strong monsoon westerlies elevate wave energy at lower frequencies; and by December, the northeast monsoon brings waves from the northeast. An examination of four specific transects at 55°, 60°, 65°, and 70°E reveals regional differences influenced by local wind, swells from the south Indian Ocean, and monsoon patterns. Significant wave height (Hs) peaks during the monsoon season and remains more stable during pre- and post-monsoon months. Inter-annual variability at P9 shows consistent seasonal trends with notable exceptions, such as an unusually low swell 1 Hs in 2006 and a 40% increase in wind-sea Hs in 2008 and 2012. The contrast between wind-sea activity during non-monsoon months and swell dominance during the monsoon underscores the influence of seasonal winds on the AS wave climate. These findings enhance our understanding of wave patterns, providing valuable insights for improving marine operations and coastal planning in the region.