Spectral peak wave period climatology and its relationship with natural climate variability over the Bay of Bengal

Abstract

The predominance of swells or wind-seas at a location can be inferred from the spectral peak wave period (Tp). The present study examines the climatology of Tp and its variability in the Bay of Bengal (BoB) during the last 40 years based on reanalysis data. The Andaman and Nicobar Islands and Sri Lanka significantly alter the spatial distribution of Tp in the BoB. Spatial variation in Tp was less than 10% for 1� latitude, except for regions blocked by the landmass. Inter-annual changes in the annual average Tp were 8-18% at different locations. In most areas, climatological monthly Tp was largest in March, April, and October, when the winds were weak. The high Tp tongue extends to the BoB through the eastern side of the bay. The study also examines the relationship between three major natural climate variabilities; El Nino-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and Southern Annular Mode (SAM) with Tp anomalies in the BoB. We observed that negative ENSO and SAM events enhance the long-period waves in the BoB, while a negative IOD event generates more short-period waves in the BoB.