Features of locally and remotely generated surface gravity waves in the inner-shelf region of northwestern Bay of Bengal

摘要

In this article, we studied the characteristics of locally and remotely generated wind waves in the inner-shelf region of northwestern Bay of Bengal (BoB) based on the measured wave data. Two well-differentiated wave systems, one young sea from the east-southeast and another more developed swell from the south lead to bimodality in the wave spectrum. Wind-sea predominance is not observed in the monthly average wave spectrum and in all the months swells dominated indicating a swell-driven wave regime. During the monsoon (JJAS), the wave climate is dominated by long-period swell from the south-southeast and the short fetch during the northeast monsoon (ONDJ) leads to weaker easterly swells, while the effects of the sea/land breeze influence on the wave generation are more relevant during this season. During November-April, diurnal variation of 0.15 m in significant wave height (SWH) is observed. The study based on seasonally averaged ERA-Interim reanalysis data reveals a weak connection between the waves in the northwestern BoB and the El Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) events. The waves are influenced by ENSO events during June-September and by IOD events during October-January, which consequently caused inter-annual variations in monthly average SWH. The present study, however, did not show a significant inter-annual variability in annual mean SWH during 1979-2015.