National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 2023

Seasonal variation of the land breeze system in the southwestern Bay of Bengal and its influence on air-sea interactions

Athulya, K., M.S. Girishkumar, M.J. McPhaden, and S.S. Kolukula

J. Geophys. Res., 128(3), e2022JC019477, doi: 10.1029/2022JC019477, View online at AGU/Wiley (external link) (2023)

This study examines the seasonal variability of the Land Breeze System (LBS) in the Bay of Bengal (BoB) using hourly moored buoy data, coastal radar data, atmospheric reanalysis data, and 6-hourly satellite-based Cross-Calibrated Multi-Platform (CCMP) wind velocity data. We first provide an overview of the LBS for the entire BoB, then focus on the pronounced LBS in southwestern BoB and its impact on the near-surface current field and latent heat flux (LHF). We show that the LBS in the southwestern BoB exhibits a maximum diurnal wind speed amplitude of ∼2 m s−1 with seaward nearshore winds best developed in the morning hours. The geographical coverage is maximum in July and August and minimum in December and January. During its peak phase in July–August, the signature of the LBS in the southwestern BoB extends up to 600 km offshore, occupies ∼20% of the basin, and accounts for approximately 15% of the seasonal mean wind speed variance. The near-surface current field shows a rapid response to the diurnal wind speed variations, with an eastward current observed between 1000–1800 IST, a westward current between 1800–0800 IST, and a diurnal range of 12 cm s−1. LHF shows well-defined diurnal variability in response to diurnal LBS wind speed variability, with a morning maximum, evening minimum, and a diurnal range of 35 W m−2. We also find that the large-scale seasonal winds are the main factor in determining the annual variability in strength and geographical coverage of the LBS in the southwestern BoB.

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