Gravity wave activities associated with convective phenomena at a tropical location near land-sea boundary

The seasonal analysis of gravity wave activity has been made for the present tropical location, Kolkata (22.5726°N, 88.3639°E) using radiosonde and European Centre for Medium-Range Weather Forecasts 60 model level data. Gravity wave generated due to intense tropical cyclone Aila has also been investigated using European Centre for Medium-Range Weather Forecasts 91 model level data over the Indian region. The gravity wave energy calculated from temperature and wind perturbation profiles show a significant enhancement during convective activities as indicated by a low outgoing longwave radiation. The pattern of zonal and meridional wind shears plays an important role in determining the seasonal variation of gravity wave activities. An intrusion of water vapor into the lower stratosphere over the cyclone affected region is detected from European Centre for Medium-Range Weather Forecasts 91 model level data. The dominant vertical wavelengths of gravity waves in the range of 2.5–3.2 km are found from spectral analysis of wind and temperature perturbations during the tropical cyclone.