Near surface atmospheric characteristics over the North Bay of Bengal during the Indian Summer Monsoon

Observations were made from a ship at 17.5°N & 89°E in the North Bay of Bengal during July–August 1999. The Bay was convectively active during this period with almost one convective event every week. The surface wind speed varied from 3 to 15 m s⁻¹. SST decreased by 0.5° to 1° C following convection. The latent heat flux was about 25–35% lower over the Bay compared to that over the West Pacific at comparable wind speeds. High resolution radiosonde observations have been made for the first time in the North Bay. The values of atmospheric mixed layer height, equivalent potential temperature, convective available potential energy and convection inhibition energy over the North Bay are comparable to those observed over the western Pacific warm pool region. The recovery timescale of the atmospheric variables such as mixed layer height, equivalent potential temperature and convective available potential energy is one to two days.