Abstract
Simultaneous intensive radiosonde observation at three stations over northeast (Sylhet), central (Dhaka), and northwest (Bogra) Bangladesh was analyzed to describe a three-dimensional thermodynamic and airflow struc-tures on 25 April 2010, in which a distinct nocturnal rainfall occurred at Sylhet. As the observation was con-ducted in the daytime, the observed structures represent convectively inactive condition in a diurnal cycle. Local circulation was unclear and larger-scale airflow was dominated over Sylhet. The radiosonde observation indicated strong subsidence within 1-5 km over Dhaka and Bogra and within 4-5 km over Sylhet, whereas topographic uplifting of southwesterly airflow was observed within 1-3 km over Sylhet. Temperature profiles of Sylhet up to 3 km were lower than that of other stations, and easterly wind was observed at the surface.
