Seasonal change of the atmospheric boundary layer over Huaihe River basin in China
The Huaihe River basin has dry winter and wet summer seasons, and the structure of the atmospheric boundary layer shows the seasonal march. The change was continuously observed using a flux tower, a Doppler sodar, and a boundary layer profiler for more than two years. The mixed layer development was strongly affected by the surface conditions, that is, the wheat field, bare soil, and paddy field. When the surface is wet, the development of the mixed layer is weak and vice versa. Generally, the development was controlled by the surface sensible heat flux. But the development of the mixed was also affected by large scale up/downdraft. When a large scale subsidence exists, the development of the mixed layer is suppressed. A so-called LES simulation was performed in order to study the vertical profiles of the sensible heat and latent heat fluxes. It was found that the profile over paddy field is in between those over dry land and over ocean. The importance of the buoyancy due to the water vapor was also confirmed.
