he Tower Layer Meteorological Elements Observation Analysis of An Advection Fog

Using the profile data observed by the Tianjin 255m Meteorological Tower, vertical distribution characteristic of meteorological elements in the advection fog on Feb. 13, 2006 has been analyzed. The results show that the meteorological elements distribution of the fog is distinct from known fog structure. There are a low level jet stream and inversion layer before the fog form, and then, the lower atmosphere state gradually became moist unstable which the temperature decreased at wet-adiabatic lapse rate and humidity increased obviously in 250m companied with the process of the low level jet stream. During the fog continuance, there is a temperature inversion layer in the surface layer and double-deck strong inversion structure at upper layer of the tower. The inversion layers disappeared in the surface layer and weaken at upper layer of the tower and humidity decreases rapidly after the fog. In addition, the wind shear is not obvious in horizontal and is remarkable in vertical during the advection fog developing. The fog dissipates from the top down.