A Comparative Analysis of Atmospheric Boundary Layer Based on Intensive Sounding Data at Different Altitude Stations

The atmospheric boundary layer characteristics at different altitude stations in Sichuan Province on the eastern edge of the Tibetan Plateau were analyzed and compared using southwest vortex intensive sounding data. The conclusions are as follows. The surface layer at high altitude stations is more influenced by land surface processes; its diurnal variation is also stronger. Temperature lapse rate in the surface layer is the most remarkable, and the daily minimum/maximum value appears at 0200 BT/1400 BT (Beijing time). The depth of the atmosphere layer affected by land surface processes is larger at high altitude stations than at low altitude stations. Temperature inversion obviously occurs below 300-m height at low altitude stations. Specific humidity in the surface layer is the smallest at 1400 BT and the biggest at 0200 BT, and its diurnal variation in the surface layer is slightly greater at high altitude stations than at low altitude stations, while the mean lapse rate in the middle and lower atmosphere is smaller at high altitude stations than at low altitude stations. Wind speed varies within a much wider range at high altitude stations and the vertical wind profiles four times a day are very different from each other, but the opposite is true at low altitude stations. The daily variation amplitude of the surface layer is larger and extreme values appear slightly earlier at high altitude stations.