Measurement report: The promotion of low-level jet and thermal-effect on development of deep convective boundary layer at the southern edge of the Taklimakan Desert

Abstract

Abstract. A vigorous development process of the deep convective boundary layer (CBL) was observed at the southern edge of the Taklimakan Desert on 6 June, 2022. Based on coherent Doppler wind lidar and ERA5 data, the formation mechanism of the deep CBL exceeding 5 km was well analyzed, which was mainly promoted by the low-level jet (LLJ) and thermal-effect. The LLJ has made sufficient momentum, energy and material preparations for the development of the deep CBL. Firstly, the cold downhill airflow of the Tibet Plateau leading to LLJ weakens the height and intensity of the temperature inversion layer, which reduces the energy demand for the broken of the IL. Secondly, the LLJ not only supplements the material and energy in the residual layer, but also suppresses the exchange with the lower atmosphere. In addition, the LLJ provides a driving force for the development of the deep CBL. In terms of thermal factors, the Tibet Plateau sensible heat driven air-pump and cold front transit provide additional impetus for the development of the deep CBL. Finally, the formation of deep CBL was catalyzed by the extreme thermal effects of the underlying surface, such as the furnace effect and the atmospheric superadiabatic expansion process. The study of the development of the deep CBL is important for revealing the land-air exchange process of momentum, energy, and material between the Taklimakan Desert and the Tibetan Plateau.