摘要
Vertical profiles of aerosol extinction coefficients were measured by an Micro Pulse Lidar over the Tibetan Plateau during summer 2011.Observations show a persistent maximum in aerosol extinction coefficients in the upper troposphere–lower stratosphere (UTLS) within the anticyclone during the Aisian summer mosoon.These aerosol layers are generally located at an altitude of 18-19 km,1-2 km higher than the tropopause,with broad layers depth ranging approximately to 3-4 km.Variations in these aerosols are closely related to the intensity of underlying deep convection.Efficient vertical transport resulting from the most intensive convection is considered to be most important for the enhancement of aerosols observed near the tropopause.Temporal variations in aerosol layer in UTLS over the Tibetan plateau show a significant peak at midnight.This further indicates that deep convection rather than condensation of water vapor plays an important role in the accumulation of aerosols in UTLS over the Tibetan Plateau.