The Tibetan Plateau as dust aerosol transit station in middle troposphere over northern East Asia: A case study

Abstract

In the process of dust transport, the Tibetan Plateau (TP) plays a significant role because of its high topography. A dust event occurred from 2 to 5 April 2018 was chosen to study the role of TP in middle troposphere using Weather Research and Forecasting Model coupled with chemistry (WRF-Chem) model. The model reproduced the meteorological parameters, spatiotemporal distribution of dust reasonably. This study found that the dust originated from Taklimakan Desert (TD) was rose to 7 km under the influence of strong updraft flow and dust elevated heat pump, then transported eastward under the guidance of flat westerly flow. Subsequently, a trough passing the TD region carried the raised dust southward to the TP, leading to a thick dust belt with the concentration >200 μg m−3 suspended over the TP. After that, the dust are entrained to upper troposphere by the TP and then continue to transport eastward to the northeast of East Asia (NE). The TP acted as a transit station that lifted dust aerosol to the upper level. Moreover, the cold vortex over Siberia was stronger compared with the climatologic mean value. Consequently, cold air separated from the vortex enhanced the East Asian trough and triggered the dust emission. The above anomaly was conducive to the TD-TP-NE transport of dust. The dust-induced heating rate over NE peaked at 1.0 K/day at 7.5 km, which was comparable to TP. The dust layer over NE may further affect atmospheric circulation, clouds properties and precipitation.