Thermodynamic and dynamic behavior in a recent dust precipitation event in north China

Abstract

The dynamic and thermodynamic characteristics of a dust precipitation event that took place on May 11, 2020 in North China are analyzed. With the invasion of cold air from Lake Baikal (107°E, 53°N), the arid area in the southeast of Mongolia (107°–108°E, 47°–48°N) was in a region with a large potential pseudo-equivalent temperature gradient, where interactions between cold and warm air led to instability of the atmospheric stratification, and became the dust source area. Meanwhile, a low-pressure cyclone formed over the area (122.3°E, 47.5°N) to the east of the dust source area. Under the joint action of the westerlies, the cyclone developed and supplied forces to the vertical ascent and transportation of dust. Strong winds carried the dust along the southeast direction to China. As the cyclone strengthened, the cold and humid air from Lake Baikal arrived and supplied water vapor for precipitation over Beijing. On the whole, the low-pressure cyclone provided momentum and water vapor for this dust–precipitation event. It is found that the horizontal helicity belt can be an indicator for the prediction of the dust transport pathway. The quick increase in surface dust concentration to its peak was closely related to the increase in downward movements in the layers above 700 hPa.