关键词: 沙尘暴, 浮尘天气, 逆温层, HYSPLIT-4轨迹模式

Abstract:

A regional gale and dust-storm weather occurred in Gansu Province from 8 to 9 March 2013, and untill 14 March the floating dust continued in central and eastern Gansu. The floating dust with such wide range and long duration had been rarely seen in recent years. This paper mainly analyzed the climate characteristics and the influence of the special meteorological conditions on the floating dust weather, and the main features of dust transportation were discussed over Lanzhou of Gansu. The results are as follows: (1) The early warm and dry climate background was favorable to the occurrence of dust weather. (2)The regional gale and dust-storm weather happened in Gansu from 8 to 9 March was caused by the northerly gale behind the cold front, and the dust and duststorm weather appeared again on 11 March in Hexi Corridor. Due to the downstream transportation of dust particulates along the northwest airflow, the stations appearing the floating dust in Hedong of Gansu increased obviously on 12 March. (3) After the gale and dust-storm the boundary layer in central and eastern Gansu was in a weak easterly wind, and the atmospheric stratification was stable for a long time so that the dust pollutants weren’t conductive to spread. (4) During the floating dust weather, the inversion layer frequently appeared over Gansu, and the height of inversion layer was obviously uplifted after 9 March, which blocked the atmospheric rising movement in lower layer, consequently, the dust particulates gathered below 700 hPa. In addition, the intensity of the floating dust weather was positively correlated with the temperature difference and thickness of inversion layer. (5) The floating dust weather in Lanzhou from 9 to 10 March derived from the sandstorm in Hexi Corridor and Mongolia on 8 March, while the sandstorm once again in Hexi Corridor on 11 March had greatly influenced on the floating dust in Hedong area. Furthermore, the floating dust weather appeared in southern Shaanxi from 10 to 13 March due to the dust transport from the north. The dust particulates kept in easterly wind because of the surface situation with higher in the eastern part and lower in the western part of Shaanxi ,which played a certain role in returning transpertation of dust particulates to the floating dust weather in central and eastern Gansu.

Key words: dust-storm, floationg dust weather, inversion layer, HYSPLIT-4 track model