Abstract
This research used enhanced observational data of dust concentrations, dynamic factors near the land surface, and vertical distributions of temperature and relative humidity collected from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL), in combination with the NCEP FNL reanalysis data, to study a typical dust event that occurred in Lanzhou during March 2010. The goals are to reveal the background circulation, dynamic factors that caused the dust storm, and vertical profiles of meteorological variables. The results show that this dust event was caused by the interaction of a shortwave trough at high altitude and meso-scale depression system underneath this. Before the dust event, the instability of the low-altitude stratification with the assistance of temperature inversion at higher altitude provided the conditions for strong convection near the surface. During the dust event, the maximum PM10 concentration appeared shortly after the maximum wind, and the change in the meridional wind component was bigger than that in the zonal component. The temperature inversion was destroyed at higher altitude, and a significant humidity inversion occurred as a response. Relative humidity gradually decreased with altitude, and the rate of decline increased over time.
Highlights
Most arid and semi-arid regions in China are located in the northwest region, of which arid regions account for more than 80% of the total area (Dong et al, 2006)
This research used enhanced observational data of dust concentrations, dynamic factors near the land surface, and vertical distributions of temperature and relative humidity collected from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL), in combination with the NCEP FNL reanalysis data, to study a typical dust event that occurred in Lanzhou during March 2010
We used the observational data of dust concentration, dynamic fluxes, vertical profiles of temperature and relative humidity collected at the SACOL, in combination with the NCEP FNL reanalysis data, to analyze the background circulation, dynamic conditions, and vertical meteorological elements during a typical dust event in Lanzhou in March 2010
Summary
Most arid and semi-arid regions in China are located in the northwest region, of which arid regions account for more than 80% of the total area (Dong et al, 2006). Studies on optical properties of dust aerosols (Fu et al, 2008; Bi et al, 2010; Wang et al, 2010), physicochemical characterization (Zhang et al, 2002, 2008; Cao et al, 2009), sources and deposition fluxes (Rastogi et al, 2006; Zhang et al, 2006, 2010), radiative forcing properties (Reddy et al, 2007; Ge et al, 2010; Zhang et al, 2010), measurements of dust aerosol’s vertical structure (Huang et al, 2010), remote sensing observations and numerical simulations of dust aerosols (Huang et al, 2007) and dust aerosols’ effects on semi-arid climate (Huang et al, 2010) using the first-hand data collected from semi-arid region stations (including the SACOL station) have provided many insightful results. In order to ensure the consistency of the data for analysis, all observational data from the SACOL were averaged over 30-min interval, except for the vertical distributions of meteorological elements
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