Analysis Of Impacts Of Dust Aerosols On Near Surface Meteorological Elements In Semi-Arid Area Of China

The observational data of meteorological elements, radiation and heat fluxes near surface and soil variables at different depth were collected at SACOL from March to May from 2007 to 2010 to analyze the interaction of dust aerosols and such variables to study the energy balance during different weather process especially dust storm days and their changing features.(1) The respond of meteorological elements to dust concentration was not so obviously as other near surface elements, which may result from the action time of dust storm was not at a fixed time, meanwhile, it could not completely remove the impact of occasional weather events although they have been averaged 10 days. During dust storm days, the frequency of northerly winds was significantly increased, and previous low air pressure and high temperature have a good relationship with dust concentration.(2) The response of radiation fluxes was later but stronger than meteorological elements. Dust particles suspended in the air resulted in the increase of downward long-wave radiation and the decrease of downward solar radiation, which at last made net radiation decreased during the daytime while increased at night.(3) The sensible heat flux and latent heat flux showed the same changing features as net radiation which decreased during the daytime while increased at night, and the energy closure was weakened during dust storm days. The changing of soil heat flux was about 3 hours later than net radiation, which reached its minimum before sunrise and maximum before sunset, and the changing of soil heat flux was not so quickly and obviously as sunny days. The previous low soil volumetric moisture content and high soil temperature at shallow soil layer have a good relationship with dust concentration, while at deep depth they not.(4) Before the dust storm, the atmosphere stratification was not stable at low altitude, there was temperature inversion at high altitude and the relative humidity decreased with height, and the decline rate of relative humidity grew larger over time. While during the dust storm, the temperature inversion at high altitude was destroyed and there was an obvious humidity inversion. (5) The uplifting of dust particles resulted from the common interaction of horizontal wind and vertical velocity. The maximum of PM10 concentration was after the horizontal wind, and the change of V wind component was higher than U.