Concentration characteristics of sand dust aerosol in atmospheric boundary layer in 2010 at Minqin, Gansu Province

In order to study transportation and outbreak mechanism of sand dust particles, the aerosol particles were continuously sampled from April to May in 2010 at Minqin of Gansu Province using a laser radar (EZ LIDAR ALS300&ALS450 type) and a particulate sampler instrument (GRIMM 180). The altitude-orbit cross section of total backscattering of sand dust aerosol and mass concentrations of PM₁₀, PM_2.5 and PM_1.0 were analyzed under clear, floating dust, blowing dust and sandstorm weather conditions, including the extremely strong sandstorm process occurring on 24 April (0424). The results show that the concentrations of sand dust aerosol are high in spring near the ground surface layer in the study area. The concentration changes largely with variation of some meteorological elements. Mean mass concentrations of PM₁₀, PM_2.5 and PM_1.0 are 202.3μg/m³, 57.4 μg/m³ and 16.7 μg/m³ respectively during the observational period. The correlation among PM₁₀, PM_2.5 and PM_1.0 is significant under the different weather conditions, while variation trends of these variables are different. The mean daily mass concentration of PM₁₀ reaches 2469.1μg/m³ under sandstorm weather, and this is about 100 times higher than that under normal weather condition, 8 times higher than under floating dust condition and 2 times higher than under blowing sand condition. The concentration of PM_2.5 is 460.3 μg/m³ under sandstorm weather, and it is about 45 times higher than that under normal weather condition, 6 times higher than under floating dust weather and 1.4 times higher than under blowing dust weather. That of PM_1.0 is 92.7μg/m³ under sandstorm weather, which is 13 times higher than under normal weather condition, 7 times higher than under floating dust weather and 1.3 times higher than under blowing dust weather. It is seen that the dust particle concentration increases with the increase of wind speed, but small particle proportion decreases and large particle proportion increases with the increase of dust concentration. Analysis of the “0424” strong sandstorm process reveals that a sandstorm process usually includes two types of sandstorm,blowing dust and floating dust. The analysis of lidar data indicates that the serious dust wind erosion occurs at Minqin during the sandstorm.