The Change Characteristics Of Particle Concentration On Sand Dust Weather

With the development of society, the scope of human activities gradually expanding and the influence to ecological environment is becoming more and more serious, especially in the vulnerable ecological environment in desert area. Unreasonable human disturbance, the surface condition serious changed, at the same time as the original desert area with dry climate, scarce precipitation, when the surface conditions changed, it’s easy to produce dust storms. There are distributed large areas of desert in Northwest of China, under appropriate conditions, the surface of sand blown by the wind, then transmission to the downwind areas. At the same time, sand and dust weather not only has a serious impact to the air quality, but also threat to human health. Dust aerosol accounts for an increasing proportion of atmospheric aerosol; dust aerosol is one of the important factors of impact on climate change and climate prediction. As the sand dust weather caused hazard more and more seriously, people gradually realize that the sand dust weather has become a serious environmental problem.Through analysis the reason of sand dust weather occurred over the past years, combined with the analysis of typical sandstorm weather process, using the monitoring data from country weather station, and satellite images. The hourly variation trend, change of daily variation trend and the monthly average were analyzed at sandstorm weather process from January to May in 2014.At the same time, through the analysis, elaborated the variation trend of TSP and PM10 at sandstorm weather process, the relationship characteristics between concentrations of TSP and influence factors of the sand dust weather were analyzed. At this basis, analysis the correlation between dust weather process and air quality, and the correlation between TSP and PM10 is analyzed too, the results of the study show that:1 Siberia cold air frequent hit most of Northern China and Northwest China are closely related for the occurrence of the sand dust weather in China. Because the path of cold air influences large area of desert, Mongolia cyclone and cold front interaction, resulting in China’s dust storms occur frequently in the spring.2 At the process of sand dust weather, there are significant correlation between the meteorological factors and the concentration of TSP: humidity will decrease significantly in the dusty weather, but in the course of transit, humidity may increase gradually; visibility directly affected by the TSP, at strong dust storm process, visibility dropped to less than 1km, change between visibility and TSP with the time difference, but the time was only 1 hour; wind direction determines the develop of dust storm and the transmission direction of particles, by the wind direction and wind speed, a large number of dust particles in the air transport to the downwind and effect the air quality.3. Through analysis the sand dust weather process in 2014, it can be found that, in the dust source region and dust affected zone city before and after the dust weather, the concentration of TSP has the very big difference, the sand dust source areas of each month value exceeds the limit value grade two of national standard only in April, and the influence of area in April and May were exceed the standard. In the dust source region with the increase of TSP concentration, the proportion of PM10 and TSP increased gradually, in the sandstorm, the concentration of TSP and PM10 values were greater than two national concentration limits. According to the daily variation of TSP concentration values, at this stage the sand dust weather in China mainly happened in April, next were March and May. In the sand dust source areas, PM10 in the proportion of TSP reached 70%, but in the dust effect, in the absence of dusty weather, the proportion less than 50%. After analysis, we can found that, influence areas are big city, urbanization and population factors determine the pollutant composition; source region is a small city, in the desert and the surrounding Gobi, relative to a single source of particulate matter.4. By analyzing changes in dust particle concentration, combined with China’s national standard definition, the sand dust weather analysis shows: in the sand dust source areas, the dust weather occurred when the TSP concentration in the range of 0.5-1.5 mg/m3, blowing sand weather when the TSP concentration is between 1.6-3mg/m3, the sandstorm weather when TSP concentration in the 5-6 mg/m3 TSP, the strong sandstorm concentration is about 8 mg/m3.