Research On Dust Aerosol And Its Impacts From Lidar Observation Data

Dust storms is a disaster weather phenomenon because of the wind on the ground blowing the dust and sand into the air and causing the air of a kind of cloudy finally. The occurrence frequency and intensity of dust storms are related to high wind speed, drought, and other climate background and abnormal atmospheric circulation etc. At the same time, they are also related to the human activities.The characteristics of dust storms in China are studied by using the observational data from1954 to 2009. In northwest of China, arid and semi-arid region is prone to dust weather, especially in the edge of the Taklimakan Desert of Tarim Basin in Xinjiang, west of Inner Mongolia, north of the Qilian Mountains in Gansu Province and central of Inner Mongolia. Dust storms in China can be divided into the transmission paths of north, west and northwest. There is a higher frequency of dust storms from the northwest path and the west path. Dust storms originated from northwest of China affect vast areas of China and surrounding countries.The observational records beginning from 1954 show that, except for a few sites, dust storms frequency in the country witness a decreasing trend with obvious inter-annual variability and relatively active and calm periods. The main weather system for forming dust storms in China is Mongolian Cyclones and the accompanying cold fronts. Abnormal rainfall, temperature, wind and other climatic factors are closely related to the formation and development of dust storms.The mobile DIfferential Absorption Lidar (DIAL) system for atmospheric pollution measurements developed by the Chinese Academy of Sciences' Institute of Optics and Fine Mechanics in Anhui was used to measure the dust aerosols optical properties during dust storms and fog haze weathers. Using Fernald aerosols optical properties inversion algorithm and the measured data, the dust aerosols optical properties in Hefei City during dust storms, mainly including the aerosol extinction coefficient profile and AOD, were calculated and analyzed. The result shows that there is an obvious difference in the profiles the dust storms move through the site. The dust storms strength and the weather and circulation background will affect the profiles. There will generally appear a layer of high concentration of dust aerosol from 3 to 6 km in Hefei when dust storms are passing. When local dust storms occurs in Hefei, there will generally appear a dust aerosol layer in 0-3km near the ground, and the aerosol extinction coefficient near the surface reaches 1. AOD will also experiences a corresponding change.The settlement of aerosol particles of dust has become the main source of Marine nutrients. Using the AOD data recorded by AERONET, the AOD evolution in dust source and the influencing area are analyzed. Research shows that, during dust storms the AOD in the dust source and influencing areas obviously increase, with a 1-3 day peak. Continuous dust-sand storms make the AOD value as high as 0.5, and the settlement is slow. In the areas of dust source, however, the AOD will resume to background level in a short time. Wind speed and dust particle size could be key factors for the difference observed.