| Atmosphere aerosols is a scatter system that solidity or liquidness particles scattered into atmosphere. Though the mass of atmospheric aerosol particles only have a proportion of one billionth of atmospheric mass, it have an important effect to the radiative process, climatic change, environmental, quality, cloud and precipitation process, and process of water circulation that make up the radiative climate effect, environmental health effect, and cloud physics effect. So that, the study of the physical and chemical characteristic, optical depth and the spatial and temporal variations become a key issue of atmospheric sciences.By using the observed direct solar radiation data gained by the automatic sun tracking spectrophotometer CE-318, the optical depth, size distribution and extinction coefficient of atmospheric aerosol is calculated and by using the result of calculation, we analyse the variation characteristic of optical depth, size distribution and extinction coefficient of aerosols in Yinchuan systematically.CE-318 is a kind of equipment with high degree of accuracy which have many advantages such as easy taking, easy fixed, automatic scanning, solar energy current supply and automatic data transferring etc. CE-318 is mainly used in the measurement of the radiative intensity of sun and sky which lies in visible light and near infrared band in different band, direction and time. By using the data of direct solar radiation, we can do pre-processing the extinction depth, optical depth of aerosols, total water content of atmosphere column, total content of ozone and the data of sky scanning can calculate size distribution and phase function of atmospheric aerosol. Now CE-318 is used in dust storm observational system in our country.We calculate the calibrate coefficient by using the method of Langley with the data of direct solar radiation whet it is fine and stratification of atmosphere is stability first. Then we calculate aerosol optical depth by using the rule Bouguer. On the basis of aerosol optical depth we calculate size distribution of by using the method of Monte carlo. We analy e characteristic of aerosol optical depth, size distribution and extinction coeff ent systematically.Yinchuan is located in the east of North-west in our country. Ba-danjilin Desert and Teng-geli Desert lie to the Northwest, and Mao-wusu sand land east. The deserts and sand land are important sources of dust aerosol in this area. Due to the plenty of sand sources and lacking of precipitation in winter and spring, its dry climate and gale result in frequent dust storm, in particularly during April and May. The direct solar radiation data which is used in this paper gained by CE-318 is the sun direct radiation in April, July, October and December. The data can represent the direct solar radiation of spring, summer, autumn and winter. By analyzing the resultof calculated optical depth and size distribution, we can supply a reference to a further study of atmospheric aerosol. There are many conclusions:(1). Aerosol optical depth change with different weather conditions and geographical location and even have a different variation in a certain wave band. The characteristic of aerosol optical depth is different in different wave band: the capability of extinction bigger in visible light than in near infrared and the variation of aerosol optical depth is obvious with physical and chemical characteristic of aerosols. Diurnal average mean of aerosol optical depth in clear atmosphere is one magnitude smaller than this in dust floating and dust blowing weather.(2). The Aerosol Optical Depth (AOD) appears apparently diurnal and seasonal variations. There are four types of diurnal variations (9:00~16:00) , and they are : 1). AOD is relatively steady. Diurnal average of a in 870nm,936nm and 1020nm is less than 0.1 and in 440nm range from 0.1 to 0.2 because the extinction is larger in visible light bands than in near infrared under this circumstances .2). AOD has a trend of increase; 3). AOD has a peak value at n... |
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