干旱区地理2011，Vol.34Issue(2)：292-299,8.
黄土高原半干旱区气溶胶光学特性季节变化特征
Seasonal variation of aerosol optical properties at AERONET of the semi-arid region in Loess Plateau
摘要
Abstract
Semi - arid regions are defined as transition zones between arid and sub - humid belts where precipitation is less than the potential evaporation. Semi -arid lands, especially those located in mid -latitude inner continental regions, are some of the most sensitive areas to climate change. One of these regions is found in western China. During the last few decades, warm winters and dry springs occurred more frequently in northwestern China where, with disturbances brought about by human activity,large areas of vegetation were destroyed, thus giving rise to anthropogenie dust emissions. Understanding how human activity and the resulting dust emissions affect aerosol optical properties in these semi -arid regions is an essential step for developing mitigation and adaptation strategies to climate changes in these transition areas. In order to monitor the global aerosol optical properties, the U. S. space agency NASA and its partners established a worldwide network of ground - based observationswhich is an international aerosol automatic monitoring network called AERONET (Aerosol Robotic Network). The sun and sky diffuse radiation was measured and thene the aerosol optical properties are retrieved by using the sun and sky scanning spectral radiation observations. The products from the AERONET direct sun and sky radiance measurements are retrived through a rigorous calibration,cloud mask processing, and quality control. In this paper, the impact of dust aerosols on the semi - arid climate of northwestern China was analyzed using Version 2 Level 2 dataset from the AERONET site located in the semi - arid region in Loess Plateau in China, which is named as Lanzhou_city site. The seasonal variation of parameters of atmospheric aerosol optical properties such as aerosol optical thickness, Angstrom exponent, volume size distribution (dV(r)/dlnr), refractive index (n-ik) and single scattering albedo ( 0 ) were analyzed. The results show that the optical properties of the dust aerosols and aerosols generated by human activities have become apparently great effect on the semi -arid climate zones in Loess Plateau in China; , the aerosol optical thickness was the largest in spring as dust events occurred most frequently; the optical thickness was second large in winter as residence heating systems and dusts combined to affect on it; the optical depth reduced in summer and autumn as rain occurred relatively frequently and that cause the removing dusts from the atmosphere; the differences of aerosol particle volume size distribution during each season, ranging from 0. 13 ～0. 34 in spring, 0. 14 ～0. 34 in winter, 0. 12 ～0.29 in summer and 0.14 ～0.31 in autunm, were mainly reflected in the volume concentration of coarse mode particles; the coarse mode volume concentrations showed significantly seasonal variation ranging from the largest to the fewest was in spring, winter, summer and autumn sequently and the particle volume concentration ratio and optical thickness had the same order of seasonal variation; that showed seasonal changes of the optical thickness for the region was mainly due to the volume concentration of coarse mode. In addition,the coarse mode volume median radius ranged from 1.80 ～3.35 in winter, 1.79 ～3.51 in autumn, 1.77 ～3.24 in summer and 1.32 ～2.80 in spring; also there were significantly seasonal changes ranging from winter, autumn, summer and spring; the order of seasonal variation of the real part of refractive index, aerosol concentration of coarse particle size and optical thickness were the same while the imaginary part of refractive index was the largest in winter and the smallest in spring; the variation of single scattering albodo with the seasons was very different that was the smallest in winter andthe largest in spring; it might caused by the chemical compositions of aerosol particle size and theirs integrated effects.关键词
沙尘气溶胶/光学特性/季节变化Key words
dust aerosol/ optical characteristics/ seasonal variation分类
天文与地球科学引用本文复制引用
白鸿涛,陈勇航,王洪强,张强,郭铌,王胜,潘鹄,张萍..黄土高原半干旱区气溶胶光学特性季节变化特征[J].干旱区地理,2011,34(2):292-299,8.基金项目
国家自然科学基金(40830957) （40830957）
国家科技支撑计划重点项目(2008BAC40B04)和干旱气象科学研究基金项目(LAM200807)资助 （2008BAC40B04）
