中亚沙尘气溶胶时空分布特征及潜在扩散特性分析

发布时间：2018-11-26 09:22

【摘要】：中亚地处干旱和半干旱气候区,是全球沙尘气溶胶贡献度较大的区域。利用中分辨率成像光谱仪(Moderate-resolution Imaging Spectrometer,MODIS)和云—气溶胶偏振雷达(CloudAerosol Lidar with Orthogonal Polarization,CALIOP)遥感数据,从宏观角度对2002-2015年中亚地区气溶胶光学厚度(Aerosol Optical Depth,AOD)时空分布特征及沙尘气溶胶光学特性垂直分布特征进行分析,利用拉格朗日混合型的扩散模型(Hybrid Single Particle Lagrangian Integrated Trajectory,HYSPLIT)讨论沙尘运输的季节性变化。结果表明:(1)中亚AOD空间分布呈现显著的季节性差异,四季均值春(0.412)夏(0.258)冬(0.167)秋(0.159),14年间呈现增加趋势;(2)中亚AOD高值区域主要集中于咸海地区和新疆的塔里木盆地,其中,咸海地区AOD年均值为0.278,年均增幅为3.175%,主要受咸海退化所导致的干涸湖底裸露面积加大的影响;塔克拉玛干沙漠地区AOD年均值为0.421,年均增幅0.062%,主要受温度和风速两方面的影响,不同季节下主导因素略有差异;(3)尘源区气溶胶主要集中在近地面0~2 km范围内,沙漠上空气溶胶退偏比范围(10%~45%)略大于咸海上空(15%~30%);咸海地区色比值(0.3~0.8)小于沙漠地区(0.5~0.9),且在0~2 km和4~6 km有两个高频色比值分别为0.5和0.3,说明相比沙尘气溶胶,咸海地区的盐尘气溶胶球形程度较高,颗粒更小,飘散高度更高;(4)咸海地区盐尘潜在扩散方向主要以东北,西南和南为主,向东北方向的扩散距离最远,影响范围可达俄罗斯中部地区,西南方向扩散路径高度和距离较近,主要影响乌兹别克斯坦和土库曼斯坦,但发生比例相对较高,塔克拉玛干沙漠地区起尘后大部分沙尘颗粒仍沉降在尘源区附近,向东部地区扩散的沙尘气溶胶,主要影响中国青海、甘肃、宁夏、陕西等地区。
[Abstract]:Central Asia is located in arid and semi-arid climate zones. The aerosol optical thickness (Aerosol Optical Depth,) in Central Asia from 2002 to 2015 was analyzed from a macro perspective by using the medium Resolution Imaging Spectrometer (Moderate-resolution Imaging Spectrometer,MODIS) and cloud-aerosol polarization radar (CloudAerosol Lidar with Orthogonal Polarization,CALIOP) remote sensing data. The temporal and spatial distribution characteristics of AOD) and the vertical distribution characteristics of dust aerosol optical properties were analyzed. The seasonal variation of dust transport was discussed by using Lagrange mixed diffusion model (Hybrid Single Particle Lagrangian Integrated Trajectory,HYSPLIT). The results showed that: (1) the spatial distribution of AOD in Central Asia showed significant seasonal difference, and the mean of spring (0.412), summer (0.258), winter (0.167) and autumn (0.159) showed an increasing trend in 14 years; (2) the high value region of AOD in Central Asia is mainly concentrated in the Aral Sea region and the Tarim Basin in Xinjiang. Among them, the annual average value of AOD in the Aral Sea region is 0.278, and the average annual increase is 3.175%. It is mainly affected by the enlarged exposed area of the dry lake bottom caused by the degradation of the Aral Sea. The annual average value of AOD in Taklimakan desert is 0.421, with an average annual increase of 0.062, which is mainly affected by temperature and wind speed, and the dominant factors are slightly different in different seasons. (3) the aerosol concentration in the dust source region is mainly within the range of 0 ~ 2 km near the ground, and the depolarization ratio of aerosols over the desert (10 ~ 45%) is slightly larger than that over the Aral Sea (15 ~ 30%); The color ratio in the Aral Sea region (0.30.80) is smaller than that in the desert area (0.50.90), and there are two high-frequency color ratios of 0.5 and 0.3 at 0 ~ 2 km and 4 ~ 6 km, respectively, indicating that there is a comparison between the dust aerosol and the sand aerosol. The salt dust aerosols in the Aral Sea area have higher spherical degree, smaller particles and higher height of dispersion. (4) the potential diffusion direction of salt dust in Aral Sea area is mainly northeast, southwest and south, and the distance to northeast is the furthest, and the influence range can reach to the central part of Russia, the height and distance of southwest diffusion path is close. It mainly affects Uzbekistan and Turkmenistan, but the occurrence ratio is relatively high. After dust rising in Taklimakan desert, most of the dust particles are still deposited near the dust source area and spread to the east of the dust aerosol. Mainly affects China's Qinghai, Gansu, Ningxia, Shaanxi and other regions.
【作者单位】：新疆大学资源与环境科学学院;绿洲生态教育部重点实验室;新疆交通职业技术学院;
【分类号】：X513

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