中亚咸海干涸湖床粉尘潜在扩散的时空变异分析

基于1969~2018年再分析气象资料，运用拉格朗日混合单粒子轨道（HYSPLIT）模型，计算了以咸海为中心未来7d的逐日气团轨迹，采用核密度分析法，绘制了5个层次（0~0.5，0.5~1，1~1.5，1.5~2，2~5km·agl）的气团轨迹密度图，分析了咸海干涸湖床粉尘扩散的时空变异.结果显示，粉尘潜在扩散具有季节分异.春、冬季粉尘扩散范围与密度最大，沿东北方向扩散比例分别占61%、35%，最远可达亚洲东部地区，其次是秋季；夏季粉尘扩散以0.5km为界限表现明显的高度差异.随着高度的增加，粉尘潜在扩散的密度逐渐降低.受地形与天气系统的影响，春、夏粉尘扩散呈现向东北，西南方向扩散趋势，秋、冬呈现沿东北方向扩散趋势.有利的天气条件下，咸海干涸湖床粉尘可远距离输送：在近源区沉降，影响乌兹别克斯坦及周边国家，在山区沉降，则可能加速天山雪冰融化.

Potential spatiotemporal variability of dust from the playa of the dry lake bed of the Aral Sea in Central Asia

In order to illustrate potential spatiotemporal variability of dust from playa of the Aral Sea, the HYSPLIT model with reanalysis meteorological data from 1969 to 2018 was used to compute the 7-day forward trajectories of the air parcel from the Aral Sea. Air parcel trajectory density plots were also mapped for five levels (0~0.5, 0.5~1, 1~1.5, 1.5~2, 2~5km.agl) with the kernel density method. The results showed that potential dust transport pathways had a conspicuous seasonal differentiation. The spring and winter gained the largest potential diffusion range at each height, in which dust from playa of the Aral Sea transported along the northeast accounted for 61% and 35%, respectively, and could reach as far as east Asia. The potential transportation of dust in autumn was weaker than that in spring and winter. Dust diffusion in summer had apparent height divergence around 0.5km. All air parcel trajectories showed densities of dust decreased with the increase of height in each season. In spring and summer, the potential transport of the air trajectory showed a tendency to move northeast and southwest, but move northeast in winter. Under favorable weather conditions, dust generated from the Aral Sea might affect regions downwind thousands of kilometers. Accordingly, the dust from the playa of the Aral Sea might influence Uzbekistan and other countries in the surrounding region. It would remarkably accelerate the melting of snow and ice on the Tianshan Mountains if deposited in the region.