塔里木盆地空中蓄尘库效应对空气质量的影响

利用WRF中尺度天气预报模式耦合GOCART大气化学气溶胶辐射传输模式，对2011年4月27日~5月2日源于我国西北沙尘源区的一次大范围沙尘天气过程进行了数值模拟，并结合MODIS卫星观测资料，发现了塔里木盆地对沙尘气溶胶分布的空中蓄尘库效应.为了对该效应及其对下风向城市空气质量的影响进行验证，期间在兰州大学监测点开展了1h分辨率PM₁₀中水溶性Ca²⁺浓度监测，并结合CALIPSO气溶胶类型垂直分布产品和HYSPLIT气团轨迹模型，利用PSCF方法分析了期间监测点的48h气团后向轨迹.模拟，遥感和监测结果共同表明，塔里木盆地的空中蓄尘库效应会对进入其内部的沙尘气溶胶产生限制-积累作用，若在限制-积累过程中盆地内部近地面风场改变，空中蓄尘库会二次释放沙尘气溶胶，对下风向城市空气质量产生影响.

The Airborne Dust Reservoir effect of Tarim Basin and its impact on air quality

The arid and semi-arid area in Northwest China is an important dust source region in the world. Compared with other major dust sources around the globe, this region is characterized by the complexity of its surrounding landform. In this paper, the WRF mesoscale weather forecast model coupled with the GOCART atmospheric chemical-aerosol radiation and transmission model was used to simulate a large-scale dust episode which originated from the dust source region in northwest China from April 27, 2011 to May 2, and verified by the MODIS remote sensing data, the airborne dust reservoir effect of Tarim Basin on dust aerosol distribution was found. In order to verify this effect and its impact on the air quality of downwind city, hourly mass concentration of water-soluble Ca²⁺ in PM₁₀ was monitored in Lanzhou during this period. Combined with CALIPSO vertical aerosol feature mask product and HYSPLIT air mass trajectory model, PSCF was used to analyze the 48-hour backward trajectories of air mass which arrived at Lanzhou during this dust episode. The simulation, remote sensing and site monitoring indicated that the effect of Airborne Dust Reservoir would constrain and accumulate the inbound dust aerosol. Meanwhile, if the wind direction changed, the suspended dust aerosol constrained by the basin could re-release as a secondary dust source, which would exacerbate the impact of the dust episode on the air quality of downwind city.