不同沙尘天气微气象和沙尘演变规律的对比研究

利用内蒙古浑善达克沙地沙尘暴实验探测资料，给出2004年春季多次沙尘天气过程近地面微气象学要素、湍流通量及沙尘浓度的极值对比，重点分析了3月27-28日强沙尘暴过境时近地面微气象学要素和辐射分量的变化特征。结果表明： 沙尘天气过程中，白天近地层温差均有不同程度的降低，夜间逆温强度减弱；净辐射与感热通量较晴空值均有不同程度的削弱。沙尘天气过境时，动量通量显著增加，动力湍流与热力湍流配合，有利于加强沙尘源区的局地起沙和沙尘的垂直输送过程。3月27-28日强沙尘暴过境时，伴随地面水平风向的转变，沙尘浓度迅速增加，风速及其垂直梯度增大；在沙尘暴增强阶段，近地层降温达7℃，比湿出现极大值，净辐射和感热通量降为负值。当沙尘浓度达到最大值后，净辐射上升至零，反映了夜间沙尘气溶胶对低层大气和地表的保温作用。

Dust Concentration and Micrometeorological Elements in Different Dust Storm Events

Based on data from the dust storm monitoring station over Hunshandake Desert Area, Inner Mongolia, the maximum values of micrometeorological variables, turbulent fluxes and dust concentration in the surface layer are compared for eight dust events in the spring of 2004, and the characteristics of micrometeorology and radiation components in the strongest dust storm event in March 27-28 are analyzed. The results show that temperature differences in the surface layer, net radiation and sensible heat fluxes all decrease during daytime, and the strength of temperature inversion weakens at night. When dust events occur, momentum fluxes increase. It is found that both mechanical turbulence and thermodynamic turbulence play important roles in local dust rising and vertical dust transport over source regions. During the passage of the strongest dust storm event in March 27-28, dust concentration, wind speed and vertical shear of wind velocity increase rapidly, together with changes of wind direction. At the strengthening stage of the dust storm, temperature falls by about 7℃, and there is a peak value of specific humidity. Both the net radiation and sensible heat fluxes become negative. When dust concentration reaches its maximum, the net radiation rises to zero, which reflects the heating effect of dust aerosol during nighttime.