特强沙尘暴灾害性天气的研究及展望

Research progress of very strong sandstorm and its future research prospects

总结特强沙尘暴天气的研究进展,梳理分析特强沙尘暴天气的基本特征以及动力学触发机制,提出进一步的研究问题,以期加深对特强沙尘暴天气过程机理的认识.分析结果表明特强沙尘暴天气事件的季节性分布特征显著,春季居多,且多发生在下午到傍晚时段,其典型特征为突发性、局地性,持续时间相对较短,对局地的大气环境质量短时产生重大影响.旺盛的地面混合层热对流胞运动和中尺度(反)气旋性涡旋过境是特强沙尘暴天气出现的必要条件.在沙尘源区,由于午后近地层温度升高,热对流加剧,近地层热层结极不稳定,易形成地面混合层热对流胞运动;沙尘源区的热对流胞与混合层上部的中尺度(反)气旋性涡旋耦合作用,涡量通过热对流胞下传促使近地层层结内的热对流胞发展成群发性旋转对流胞,特强沙尘暴天气出现.进一步理解特强沙尘暴的风沙流特征及能量快速耗散机制,提高预测预警能力,需要加强特沙尘暴的气象观测数据积累和多尺度数值模拟.

The up-to-date research progress of very strong sandstorms was summarized in this study,including the characteristics and evolution mechanism of very strong sandstorms.Issues for further research have been also put forward.The very strong sandstorms showed a seasonal variation and appeared more often in spring,usually occurring from afternoon to evening suddenly and locally,with short duration.The triggering of very strong sandstorms is due to the coincidence of the upper weak air mass with certain vorticity and the developed convective bubbles in the near-surface unstable mixing layer,resulting in the onset of swirling bubbles from the common convective bubbles.The sand and dust are lifted due to the entrainment of swirling bubbles.The front of a very strong sandstorm would move slowly and finally disappeared quickly with the occurrence of secondary vortices in swirling bubbles.The occurrence of secondary vortices in swirling bubbles played a role in speeding up the energy dissipation of a very strong sandstorm.To further understand the characteristics of the wind-sand two-phase flow and the mechanism of energy dissipation of very strong sandstorms,and further improve the accuracy of sandstorm forecast,there is a need to strengthen the accumulation of meteorological observation data and the multi-scale numerical simulation of very strong sandstorms.