摘要
利用NCEP1°×1°全球格点再分析资料和常规地面观测资料,对2015年4月27日北疆沿天山一带的沙尘暴天气过程进行了诊断分析。结果表明:乌拉尔山低槽分裂短波槽与中纬度锋区上中亚低槽汇合东移是沙尘暴发生的影响系统,地面冷锋过境是沙尘暴出现的直接原因;前期高温少雨,时值春播期为沙尘暴的发生提供了丰富的沙尘源;中层400 hPa至低层700 hPa强冷平流的入侵,加大了热力不稳定;假相当位温锋区的强迫抬升作用,触发了不稳定能量的释放;300 hPa高空西南急流的增强,以及低空西北急流的快速东移,为沙尘暴提供了充足的动力;水平风速增大和局地上升运动的共同作用,加大了空气的扰动和流动,促进了沙尘暴的产生。沙尘暴天气发生在地面冷锋后部西北大风区内、ΔP_3中心前部、850 hPa强冷平流前部以及850 hPa强上升运动区内。ΔP_3≥10.0 hPa、水平螺旋度≤-300 m^2·s^(-2)对沙尘暴天气的预报有较好的指示意义。
Based on NCEP 1° ×1° reanalysis data and the conventional observation data,the sandstorm happened along Tianshan Mountains of Northern Xinjiang on April 27th,2015 was analyzed.The results showed that the low trough composed by part of the Ural trough and the Central Asia trough was the effect system of the sandstorm,and the cold front directly initiated it.The extremely high temperature,less rainfall,and the spring sowing period provided rich sand-dust sources.The cold convection from 700 hPa to 400 hPa increased the thermal instability.Then the uplift of the potential pseudo-equivalent temperature zone helped the release of the unstable energy.Besides,the enhancement of westerly jet on 300 hPa and the rapid movement of northwest jet on low-altitude both provided plenty of power for the sandstorm.Then the increasing horizontal wind velocity and the local ascending motion enhanced the air turbulence,which promoted the emergence of the sandstorm.The analysis showed that sandstorm occurred in the northwest wind zone back of the cold front,at the front of ΔP_3 center,at the front of 850 hPa strongest cold convection,and in the 850 hPa strongest ascending motion.In addition,the conditions that ΔP_3 greater than 10.0 hPa and the horizontal helicity value less than-300 m^2·s^(-2) predicted the occurrence of a strong sandstorm.
出处
《沙漠与绿洲气象》
2017年第5期30-37,共8页
Desert and Oasis Meteorology
基金
新疆维吾尔自治区科技计划项目"新疆大风沙尘暴灾害性天气数值预报技术研究"(201433112)资助
关键词
沙尘暴
冷锋
物理量特征
sandstorm
cold front
physical characteristics
