2021年3月27-28日中国北方沙尘天气特征分析

Analysis of the weather characteristics of a sand-dust event in Northern China from March 27 to 28,2021

选用常规气象观测资料、探空站气象观测资料、卫星云图反演沙尘产品、NCEP/NCAR再分析资料对2021年3月27—28日中国北方一次典型强沙尘天气进行分析。结果表明:干燥(平均降水量小于10 mm、降水量负距平的地区超过80%)、高热(气温较常年偏高超过6℃)为此次沙尘天气的气候条件。同时,受蒙古气旋影响,中低空、地面大风和强烈的垂直上升运动为此次沙尘天气提供了动力条件。大气温度直减率、抬升指数、K指数、对流有效位能指数、I_(Conve(700—850))指数、I_(Conve(700—sfc))指数、PW指数表明,沙源地大气层结存在不稳定状态,为沙尘天气发生提供了热力条件。24 h后向轨迹模型表明,沈阳上空500 m高度的沙尘来自内蒙古地表抬升至1000 m高空后远距离输送,而1000~2500 m高度的沙尘源自蒙古国4000~5000 m高空,随气流下沉远距离输送至目标区域。

A typical strong sand-dust event in Northern China from March 27 to 28,2021 was analyzed using conventional meteorological data,sounding station meteorological observation data,retrieval data of sand-dust from satellite cloud images and the NCEP/NCAR(National Center for Environmental Prediction/National Center for Atmospheric Research)reanalysis data.The results show that the dry(the average precipitation is less than 10 mm,and the area with negative precipitation anomaly is more than 80%)and hot(the temperature is 6℃higher than usual)weather are the climatic background factors for the dust weather.At the same time,under the influence of the Mongolian cyclone,the strong wind at medium-low altitude and on the ground,the strong vertical ascending motion is the dynamic conditions for the dust weather.Based on the atmospheric temperature lapse rate,uplift index,K index,convective effective potential energy index,I_(Conve)index from 700 hPa to 850 hPa,I_(Conve)index from 700 hPa to the ground,and PW index,it indicates that the atmospheric structure in the sand source area is unstable,which provides thermal conditions for the occurrence of dust weather.The 24-hour backward trajectory analysis shows that the dust near the surface of Inner Mongolia is uplifted to 1000 m and transported over a long distance to a low level of about 500 m at Shenyang.The dust at the height of 4000~5000 m is transported to the high level about 1000~1500 m at Shenyang.