西安雾区垂直结构气象要素特征分析

On Characteristics of Meteorological Elements of Xi'an Fog

利用2007-2012年L波段探空边界层资料,采用气候统计学方法分析雾过程边界层气象要素的分布特征.结果表明:西安一年四季都有大雾,雾区温度廓线有等温、贴地逆温和温度减小等变化,其中等温变化约占记录总数的64%,贴地逆温约占记录总数的33%;湿度有等湿、湿度增大、湿度减小等变化,其中湿度随高度减小的记录比例较大,约占记录总数的74%,其廓线表现出高湿—减小—增大—等温的变化;风向有静风(C)、东北(N-NE)偏东和西南(SSW-WSW)偏西等变化,西南向西偏转的频次约占记录总数59%,静风频率成分约占35%,风速变化≤1m/s的约占记录总数的40%;气象要素分析表明西安的雾多为辐射雾.

The characteristics of meteorological elements in the boundary layer of fog were analyzed by u- sing the 2007-2012 L-band sounding boundary layer data and the climatic statistical method. The results show that fog appears all the year round in Xi＇an, temperature changes in fog areas include isothermy, ground inversion and temperature decrease,among which the isothermal change accounts for about 64% of the records and ground inversion accounts for about 33 % of the records. Humidity changes include equal temperature, humidity increase and humidity decrease,and the records of humidity decrease with height occupies a larger proportion of the total records （74%）. And wind direction changes mainly include calm （C） ,northeast easterly,and southwest westerly,frequency of southwest westerly accounts for 59% of the records,and frequency of calm accounts for 35% ,and wind speed changes （≤1 m/s） accounts for about 40% of the records. Meteorological analysis indicates that fog in Xi＇an is mainly radiation fog.