摘要
利用1960—2010年陕西76个台站地面观测中的天气现象(雾)资料、NCEP/NCAR逐月再分析资料,基于EOF、小波分析、回归分析方法探讨了陕西雾的时空变化特征以及与雾日多发季节相联系的大气环流异常,主要结论如下:①陕西雾地域性分布特征明显,空间上呈"三高三低"态势,河流或水域对雾的空间分布有重要影响,但不起决定作用;②年际上,陕西平均雾日数在20世纪80年代中后期至90年代雾日达到峰值,季节上,秋冬季雾日数占全年雾日数的66.5%以上;③SEOF分析表明陕西不同区域雾多发季节具有明显差异,8—10月关中北部雾明显偏多,峰值出现在9月,10—12月陕南、关中雾偏多,峰值出现在11月;④年际变化的时间尺度上陕西雾主要表现为东西振荡(EOF1)和南北振荡两个主模态(EOF2);⑤与雾日多发季EOF1相联系的环流异常表现为东亚中低纬度大陆上海平面气压(SLP)、500hPa位势高度异常偏高,陕西位于850hPa平均风场上反气旋性环流中心附近;当反气旋性异常环流位置偏西偏北(EOF2),北风异常分量偏强时,从海上来的水汽输送偏南,从而导致陕北雾偏少,关中、陕南雾偏多。
Using the ground-based weather phenomena （fog） observations data of 76 stations over Shaanxi Province, and the monthly re-analyzed NCEP/NCAR reanalysis dataset from 1960 to 2010, by menas of the EOF, wavelet, and regression analysis methods, the spatial-temporal change characteristics of Shaanxi fogs and associated atmospheric circulation abnormity in the fog prone season are studied. The results show that： （1） Shaanxi fogs have obviously regional distributional feature, with three high- and low- frequency centers of fog days; rivers have significant influence on fog distribution, but it is not the main cause. （2） The average number of fog days reaches the peak from the middle and late 1980s to 1990s; the number of autumn fog days accounts more than 66.5% of fog days for the whole year. （3） The SEOF analysis shows that the number of fog days differs from one place to another. From August to October, fogs mainly appear in the north of Guanzhong, reaching the peak in September, while from October to December in the south of Shaanxi and in Guanzhong, reaching the peak in November. （4） The inter-annual variability of Shaanxi fog mainly includes two modals： EOF1 and EOF2. （5） The circulation anomalies are associated to EOF1, which shows that SLP and 500 hPa geopotential heights over the land at middle latitudes in East Asia are abnormally higher. Shaanxi lies near the center of anticyclonic circulation over the 850 hPa average wind field, so when the anticyclonic anomalous circulation is in the west-north and the northerly abnormal component is stronger, and the water vapor transport from the sea is in the south, fogs in Shaanxi are relatively rare in the north, and abundant in the central and southern Shaanxi.
出处
《气象科技》
2013年第4期703-712,共10页
Meteorological Science and Technology
基金
陕西省气象局科技创新基金(2013M-37
2011M-5)资助
关键词
雾
时空变化
主模态
大气环流
fog, spatial-temporal change, major mode, atmospheric circulation
