河南省大雾的时空分布特征及500hPa环流特点分析

对河南省45年的大雾日数进行分析研究，结果表明：河南省年平均大雾日数秋冬季多，春夏季少，雾日主要集中在11月到翌年1月；大雾区域分布极不均匀，总体来说是东多西少，平原和盆地多山区明显少，全省有5个多雾中心。选择40个代表站进行经验正交函数（EOF）展开分析，前三个模态的积累方差贡献率为76．5％，通过相关系数和第一模态的时间系数分析，全省大部分地区大雾日数呈增加的趋势，与温度变化趋势相同。小波分析存在2～4年、8～10年和19～22年的周期变化。进一步对历史上典型多雾年和少雾年500hPa高度距平场分析，发现多雾年与少雾年欧亚中高纬度地区高度距平趋势恰好相反，多雾年呈＋-＋分布，而少雾年呈-＋-分布。

The Temporal and Spatial Distribution of Heavy Fogs in Henan Province and Analysis of the Features of 500hPa Circulation

The fog days in Henan Province from 1961 to 2005 are analyzed. The results show that the yearly averaged number of fog days is more in autumn and winter than in spring and summer, fog mainly appears in November to January of the next year. The spatial distribution is very uneven and shows the trend of increase from east to west and from basin to hills. There are 5 fog centers in Henan province. 40 stations are chosen for analyzing by using EOF. The results show that the first 3 modes account for 76.5% of the total accumulative variance contribution. The analyses on the correlation coefficient and the time coefficient of the 1st mode indicate that the fog days in most areas in Henan province is increasing, which is the same as the trend of temperature variation. Wavelet analysis indicates that fog days have periods of 2-4 years, 8-10 years and 19-22 years. The 500hPa anomaly height fields in more-fog years and in less-fog years are examined. It shows the anomaly height fields of the middle and high latitude in Europe and Asia are opposite, and display +-+ mode in more-fog years, and-+-mode in less-fog years, respectively.