THE PHYSICAL MECHANISMS ANALYSIS AND FORECAST RESEARCH ABOUT THE HEAVY FOG IN HUZHOU

Using the daily temperature data of 234 stations during recent 50 years in China, the trend of daily maximum/minimum, the changes of days with characteristical temperature, the growing season length and effective accumulative temperature are studied. The result shows the daily maximum displays an obvious increase trend in summer for most of northern part of the country, while there is a decrease trend in south part of Xinjiang and middle Huanghe river basin and Huaihe river basins. The daily minimum of summer in most part of northern China has increasing trend, while in south part of Xinjiang and Changjiang river basin it is decreased. During winter time, both daily maximum and minimum have increasing trend, especially in northern China. The number of hot day with 30℃ or above is not change obviously, but the number of warm days with temperature 20~30 ℃ increased during the last 50 years. Number of days with temperature below 5 ℃ are decreased. The cold days with daily temperature below 0 ℃ are decreased in the region north to Changjiang river. Also the very cold days with daily temperature below-10 ℃ are decreased along the region 40º~45ºN deceased very obviously. The growing season length in most parts of the country, except the southwest region increased during recent 50 years. Accordingly the effective accumulative temperature increased too。