临汾市近58年初、终霜日和无霜期变化趋势分析

为了更好地掌握无霜期变化对临汾市农业生产的影响，提高霜冻的预报预测能力，尽可能降低其对农作物造成的危害，利用临汾市17个县（区）站建站以来的初、终霜日及无霜期日数的气象观测资料，采用基本的数理统计、线性趋势分析、5年滑动平均等气候统计方法，分析初、终霜日及无霜期日数的基本特征及其变化趋势。结果表明：（1）临汾市初霜日呈逐年推迟的趋势，趋势率为1.327 d/10 a，初霜日平均值为10月18日，最早与最晚初霜日分别出现在9月20日与11月5日，相差46天，最大相差56天，出现在蒲县。（2）终霜日的趋势率为-1.83 d/10 a，呈逐年提前的变化趋势，终霜日平均值为4月2日，最早出现在2月19日，最晚出现在5月2日，相差73天，比初霜日的间隔天数多近1倍。（3）临汾市近58年无霜期的趋势率为3.156 d/10 a，呈逐年增长的趋势，无霜期变化速率基本稳定。最长无霜期出现在1961年的翼城，为301天；最短无霜期出现在1980年的隰县，为127天；极差为174天。

The Changing Trends of the First and Last Frost Dates, Frost-free Periods in Recent 58 Years in Linfen City

In order to master the change of frost-free periods that effect on the agricultural production in Linfen, improve the frost forecast and prediction abilities, try the best to reduce the harm that frost-free periods cause in crops. Meteorological observation data of the first and last frost dates and frost-free period days was been used since the stations of 17 counties （areas） in Linfen, and the author adopted these climate statistical methods which there were about trend analysis, 5 years moving average, analyzed the basic features and changing trends of the first and last frost dates, frost-free period days. The results showed that： （1） the first frost day of Linfen delayed trend year by year, the trend rate was 1.327d/10 a. The city＇ s average first frost day was on October 18th, first appeared in September 20th, late appeared in November 5th, there are 46 days between them, maximum differential Puxian County was 56 days. （2） The trend rate of the last frost date was -1.83 d/10 a, showed a tendency to advance year by year, the city＇ s average last frost day was on April 2th, first appeared in February 19th, late in May 2th, there were 73 days between them, compared with the first frost day interval number nearly twice as many days. （3） The trend rate of the frost-free period was 3.156 d/10 a in recent 58 years in Linfen, which appeared a trend of increasing year by year, the variation rate of frost-free period was stable basically. The longest frost-free period appeared in Yicheng County three hundred and one days. The shortest frost-free period appeared in Xixian County in 1961, it had lasted for in 1980, it had lasted for one hundred and twenty-seven days; there were 174 days about the range.