华北异常初终霜冻气候特征的研究

STUDY ON CLIMATIC FEATURES OF UNUSUAL FIRST AND LAST FROST IN NORTH CHINA

本文利用1953～1990年地面最低温度资料,并以≤0℃作为霜冻指标,定量地确定出现异常霜冻判别标准,研究了华北地区初、终霜冻异常的气候特征。结果表明:异常初、终霜冻发生频率地理分布差异显著;其年际变化具有明显的周期波动,主要周期有2年、6年和8～12年等;当初,终霜冻出现异常后,其均值持续时间,分别为1.0～3.4天和1.0～1.3天;初、终霜冻波动位相特征及其长期变化趋势大致可分为三种类型:(1)华北偏北部型;(2)偏南部平原型;(3)山西高原型。这些结果为各地有效防御霜冻灾害提供了重要参考。

According to frost index defined by the minimun temperature≤0℃ of earth surface, the criterion for the unusual frost is quantitatively given and the climatic features of the unusual first or last frost in North China during 1953-1990 are studied. The results show that the frequency of unusual first or last frost exhibited a distinct difference with geography, and its interannual variation is of significant oscillation period character. In general, its quasi-cycles are mainly 2, 6, and 8-12 years etc.. When the unusual first or last frost appears, its lasting time of average values are 1. 0 - 3. 4 days and 1. 0 - 1. 3 days respectively. Their oscillation phase feature and its long change tendency is divided into three types: (1) the northern of North China, (2) the southeast flatland. (3) ShanXi highland. These results are of great worth for .defending frost.