frost index

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.

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。

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Comparing to the old microtherm standard for cold of the late spring and late frost index, the new standard is much more flexible and practical.

并与旧标准中的倒春寒和晚霜冻指标进行了对比分析。

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