| Based on the data of average temperature, first-last frost dates and frost-free period in spring, autumn season and year from 1971 to 2010 in 11 weather stations at southeast Shanxi province, the time-space distribution characteristics and genesis of the first-last frost and the variation characteristics of first-last frost dates and frost-free period under the background of climate warming were analyzed by using the mathematical statistics and contrast methods. The results showed that: The annual temperature change during 1971—1996 was belonged to the slow warming period with oscillation, After 1997 the climate started to be the apparent warming period, the climate warming rate was 0.3℃·10a-1. The time-space distribution of the first-last frost was the close relation with the special geographical environment conditions. Under the precondition of the autumn climate warming, the occurrence of the first frost date pushed back rate was 2 d·10a-1, the inter annual variation trend showed three stages as positive and negative oscillation push later period, partial early period and smoothly push later period. The average warming rate in spring season was 0.25℃·10a-1, the corresponding appearance of last frost date presented an adv
ance tendency, the advance rate was 4 d·10a-1. The inter annual variation characteristics can be divided into four stages as partial later period, partial early period, positive and negative oscillation period and partial early period. Under the background of climate warming of the frost-free period, the inter annual variation features could be divided into three stages as extended period, shrinkage period and stable extension period, the linear change extended rate of frost-free
period was 7 d·10a-1. |