关键词: 山西, 终霜冻, 区域特征

Abstract: Frost is a common agro-meteorological disaster.  Advancing of the first frost and delaying of the last frost all have harmful impact on crops.  The previous researches about frost of Shanxi Province were mainly focused on variation features of the first （or last） frost date and the frost-free period，did not involve the regional characteristics of Shanxi’s last frost.  Based on each year’s last frost data and each day’s minimum ground temperature data of 62 meteorological stations in Shanxi Province from 1961 to 2012，using daily minimum ground temperature less than 0℃，-2℃，-5℃ as indexes，and applying statistical method and EOF & REOF method，this paper analyzed the regional characteristics of Shanxi’s last frost （different levels）.  The results show as follows：First，the average last frost date of Shanxi province in latest 52 years has a trend of advance and has an asymmetric “W” distribution，it was slightly advanced in 1960s & 1970s，and was delayed in 1980s，from 1980s to 2005 it was obviously advanced，after 2005 it was significantly delayed.  Second，the average last frost date of Shanxi province in latest 52 years is April 12.  The last frost emerges from the second ten days of March in the south to the second ten days of May in the north.  Third，the occurrence time of the mild last frost，the moderate last frost and the severe last frost shows the same “delay” or “advance” in most years，but there are differences between the south and the north. Fourth，the mild last frosts have 5 relatively independent abnormal types in following regions: the Midwest，the Northwest，the Northeast，the South and the Mideast，which are associated with the average last frost date distribution and the normal last frost occurrence probability distribution.  Fifth，the moderate last frosts have 5 relatively independent abnormal types in following regions: the Central，the Northwest，the Northeast，the South and the North centre，which are associated with the later last frost occurrence probability distribution and the last frost variation trend distribution.  Sixth，the severe last frosts have 3 relatively independent abnormal types in following regions: the Northwest，the South and the Mideast，which are associated with the latest last frost occurrence probability distribution and the last frost mutation distribution.  Seventh，terrain and local climate change have obvious impact on regional characteristics of the mild last frost and the moderate last frost but have little impact on regional characteristics of the severe last frost.  This study is helpful to crops rational distribution and frost disaster prevention of Shanxi Province.

Key words: Shanxi, last frost, regional characteristics