Abstract:

In recent years,global climate change as a hot topic is being widely concerned. Air temperature,one of the important climate factors,has a strong influence on production and living in the world.The past studying on climate change indicated that air temperature variation in China had remarkable periodicity,spatial differentiation and abrupt change from time perspective.There are some researches on temporal and spatial variations of air temperature in Shanxi Province,which is a typical inland province of China.But those works normally focus on analyzing the air temperature data in a fixed time scale such as year,season,month etc.Maybe it is useful in understanding the characteristic of air temperature variation from a rather macroscopic perspective.However,few studies on climate in Shanxi province concern the temporal and spatial variations of air temperature in a distinct time or a special season.“Jiu” means nine days in the traditional Chinese calendar and has a long history for traditional agricultural production and daily life in China.It begins from the winter solstice and ends after eighty one days and then is divided as nine “Jiu” periods.In China,the “Jiu” periods are the coldest days of the whole year.Based on daily air temperature data from 24 meteorological stations in Shanxi province from 1960 to 2016,this study used the methods of the linear tendency estimation,Mann-Kendall nonparametric test,and Morlet wavelet analysis to analyze the temporal and spatial variations of air temperature during the “Jiu” periods for the past 56 years.The results indicate the following conclusions: (1) The air temperature in the “Jiu” periods shows an increasing variation in the past 56 years,especially the mean maximum temperature was increased by 0.5 ℃·(10 a) ^-1.From time perspective,the fourth “Jiu” period had the lowest temperature,the temperature started to increase from the fifth “Jiu” period with a sharp warming in the sixth period.After 1990,the number of cold days during the “Jiu” periods became smaller. (2) The higher temperature usually appeared at the basin and river valley of South Shanxi like Yuncheng Basin,and the lower temperature normally happened in the mountain and hill regions of Northeast Shanxi like Wutai Mountain.But the distribution of the regions about the temperature increase range at the same time displayed a reverse variation. (3) After 1990,the air temperature during the “Jiu” periods presented a warm abrupt change,particularly the mean maximum temperature being increased by 1.73 ℃. (4) There is a distinct air temperature cycle in this area with a 4~8 years cycling period.This study provided additional information for the evaluation of climate resource and distribution of agricultural production in this area by covering the special “Jiu” periods.

Key words: “Jiu” period')">

“Jiu” period, air temperature, Shanxi Province, temporal and spatial changes, numerical analysis