关键词: 外观, 外观

Abstract:

In order to find the characteristics of temperature variation in past 48 years in Zhangjiakou City, and to provide a theoretical basis for agricultural production, the temperature variation of Zhangjiakou Region was analyzed on the basis of statistical methods, such as linear regression, correlation analysis and wavelet cycle by using the temperature data of 13 counties from 1962 to 2009. The results showed that: with altitude decreasing, annual average temperature showed a gradual increasing trend from north to south, and annual difference showed a decreasing one from northwest to southeast in Zhangjiakou region. Temperature standard deviation and coefficient of deviation were less in summer than that in other seasons and diurnal range was relatively small. So the temperature was the most stable and it was the most suitable for agricultural production in summer. The period from 1962 to 1986 kept cold and began to enter a warming one since 1987, with the warmest year of 2007. There was quasi-periodic of 16 years and 23 years on the annual average temperature above the dam, that of 15 years and 22 years below the dam, and inter-annual changing cycles of 8 years and that of 4 years were more obvious. The temperature was rising with the warming rate of 0.4℃/10 a, and 1.0℃/10 a in the period from 1985 to 1998, the maximum warming period, in the region in the past 48 years. There had been no unusual colder year, and abnormally and significantly warmer years appeared in the recent 12 years, on the average temperature in past 48 years.