北京地区气温和降水百年变化规律的探讨

The Changes of Temperature and Precipitation in Beijing during Last 100 Years

本文通过对北京地区１２０年气温和１５０年降水资料的分析发现：（１）年和季的平均气温变化有着明显的一致性，１９２０年是个转折点，前期偏低，后期偏高。（２）冬、夏季的极端最高气温近２０年来呈偏低趋势，而极端最低气温呈持续偏高趋势。（３）年、季极端气温差值距平１９７２年以前以正距平为主，１９７２年以后以负距平为主。５０年来差值持续变小。（４）北京与中国东部、北半球，全球平均气温在１９２０年以前趋势相同。１９２０年以后，北京和中国东部的趋势相同，而和北半球、全球有着明显的差别。（５）北京的年降水从５０年代至８０年代持续下降，平均每１０年下降１２．２％，而年气温平均每１０年增温０．２℃，与年降水基本呈反相关关系。

By analysing the temperature data (1870-1989) and precipitation data (1850-1989) in Beijing some features are shown as follows. The variations of seasonal and annual mean t6mpeature departures are similar. There is a turning point in 1920. Before 1920, there is a cold temperature trend, and after 1920 there is a warm trend. The warming ratio is 0.2℃ per 10-year during last 40 years. The maximum temperature in winter and summer shows a trend of decrease, while the minimum temperature shows a warming trend. Before 1972, the departures of annual and seasonal temperature range are basically positive. After 1972, they are mainly negative. Before the 1920s the mean tempearture in Beijing has the same cold trend as in eastern China, the Northern Hemisphere and the globe. Since 1920, the trend in Beijing and eastern China has been very similar but different from that in the Northern Hemisphere and the globe. From 1950 to 1989 the normalized precipitation departures (△R/R) continuously decrease with the ratio of -11.1%. The 10-year annual mean temperature and normolized. precipitation departures are basically out of phase.