近百余年上海气温变化的若干特征

SOME FEATURES OF TEMPERATURE VARIATIONS IN SHANGHAI FOR THE 118 YEAR PERIOD

本文根据1873—1990年上海的年、冬、夏平均气温资料,并利用1956—1990年其郊区气温资料,对城市热岛效应对气温的影响作了处理,重建了近118a的上海气温序列。在此基础上对上海的气温变化特征进行分析,并与同期的北半球气温变化作了比较。结果表明,上海的气温变化有其明显的阶段性、跃变性和周期性。近百余年上海气温变化的总体特征与北半球相似,呈缓慢变暖趋势,但具体的变化过程和幅度有差别,尤其近20多年来的变化与北半球不一致,没有明显的增温现象。

Based on the data of annual, winter and summer mean temperature in Shanghai during the period of 1873?990, the mean landsurface air temperature series for Shanghai for the last 118 yeari period are reconstructed, in which the effect of urban heat island on temperature is dismissed by using he tempperature data from the suburbs of Shanghai during 1956?990. The features of temperature long-term variations in Shanghai have been analyzed, and these features are compared with those in the northern hemisphere. The results obtained are as follow: 1) The features of temperature long-term variations in Shanghai vary obviously with stages. It can be divided into three stages- The temperature was low from the end of 19th century to the 1920s, and high from the 1930s to the middle of the 1960s, the warmest period lies in 1940s with temperature higher than the average of recent 118 years by 0.62%. The temperature was normal for the recent more than 20 years, and there was a tendency to have warming winters and cooling summers during this period. 2) In the beginning of the 1930s the temperature variation in Shanghai underwent a remarkable stage-turning. The stage-turning from low to high temperature period was achieved by a jumping change. 3)The maximum entropy spectrum was analysed for the time series (1873?990) of annual mean air temperature in Shanghai. The pronounced oscillation periods are the long period of about 60-yr and the short to medium periods of 3, 6-yr. Over the recent one hundred-odd yean period, Shanghai has experienced slow warming: total of 0.52%, 0.57%and 0.41%in annual, winter and summer mean temperature, respectively. The general trend of temperature variation is similar to that in the northern hemisphere, however, there is some difference between Shanghai and the northern hemisphere in the course of temperature variation in detail. The stageturning from low to high temperature period in Shanghai was about 10 years later than that in the northern hemisphere. The norther hemisphere has undergone considerable warming durning the last more than 20 years. In contrast, this warming has not occured in Shanghai.