日平均气温的两种计算方法比较

日平均气温是反映气候特征的重要指标之一,通常有2种计算方法:日最高和最低气温平均,4个定时气温平均.为了比较2种方法计算的日平均气温是否有显著差异,说明何种方法更接近实际日平均气温,选择我国8个气象站冷年、正常年、暖年的日气温资料和北京密云1991年中28d每日整点气温资料进行分析,结果表明:2种方法得到的日均温差异显著,但极值平均温与实际日平均气温(24h整点气温的平均)、四时平均温与实际日平均气温均无显著差异,其中四时平均温接近实际日平均气温的程度略好.另外,2种方法的差异基本无年际间的差别,但在各个季节和地区是不同的.

A COMPARISON OF MEAN DAILY TEMPERATURE CALCULATED BY TWO METHODS

The mean daily temperature is one of the important variables to describe climate. There are two calculations based on different available data: the mean of daily maximum and minimum temperatures and the mean of temperatures recorded at four certain times a day. According to daily temperature selected from 8 weather stations of China in warmer, normal and cooler years respectively, this study analyzes the relationship between two calculations. The results indicate significant difference between the two calculations and the difference varies in different seasons and regions. But the difference between years is not significant. Compared with the mean daily temperature calculated from hourly temperatures observed at Miyun in Beijing, It is found that the values of two calculations are approximate to the mean of 24 hour temperatures which is regarded as the actual mean daily temperature. Of the two calculations, the mean of four time temperatures is a little better.