不同观测时次对日平均气温统计的影响——以黑龙江地区为例

Influence of Observation Times on the Daily Mean Air Temperature Statistics:A Case Study of Heilongjiang

日平均气温是统计月、年和多年平均气温的基础,也是分析气温长期变化特征的重要指标。了解不同观测时次或计算方法获得的日平均气温值之间的差异,对于气候学和气候变化研究十分重要。在分析哈尔滨站分钟气温观测资料基础上,指出24次定时气温平均值可以代表每日平均气温真值。然后利用黑龙江省8个国家基准气候站多年24 h观测数据,分析评价不同观测时次和日平均气温统计方法对长时间尺度平均气温估计的影响。结果表明:(1)3次加权计算值(T3)和最高最低平均值(Tmn)获得的年平均气温都明显偏高,每日4次平均(T4)与每日24次平均(T24)获得的年平均气温值接近;(2)从季节平均看,T3春、夏季平均偏高,冬季偏低,Tmn夏、秋、冬季偏高。相对T24,全省平均T3在3—10月普遍偏高;Tmn除5月外,其余11个月均偏高;T4在4—7月偏高。T3和T4,各站上半年的后期偏高,年初和年尾偏低;(3)Tmn平均结果存在明显的南北差异,西南部台站全年偏高,北部台站年初和下半年偏高;(4)在偏暖年份,T3、Tmn平均值一般偏高更多。

The daily mean temperature is the basis for the statistic analysis of monthly, annual and multi-year average temperature, and is also an important indicator for studying the characteristics of long-term temperature change. Understanding the differences between the daily mean temperature values obtained by different observation times or calculation methods is important for the study of climatology and climate change.Based on the analysis of minute air temperature data of Harbin station, the mean value of 24 times timing air temperature could represent daily mean temperature. Using the 24 h data of 8 national reference climatological stations, we analyzed the effect of observation times and calculation method on the evaluation of meant emperature in long-time scale. The results showed that:(1) the annual average temperature obtained by three times weighted value(T3) and the maximum and minimum average(Tmn) were all on the high side, and the annual average temperature obtained by four times average(T4) was closed to 24 times average(T24);(2) on seasonal average, T3 was higher in spring and summer, meanwhile lower in winter;Tmn was higher in summer,autumn and winter;compared with T24, T3 of the whole province was generally higher from March to October;Tmn was on the high side except May;T4 was higher from April to July;T3 and T4 were higher in the latter stage of the first half of the year, and lower in the beginning and the end of the year in each station;(3) Tmn was high throughout the year in southwest stations and in the beginning of the year and the second half of the year in northern stations;(4) T3 and Tmn were higher in warmer years.