三次观测站02时气温插补方法的比较分析

The Comparative Analysis of Interpolation Method About 02 BT's Temperature at 3 Times Daily Observation Stations

现行的国家级地面气象观测站网(共2416个站)包括基准站、基本站和一般站,其中1590个一般站(占总站数的65.8%)夜间不观测,但是按照《地面气象观测规范》的规定,在计算日平均气温时,必须通过数学方法给02时赋一个替代值或近似值,这种赋值过程无形中会带来计算误差。本文利用1961—2009年陕西19个国家基本/基准站的定时气温资料,对这种赋值误差进行定量评估分析,并通过多种方案的比较,提出新的赋值(或称插补)方法。结果表明:(1)传统方法所赋予的02时气温替代值比实测值偏高,19个站平均偏高0.77℃;(2)台站所处的纬度,以及季节、天气状况所引起的辐射强弱的差异,通过赋值变量(前一日20时气温)的传导,较明显地影响着02时气温的赋值误差;(3)用逐步回归分析方法,将传统方法的平均加权法调整为多因子非对称加权,显著减小了前一日20时气温的权重,降低了辐射强弱的影响,赋值与实测值更为接近,19个站平均偏差近似为零;新的回归方程对月平均气温、年平均气温产生一定的修正作用,年平均气温值可调降0.1～0.4℃,月平均气温甚至可下降0.5℃。

Current national ground meteorological observation net consists of the benchmark,basic and general stations（counting up to 2416 stations）,of which about 65.8%the general stations didn＇t observe at night time.According to Specification of Surface Meteorological Observation,the average daily temperature must be calculated through mathematical methods,giving a replacement value for 02 BT＇s temperature. This process virtually brings about calculation errors.Using the timing temperature data of 19 national basic stations in Shaanxi from 1961 to 2009,the assignment errors are analyzed and evaluated quantitatively through various schemes comparison,and a new assignment（or interpolation） method is raised. The results show that：（1） The replacement value of 02 BT＇s given by traditional method is higher than the observed temperature,the average difference at 19 stations is 0.77℃.（2） Radiation intensity caused by stations in place of latitude,season and weather conditions conducting to assigned variable（20 BT＇s temperature the day before） magnifies obviously 02 BT＇s temperature assignment error.（3） Using stepwise regression analysis method to adjust the traditional weighted average as multi-factor asymmetric weighting method can reduce significantly the weighting coefficient of 20 BT＇s temperature the day before and reduce the influence caused by the intensity of radiation,thus making the assignment closer to the observed one.The average difference at 19 stations is approximately zero.New regression equations have certain correction effect on the monthly and yearly average temperature,and the annual average temperature can be decreased by 0.1 to 0.4℃,the monthly average temperature even by 0.5℃.