直接辐射表与日照计观测日照时数的差异评估

Comparative Evaluation of Sunshine Duration Observations by Pyrheliometer and Operational Sunshine Recorders

随着自动化气象资料业务的发展,直接辐射表自动跟踪太阳位置观测日照时数逐渐在业务中使用,那么直接辐射表与传统日照计观测资料的差异如何,需要对两种资料定量评估。文章选取我国15个气象辐射一级站的直接辐射表与日照计平行观测日照时数资料,探讨了两种观测日照时数在不同区域、不同季节、不同时间尺度和不同天气条件下的差异分布特征,结果表明:(1)直接辐射表比日照计观测记录平均偏低0.51 h·d^(-1)(8.30%),两种资料差异具有明显的季节变化规律和区域变异,在夏季和春季较大,冬季最小,在西北及海南地区较大,东北、黄淮地区及四川盆地最小;(2)日出时段直接辐射表较日照计观测记录低0~0.3 h·h^(-1),日落时段直接辐射表较日照计观测记录高0~0.3 h·h^(-1),其他时段直接辐射表与日照计观测差值在±0.2 h·h^(-1);(3)受观测仪器和天气条件影响,在晴空、多云和阴天条件下,直接辐射表较日照计观测记录分别平均偏低0.17 h·d^(-1)(1.88%)、0.64 h·d^(-1)(9.08%)和0.62 h·d^(-1)(26.73%);(4)两种观测日照时数的相关系数在0.88以上。

With the development of automation of meteorological data,pyrheliometer which can automatically track solar position to observe sunshine duration has been gradually used in meteorological operations.It is necessary to quantitatively evaluate the difference between pyrheliometer and sunshine recorder observations.This paper discusses the differences between pyrheliometer and sunshine recorder observations over different regions,seasons and time scales.The results are as follows:(1) The sunshine duration observed by pyrheliometer is 0.51 h · d^(-1)(8.30%) less than that by sunshine recorder.The difference has obvious seasonal and regional variations,which are larger in summer and spring,but the minimum in winter,and also larger in Northwest and Hainan,but the least in Northeast,Huang-Huai and Sichuan Basin.(2) Pyrheliometer observation is about 0 — 0.3 h · h^(-1) less than sunshine recorder observation at sunrise,and 0 —0.3 h · h^(-1) larger than sunshine recorder observation at sunset while the difference is between+ 0.2 h · h^(-1) in other hours.(3) Affected by observing instruments and weather conditions,the difference between two kinds of sunshine durations are —0.17 h · d^(-1)(— 1.88%) under clear sky conditions,—0.64 h · d^(-1)(— 9.08%) under cloudy conditions,and —0.62 h · d^(-1)(— 26.73%) under overcast conditions.(4) The correlation coefficient between the two kinds of sunshine durations is above 0.88.