Deriving cie sky types from horizontal irradiances
CIE standard S011 describes the luminance distribution of the sky under all weather conditions. It defines a set of 15 CIE sky types ranging from overcast to clear. This paper describes a method which characterizes sky conditions with CIE sky types using horizontal irradiances which are now widely available through the processing of geostationary satellite images. The method relies on a sky luminance model. We considered three models, two by Perez: Interpolated (Perez, 1990) and General (Perez, 1993), and one by Igawa (Igawa, 2004). In order to select the model, we prepared a database of sky luminance measurements and we added the global and diffuse horizontal irradiances measured at our IDMP station. Then, we compared the CIE sky types obtained from the luminance measurements to those produced by each model. The comparison shows that it is possible to produce CIE sky type information accurately from horizontal irradiances using the Perez Interpolated model. The Perez General model misses the CIE standard overcast sky 1 (13.8% of our measurements) and sometimes considers overcast conditions as quasi clear conditions. The Igawa model leads to cloudless skies which are more turbid than the real ones.
sky luminances irradiances CIE sky types gradation indicatrix.
Dumortier Dominique Kobav Matej
DGCB-LASH, Lyon, France Univ. of Ljubljana, Slovenia
国际会议
26th Session of the CIE(国际照明委员会(CIE)第26届大会)
北京
英文
414-417
2007-07-04(万方平台首次上网日期,不代表论文的发表时间)