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Standardization of sky radiance distribution in an attempt to improve the accuracy of skydiffuse radiation data

天空辐射分布标准化，试图提高天空漫辐射数据的准确性

基本信息

批准号：
60550406
负责人：
NAGATA Tadahiko
金额：
$ 1.34万
依托单位：
University of Fukui
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

The states of radiance distribution on various skies are quite different from each other. From the practical point of view, it is reasonable that we classify various sky states into three categories (cloudless clear sky, overcast sky, and intermediate sky) and try to standardize the radiance distribution of each sky category.As for clear sky radiance distribution, the modified equation of Nagata's equation for predicting clear sky luminance distribution was found to be fairly useful for predicting clear sky radiance distribution. However, if we want to get an even better approximate equation, we should devide the radiance of every sky element into the first component caused by primary scattering of direct sunlight and the second component caused by all the other processes, and then we should try to get good approximate equations for predicing respective components.The pattern of overcast sky radiance distribution is quite similar to the pattern of the luminance distribution on the CIE Overcast Sky. But radiance ratio between the zenith and the sky element near the horizon is approximately 5:2 and this is smaller than the corresponding luminance ratio 3:1 of the CIE Overcast Sky. The radiance of the zenith of overcast sky is approximately propotional to the solar altitude.All the sky states other than clear and overcast skies are classified into intermediate sky category. Therefore, the radiance distribution pattern of each intermediate sky is usually complicated and quite different from each other. There is almost no regularity about radiance distribution pattern throughout whole intermediate skies. However, the averaged radiance distribution pattern of many intermediate skies of about the same solar altitude has fairly distinct characteristics. The standardization of intermediate sky radiance distribution should be done by taking account of such averaged intermediate skies.

不同天空的辐射分布状态有很大差异。从实际应用的观点出发，我们把各种天空状态分为三类（无云晴空、阴天和中间天空），并试图对每一类天空的辐射亮度分布进行标准化，这是合理的。对于晴空辐射亮度分布，我们发现Nagata的晴空亮度分布预测公式的修正公式对晴空辐射亮度分布的预测是相当有用的。然而，如果我们想得到一个更好的近似方程，我们应该将每个天空元素的辐射分为由直射阳光的初级散射引起的第一分量和由所有其他过程引起的第二分量，阴天的亮度分布与阴天的亮度分布非常相似，阴天的亮度分布与阴天的亮度分布相似，阴天的亮度分布与阴天的亮度分布相似在国际照明委员会的阴天。但是天顶和地平线附近的天空元素之间的辐射率比约为5：2，这小于CIE阴天的相应亮度比3：1。阴天的天顶辐亮度与太阳高度近似成正比，除晴天和阴天外的所有天空状态都被归为中间天空类别。因此，每个中间天空的辐射分布模式通常是复杂的，并且彼此之间有很大的差异。整个中间天空的辐射分布几乎没有规律性。然而，在同一太阳高度上的许多中间天空的平均辐亮度分布型却具有相当不同的特征。中间天空辐射分布的标准化应考虑到这种平均的中间天空。