Amauri P. de Oliveira, Antonio J. Machado, João F. Escobedo
摘 要
A new shadow-ring device for measuring diffuse solar radiation at the surface is presented. In this device the
seasonal variation of shadow is followed by moving the detector horizontally. This unique characteristic facilitates
its application for long and continuous periods of time. The blocking effect caused by the ring and other related
geometric properties are formulated considering the diffuse solar radiation isotropic. The correction factor, shadow
size, and ring-detector distance are derived as a function of radius and width of the ring, sun position, and local
latitude. The largest blocking occurs during summer, when the ring-detector distance and the shadow width are
the smallest, and it is compensated by a smaller blocking effect in the winter period. The performance of the
new device is verified comparing daily values of diffuse solar radiation measured simultaneously with a similar
device from Kipp & Zonen, Inc. The results show a very good agreement (within 2.5%) between both devices.
The new device was also able to reproduce the radiometric properties of the local atmosphere based on 3-yrlong
measurements of direct solar radiation using a pyrheliometer. The new device can be applied to estimate
daily values of diffuse solar radiation at the surface in the range of 308N–308S with results comparable to other
similar apparatuses.
详细资料
文献种类: Journal Article
期刊名称: Journal of Atmospheric and Oceanic Technology