Shade-ring corrections for pyranometer measurements of diffuse solar radiation from cloudless skies

✍ Scribed by M. D. Steven; M. H. Unsworth

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 448 KB
• Volume: 106
• Category: Article
• ISSN: 0035-9009
• DOI: 10.1002/qj.49710645015

✦ Synopsis

Abstract

When a shade ring is used to shield a pyranometer from direct solar radiation, a correction to the measured diffuse radiation is necessary to account for diffuse radiation intercepted by the ring. A general analysis is developed to relate shade‐ring corrections to the radiance distribution of diffuse radiation. The corrections are split into two components: a geometric component based on an isotropic sky and varying with shade‐ring dimensions; and an anisotropy component, relatively independent of ring dimensions. Shade‐ring corrections are calculated using mean distributions of the radiance of cloudless skies. Tables and figures are given for calculating these corrections as functions of latitude, ring dimensions and time of year. Comparisons with published measurements at a variety of sites reveal generally good agreement with calculations. Some of the discrepancies may be due to differences in aerosol scattering.