On the Relation between Solar Activity and Clear-Sky Terrestrial Irradiance
Abstract
The Mauna Loa Observatory record of direct-beam solar irradiance measurements for the years 1958-2010 is analysed to investigate the variation of clear-sky terrestrial insolation with solar activity over more than four solar cycles. The raw irradiance data exhibit a marked seasonal cycle, extended periods of lower irradiance due to emissions of volcanic aerosols, and a long-term decrease in atmospheric transmission independent of solar activity. After correcting for these effects, it is found that clear-sky terrestrial irradiance typically varies by about 0.2 +/- 0.1% over the course of the solar cycle, a change of the same order of magnitude as the variations of the total solar irradiance above the atmosphere. An investigation of changes in the clear-sky atmospheric transmission fails to find a significant trend with sunspot number. Hence there is no evidence for a yet unknown effect amplifying variations of clear-sky irradiance with solar activity.
Cite
@article{arxiv.1209.0602,
title = {On the Relation between Solar Activity and Clear-Sky Terrestrial Irradiance},
author = {Georg Feulner},
journal= {arXiv preprint arXiv:1209.0602},
year = {2013}
}
Comments
16 pages, 7 figures, in press at Solar Physics; minor changes to the text to match final published version