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Irradiance Observations of the Sun

Published online by Cambridge University Press:  12 April 2016

Claus Fröhlich
Claus Fröhlich*
Affiliation:
Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center CH-7260 Davos Dorf, Switzerland

Abstract

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Measurements of the total solar irradiance during the last 14 years from satellites show variations over time scales from minutes to years and decades. The most important variance is in the range from days to several months and is related to the photospheric features of solar activity: decreasing the irradiance during the appearance of sunspots, and increasing it by faculae and the bright magnetic network. Long-term modulation by the 11-year activity cycle is observed conclusively with the irradiance being higher during solar maximum. The accuracy of the determined variability and its interpretation in terms of manifestations of activity related features on the photosphere is discussed. Besides the direct influence of the spots, faculae and magnetic network more profound changes in the thermal transport seem to influence the behaviour of the solar photospheric radiation on the solar cycle and longer time scales.

Type
General Reviews on Observations of Solar and Stellar Irradiance Variability from Space and from the Ground
Information
International Astronomical Union Colloquium , Volume 143: The Sun as a Variable Star: Solar and Stellar Irradiance Variations , 1994 , pp. 28 - 36
Copyright
Copyright © Kluwer 1994

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