Title: Solar Irradiance and Magnetic Field Variations
from Solar Cycles 21 to 23
Author: Judit M. Pap
Affil: GEST/University of Maryland, Baltimore County and University of California, Los Angeles
Email: papj@marta.gsfc.nasa.gov
Authors: 
Michael Turmon, 
Claus Fröhlich, and 
Linton Floyd
Affils: Jet Propulsion Laboratory, Pasadena, CA,
Physikalisch-Meteorologishes Observatorium Davos,
Switzerland,
Interferometrics Inc.,Naval Research Laboratory, Washington, D.C.
Abstract: Total solar and UV irradiances have now been measured for three consequtive solar cycles: from the maximum of solar cycle 21 to the beginning of the declining portion of solar cycle 23. It has been shown that solar irradiance varies in parallel with the solar activity cycle, being higher during maximum solar activity conditions. However, as shown by various studies, there is a phase shift between solar irradiance and the magnetic field variations during solar minimum, i.e., solar irradiance started to rise sooner than the magnetic flux at the beginning of the rising portions of both cycles 22 and 23, and significant differences exist between magnetic field and irradiance variations at the time of solar maximum. We discuss these differences between the observed irradiance and magnetic field changes, using the magnetic field measurements performed at the National Solar Observatory at Kitt Peak and by the MDI experiment on SOHO. Climate implications of these results are also discussed.