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A model of solar luminosity modulation by magnetic activity between 1954 and 1984
Science (New York, N.Y.)
|May 13, 1988
Summary
A simple model shows solar irradiance changes due to magnetic activity. The sun is brighter during solar maximum, with the 1980 peak showing a more pronounced brightening than previous cycles.
Area of Science:
- Solar physics
- Stellar irradiance
- Space weather
Background:
- Total solar irradiance (TSI) exhibits slow variations.
- These variations are linked to solar magnetic activity, specifically bright faculae and dark sunspots.
- Previous satellite measurements (ERB and ACRIM) provide data from 1981-1984.
Purpose of the Study:
- To model and reconstruct solar irradiance modulation by magnetic activity over multiple solar cycles.
- To compare the magnitude of irradiance brightening during recent solar cycles.
Main Methods:
- Developed a simple model based on excess radiation from bright magnetic faculae and reduced radiation from dark spots.
- Validated the model against simultaneous ERB and ACRIM satellite radiometer data (1981-1984).
- Extended the model back to 1954 to analyze three 11-year solar cycles.
Main Results:
- The model successfully matched observed slow variations in total solar irradiance.
- The model predicts consistently higher solar irradiance at activity maximum compared to minimum.
- The solar cycle peaking in 1980 showed a 0.07% brightening, more pronounced than in the two preceding cycles.
Conclusions:
- Solar magnetic activity significantly modulates total solar irradiance.
- Despite lower sunspot numbers, the most recent solar cycle (peaking 1980) exhibited a stronger irradiance brightening.
- The relationship between sunspot amplitude and irradiance modulation may not be linear across all solar cycles.
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