Abstract The total solar irradiance, measured in recent years by satellite detectors /1, 2/, has shown variations both short term and long term. Attempts to understand these variations in terms of sunspots and faculae have met with limited success /3–5/. Correlations between satellite total irradiance measurements and proxy irradiance based on sunspot and plage or facular areas explain only 50–70% of the variance. It is important to know if this poor correlation is due to the irradiance models' noise in the sunspot and plage areas, or some global solar fluctuation. Comparisons will be presented between published sunspot areas and digital, ground-based measurements. A new program of precise, relative photometry at the San Fernando Observatory will be described and its results will be compared with the ACRIM/SMM data and with model irradiance fluctuations based on published sunspot and plage areas. The San Fernando photometric data can produce sunspot irradiance fluctuation information that is repeatable to within about 10 millionths of the mean irradiance. Individual sunspot areas can be several standard deviations from published values.
Modelling of total solar irradiance variability from ground-based observations
Advances in Space Research ; 8 , 7 ; 21-30
1989-01-01
10 pages
Article (Journal)
Electronic Resource
English
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