Variability of solar ultraviolet irradiance.
Abstract
A model of solar Lyman alpha irradiance developed by multiple linear regression analysis, including the daily values and 81-day running means of the full disk equivalent width of the Helium line at 1083 nm, predicts reasonably well both the short- and long-term variations observed in Lyman alpha. In contrast, Lyman alpha models calculated from the 10.7 cm radio flux overestimate the observed variations in the rising portion and maximum period of solar cycle, and underestimates them during solar minimum. The authors show models of Lyman alpha based on the He line equivalent width and 10.7 cm radio flux for those time intervals when no satellite observations exist, namely back to 1974 and after April 1989, when the measurements of the Solar Mesosphere Satellite were terminated.
- Publication:
-
Journal of Atmospheric and Terrestrial Physics
- Pub Date:
- December 1991
- DOI:
- 10.1016/0021-9169(91)90045-9
- Bibcode:
- 1991JATP...53..999P
- Keywords:
-
- Helium;
- Line Spectra;
- Lyman Alpha Radiation;
- Solar Flux Density;
- Ultraviolet Radiation;
- Periodic Variations;
- Radiation Measurement;
- Regression Analysis;
- Solar Cycles;
- Solar Radio Emission;
- Spectral Line Width;
- Solar UV Radiation: Variations;
- Solar Spectrum: Lyman Alpha