A three component proxy model for the solar far-ultraviolet irradiance

This dissertation presents a solar irradiance proxy model for the solar far ultraviolet (FUV) irradiance between 120 nm and 200 nm. The solar features which emit almost all of the solar UV irradiance below 200 nm can be classified into three primary components: quiet sun, active network, and plage. Parameterization of these three components is characterized by the following equation: F({dollar}lambda{dollar},t) = F{dollar}sb{lcub}rm q{rcub}{dollar}({dollar}lambda{dollar}) ({dollar}1-Csb{lcub}N{rcub}(lambda){dollar} + C{dollar}sb{lcub}rm N{rcub}(lambda){dollar}X{dollar}sb{lcub}rm N{rcub}{dollar}(t) + C{dollar}sb{lcub}rm P{rcub}(lambda){dollar}X{dollar}sb{lcub}rm p{rcub}{dollar}(t)), where F({dollar}lambda{dollar},t) is the predicted irradiance, F{dollar}sb{lcub}rm q{rcub}(lambda){dollar} is the reference irradiance. The C{dollar}sb{lcub}rm N{rcub}{dollar} and C{dollar}sb{lcub}rm P{rcub}{dollar} are linear regression coefficients. The X{dollar}sb{lcub}rm N{rcub}{dollar} and X{dollar}sb{lcub}rm P{rcub}{dollar} are the active network and plage components of the NOAA Mg II core to wing ratio. The highly accurate solar FUV irradiance measurements from the UARS SOLSTICE are used as input to the model. Parameterization of these three components better represents the multivariant trends that are seen in two component proxy models and which can add uncertainties of 20% or more to a model. These trends include differences between the 27-day rotation variability and the solar cycle variability when comparing solar UV irradiance time series, and a hysterisis effect which is the result of a time lag between the time series of two solar UV irradiances or indices. The daily plage area, from 1992 through 1995, is extracted from solar Ca II K line spectroheliograms and is used to derive the active network and plage components of the solar FUV irradiance and the Mg II core to wing ratio. The plage area is derived from the spectroheliograms using characteristics such as intensity, size, and filling factor. This three component proxy model is available from 1985 through 1995 and it has uncertainties of 7% or less for the solar FUV irradiance. Solar physics results are also presented. It is found that the daily averaged intensity of the Ca II K line active network, and plage, remains essentially constant over the solar cycle. Also, the absolute values of the plage intensity, relative to the quiet sun intensity, have been derived with unprecedented accuracy for the Ca II K line, Mg II h and k line, and the FUV wavelengths.