HR: 1340h
AN: SH53A-0304    [Abstracts]
TI: Inferring Total and Spectral Solar Irradiance From Sunspot Areas Only
AU: * Preminger, D G
EM: dora.preminger@csun.edu
AF: San Fernando Observatory Cal State Northridge, 18111 Nordhoff St, Northridge, CA 91330-8268
AU: Walton, S R
EM: stephen.walton@csun.edu
AF: San Fernando Observatory Cal State Northridge, 18111 Nordhoff St, Northridge, CA 91330-8268
AB: We show that daily sunspot area can be used in simple models to reconstruct daily variations in total or spectral solar irradiance. The models assume that all solar irradiance fluctuations can be traced back to the emergence of sunspots on the solar disk. Cotemporal data for irradiance and sunspot area are analysed to extract a detailed impulse response function that describes the time evolution of the irradiance in response to a sunspot that is a delta function. The analysis is carried out using data for total solar irradiance (the Fr\"ohlich-Lean TSI composite) and spectral solar data (the Mg~ii core-wing ratio and the 10.7cm solar radio flux F10.7). The details of the impulse response functions are different in each case, but overall they clearly show the evolution of a dark sunspot into a well-defined bright region which then spreads out and decays over a period of about 500 days. The impulse response functions can be used to produce a daily record of spectral or total solar irradiance from the Greenwich daily sunspot area database, which extends from the late 1800's to the present. The reconstructions of TSI, Mg~ii core-wing ratio and F10.7 show little long-term trend in their levels at solar minimum.
DE: 7537 Solar and stellar variability
DE: 7538 Solar irradiance
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting