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A new model of total solar irradiance based on sunspot areas
Author(s) -
Preminger Dora G.,
Walton Stephen R.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl022839
Subject(s) - sunspot , greenwich , solar irradiance , solar minimum , physics , meteorology , environmental science , atmospheric sciences , climatology , geology , solar cycle , solar wind , magnetic field , quantum mechanics , soil science
We show that daily sunspot area can be used in a simple model to reconstruct daily variations in the total solar irradiance, S . The model assumes that all fluctuations in S are correlated with the emergence of sunspots on the solar disk. Cotemporal data for S and sunspot area are analysed to extract the finite impulse response function that describes the time evolution of S in response to a sunspot. The impulse response function clearly shows the evolution of a dark sunspot into a well‐defined bright region which then spreads out and decays over a period of about 400 days. This function can be used to reconstruct S from the Greenwich daily sunspot area database, which extends from the late 1800's to the present. We find that the level of S at solar minimum has no long‐term secular trend that is correlated with the level of sunspot activity.