HR: 10:55h
AN: SH31C-03 INVITED     [PDF]
TI: Are there links between long-term changes in open solar flux, the distribution of emerged flux, cosmogenic isotopes and the total solar irradiance?
AU: * Lockwood, M
EM: m.lockwood@rl.ac.uk
AF: Rutherford Appleton Lab., Space Science Department Chilton Oxfordshire, Didcot, OX11 0QX United Kingdom
AU: Foster, S S
EM: S.S.FOSTER@soton.ac.uk
AF: University of Southampton, Department of Physics and Astronomy, Hampshire, Southampton, SO17 1BJ United Kingdom
AB: Recent reconstructions of variations in the total solar irradiance (TSI) over the last 300 years are similar in form to the variations of cosmogenic isotope abundances and the inferred variation of the open solar flux over the same interval. These reconstructions show a century-scale drift in TSI which is comparable in magnitude to the amplitude of recent solar cycle changes, namely of order 1 W m-2. In addition, strong links between paleoclimate records and cosmogenic isotopes have been found. These results also suggest a link between open solar flux and total solar irradiance. Modelling of the evolution of emerged flux by Wang et al. (2002) reproduces the inferred large changes (by a factor of order 2) in the open solar flux on century timescales, explaining the changes in cosmic ray fluxes and hence cosmogenic isotope abundance: however, this modelling also suggests that this is not associated with significant change in the photospheric magnetic flux, which modulates TSI on 11-year timescales. Thus the changes in the open flux and cosmogenic isotopes do not appear to be linked to the 100-year drift in TSI. The long-term variation in open flux has been shown to be associated with changes in the heliographic latitude of active regions and we show that the contribution of active region faculae to the TSI has changed by 0.2 W m-2 in the past 100 years because of the directional characteristics of the excess radiation from faculae. This suggests that small flux tubes of the "extended solar cycle", and any long-term change in their latitudes, could also have made a significant contribution to the long-term drift in TSI .
DE: 2104 Cosmic rays
DE: 7524 Magnetic fields
DE: 7536 Solar activity cycle (2162)
DE: 7538 Solar irradiance
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting