Solar variability

FIGURE 14.54 Annual average number of sunspots from 1880 to 2000, showing the 11-year cycle (adapted from diver et al., 1998). 

FIGURE 14.55 Reconstructed total solar irradiance from f6f0 to f995 using an 11-year solar cycle plus a longer term component of variability (adapted from Lean et al., 1995a). 

Age from 1450 to 1850. The long-term component has been scaled to agree with the estimate of an overall increase in total irradiance from the Maunder Minimum to the present of 0.24% (Lean et al., 1992,1995b). 

However, it should be noted that the effect is somewhat geographically and temporally variable. For example, Robock and Mao (1995) have examined climate records since about 1850 and correlated them to volcanic eruptions both before and after removal of the 

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Hurt, P. H., Stable Oxygen Isotopes in Tree Rings as an Indicator of Solar Variability, Masters Thesis, Chemistry Department, University of California at Los Angeles, 1978. 

In addition to these indirect effects of volcanic emissions, there are a variety of nonvolcanic parameters that, of course, can change 03 as well, and these must be taken into account in assessing the role of the volcanic emissions alone. For example, there is a natural solar variability, part of which cycles on a time scale of about 11 years and part of which is on a much longer time scale (Lean, 1991 Lean et al., 1995a, 1995b Labitzke and van Loon, 1996). In addition, stratospheric ozone levels vary with the quasi-biennial oscillation (QBO), which is associated with a periodic variation in the zonal winds at the equator between 20 and... 

Cliver, E. W., V. Boriakoff, and J. Feynman, Solar Variability and Climate Change Geomagnetic aa Index and Global Surface Temperature, Geophys. Res. Lett., 25, 1035-1038 (1998). 

Raisbeck GM, Yiou F, Jouzel J, Petit JR (1990) 10Be and d2H in polar ice cores as a probe of the solar variability s influence on climate. Phil Trans Royal Soc London A 330 471-480 Reedy RC, Nishiizumi K, Lai D, Arnold JR, Englert PAJ, Klein J, Middleton R, Jull AJT, Donahue DJ (1994) Simulations of terrestrial in-situ cosmogenic nuclide production. Nucl Instrum Methods Phys Res B 92 297-300... 

Solar Variability, Weather, and Climate (Studies in Geophysics), National Academy of Sciences, 1982a, 120 pp. 

Neff U., Burns S. J., Mangini A., Mudelsee M., Fleitmann D., and Matter A. (2001) Strong coherence between solar variability and the monsoon in Oman between 9 and 6 kyr ago. Nature 411, 290-293. 

The intermediate region which extends from about 10 to 100 km altitude is sometimes called the middle atmosphere. This region is somewhat less accessible to observation and has on een systematically studied for the past 25 to 30 years. The purpose of this volume is to outline some of the factors which control the behavior of this layer of the atmosphere, a region which is particularly vulnerable to external perturbations such as solar variability and volcanic eruptions or the emission of anthropogenic material, either at the surface or at altitude. 

Brasseur, G.P., The response of the middle atmopshere to a long-term and short-term solar variability A two dimensional model. J Geophys Res 98, 23,079, 1993. 

Huang, T.Y.W., and G.P. Brasseur, The effect of long-term solar variability in a two-dimensional interactive model of the middle atmosphere. J Geophys Res 98, 20,410, 1993. 

Brasseur, G., P. DeBaets, and A. de Rudder, Solar variability and minor constituents in the lower thermosphere and in the mesosphere. Space Sci Rev 34, 377, 1983. 

The effect of solar variability is not accounted for in this expression and needs to be added for detailed calculations. 

If the low-frequency variations in the solar irradiation were correct, they could explain the climate variability in the period before 1900 or so, but because of the small amplitudes they cannot explain the rapid warming during this century. The solar forcing must therefore with high probability be excluded as the major cause of climate warming during the 20th century. Neither is the solar variability required to explain the variability of climate as documented over the last millennium, since this can be explained by internal variability of the climate system. 

Haigh, J. D. (1996) The impact of solar variability on climate, Science 272, 981-984. 

Estimated forcing from stratospheric O3 loss is —0.2 W m Increase of tropospheric O3 since preindustrial times is estimated to contribute a forcing of -t-0.55 W m . The range of forcing resulting from solar variability since about 1850 is estimated to range from 0.1 to 0.5 W m with a mean of 0.3 W m... 

The 0.6°C rise in globally averaged temperatures is compatible with, in terms of both magnitude and timing, that predicted by models which take the combined influences of human factors and solar variability into account. More recent studies of attribution have considered the patterns of temperature change, both spatially and in the vertical column of the atmosphere. Climate models indicate... 

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