Solar dynamics and its impact on solar irradiance and the terrestrial climate

Abstract

Among the various uncertainties present in climate modeling, the variability of total solar irradiance is not one of the least. For lack of any direct measure of the solar irradiance in the past, substitutes are needed. However, the difficulties are twofold: (1) the reliability of the proxies and (2) the need for some physical mechanism relating these proxies to the solar luminosity. On the basis of a better understanding of the solar machinery we can now propose a plausible scenario connecting the exchanges of energy between the various reservoirs: magnetic, thermal, gravitational, and kinetic. In the present paper we discuss the available proxies and suggest a way to reconstruct total solar irradiance over the past four centuries. The response of the Laboratoire de Météorologie Dynamique atmospheric general circulation model to magnetoconvective solar forcing during the Maunder minimum is discussed. The simulated cooling appears to be compatible with temperature data from the Little Ice Age; in addition, it is found that variations of globally homogeneous external forcing parameters, like incoming solar flux or greenhouse gas loading, yield climate responses with very similar geographical patterns.

Modeling the Sun’s Small-Scale Global Photospheric Magnetic Field

“…A much reduced level of magnetic activity and IMF would therefore result in a significant increase in cosmic rays at Earth. It has been suggested that there is a connection between cosmic rays and the Earth's climate, although the exact link is still an open question (see, e.g., Nesme-Ribes et al 1993;Svensmark & Friis-Christensen 1997;Jørgensen & Hansen 2000;Usoskin & Kovaltsov 2008;Mironova et al 2015).…”

Solar Influences on Global Change

“…The absence of sunspots and possible supression of the l 1-year cycle during this extended period suggests that the flux emergence process may have stopped completely for several decades. Relative to the present, the Sun's internal circulation may have been substantially different , and its diameter larger (Nesme- Ribes et al, 1993). Indirect evidence for many similar episodes in solar behavior comes from the radiocarbon and auroral records (Eddy, 1976), but only very recently has it been recognized that substantial decreases in the Sun's radiative output might have accompanied these episodes (White et al, 1992;Lean et al, 1992a).…”

“…Using apparent solar radius as a surrogate for solar irradiance leads to speculation of a reduction as large as 1 percent during the late seventeenth century (Nesme- Ribes et al, 1993). In addition to uncertainties about the amplitude of solar irradiance values in the Maunder Minimum, there are also differences in reconstructions of the relative temporal variations in the irradiance since then --over the past 300 years.…”

“…Solar observations made by telescopes in the seventeenth century also suggest increased solar diameter and equatorial surface rotation during the Maunder Minimum, compared with the modern Sun Nesme-Ribes et al, 1993). Using apparent solar radius as a surrogate for solar irradiance leads to speculation of a reduction as large as 1 percent during the late seventeenth century (Nesme- Ribes et al, 1993).…”

“…The first steps can be taken with empirical models now available (e.g., Foukal and Lean, 1990;White et al, 1992;Lean et al, 1992a;Hoyt and Schatten, 1993;Nesme-Ribes et al, 1993), but the credibility of such research would be strengthened immeasurably through development of a successful physical model of the solar cycle.…”