Time scales and Mechanisms of Climate Interactions with the Sun
Abstract
Various correlations have been obtained between observed or deduced changes in solar irradiance and climate variations. During the Quaternary, these include: ice age cycles (circa 100,000 years), associated with Milankovitch orbital variations; apparent climate periodicities on the order of 2300, 210, 88, 22 or 11 years, presumably associated with variations of these periods in the activity of the sun, including sunspots; and even daily responses of cyclone intensity related to high energy particles. The problem in each of these respects is to decipher how the relatively small energy variations (at most on the order of 0.5 percent of total solar irradiance, or 1 W/m2) could be responsible for the impacts in the massive troposphere ascribed to them. One explanation is that they cannot: that the correlations are either circular reasoning, associated with dating uncertainties, or quasi-periodicities related to naturally occurring cycles that happen to match solar ones. Alternatively, the climate system could be sensitive to the spectral frequencies or latitudinal distribution of the solar irradiance changes, thereby amplifying the forcing via naturally occurring mechanisms. Our current understanding of this subject will be reviewed, with emphasis on the potential interaction between different levels of the atmosphere as amplifying mechanisms, including impacts on both radiative and atmospheric-dynamical processes.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.U22B..01R
- Keywords:
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- 0340 Middle atmosphere: composition and chemistry;
- 1620 Climate dynamics (3309);
- 1650 Solar variability;
- 3359 Radiative processes;
- 3362 Stratosphere/troposphere interactions