Jena 2013 – wissenschaftliches Programm

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SYES: Symposium Einfluss der Sonne auf das Klima der Erde

SYES 1: Einfluss der Sonne auf das Klima der Erde

SYES 1.4: Hauptvortrag

Donnerstag, 28. Februar 2013, 15:30–16:00, HS 2

Impact of the solar 11-year and 27-day cycles on the Earth's middle atmosphere — •Christian von Savigny — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, Greifswald, Germany

Separating potential anthropogenic effects from natural variability - induced by solar variability in particular - is an important issue in atmospheric science. This is especially true for the middle atmosphere where both anthropogenic and solar effects are generally significantly larger than near the surface. This contribution will provide an overview of the current understanding of the impact of solar variability at the 11-year and 27-day time scales on the middle atmosphere with a special focus on temperature effects. The existence of an 11-year solar cycle signature in middle atmospheric temperature is well established, but estimates of the quantitative temperature sensitivity to changes in solar forcing differ considerably. The majority of the studies yield sensitivities of mesospheric temperature to solar forcing of about 1 - 4 K / (100 sfu). Recent studies suggest that the sensitivity values for the 11-year and the 27-day cycles are very similar, implying that the same underlying physical/chemical processes drive atmospheric temperature variability at these very different time scales. These studies also provide evidence that solar variability affects the middle atmosphere essentially instantaneously showing time lags of 1-2 days at most. The individual contributions of the chemical and physical processes driving the atmosphere's temperature response to changes in solar forcing are, however, not well known.