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Our sun does not radiate evenly. The best known example of radiation fluctuations is the famous 11-year cycle of sun spots. Nobody denies its influence on the natural climate variability, but climate models have, to-date, not been able to satisfactorily reconstruct its impact on climate activity.
Researchers from the USA and from Germany have now, for the first time, successfully simulated, in detail, the complex interaction between solar radiation, atmosphere, and the ocean. As the scientific journal „Science“ reports in its latest issue, Gerald Meehl of the US-National Center for Atmospheric Research (NCAR) and his team have been able to calculate how the extremely small variations in radiation brings about a comparatively significant change in the System “Atmosphere-Ocean”.
The complex interplay mechanisms in the stratosphere and the troposphere found in the research create measurable changes in the water temperature of the Pacific and in precipitation, causing extreme weather phenomena on our planet.
The initial process runs from increased solar radiation leading to more ozone and higher temperatures in the stratosphere. The ultraviolet radiation share varies much more strongly than the other shares in the spectrum – i.e. by five to eight per cent – and that forms more ozone. As a result, especially the tropical stratosphere becomes warmer, which in turn leads to changed atmospheric circulation. Thus, the interrelated typical precipitation patterns in the tropics are also displaced.
The second process takes place in the opposite way: the higher solar activity leads to more evaporation in the cloud free areas. With the trade winds the increased amounts of moisture are transported to the equator, where they lead to stronger precipitation, lower water temperatures in the East Pacific and reduced cloud formation, which in turn allows for increased evaporation. With this it is possible to explain the respective measurements and observations on the Earth’s surface.