Small fluctuations in solar activity, large influence on the climateAugust 28, 2009Sun spot frequency has an unexpectedly strong influence on cloud formation and precipitation 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". Katja Matthes of the GFZ German Research Centre for Geosciences, and co-author of the study, states: „Taking into consideration the complete radiation spectrum of the sun, the radiation intensity within one sun spot cycle varies by just 0.1 per cent. Complex interplay mechanisms in the stratosphere and the troposphere, however, create measurable changes in the water temperature of the Pacific and in precipitation". Top Down - Bottom up In order for such reinforcement to take place many small wheels have to interdigitate. The initial process runs from the top downwards: increased solar radiation leads 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" explains Katja Matthes. 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. Katja Matthes: "It is this positive back coupling that strengthens the process". With this it is possible to explain the respective measurements and observations on the Earth's surface. Professor Reinhard Huettl, Chairman of the Scientific Executive Board of the GFZ (Helmholtz Association of German Research Centres) adds: "The study is important for comprehending the natural climatic variability, which - on different time scales - is significantly influenced by the sun. In order to better understand the anthropogenically induced climate change and to make more reliable future climate scenarios, it is very important to understand the underlying natural climatic variability. This investigation shows again that we still have substantial research needs to understand the climate system". Together with the Alfred Wegener-Institute for Polar and Marine Research and the Senckenberg Research Institute and Natural History Museum the GFZ is, therefore, organising a conference "Climate in the System Earth" scheduled for 2./3. November 2009 in Berlin. Helmholtz Association of German Research Centres |
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| Related Solar Activity Current Events and Solar Activity News Articles A Lightning Strike in Africa Helps Take the Pulse of the Sun Sunspots, which rotate around the sun's surface, tell us a great deal about our own planet. Scientists rely on them, for instance, to measure the sun's rotation or to prepare long-range forecasts of the Earth's health. Cosmic Rays Hit Space Age High Planning a trip to Mars? Take plenty of shielding. According to sensors on NASA's ACE (Advanced Composition Explorer) spacecraft, galactic cosmic rays have just hit a Space Age high. Solar cycle linked to global climate Establishing a key link between the solar cycle and global climate, research led by scientists at the National Science Foundation (NSF)-funded National Center for Atmospheric Research (NCAR) in Boulder, Colo., shows that maximum solar activity and its aftermath have impacts on Earth that resemble La Niña and El Niño events in the tropical Pacific Ocean. Solar cycle linked to global climate, drives events similar to El Nino, La Nina Establishing a key link between the solar cycle and global climate, new research led by the National Center for Atmospheric Research (NCAR) shows that maximum solar activity and its aftermath have impacts on Earth that resemble La Nina and El Nino events in the tropical Pacific Ocean. Scientists find solution to solar puzzle Scientists from the University of Sheffield and Queen's University Belfast have made a unique discovery which will help us understand one of the most puzzling features of the Sun. Queen's scientists discover giant solar twists Scientists at Queen's University have made a finding that will help us to understand more about the turbulent solar weather and its affect on our planet. NASA's Fermi Telescope Reveals Best-Ever View of Gamma-Ray Sky A new map combining nearly three months of data from NASA's Fermi Gamma-ray Space Telescope is giving astronomers an unprecedented look at the high-energy cosmos. To Fermi's eyes, the universe is ablaze with gamma rays from sources ranging from within the solar system to galaxies billions of light-years away. New climate record shows century-long droughts in eastern North America A stalagmite in a West Virginia cave has yielded the most detailed geological record to date on climate cycles in eastern North America over the past 7,000 years. Scientists identify origin of hiss in upper atmosphere Scientists have solved a 40-year-old puzzle by identifying the origin of the intense radio waves in the Earth's upper atmosphere that control the dynamics of the Van Allen radiation belts - belts consisting of high-energy electrons that can damage satellites and spacecraft and pose a risk to astronauts performing activities outside their spacecraft. The light and dark of Venus Venus Express has revealed a planet of extraordinarily changeable and extremely large-scale weather. Bright hazes appear in a matter of days, reaching from the south pole to the low southern latitudes and disappearing just as quickly. More Solar Activity Current Events and Solar Activity News Articles |
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