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STP12 Abstracts Berlin, 12 - 16 July 2010 SCOSTEP Symposium 2010 Observations of the Phase-Locked Two day Wave Over the Australian Sector Using Medium Frequency Radar and Airglow Data Hecht James 1 , Walterscheid Richard 1 , Gelinas Lynette 1 , Vincent Robert 2 , Reid Iain 2 , Woithe Jonathan 2 1 2 The Aerospace Corporation, Department of Physics and Mathematical Physics, University of Adelaide The quasi two day wave (QTDW), with a nominal mean period just above 50 hours, is a significant feature of the 80 to 100 km altitude region in both hemispheres. It becomes particularly prominent in the southern hemisphere summer at mid latitudes where, a short time after summer solstice, its amplitude rapidly increases and its mean period is found to be approximately 48 hours, producing an oscillation phase locked in local time. This lasts for a few weeks. Presented here are observations of the meridional winds and airglow over two sites in Australia, for four years during the austral summers of 2003 to 2006. We show that during those times when the large-amplitude phase-locked two-day wave (PL-TDW) is present the diurnal tide greatly decreases. This is consistent with the Walterscheid and Vincent (1996) model in which the PL-TDW derives its energy from a parametric excitation by the diurnal tide. These data also show that the diurnal tide is more suppressed, and the PL- TDW amplitude is larger, in odd-numbered years, suggesting a biannual effect. The airglow data indicated that, for the PL-TDW, the winds and temperature are close to out of phase. When the PL-TDW is present airglow amplitudes can become quite large, a result dependent on the local time of the PL-TDW maximum. The airglow intensity response was in general much larger than what would be expected from the airglow temperature response suggesting that the PL-TDW is causing a significant composition change possibly due to minor constituent transport. Walterscheid, R., and R. Vincent (1996), Tidal generation of the phase-locked 2-day wave in the southern hemisphere summer by wave-wave interactions, J. Geophys. Res., 101(D21), 26567-26576.
STP12 Abstracts Berlin, 12 - 16 July 2010 SCOSTEP Symposium 2010 Production Rate of cosmogenic nuclides in the Earth's atmosphere Herbst Klaudia 1 , Matthiä Daniel 2 , Steinhilber Friedhelm 3 , Heber Bernd 1 1 Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Germany, 2 Institut für Luft- und Raumfahrtmedizin, Deutsches Zentrum für Luft- und Raumfahrt, Köln, Germany, 3 Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Dübendorf, Switzerland Galactic cosmic rays which interact with the Earth's atmosphere produce a cascade of secondary particles. These secondary particles are able to generate cosmogenic nuclides, in particular 7 Be, 10 Be, 14 C and 37 Cl, by spallation reactions between secondary neutrons as well as protons and atmospheric gases like nitrogen and oxygen. Complex atmospheric processes lead to the fact that these nuclides are stored in natural archives such as tree rings and ice cores. In order to model these concentrations the production rate as well as loss processes have to be simulated. The first step is to determine the production rate, which will be presented here using the GEANT4 tool PLANETOCOSMICS to model the radiation field, i. e. neutrons and protons in the atmosphere and the corresponding production rate of the cosmogenic nuclides 7 Be, 10 Be, 14 C and 37 Cl.
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scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

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