HR: 17:50h
AN: GP54A-06 INVITED     [Abstracts]
TI: Solar Activity Effects on Long-Term Trends in the Upper Atmosphere
AU: * Lastovicka, J
EM: jla@ufa.cas.cz
AF: Institute of Atmospheric Physics, Bocni II, Prague, 14131, Czech Republic
AB: The long-term continuous increase of greenhouse gas concentration in the atmosphere and other anthropogenic influences excite long-term trends and changes in the atmosphere-ionosphere system. The observed long-term trends in the 20th century might be, however, influenced by contribution of Sun's origin, and the process of determination of anthropogenic trends from observational data may be "spoilt" by the 11-year solar cycle. After brief presentation of global trend pattern, the role of solar/geomagnetic activity in long-term trends in various regions of the atmosphere/ionosphere system is reviewed. The ways of avoiding or at least diminishing the effect of solar cycle on trend determination are mentioned. As for the possible solar and geomagnetic activity responsibility for part of the observed long-term trends, the two main conclusions are as follows: (i) The role of solar and geomagnetic activity in the observed long-term trends decreases with decreasing altitude from the F- region ionosphere down to the troposphere. (ii) In the 20th century the role of solar and geomagnetic activity in the observed long-term trends/changes was decreasing from its beginning towards its end. While at the beginning of the 20th century changes of the solar activity played some role even in the troposphere, at present only in the F2 region ionosphere the geomagnetic activity seems to play important and/or dominant role in trends. The trends in the E region ionosphere turned from the geomagnetic control to the dominant anthropogenic control around 1970.
DE: 1610 Atmosphere (0315, 0325)
DE: 1630 Impacts of global change (1225)
DE: 1650 Solar variability (7537)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly