scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...
scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...
scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...
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STP12 Abstracts<br />
Berlin, 12 - 16 July <strong>2010</strong><br />
SCOSTEP Symposium <strong>2010</strong><br />
Long-term ch<strong>an</strong>ges <strong>an</strong>d trends in the upper atmosphere <strong>an</strong>d ionosphere<br />
Lastovicka J<strong>an</strong><br />
<strong>Institut</strong>e of Atmospheric Physics ASCR, Bocni II, 14131 Prague, Czech Republic; jla@ufa.cas.cz<br />
The <strong>an</strong>thropogenic emissions of greenhouse gases influence the atmosphere at nearly all<br />
altitudes between ground <strong>an</strong>d space. The greenhouse gases are the main driver of trends in the<br />
upper atmosphere (mesosphere <strong>an</strong>d thermosphere) but other factors, namely stratospheric<br />
ozone depletion, middle atmosphere water vapour, long-term ch<strong>an</strong>ges of geomagnetic activity<br />
<strong>an</strong>d secular ch<strong>an</strong>ge of the Earth’s magnetic field play some role as well. The first scenario of<br />
long-term trends (<strong>an</strong>d/or global ch<strong>an</strong>ge) in the upper atmosphere <strong>an</strong>d ionosphere has been<br />
constructed in 2006. The scenario consists of mutually consistent trends in mesospheric<br />
temperatures, thermospheric densities, upper ionosphere ion temperatures, <strong>an</strong>d electron<br />
densities <strong>an</strong>d heights of F1, E <strong>an</strong>d D ionospheric layers. However, there were three areas,<br />
characterized by key words F2 region, MLT (mesosphere <strong>an</strong>d lower thermosphere) dynamics,<br />
middle atmosphere water vapour, which did not fit this scenario. I will deal with the overall<br />
pattern of trends in the upper atmosphere <strong>an</strong>d ionosphere with special emphasis to possible<br />
effects of solar/geomagnetic activity, to impact of ch<strong>an</strong>ging trends in stratospheric ozone, <strong>an</strong>d<br />
to the three exceptional areas. According to recent model calculations <strong>an</strong>d observational<br />
<strong>an</strong>alyses, F2 region parameters foF2 <strong>an</strong>d hmF2 could be at present domin<strong>an</strong>tly controlled by<br />
geomagnetic activity <strong>an</strong>d increasing concentration of greenhouse gases, respectively, or even<br />
only by greenhouse gases, which removes part of contradictions. Relatively little progress has<br />
been reached in mesospheric dynamics; new data on trends in pl<strong>an</strong>etary wave activity remain<br />
controversial but indications of positive trend in the MLT region turbulence, which is thought<br />
to be produced by gravity wave dissipation, have been reported. As for mesospheric water<br />
vapour, there is strong indication that after consi<strong>der</strong>ing different latitudes of satellite <strong>an</strong>d<br />
ground-based NLC observations the difference between trends deduced from ground- <strong>an</strong>d<br />
satellite-based data remains within limits given by the accuracy of observations, i.e. these<br />
measurements need not differ as it was thought earlier. Two key questions for future<br />
investigations are trends in MLT (or middle atmosphere) dynamics <strong>an</strong>d links between trends<br />
in the upper atmosphere <strong>an</strong>d stratosphere/troposphere.
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