Greenhouse Cooling of the Upper Atmosphere
Observed in High-Latitude Ionosonde Data

Thomas Ulich(1,2) and Esa Turunen(1)

(1)Geophysical Observatory, FIN-99600 Sodankylä, Finland
(2)Dept. of Physical Sciences, University of Oulu, FIN-90570 Oulu, Finland


Increased concentrations of greenhouse gases in the air cause a cooling of the strato-, meso-, and thermosphere (Roble and Dickinson, 1989); the atmosphere is expected to shrink. Rishbeth (1990) predicted a lowering of the peak height of the ionospheric F2-layer which was confirmed for mid-latitudes by Bremer (1992). In the present study we compare long-term data from Sodankylä, Finland, (high latitude, 67.4N, 26.7E) with Bremer's results and another ionosonde record of lower latitudes. In all data we observe cooling of the upper atmosphere.