Tuesday, 11 January 2005: 3:45 PM
Greenhouse cooling: A manifestation of global change in the upper atmosphere
Carbon dioxide and water vapor are the primary gases responsible for the greenhouse warming in the troposphere but they mainly act to cool the middle and upper atmosphere. The "greenhouse cooling" in the 15-μm CO2 band has been identified as a major driver of global change in the upper atmosphere. The ozone depletion and a substantial increase of the water vapor content have been shown to contribute significantly to the cooling trends observed in the stratosphere over the last few decades. It has been also suggested that this effect may extend well into the thermosphere and complement the in situ cooling due to increasing amounts of carbon dioxide. Modeling work to assess possible effects of these composition changes on the thermal and density structure of the mesosphere and thermosphere will be presented and compared with recent data analyses, in particular, from long-term satellite drag records.