Upper Atmosphere (Greenhouse?) Cooling as seen in Riometer and Ionosonde Data
Thomas Ulich, Esa Turunen, and Hilkka Ranta+
Geophysical Observatory, FIN-99600 Sodankylä, Finland
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1. Abstract
2. Abstract (cont'd)
3. Greenhouse Cooling

4. Ionosonde in Sodankylä
5. Calculating F2 Peak Height
6. External Influences

7. Removing External Influences
8. General Trend
9. Sodankylä vs. Alma Ata

10. Seasonal Variations
11. Concluding Remarks
12. Acknowledgment / References

13. Contact Address

Upper Atmosphere (Greenhouse?) Cooling
as seen in Riometer and Ionosonde Data

Thomas Ulich, Esa Turunen and Hilkka Ranta+

Geophysical Observatory, FIN-99600 Sodankylä, Finland

Abstract
Model estimates of the effects of increasing greenhouse gas emissions predict cooling of the upper atmosphere. Experimental evidence for the cooling is, however, scarce and mostly based on short time scales. Recently, however, a clear trend hinting to a cooling effect has been found in the (local) record of F2 layer peak heights at Sodankylä. Since the absorption of cosmic radio noise depends on electron-neutral collision frequency, which in turn is a function of temperature, the cosmic radio noise measurements reflect long-term changes of temperature. We analyse the long-term recordings of the Finnish riometer chain for signs of cooling of the upper atmosphere and compare the result with the trend found in ionosonde data.