31st Annual European Meeting on Atmospheric Studies by Optical Methods, Ambleside, Lake District, U.K., 22-28 August 2004

Negative ion chemistry studied by RF heating and riometer observations- model results

C.-F. Enell1, A. Kero1, E. Turunen1, Th. Ulich1, P. Verronen2, F. Honary3, A. Senior3

1Sodankylä Geophysical Observatory, Sodankylä, Finland
2Finnish Meteorological Institute, Geophysical Research Division, Helsinki, Finland
3Dept. of Communication Systems, Lancaster University, U.K.


The chemistry of the upper mesosphere and lower thermosphere (UMLT) is still to a large extent unknown. In this altitude region, electrons attach to neutral atoms and molecules to form negative ions. Negative ion chemistry has been shown to have a potentially large effect e.g. on ozone balance under certain circumstances.

The coupled ion-neutral chemistry model SIC (Sodankylä Ion Chemistry) has recently been extended to incorporate effects of electron temperature modifications, and additionally a model of electron heating by RF waves has been developed. This allows studying these effects actively through the use of the Eiscat RF Heating facility in Tromso, which can be tuned for maximum RF absorption in the UMLT region. The resulting modifications can be studied e.g. with the Eiscat radar and imaging riometers.

This talk will present preliminary SIC/Heating model results and discuss experiments for verification of these results.