12th Conference on Middle Atmosphere

Tuesday, 5 November 2002
Radio Aeronomy at Onsala Space Observatory
Peter M. Forkman, Chalmers University of Technology, Onsala, Sweden; and P. Eriksson and A. Winnberg
Radio aeronomy has developed into a powerful tool in aeronomy research. The method has been successfully used to detect a number of gases in the stratosphere and mesosphere and to estimate the vertical abundance profiles of molecules. The technique makes it possible to perform spectral line measurements of purely rotational lines, which are sufficiently optically thin to be observable from the ground. These lines are primarily pressurebroadened in the middle atmosphere and therefore the measured shape of the line profiles contains information on the abundance of the emitting constituent as a function of pressure, or equivalently, altitude. We measure H2O with a new HEMT receiver at 22GHz, certified by the network for the detection of stratospheric change, and CO at 115GHz with the spare 3mm Schottky mixer receiver of the observatory. CO is produced in the upper mesosphere through photodissociation of CO. Its destruction is dominated by the reaction with OH, which is a photodissociation product of H2O in the mesosphere. Synoptic observations of CO and H2O can be very useful in order to understand the coupling between chemistry and dynamics in the mesosphere and stratopause region. We present the receiver systems, the observation technique and measured results of carbon monoxide and water vapour from 2001 and 2002.

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