Millimeter wave measurements of stratospheric ClO at the Jungfraujoch Station

In the past years a mm-wave radiometer has been used at the Jungfraujoch Alpine Station in the Swiss Alps (3580 m.a.s.l.). In this dry and cold environment it is possible to detect weak spectral lines as well as transitions that normally are strongly affected due to absorption of water vapor in the lower troposphere. In the winter periods the radiometer has mainly been used to detect the 204 GHz transition of stratospheric chlorine monoxide. As ClO is a key molecule in the ozone chemistry continuous registrations of this trace gas are important for the understanding of the global ozone layer