USE OF MST RADARS TO PROBE THE MESOSCALE STRUCTURE OF THE TROPOPAUSE

Profiles of the power scattered at vertical incidence by an MST radar have been compared with temperature profiles measured by radiosondes l aunched nearby. The results are consistent with a standard scattering model for low and medium scattered power, but deviate from the model a t high power. Tropopause heights have been derived from the radar data by two methods: the maximum power and maximum power gradient. The two criteria appear to be equally effective as predictors of the tropopau se, despite the theoretical expectation that the latter should be supe rior. Radiosonde tropopauses which were highly indefinite (no marked c hange in lapse rate between troposphere and stratosphere) were associa ted with a shallower minimum than normal in the radar power profile in the upper troposphere. This ability to detect highly indefinite tropo pauses shows that an MST radar may be used to monitor continuously the structure of the thermal tropopause.