Monitoring the stratospheric ozone profile with ground-based microwave radiometer

The destructive effects of stratospheric pollution (e.g. CFC-compounds) to the atmospheric ozone have been known for several years. Continuous monitoring of ozone in the stratosphere helps us to learn more about the chemistry of ozone in the atmosphere. A low noise superheterodyne receiver has been designed and constructed for ground-based monitoring of stratospheric ozone at Helsinki University of Technology. Ozone profiles are measured at a 110.836 GHz centre frequency with a 1200 MHz bandwidth. With the radiometer the authors are able to determine the ozone profile from 15 km to 70 km with a vertical resolution of 5 km. Continuous monitoring of ozone spectral lines has been carried out since August 1993. The first results are compared to balloon sounding measurements from a nearby sounding location. Various inversion methods for retrieving the ozone profile from measurements are presented including the Backus-Gilbert method. Some recent results are presented and short-time variations of atmospheric ozone are discussed (e.g. day-time vs. night-time variations)