Ground-based microwave radiometry to determine stratospheric and mesospheric ozone profiles

Abstract From April 1984 to April 1985 a microwave radiometer was operated at Bern (Switzerland, latitude 47°N) measuring the thermal emission of the rotational ozone transition at 142.2 GHz to determine stratospheric and mesospheric ozone abundances in the range ~25–~75 km altitude. From a total of 334 retrieved day-time profiles, monthly mean ozone partial pressures for Umkehr layers 6–10 were calculated. On this basis ozone variations compare favorably with Umkehr data from the nearby Arosa (Switzerland, 150 km east of Bern) station and with a monthly zonal mean model compiled from satellite data by Keating and Young. From the microwave data an annual mean ozone distribution was determined. The method retrieves somewhat larger ozone volume mixing ratios between 25 and 30 km altitude. For the rest of the measurement range of the sensor there is good agreement with 20 year annual mean ozone values from Arosa, with the Krueger and Minzner profile and with the respective annual mean data given by Keating and Young. The microwave ozone sensor can easily be adapted for operational use, where it can supplement and expand the measurement range of the traditional Umkehr network.