15 Jul 2022
15 Jul 2022
Status: this preprint is currently under review for the journal AMT.

Harmonized retrieval of middle atmospheric ozone from two microwave radiometers in Switzerland

Eric Sauvageat1,2, Eliane Maillard Barras3, Klemens Hocke1,2, Alexander Haefele3, and Axel Murk1,2 Eric Sauvageat et al.
  • 1Institute of Applied Physics, University of Bern, Bern, Switzerland
  • 2Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
  • 3Federal Office of Meteorology and Climatology MeteoSwiss, Payerne, Switzerland

Abstract. We present new harmonized ozone time series from two ground-based microwave radiometers in Switzerland: GROMOS and SOMORA. Both instruments measure hourly ozone profiles in the middle atmosphere (20–75 km) since more than two decades. As inconsistencies in long-term trends derived from these two instruments were detected, a harmonization project was initiated in 2019. The goal was to understand and reduce the discrepancies between the two data records. The harmonization has been completed for the data from 2009 until 2022 and has been successful at reducing the differences observed between both time series. It also explains the remaining differences between both instruments and flags their respective anomalous measurement periods in order to adapt their consideration for future trend computations.

We describe the harmonization and the resulting time series in detail. We also highlight the improvements in the ozone retrievals with respect to the previous data processing. In the stratosphere and lower mesosphere, the seasonal ozone relative differences between both instruments are now within 10 % and show good correlations (R > 0.7) except for summertime. We also perform a comparison of these new data series against measurements from the satellite instruments Microwave Limb Sounder (MLS) and Solar Backscatter Ultraviolet Radiometer (SBUV) over Switzerland. Seasonal mean differences with MLS and SBUV are within 10 % in the stratosphere and lower mesosphere up to 60 km and increase rapidly above.

Eric Sauvageat et al.

Status: open (until 02 Sep 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2022-212', Giovanni Muscari, 03 Aug 2022 reply

Eric Sauvageat et al.

Data sets

Harmonized retrievals of middle atmospheric ozone from Swiss microwave radiometers Eric Sauvageat

Model code and software

GROMORA calibration and retrievals code Eric Sauvageat

Eric Sauvageat et al.


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Short summary
We present new harmonized ozone time series from two ground-based microwave radiometers in Switzerland. The new series consist of hourly ozone profiles in the middle atmosphere (~20–70 km) from 2009 until 2021. Cross-validation of the new data series shows the benefit of the harmonization process compared to the previous versions. Comparisons with collocated satellite observations is used to further validate these time series for long-term ozone monitoring over Central Europe.