Speaker
Leonie Bernet
(Institute of Applied Physics, University of Bern, Bern, Switzerland and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland)
Description
After the Montreal protocol banned ozone depleting substances in 1987, first signs of an ozone recovery in the stratosphere were observed starting in 1997. Recent studies have confirmed that mid-latitudinal ozone is increasing in the middle stratosphere due to chemical and dynamical effects, whereas evidence for a continuous decrease in the lower stratosphere exists. To improve trend estimations of stratospheric ozone profiles, continuous and stable time series are crucial and trend uncertainties need to be addressed.
This study helps to explain inconsistencies in recent ground-based trend profiles of stratospheric ozone at northern mid-latitudes by comparing ground-based ozone time-series and assessing their trends and uncertainties. We present an updated and improved 23-years time series of stratospheric ozone from the GROMOS (GROund-based Millimeter-wave Ozone Spectrometer) microwave radiometer located at Bern, Switzerland. We compared the GROMOS data with data from other ground-based instruments in Central Europe from the Network for the Detection of Atmospheric Composition Change (NDACC), namely lidars, ozonesondes and microwave radiometers. We found a good agreement in the middle and upper stratosphere with relative differences of 3 to 10% and identified some biased periods possibly due to instrumental issues. Further our data indicate positive trends of 1 to 3 % per decade at an altitude of about 40 km.
Primary author
Leonie Bernet
(Institute of Applied Physics, University of Bern, Bern, Switzerland and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland)
Co-authors
Klemens Hocke
(Institute of Applied Physics, University of Bern, Bern, Switzerland and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland)
Kämpfer Niklaus
(Institute of Applied Physics, University of Bern, Bern, Switzerland and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland)