Atmospheric Chemistry and Physics Evaluation of tropospheric and stratospheric ozone trends over Western Europe from ground-based FTIR network observations

ries of Upper Free Troposphere observations from an Eu-ropean ground-based FTIR network), six ground-based sta-tions in Western Europe, from 79 ◦ N to 28 ◦ N, all equipped with Fourier Transform infrared (FTIR) instruments and part of the Network for the Detection of Atmospheric Compo-sition Change (NDACC), have joined their efforts to evalu-ate the trends of several direct and indirect greenhouse gases over the period 1995–2004. The retrievals of CO, CH4, C2H6, N2O, CHClF2, and O3 have been optimized. Us-ing the optimal estimation method, some vertical informa-tion can be obtained in addition to total column amounts. A bootstrap resampling method has been implemented to de-termine annual partial and total column trends for the target gases. The present work focuses on the ozone results. The retrieved time series of partial and total ozone columns ar