Abstract
Abstract. The coherence of stratospheric ozone time series retrieved from various observational records is investigated at Haute-Provence Observatory (OHP–43.93° N, 5.71° E). The analysis is accomplished through the intercomparison of collocated ozone measurements of Light Detection and Ranging (lidar) with Solar Backscatter UltraViolet(/2) (SBUV(/2)), Stratospheric Aerosol and Gas Experiment II (SAGE~II), Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS) on Upper Atmosphere Research Satellite (UARS) and Aura and Global Ozone Monitoring by Occultation of Stars (GOMOS) satellite observations as well as with in situ ozonesondes and ground-based Umkehr measurements performed at OHP. A detailed statistical study of the relative differences of ozone observations over the whole stratosphere is performed to detect any specific drift in the data. On average, all instruments show their best agreement with lidar at 20–40 km, where deviations are within ±5 %. Discrepancies are somewhat higher below 20 and above 40 km. The agreement with SAGE II data is remarkable since average differences are within ±1 % at 17–41 km. In contrast, Umkehr data underestimate systematically the lidar measurements in the whole stratosphere with a near zero bias at 16–8 hPa (~30 km). Drifts are estimated using simple linear regression for the data sets analysed in this study, from the monthly averaged difference time series. The derived values are less than ±0.5 % yr−1 in the 20–40 km altitude range and most drifts are not significant at the 2σ level. We also discuss the possibilities of extending the SAGE II and HALOE data with the GOMOS and Aura MLS data in consideration with relative offsets and drifts since the combination of such data sets are likely to be used for the study of stratospheric ozone recovery in the future.
Highlights
The discovery of the Antarctic ozone hole by Farman et al (1985) called for a tight monitoring of ozone and related trace species in the middle atmosphere
Relative differences are calculated for Stratospheric Aerosol and Gas Experiment II (SAGE II), Halogen Occultation Experiment (HALOE), ozonesondes, Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS), Aura MLS and Global Ozone Monitoring by Occultation of Stars (GOMOS) at altitudes 18, 21, 25, 30, 35 and 40 km by averaging ozone over a range of ±2 km in order to provide relatively smooth time series of ozone measurements and to homogenise different data sets for the comparisons
Average results are shown with black dots and daily values are with grey dots in the background
Summary
The discovery of the Antarctic ozone hole by Farman et al (1985) called for a tight monitoring of ozone and related trace species in the middle atmosphere. Ozone depletion in the mid-latitudes was noted from observations (WMO, 1992). Significant decrease of upper stratospheric ozone in the northern mid-latitudes was observed in 1979–1995 by various measurements – (SPARC, 1998; WMO, 2007). Randel et al (1999) found statistically significant trends of −7 to −8 %/decade at 40 km in 1979–1996 from SAGE I/II (Stratospheric Aerosol and Gas Experiment I/II), SBUV(/2) (Solar Backscatter UltraViolet (/2)), Umkehr and ozonesonde measurements. A study by Li et al (2002) confirmed the findings of Randel et al (1999), and led to an estimate of about −9 %/decade in the upper stratosphere using SAGE I/II measurements in the same period. A similar trend (∼ −0.8 % yr−1), in the upper stratosphere (∼40 km), was estimated by Newchurch et al (2000) from SAGE I/II, SBUV(/2) and Published by Copernicus Publications on behalf of the European Geosciences Union
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