Abstract. The trends and variability of ozone are assessed over a northern mid-latitude station, Haute-Provence Observatory (OHP: 43.93 • N, 5.71 • E), using total column ozone observations from the Dobson and Système d'Analyse par Observation Zénithale spectrometers, and stratospheric ozone profile measurements from light detection and ranging (lidar), ozonesondes, Stratospheric Aerosol and Gas Experiment (SAGE) II, Halogen Occultation Experiment (HALOE) and Aura Microwave Limb Sounder (MLS). A multivariate regression model with quasi-biennial oscillation (QBO), solar flux, aerosol optical thickness, heat flux, North Atlantic Oscillation (NAO) and a piecewise linear trend (PWLT) or equivalent effective stratospheric chlorine (EESC) functions is applied to the ozone anomalies. The maximum variability of ozone in winter/spring is explained by QBO and heat flux in the ranges 15-45 km and 15-24 km, respectively. The NAO shows maximum influence in the lower stratosphere during winter, while the solar flux influence is largest in the lower and middle stratosphere in summer. The total column ozone trends estimated from the PWLT and EESC functions are of −1.47 ± 0.27 and −1.40 ± 0.25 DU yr −1 , respectively, over the period 1984-1996 and about 0.55 ± 0.30 and 0.42 ± 0.08 DU yr −1 , respectively, over the period 1997-2010. The ozone profiles yield similar and significant EESCbased and PWLT trends for [1984][1985][1986][1987][1988][1989][1990][1991][1992][1993][1994][1995][1996], and are about −0.5 and −0.8 % yr −1 in the lower and upper stratosphere, respectively. For 1997-2010, the EESC-based and PWLT estimates are of the order of 0.3 and 0.1 % yr −1 , respectively, in the 18-28 km range, and at 40-45 km, EESC provides significant ozone trends larger than the insignificant PWLT results. Furthermore, very similar vertical trends for the respective time periods are also deduced from another long-term satellitebased data set (GOZCARDS-Global OZone Chemistry And Related trace gas Data records for the Stratosphere) sampled at northern mid-latitudes. Therefore, this analysis unveils ozone recovery signals from total column ozone and profile measurements at OHP, and hence in the northern midlatitudes.
The long-term evolution of stratospheric ozone at different stations in the low and mid-latitudes is investigated. The analysis is performed by comparing the collocated profiles of ozone lidars, at the northern mid-latitudes (Meteorological Observatory Hohenpeißenberg, Haute-Provence Observatory, Tsukuba and Table Mountain Facility), tropics (Mauna Loa Observatory) and southern mid-latitudes (Lauder), with ozonesondes and space-borne sensors (SBUV(/2), SAGE II, HALOE, UARS MLS and Aura MLS), extracted around the stations. Relative differences are calculated to find biases and temporal drifts in the measurements. All measurement techniques show their best agreement with respect to the lidar at 20–40 km, where the differences and drifts are generally within ±5% and ±0.5% yr<sup>−1</sup>, respectively, at most stations. In addition, the stability of the long-term ozone observations (lidar, SBUV(/2), SAGE II and HALOE) is evaluated by the cross-comparison of each data set. In general, all lidars and SBUV(/2) exhibit near-zero drifts and the comparison between SAGE II and HALOE shows larger, but insignificant drifts. The RMS of the drifts of lidar and SBUV(/2) is 0.22 and 0.27% yr<sup>−1</sup>, respectively at 20–40 km. The average drifts of the long-term data sets, derived from various comparisons, are less than ±0.3% yr<sup>−1</sup> in the 20–40 km altitude at all stations. A combined time series of the relative differences between SAGE II, HALOE and Aura MLS with respect to lidar data at six sites is constructed, to obtain long-term data sets lasting up to 27 years. The relative drifts derived from these combined data are very small, within ±0.2% yr<sup>−1</sup>
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