Ozone trends derived from the total column and vertical profiles at a northern mid-latitude station

Abstract

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.

Detectability of the impacts of ozone-depleting substances and greenhouse gases upon stratospheric ozone accounting for nonlinearities in historical forcings

“…In fact, the influence of the solar cycle on ozone is difficult to discern in the lower stratosphere (see expanded axis). This is consistent with results from previous studies, which have shown that the solar cycle effect on ozone maximizes around 35 km and weakens in the lower stratosphere (Egorova et al, 2004;Lee and Smith, 2003;Newchurch et al, 2003). The QBOdriven anomalies in NAT-h (Fig.…”

“…The NAT-derived estimate of the change in upper- stratospheric ozone from solar maximum to solar minimum is approximately 2-4 %. This is in agreement with results from previous observational and model-based studies (Lee and Smith, 2003;Newchurch et al, 2003;Randel and Wu, 2007). NAT also shows longer-timescale variability in upperstratospheric ozone concentrations in response to solar insolation changes over multiple decades to centuries.…”

“…In the last millennium NAT simulation, ozone fluctuations result from both internal variability and solar forcing (lower panels). Previous work has shown that the solar cycle, El Niño-Southern Oscillation (ENSO), and the QBO are the main contributory factors to natural variability in stratospheric ozone, affecting ozone concentrations through chemistry and transport mechanisms (Kirgis et al, 2013;Nair et al, 2013). Below we show the different effects of these contributory factors in the upper and lower stratosphere.…”

“…The slopes of the piecewise trends are not constrained by physical and chemical considerations and are typically arbitrarily chosen to enhance the slopes for each of the eras. Another approach is to quantify changes over the entire record using regression to a nonlinear proxy, such as the halogen loading in the stratosphere, described by the equivalent effective stratospheric chlorine (EESC; see, e.g., Newchurch, 2003). Many studies have employed EESC-based regression to quantify trends in ozone (e.g.…”

Trends in stratospheric ozone profiles using functional mixed models

“…In order to improve the fit, it is important to study dynamical processes to find their effects on long-term changes in ozone distribution in middle latitudes and in the upper stratosphere. Several studies have addressed the significance of contributions of dynamical processes to long-term ozone changes (Appenzeller et al, 2000;Weiss et al, 2001;Wohltmann et al, 2007;Mäder et al, 2007;Rieder et al, 2010;Frossard et al, 2013;Rieder et al, 2013;Nair et al, 2013). Several papers (Harris et al, 2008;WMO, 2007) found that a significant part of the change in total ozone after the middle of the 1990s and until 2005 was caused by dynamical variability.…”