Articles | Volume 18, issue 9
Atmos. Chem. Phys., 18, 6567–6584, 2018

Special issue: Quadrennial Ozone Symposium 2016 – Status and trends...

Atmos. Chem. Phys., 18, 6567–6584, 2018

Research article 08 May 2018

Research article | 08 May 2018

Stratospheric ozone measurements at Arosa (Switzerland): history and scientific relevance

Johannes Staehelin1, Pierre Viatte2, Rene Stübi2, Fiona Tummon1, and Thomas Peter1 Johannes Staehelin et al.
  • 1Institute for Atmospheric and Climate Science, ETHZ, Zürich, Switzerland
  • 2Federal Office of Meteorology and Climatology MeteoSwiss, Payerne, Switzerland

Abstract. Climatic Observatory (LKO) in Arosa (Switzerland), marking the beginning of the world's longest series of total (or column) ozone measurements. They were driven by the recognition that atmospheric ozone is important for human health, as well as by scientific curiosity about what was, at the time, an ill characterised atmospheric trace gas. From around the mid-1950s to the beginning of the 1970s studies of high atmosphere circulation patterns that could improve weather forecasting was justification for studying stratospheric ozone. In the mid-1970s, a paradigm shift occurred when it became clear that the damaging effects of anthropogenic ozone-depleting substances (ODSs), such as long-lived chlorofluorocarbons, needed to be documented. This justified continuing the ground-based measurements of stratospheric ozone. Levels of ODSs peaked around the mid-1990s as a result of a global environmental policy to protect the ozone layer, implemented through the 1987 Montreal Protocol and its subsequent amendments and adjustments. Consequently, chemical destruction of stratospheric ozone started to slow around the mid-1990s. To some extent, this raises the question as to whether continued ozone observation is indeed necessary. In the last decade there has been a tendency to reduce the costs associated with making ozone measurements globally including at Arosa. However, the large natural variability in ozone on diurnal, seasonal, and interannual scales complicates the capacity for demonstrating the success of the Montreal Protocol. Chemistry-climate models also predict a super-recovery of the ozone layer at mid-latitudes in the second half of this century, i.e. an increase of ozone concentrations beyond pre-1970 levels, as a consequence of ongoing climate change. These factors, and identifying potentially unexpected stratospheric responses to climate change, support the continued need to document stratospheric ozone changes. This is particularly valuable at the Arosa site, due to the unique length of the observational record. This paper presents the evolution of the ozone layer, the history of international ozone research, and discusses the justification for the measurements in the past, present and into future.

Short summary
In 1926, total ozone series started in Arosa (Switzerland). Since the mid-1970s ozone is measured to document the effects of anthropogenic ozone-depleting substances (ODSs). ODSs peaked around the mid-1990s, resulting from the Montreal Protocol (1987) and its enforcement. Chemical ozone depletion stopped worsening around the mid-1990s but the large variability complicates demonstrations of the success of the protocol and the effect of ongoing climate change still requires continuous measurement.
Final-revised paper