资源环境科技发展态势分析平台

As ozone depleting substances decline, stratospheric ozone is displaying signs of healing in the Antarctic lower stratosphere. Here we focus on higher altitudes and the global stratosphere. Two key processes that can influence ozone recovery are evaluated: dynamical variability and solar proton events (SPEs). A nine-member ensemble of free-running simulations indicates that dynamical variability dominates the relatively small ozone recovery signal over 1998-2016 in the subpolar lower stratosphere, particularly near the tropical tropopause. The absence of observed recovery there to date is therefore not unexpected. For the upper stratosphere, high latitudes (50-80 degrees N/S) during autumn and winter show the largest recovery. Large halogen-induced odd oxygen loss there provides a fingerprint of seasonal sensitivity to chlorine trends. However, we show that SPEs also have a profound effect on ozone trends within this region since 2000. Thus, accounting for SPEs is important for detection of recovery in the upper stratosphere.

Plain Language Summary With the continuing decline in ozone depleting substances, upper-atmospheric ozone is displaying signs of healing in the Antarctic region. Using a state-of-the-art model that simulates the Earth system, the nature of future ozone recovery outside of the Antarctic region is investigated to identify potential fingerprints for observing future ozone recovery. The model results show that ozone recovery near 40km is expected to be largest near the poles in both hemispheres during winter and spring, while there is still large variability in the tropical region. However, energetic protons from solar events also have an effect on ozone in these regions through well-known chemical mechanisms. Therefore, taking these effects into account will be important for detecting this ozone recovery in observations.