Dynamical Mechanisms for the Recent Ozone Depletion in the Arctic Stratosphere Linked to the North Pacific Sea Surface Temperatures

The ozone layer, which prevents solar ultraviolet radiation from reaching the surface and thereby protects life on earth, is expected to recover from past depletion during this century due to the impact of the Montreal Protocol. However, how the ozone column over the Arctic will evolve over the next few decades is still under debate. In this study, we found that the ozone level in the Arctic stratosphere during the period of 1998–2018 exhibits a decreasing trend of –0.12±0.07 ppmv decade –1 from MERRA2, suggesting a continued depletion during this century. This ozone depletion is contributed by the second leading mode of North Pacific sea surface temperature anomalies (SSTAs) with one month leading and therefore dynamical in origin. The North Pacific SSTAs associated with this mode tend to result in a weakened Aleutian low, a strengthened Western Pacific pattern and a weakened Pacific–North American pattern, which impede the upward propagation of planetary wavenumber-1 waves into the lower stratosphere. The changes in the stratospheric wave activity tend to result in decreased ozone in the Arctic lower stratosphere through weakening the Brewer-Dobson circulation. Our findings will provide new understanding of how dynamical processes control Arctic stratospheric ozone and will help to improve prediction of how Arctic ozone will evolve in the future.