Abstract
The stratospheric 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 at 100–150 hPa during 1998–2018 exhibits a decreasing trend of − 0.12 ± 0.07 ppmv decade–1 from MERRA2, suggesting a continued depletion during this century. About 30% of this ozone depletion is contributed by the second leading mode of sea surface temperature anomalies (SSTAs) over the North Pacific with one month leading and therefore is 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 wavenumber-1 waves into the lower stratosphere. The changes in the stratospheric wave activity may result in decreased ozone in the Arctic lower stratosphere through weakening the Brewer-Dobson circulation. Our findings uniquely linked the recent ozone depletion in the Arctic stratosphere to the North Pacific SSTs and might provide new understanding of how dynamical processes control Arctic stratospheric ozone.
Highlights
Stratospheric ozone, which comprises about 90% of the total amounts present in the Earth’s atmosphere, is a radiatively and chemically active gas that shields the Earth from harmful solar ultraviolet radiation (WMO, 2018)
Our results show that the ozone has declined during this period, which can be ascribed to the second leading mode of the North Pacific sea surface temperature anomalies (SSTAs) or Victoria mode, the lowfrequency variability in the North Pacific that cannot be explained by the Pacific decadal oscillation alone (Bond et al, 2003; Ding et al, 2015)
From MERRA2 and –0.09±0.07 ppmv decade–1 from TOMCAT after 1998, in the Further analysis suggested that the SSTAs over the North Pacific associated with the second leading mode in February appear to have large impacts on ozone in the Arctic lower stratosphere in March
Summary
Stratospheric ozone, which comprises about 90% of the total amounts present in the Earth’s atmosphere, is a radiatively and chemically active gas that shields the Earth from harmful solar ultraviolet radiation (WMO, 2018). Given the declining ODS concentrations, extensive research, vigorous debate and a number of papers tried to refine the results and propose potential mechanisms after the continuing decline of the ozone in the lower stratosphere in the 21st century was first reported by Ball et al (2018). While these studies focused on tropical and midlatitudinal ozone trends. The recent ozone depletion in the Arctic lower stratosphere and its links to the North Pacific SSTs suggest that some potential dynamical processes play a key role in the Arctic ozone variations, the ODSs controlled by the Montreal Protocol and the associated chemical processes
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