2020년 봄에 발생한 북반구 오존 감소의 역학적 메커니즘 및 배경 조건 분석

Abstract

The Arctic ozone depletion in 2020 spring drew significant scientific attention due to its rare occurrence in the Northern Hemisphere. Although relatively small in amplitude compared to the Antarctic ozone hole, the 2020 Arctic ozone depletion is the most extensive and markedly prolonged event in the Northern Hemisphere. This study investigates the 2020 Arctic ozone depletion within the context of the background conditions in the stratosphere by comparing it to the 2019 conditions when the stratospheric ozone concentration was high. In early spring 2020, the enhanced meridional temperature gradient strengthened the polar vortex and maintained a cold Arctic condition in the stratosphere, which is markedly different from the 2019 spring and climatological conditions. These background fields create favorable conditions for forming polar stratospheric clouds, which could efficiently cause chemical ozone destruction. Wave activity analysis reveals that the vertical Rossby wave propagation from the high-latitude troposphere and associated stratospheric drag were noticeably weaker than normal in the preceding winter. This contributed to the strong polar jet and weaker Brewer-Dobson circulation in the stratosphere. The strong positive Arctic Oscillation in early 2020 indicates a weaker Rossby wave drag in the high-latitude regions, and 3D stationary wave activity flux (Plum flux) manifests a clear decrease in vertical wave activity over the high-latitude Atlantic. However, its physical causes remain unclear.