Abstract
Dynamical processes and changes in the ozone layer in the Arctic stratosphere during the winter of 2019–2020 were analyzed using numerical experiments with a chemistry-transport model (CTM) and reanalysis data. The results of numerical calculations using CTM with Dynamic parameters specified from the Modern Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) reanalysis data, carried out according to several scenarios of accounting for the chemical destruction of ozone, demonstrated that both Dynamic and chemical processes contribute significantly to ozone changes over the selected World Ozone and Ultraviolet Radiation Data Centre network stations, both in the Eastern and in the Western hemispheres. Based on numerical experiments with the CTM, the specific Dynamic conditions of winter–spring 2019–2020 described a decrease in ozone up to 100 Dobson Units (DU) in the Eastern Hemisphere and over 150 DU in the Western Hemisphere. In this case, the photochemical destruction of ozone in both the Western and Eastern Hemispheres at a maximum was about 50 DU with peaks in April in the Eastern Hemisphere and in March and April in the Western Hemisphere. Heterogeneous activation of halogen gases on the surface of polar stratospheric clouds, on the one hand, led to a sharp increase in the destruction of ozone in chlorine and bromine catalytic cycles, and, on the other hand, decreased its destruction in nitrogen catalytic cycles. Analysis of wave activity using 3D Plumb fluxes showed that the enhancement of upward wave activity propagation in the middle of March over the Gulf of Alaska was observed during the development stage of the minor sudden stratospheric warming (SSW) event that led to displacement of the stratospheric polar vortex to the north of Canada and decrease of polar stratospheric clouds’ volume.
Highlights
The circulation of the Arctic stratosphere in the winter-spring season is characterized by strong interannual and seasonal variability [1], which can affect the tropospheric circulation and weather conditions (e.g., [2,3,4,5,6]), and the temperature and chemical composition of the stratosphere, upper atmosphere (e.g., [7,8]), and ozone layer (e.g., [9,10])
We quantitatively evaluated the destruction of ozone in halogen catalytic cycles, which occurs as a result of heterogeneous processes on the surface of the Polar Stratospheric Clouds (PSCs), and a decrease in its destruction in nitrogen catalytic cycles as a result of a decrease in the content of nitrogen radicals
A comparison of the influence of Dynamic and photochemical factors on the variability of the Arctic stratospheric ozone in the spring of 2020 showed that, based on the analysis of the difference between the not include any chemical ozone destruction (noCHEM) scenario and SBUV climatology, it was concluded that the specific Dynamic conditions of winter–spring 2019–2020 described a decrease in ozone up to 100 Dobson Units (DU) in the Eastern Hemisphere and over 150 DU in the Western
Summary
The circulation of the Arctic stratosphere in the winter-spring season (hereinafter, winter season) is characterized by strong interannual and seasonal variability [1], which can affect the tropospheric circulation and weather conditions (e.g., [2,3,4,5,6]), and the temperature and chemical composition of the stratosphere, upper atmosphere (e.g., [7,8]), and ozone layer (e.g., [9,10]). Due to the strong wave activity and the frequent occurrence of SSW events, and, the unstable and warm stratospheric polar vortex, significant ozone anomalies are observed in the Arctic less often than in the Antarctic, where a major. Prior to the 2019–2020 winter season, the large ozone depletion was observed in the Arctic stratosphere in the spring of 1996 [12], 1997 [13], 2000 [14], 2005 [15], and the largest one in 2011 [16,17]. A possibly even greater ozone reduction in the Arctic stratosphere in the 2015–2016 winter season compared to 2010–2011 was prevented by a SSW event in March 2016 [18,19]. Analysis of the model simulation revealed that these anomalies were mainly due to Dynamic reasons [21]
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