Dynamic Processes in the Arctic Stratosphere in the Winter of 2018/2019
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mic Processes in the Arctic Stratosphere in the Winter of 2018/2019 P. N. Vargina*, A. N. Luk’yanova, and B. M. Kiryushova a
Central Aerological Observatory, ul. Pervomaiskaya 3, Dolgoprudny, Moscow oblast, 141700 Russia *e-mail: [email protected] Received October 1, 2019 Revised October 30, 2019 Accepted December 17, 2019
Abstract—The major dynamic processes in the Arctic stratosphere in the winter of 2018/2019 and their impact on the troposphere, mesosphere, and ozone layer are analyzed using the NCEP reanalysis and MLS satellite data. Based on the results of simulations with the TRACAO trajectory model, the comparative analysis of stratospheric polar vortex evolution in winters of 2015/2016 and 2018/2019 is performed. DOI: 10.3103/S1068373920060011 Keywords: Arctic stratosphere, sudden stratospheric warming, ozone layer, wave activity
1. INTRODUCTION The Arctic stratosphere dynamics in winter is characterized by high interannual and intraseasonal variability which affects the tropospheric circulation [10, 25], temperature and chemical composition of the upper atmosphere [36] and determines the pattern of the ozone layer depletion. Over the recent 20 years, the strong depletion of Arctic stratospheric ozone was observed in the spring of 1996, 1997, 2000, 2005, and 2016. The record depletion over the whole observation period was registered in 2011 [33], which led to the increased levels of UV radiation in many Northern Hemisphere regions [44], in particular, in Moscow in April [1]. The significant ozone anomalies in Arctic spring comparable to 2011 can increase surface UV radiation in summer by 20–40% [23] and can also influence surface temperature in April and May [12]. The record ozone depletion in the spring of 2011 and the significant ozone loss in the winter of 2015/2016 [24, 40] with ozone mini-holes in northern Russia [7, 42] occurred despite a decrease in the atmospheric concentration of ozone-depleting compounds, which has been revealed from satellite data in the recent years. So, the internal variability of the Arctic stratosphere dynamics plays an important role in the formation of conditions required for significant ozone depletion (see, for example, [8]). According to model simulations which take into account the decreasing concentration of ozone-depleting substances and an increase in the amount of greenhouse gases, significant ozone anomalies comparable to the spring of 2011 are possible in the Arctic till the middle of the 21st century [30]. The weakening of the stratospheric polar vortex during sudden stratospheric warming events (SSW) leads to the significant decrease in the speed of zonal wind and, in case of major SSW, to the change in its direction and to the temperature rise by 20–40 K per several days. As a result, the volume of polar stratospheric clouds (PSCs) decreases, that prevents significant ozone loss. At the same time, the propagation of circulation anomalies from the stratosphere to the troposphere associated with the weakening of the stratospheric polar vortex may lead to surface
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