Abstract

Polar stratospheric clouds (PSCs) play a significant role in ozone depletion in the polar regions, acting as “surfaces” for heterogeneous reactions proceeding with the release of photochemically active molecular chlorine from late winter to early spring. Moreover, during the winter, chlorine “reservoirs,” which are reagents for heterogeneous reactions, accumulate on PSC particles. When PSC particles are destroyed in midwinter, the accumulation of chlorine compounds is interrupted, and from late winter to spring, ozone depletion is not observed even under conditions of the strong polar vortex, in the presence of newly formed PSCs. Using the vortex delineation method, we studied the dynamics of the Arctic polar vortex in the winters of 1984–1985, 1998–1999, 2001–2002, 2012–2013, and 2018–2019 as the reasons for the abnormally long absence of PSCs in the Arctic in midwinter, when they existed in January within no more than 5 days according to satellite observations. The PSC melting in these years was observed when the dynamic barrier of the polar vortex weakened due to a local decrease in wind speed along the vortex edge below 20 m/s in the lower stratosphere, which was recorded throughout almost all of January. These cases are the only examples of unusual weakening of the Arctic polar vortex in midwinter for the period from 1979 to 2022.

中文翻译：

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根据卫星观测，北极地区仲冬极地平流层云异常长时间消失

摘要

极地平流层云（PSC）在极地臭氧消耗中发挥着重要作用，作为非均质反应的“表面”，从冬末到早春释放光化学活性分子氯。此外，在冬季，作为非均相反应试剂的氯“储存库”会积聚在 PSC 颗粒上。当PSC颗粒在仲冬被破坏时，氯化合物的积累被中断，从冬末到春季，即使在强极涡条件下，在新形成的PSC存在的情况下也不会观察到臭氧消耗。利用涡圈描绘方法，研究了1984-1985年、1998-1999年、2001-2002年、2012-2013年和2018-2019年冬季北极极地涡旋的动态，作为导致北极地区PSC异常长期缺失的原因。根据卫星观测，北极在仲冬时节，它们在一月份的存在时间不超过 5 天。这些年的PSC融化是在平流层低层涡旋边缘风速局部降低到低于20 m/s的情况下，极涡动态屏障减弱时观察到的，几乎整个一月份都有记录。这些案例是 1979 年至 2022 年期间仲冬北极极地涡旋异常减弱的唯一例子。