Two recent occurrences in February 2018 and January 2019 of a dynamic split in the Northern Hemisphere stratospheric polar vortex are compared in terms of their evolution and predictability. The 2018 split vortex was associated with primarily wavenumber‐2 wave forcing that was not well predicted more than 7–10 days ahead of time, and was followed by persistent coupling to the surface with strong weather impacts. In 2019 the vortex was first displaced by slow wavenumber‐1 amplification into the stratosphere, which was predictable at longer lead times and then split; the surface impacts following the event were weaker. Here we examine the role of large‐scale climate influences, such as the phase of the El Niño–Southern Oscillation, the Quasi‐biennial Oscillation and the Madden–Julian Oscillation, on the wave forcing, surface impacts and predictability of these two events. Linkages between the forecast error in the stratospheric polar vortex winds with the forecast error in the Quasi‐biennial Oscillation and Madden–Julian Oscillation are examined.

中文翻译：

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2018年和2019年平流层极涡旋裂事件之间的差异

比较了2018年2月和2019年1月在北半球平流层极涡中发生的两次动态分裂的演变和可预测性。2018年的分裂涡主要与2号海浪强迫有关，在7到10天之前还没有得到很好的预测，其后是与地面的持续耦合，受到强烈的天气影响。在2019年，涡流首先被慢波1放大到平流层，这可以预料到更长的交付时间然后分裂; 事件后的表面影响较弱。在这里，我们考察了大规模气候影响的作用，例如厄尔尼诺-南方涛动的阶段，准两年期涛动和马登-朱利安涛动在波浪强迫上的作用，这两个事件的表面影响和可预测性。研究了平流层极地涡旋风的预报误差与准双年度涛动和马登-朱利安涛动的预报误差之间的联系。