The Remarkably Strong Arctic Stratospheric Polar Vortex of Winter 2020: Links to Record-Breaking Arctic Oscillation and Ozone Loss

Lawrence, Zachary D.; Perlwitz, Judith; Butler, Amy H.; Manney, G. L.; Newman, Paul A.; Lee, Simon H.; Nash, Eric R.

doi:10.1002/essoar.10503356.1

Cited by 32 publications

(81 citation statements)

References 93 publications

(124 reference statements)

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“…These results are consistent with Lawrence et al. (2020), who found that low vertically propagating tropospheric wave activity was present during the winter.…”

Section: Linking Tropospheric and Stratospheric Forecastssupporting

confidence: 93%

“…The Northern Hemisphere (NH) winter of 2019–2020, particularly January–March (JFM) 2020, was characterized by a strong and persistent positive phase of the Arctic Oscillation (AO) (Hardiman et al., 2020; Lawrence et al., 2020)—the leading mode of extratropical tropospheric wintertime variability, analogous to the surface Northern Annular Mode (NAM) (e.g., Black & McDaniel, 2004; Thompson & Wallace, 1998, 2001) and closely related to the North Atlantic Oscillation (NAO) (Feldstein & Franzke, 2006). The magnitude and persistence of this pattern, associated with strengthened and poleward‐shifted extratropical storm tracks, led to unusually warm conditions across NH midlatitudes, as well as hydrometeorological extremes associated with the shifted storm tracks.…”

Section: Introductionmentioning

confidence: 99%

“…For example, while the United Kingdom experienced its wettest February since at least 1862, Spain experienced its driest February in at least 56 years (NOAA, 2020). Coupled to the strongly positive tropospheric NAM was an extremely strong stratospheric polar vortex (SPV) (Lawrence et al., 2020); significant disturbances to the SPV, so‐called sudden stratospheric warmings (SSWs) (e.g., Butler et al., 2015; Charlton & Polvani, 2007), were entirely absent during their climatological peak of January–March. The record‐cold temperatures within the undisturbed SPV led to unprecedented ozone loss over the Arctic during spring 2020 (Manney et al., 2020; Wohltmann et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

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Seasonal Forecasts of the Exceptional Northern Hemisphere Winter of 2020

Lee

Lawrence

Butler

et al. 2020

Geophysical Research Letters

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The winter of 2019-2020 was dominated by an extremely strong stratospheric polar vortex and positive tropospheric Arctic Oscillation (AO). Here, we analyze forecasts from six different prediction systems contributing to the C3S seasonal forecast database. Most performed very strongly, with consistently high skill for January-March 2020 from forecasts launched through October-December 2019. Although the magnitude of the anomalies was underestimated, the performance of most prediction systems was extremely high for a positive AO winter relative to the common hindcast climate. Ensemble members which better predicted the extremely strong stratospheric vortex better predicted the extreme tropospheric state. We find a significant relationship between forecasts of the anomalous midlatitude tropospheric wave pattern in early winter, which destructively interfered with the climatological stationary waves and the strength of the stratospheric vortex later in the winter. Our results demonstrate a strong interdependence between the accuracy of stratospheric vortex and AO forecasts. Plain Language Summary Westerly winds during the winter of 2019-2020 were unusually strong and long lasting through a deep layer of the atmosphere. We investigate how well this was predicted months ahead of time. We find that seasonal weather forecast systems predicted the winter pattern very well, especially when compared with previous winters. Forecasts which better predicted the strength of the winds higher in the atmosphere did better overall. We find that there was a link between predictions of the weather patterns lower down in the atmosphere and how they suppressed large-scale atmospheric waves in the midlatitudes, which likely helped the winds remain stronger higher up.

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“…These results are consistent with Lawrence et al. (2020), who found that low vertically propagating tropospheric wave activity was present during the winter.…”

Section: Linking Tropospheric and Stratospheric Forecastssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seasonal Forecasts of the Exceptional Northern Hemisphere Winter of 2020

Lee

Lawrence

Butler

et al. 2020

Geophysical Research Letters

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“…https://doi.org/ 10.1029/2020GL089063 (Johansson et al, 2019;Manney & Lawrence, 2016). In 2019/2020, lower stratospheric temperatures were persistently below the threshold for chemical processing earlier than in any other year observed by MLS and remained low approximately as late as in 2011 (Lawrence et al, 2020, describe stratospheric vortex meteorology in 2019/2020).…”

Section: Citationmentioning

confidence: 96%

Record‐Low Arctic Stratospheric Ozone in 2020: MLS Observations of Chemical Processes and Comparisons With Previous Extreme Winters

Manney

Livesey

Santee

et al. 2020

Geophysical Research Letters

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Aura Microwave Limb Sounder (MLS) measurements show that chemical processing was critical to the observed record‐low Arctic stratospheric ozone in spring 2020. The 16‐year MLS record indicates more polar denitrification and dehydration in 2019/2020 than in any Arctic winter except 2015/2016. Chlorine activation and ozone depletion began earlier than in any previously observed winter, with evidence of chemical ozone loss starting in November. Active chlorine then persisted as late into spring as it did in 2011. Empirical estimates suggest maximum chemical ozone losses near 2.8 ppmv by late March in both 2011 and 2020. However, peak chlorine activation, and thus peak ozone loss, occurred at lower altitudes in 2020 than in 2011, leading to the lowest Arctic ozone values ever observed at potential temperature levels from ∼400–480 K, with similar ozone values to those in 2011 at higher levels.

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“…Outside of the intervals impacted by these three events, the largest enhancements in the MLS 46.4 hPa CO record are associated with descent of high CO from the mesosphere into the winter polar vortices, with significant interannual variability in the strength and persistence of this descent. Indeed, enhancements exceeding 100 ppbv in Apr-May ( Figure 1a) are not related to the Jan-Feb ANY plume, but rather arise from descent of high CO air to 46.4 hPa in the unusually long-lived 2019-2020 Arctic vortex (Lawrence et al, 2020;Manney et al, 2020).…”

Section: Outliers Of Co and H 2 Omentioning

confidence: 99%