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

Manney, G. L.; Livesey, N. J.; Santee, M. L.; Froidevaux, L.; Lambert, A.; Lawrence, Zachary D.; Millán, Luis; Neu, J. L.; Read, W. G.; Schwartz, M.; Fuller, R. A.

doi:10.1029/2020gl089063

Cited by 126 publications

(186 citation statements)

References 32 publications

(71 reference statements)

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“…Stratospheric ozone values over large parts of the Arctic reached record low values in March and April 2020 (Manney et al, 2020) with ozone severely depleted between mid-March and mid-April 2020 when ozonesondes observed minimum mixing ratios of 0.1-0.2 ppm around 17-19 km (Wohltmann et al, 2020), lower than observed in any previous year. Model simulations and evaluation against MLS data by Groß and Müller (2020) also confirmed these findings.…”

Section: Introductionmentioning

confidence: 75%

“…Lawrence et al (2020) showed that the record breaking strong polar vortex in winter/spring 2020 developed as a combination of weak wave driving from the troposphere and a wave-reflecting configuration in the upper stratosphere. The 2020 Arctic polar vortex was cold enough to allow PSCs to form (Manney et al, 2020), leading to large stratospheric ozone losses.…”

Section: Introductionmentioning

confidence: 99%

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Exceptionally Low Arctic Stratospheric Ozone in Spring 2020 as Seen in the CAMS Reanalysis

et al. 2020

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A reanalysis data set produced by the Copernicus Atmosphere Monitoring service (CAMS reanalysis, 2003 to present day) augmented by ERA5 data for the years before 2003 is used to describe the evolution of the 2020 Arctic ozone season and to compare it with years back to 1979. Ozone columns over large parts of the Arctic reached record low values in March and April 2020 because of an exceptionally strong, cold, and persistent Arctic polar vortex. Minimum ozone columns were below 250 DU for most of March and the first half of April, with the lowest values of 211 DU in the CAMS reanalysis found on 18 March. Such low values are extremely unusual for the Arctic. The previous years with similarly strong Arctic ozone depletion were 2011 and 1997 with minimum values of 232 and 217 DU, respectively. The performance of the CAMS ozone analysis is assessed by comparison with ozonesonde data and found to agree well with the independent observations. We find a clear sign of chemical ozone destruction with ozone severely depleted in a layer between 80 and 50 hPa in late March and early April when partial pressure values below 2 mPa were observed. Profiles from the limb sounders Atmospheric Chemistry Experiment‐Fourier Transform Spectrometer (ACE‐FTS) and Microwave Limb Sounder (MLS) show clear signs of chlorine activation and the presence of polar stratospheric clouds. Monthly mean ozone columns in March 2020 were up to 180 DU or 40% lower than the CAMS climatology (2003–2019) while values for 2011 and 1997 were lower by 31% and 35%, respectively.

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Section: Introductionmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Exceptionally Low Arctic Stratospheric Ozone in Spring 2020 as Seen in the CAMS Reanalysis

et al. 2020

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“…However, the combination of the persistent polar processing conditions conducive for chemical loss and the persistently low column ozone values point to chemical depletion in 2019/2020 being a large factor. Further, Manney et al (2020) show evidence of chemical loss in vertically resolved ozone profiles matching or exceeding that in 2011.…”

Section: Polar Processing and Ozone Lossmentioning

confidence: 85%

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

et al. 2020

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The Northern Hemisphere (NH) polar winter stratosphere of 2019/2020 featured an exceptionally strong and cold stratospheric polar vortex. Wave activity from the troposphere during December-February was unusually low, which allowed the polar vortex to remain relatively undisturbed. Several transient wave pulses nonetheless served to help create a reflective configuration of the stratospheric circulation by disturbing the vortex in the upper stratosphere. Subsequently, multiple downward wave coupling events took place, which aided in dynamically cooling and strengthening the polar vortex. The persistent strength of the stratospheric polar vortex was accompanied by an unprecedentedly positive phase of the Arctic Oscillation in the troposphere during January-March, which was consistent with large portions of observed surface temperature and precipitation anomalies during the season. Similarly, conditions within the strong polar vortex were ripe for allowing substantial ozone loss: The undisturbed vortex was a strong transport barrier, and temperatures were low enough to form polar stratospheric clouds for over 4 months into late March. Total column ozone amounts in the NH polar cap decreased and were the lowest ever observed in the February-April period. The unique confluence of conditions and multiple broken records makes the 2019/2020 winter and early spring a particularly extreme example of two-way coupling between the troposphere and stratosphere. Plain Language Summary Wintertime westerly winds in the polar stratosphere (from ∼15-50 km), known as the stratospheric polar vortex, were extraordinarily strong during the Northern Hemisphere winter of 2019/2020. The exceptional strength of the stratospheric polar vortex had consequences for winter and early spring weather near the surface and for stratospheric ozone depletion. Typically atmospheric waves generated in the troposphere spread outward and upward into the stratosphere where they can disturb and weaken the polar vortex, but tropospheric wave activity was unusually weak during the 2019/2020 winter. In addition, an unusual configuration of the stratospheric polar vortex developed that reflected waves traveling upward from the troposphere back downward. These unique conditions allowed the vortex to remain strong and cold for several months. During January-March 2020, the strong stratospheric polar vortex was closely linked to a near-surface circulation pattern that resembles the positive phase of the so-called "Arctic Oscillation" (AO). This positive AO pattern was also of record strength and influenced the regional distributions of temperatures and precipitation during the late winter and early spring. Cold and stable conditions within the polar vortex also allowed strong ozone depletion to take place, leading to lower ozone levels than ever before seen above the Arctic in spring.

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“…A connection between Arctic ozone variability and extratropical surface is probably mediated by the dynamical variability that typically drives the anomalous ozone concentrations rather than the opposite (Harari et al, 2019). Manney et al (2020) recently reported on the chemical processes during the extreme ozone loss in March 2020; however, the predictability of the extreme ozone loss in March 2020 (andin March 1997 and and of the subsequent surface impact has still not been explored. This paper focuses on the general -hPa height (units: km, right column) in late winter (February-March, FM hereafter) from 1979 to 2020 in the ERA5 reanalysis.…”

Section: Introductionmentioning

confidence: 99%

Arctic Ozone Loss in March 2020 and its Seasonal Prediction in CFSv2: A Comparative Study With the 1997 and 2011 Cases

Rao

Garfinkel

2020

JGR Atmospheres

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Using reanalysis data, observations, and seasonal forecasts, the March Arctic ozone loss events in 1997, 2011, and 2020 and their predictability are compared. All of the three ozone loss events were accompanied by an extremely strong and cold polar vortex, with the shape and centroid of the ozone loss controlled by the polar vortex. The high autocorrelation of the March Arctic ozone at a lead/lag time of 1-2 months from observations might suggest that a reasonable prediction can be obtained if one initializes 1-2 months in advance. Based on the chemical scheme assessment in CFSv2 and several empirical models using the forecasted metric(s) of the stratospheric polar vortex as predictor(s), the predictability of the 2011 ozone loss event is shown to be longer (1-2 months) than the other two (~1 month), possibly due to a moderate La Niña and quasi-biennial oscillation westerly winds favorable for the formation of a strong polar vortex. However, the overall predictive skills of ozone from empirical models (using a forecasted substitute index to forecast the Arctic ozone) during 1982-2020 are lower than the chemical module assessment in the forecast system, though empirical models have some skill. Contrary to the ozone predictions, the lower tropospheric temperature pattern in March 2011 is less reasonable than in 1997 and 2020. Similar conclusions are also true in other years (2005 versus 2016). Those findings might indicate a weak relationship between the Arctic ozone and the surface climate in the Northern Hemisphere. Plain Language Summary Extremely low ozone concentrations (or an "ozone hole") develop in the Antarctic every austral spring in present-day atmospheric burdens of ozone-depleting substances. However, similar ozone losses are not observed in the Arctic, though in 1997, 2011, and 2020, ozone loss locally approached that in the Antarctic. This study focuses on the meteorological conditions and predictability for those Arctic ozone loss events. All of the three historical ozone loss events were related to a stratospheric circulation system encircling North Pole (i.e., the stratospheric polar vortex). The shape and centroid of the ozone losses were also controlled by the polar vortex: the ozone loss in March 2020 was displaced toward the North American sector, the March 2011 ozone loss was centered over the North Pole, while the 1997 ozone loss was displaced toward the Eurasian sector. Using the chemical scheme in a seasonal forecasting model and/or empirical models, the lead times for forecasting the three ozone loss events are different due to the tropical forcing. The moderate cold state in the tropical Pacific (i.e., La Niña) and westerly winds in the equatorial stratosphere (i.e., westerly QBO) propel the predictability of the 2011 ozone loss event to around 1-2 months, while the 1997 and 2020 March ozone losses can only be forecasted~1 month in advance. Nevertheless, a good prediction of the stratospheric ozone shows little impact on the surface predictability in the Northern Hemisphere.

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

Cited by 126 publications

References 32 publications

Exceptionally Low Arctic Stratospheric Ozone in Spring 2020 as Seen in the CAMS Reanalysis

Exceptionally Low Arctic Stratospheric Ozone in Spring 2020 as Seen in the CAMS Reanalysis

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

Arctic Ozone Loss in March 2020 and its Seasonal Prediction in CFSv2: A Comparative Study With the 1997 and 2011 Cases

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