Brief communication &amp;quot;Stratospheric winds, transport barriers and the 2011 Arctic ozone hole&amp;quot;

Olascoaga, M. J.; Brown, Michael G.; Beron-Vera, F. J.; Koçak, Hüseyin

doi:10.5194/npg-19-687-2012

Cited by 11 publications

(14 citation statements)

References 33 publications

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“…For example, Arnone et al (2012) analyzed the Arctic dynamics and chemistry during the 2010/2011 ozone loss using the limb sounding infrared measurements. Two major processes are responsible for the low ozone in early spring over the Arctic: heterogeneous chemical loss (Hommel et al, 2014; Solomon, 1999) and a quiescent stratosphere in winter (Olascoaga et al, 2012; Shaw & Perlwitz, 2014; Strahan et al, 2013). When the stratosphere is quiescent and the stratospheric westerly jet is strong, the poleward mass transport from the ozone‐rich tropics to the ozone‐poor polar regions is blocked with the anomalously strong jet serving as a barrier for the ozone transport (Strahan et al, 2013).…”

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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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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“…The spatial extent and strength of the vortex edge determine the severity, location and size of the ozone hole in the stratosphere [1,45,61,67], which is more prominent in the southern hemisphere. The chemical composition of the polar stratospheric air differs significantly from the mid-latitudinal air [39,36,40,58], and the dynamics of the polar vortex profoundly affect such composition [56,29,28]. The chemical isolation and low temperatures inside the polar vortex are necessary for the formation of Polar Stratospheric Clouds (PSCs), the main factor responsible for the rapid stratospheric ozone loss during spring.…”

Section: Introductionmentioning

confidence: 99%

“…Beron-Vera et al [7] identify zonal jets in the lower stratosphere as transport barriers using locally minimizing curves of FTLE fields. Several papers describe the connection between meridional transport barriers and stratospheric zonal jets [7,6,56,59,8] [35] compute the Finite Size Lyapunov Exponent (FSLE) field over 500 K isentropic data from the European Centre for Medium-Range Weather Forecasts (ECMWF) to identify transport barriers. Joseph and Legras [30] conclude that high values of FSLE do not correctly identify the vortex boundary, but rather delineate a highly mixing region outside the boundary called the 'stochastic layer'.…”

Section: Introductionmentioning

confidence: 99%

Uncovering the Edge of the Polar Vortex

Serra

Sathe

Beron-Vera

et al. 2017

Journal of the Atmospheric Sciences

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The polar vortices play a crucial role in the formation of the ozone hole and can cause severe weather anomalies. Their boundaries, known as the vortex 'edges', are typically identified via methods that are either frame-dependent or return non-material structures, and hence are unsuitable for assessing material transport barriers. Using two-dimensional velocity data on isentropic surfaces in the northern hemisphere, we show that elliptic Lagrangian Coherent Structures (LCSs) identify the correct outermost material surface dividing the coherent vortex core from the surrounding incoherent surf zone. Despite the purely kinematic construction of LCSs, we find a remarkable contrast in temperature and ozone concentration across the identified vortex boundary. We also show that potential vorticity-based methods, despite their simplicity, misidentify the correct extent of the vortex edge. Finally, exploiting the shrinkage of the vortex at various isentropic levels, we observe a trend in the magnitude of vertical motion inside the vortex which is consistent with previous results.

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“…Due to the Brewer‐Dobson circulation, air within the polar vortex tends to descend to lower altitudes. Changes in the strength of the barrier and the rate of descent within the vortex have profound impacts on the composition of air in the polar stratospheric regions [ Hood and Soukharev , ; Huck et al , ; Harvey et al , ; Randall et al , ; Olascoaga et al , ]. This is particularly evident during stratospheric sudden warmings (SSWs) [ Matsuno , ], during which the polar vortex is severely disrupted and large‐scale mixing between air inside and outside the vortex can occur.…”

Section: Introductionmentioning

confidence: 99%

A quantitative measure of polar vortex strength using the function M

Smith

McDonald

2014

JGR Atmospheres

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Changes in the dynamics of the stratospheric polar vortices can significantly affect the composition of air in the polar stratosphere, with the dynamics of the vortex barrier being particularly important. The "Function M" is a recently proposed measure for quantifying transport in dynamical systems. We show that it can be used not only to visualize the structure of the stratospheric polar region in detail but also to provide a basis for quantitative measures capturing important aspects of vortex dynamics. Two such measures have been calculated daily for August-October 2009 and 2010 in the Southern Hemisphere for potential temperatures of 600, 700, and 900 K, as well as for three different Northern Hemisphere winter periods for 900 K. We discuss a measure of vortex barrier strength and permeability based on the average value of the function M near the vortex edge. The second measure, associated with vortex barrier area, is obtained by calculating the area associated with values of M above a threshold. Both measures are found to be potentially useful, with the area-based measure providing the most convincing results. The measures are based on a Lagrangian framework and follow the vortex edge, allowing periods when the vortex retains its dynamical integrity to be identified even when the vortex is greatly distorted. We also discuss a strong linear correlation near the vortex edge between values of the function M calculated over different time periods, suggesting that the structure of the polar vortex is coherent over periods of at least 30 days.

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Brief communication "Stratospheric winds, transport barriers and the 2011 Arctic ozone hole"

Cited by 11 publications

References 33 publications

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

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

Uncovering the Edge of the Polar Vortex

A quantitative measure of polar vortex strength using the function M

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