Tracer transport during the Arctic stratospheric final warming based on a 33‐year (1979‐2011) tracer equivalent latitude simulation

Allen, Douglas R.; Douglass, Anne R.; Nedoluha, Gerald E.; Coy, L.

doi:10.1029/2012gl051930

Cited by 8 publications

(25 citation statements)

References 31 publications

(31 reference statements)

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“…We thus were able to detect 9 FrIACs events : in 1966, 1982, 1994, 1997, 2002, 2003, 2005, 2007, and 2011. [47] We also studied the latitudinal origin of the air masses captured in the FrIACs. The results show that the 2011 event was not only the largest in spatial extent but also contained the largest amount of tropical air (meaning air originating equatorwards of 30 N), again in agreement with the results of Allen et al [2012]. Conversely, the 1966 and 2002 events have been the weakest, predominantly capturing midlatitude air masses.…”

Section: Resultssupporting

confidence: 79%

“…[39] These FrIAC occurrences are largely consistent with those of Allen et al [2012]. Exceptions are in 2000 and 2004, when they found weak TrEL reductions at high latitudes.…”

Section: Discussionsupporting

confidence: 70%

“…By examining L GPH-PV for both years, we also found that no bowl-shaped structure developed so that we do not classify these events as FrIACs. Furthermore, the 2007 event led to a very weak TrEL reduction at the pole in Allen et al [2012], yet we do classify it clearly as a FrIAC, albeit of small spatial extent (Figure 7h or Thiéblemont et al, 2011). These small discrepancies between the two studies are mostly due to the criteria used to define what a FrIAC is.…”

Section: Discussionmentioning

confidence: 66%

“…The latitude Φ circle circumscribing the polar region is here chosen as 60 N. The tracer that we use is the MIMOSA-advected PV (hence is not the true dynamical PV), and it does not allow following a FrIAC until summer because of the applied diabatic relaxation. Due to these processes, we lose the PV signature of a FrIAC more quickly than if using a long-lived chemical tracer [Manney et al, 2006;Allen et al, 2011] or a TrEL [Allen and Nakamura, 2003;Allen et al, 2012]. Nevertheless, it allows following intrusions and their potential development into FrIACs, as shown for the 2007 case by Thiéblemont et al [2011] and for the 2011 case in section 3.…”

Section: Detection Of Low-latitude Air Masses In the Polar Regionmentioning

confidence: 99%

“…Thiéblemont et al [2011] also used the PV contour advection model MIMOSA (Modélisation Isentrope du transport Méso-échelle de l'Ozone Stratosphéri-que par Advection) over the last decade (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009) to show that FrIACs are favored if (i) no deep sudden stratospheric warming occurs during winter and if (ii) the Quasi-Biennal Oscillation (QBO) is in easterly phase. Recently, Allen et al [2012] performed a climatology of tracer transport during SFW using the tracer equivalent latitude (hereinafter TrEL) diagnostic over a 33-year period (1979-2011). By examining the decrease of TrEL averaged northward of 80 N from 10 May to 20 June, they found evidences of FrIACs in 1982FrIACs in , 1994FrIACs in , 1997FrIACs in , 2000FrIACs in , 2002FrIACs in , 2003FrIACs in , 2004FrIACs in , 2005FrIACs in , and 2011.…”

Section: Introductionmentioning

confidence: 99%

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A climatology of frozen‐in anticyclones in the spring arctic stratosphere over the period 1960–2011

et al. 2013

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During springtime, following the stratospheric final warming, intrusions from low latitudes can become trapped at polar latitudes in long‐lived anticyclones. Such “frozen‐in” anticyclones (FrIACs) have occasionally been observed to persist as late as August, advected by summer easterlies.In this study, the high‐resolution advection contour model MIMOSA is used to advect a pseudo‐potential vorticity tracer. The model is driven by ERA‐40 and the ERA‐Interim reanalyses over the period 1960–2011. We first identify a remarkable FrIAC event in spring 2011. In addition, we developed a method to detect the characteristic size of low‐latitude intrusions into the polar region at the time of the spring transition, over the period 1960–2011. Years are classified as either Type‐A when the intrusions are small or as Type‐B when intrusions are large, potentially evolving into FrIACs. For a FrIAC to occur, we require an additional criterion based on the in‐phase character of the core of the intrusions and the anticyclone.During the 52 analyzed years, 9 events have been identified: 1 in the 1960s, 1 in the 1980s, 2 in the 1990s, and 5 from 2002. FrIAC are predominantly long‐lived intrusions, which occur in association with abrupt and early reversal to summer easterlies with a large heat flux pulse around the date of this wind reversal. Finally, the results are discussed in a climatological context.

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Section: Resultssupporting

confidence: 79%

“…[39] These FrIAC occurrences are largely consistent with those of Allen et al [2012]. Exceptions are in 2000 and 2004, when they found weak TrEL reductions at high latitudes.…”

Section: Discussionsupporting

confidence: 70%

Section: Discussionmentioning

confidence: 66%

Section: Detection Of Low-latitude Air Masses In the Polar Regionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A climatology of frozen‐in anticyclones in the spring arctic stratosphere over the period 1960–2011

et al. 2013

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Poleward transport variability in the Northern Hemisphere during final stratospheric warmings simulated by CESM(WACCM)

et al. 2016

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Observational studies of Arctic stratospheric final warmings have shown that tropical/subtropical air masses can be advected to high latitudes and remain confined within a long‐lived “frozen‐in” anticyclone (FrIAC) for several months. It was suggested that the frequency of FrIACs may have increased since 2000 and that their interannual variability may be modulated by (i) the occurrence of major stratospheric warmings (mSSWs) in the preceding winter and (ii) the phase of the quasi‐biennial oscillation (QBO). In this study, we tested these observational‐based hypotheses for the first time using a chemistry climate model. Three 145 year sensitivity experiments were performed with the National Center of Atmospheric Research's Community Earth System Model (CESM): one control experiment including only natural variability, one with an extreme greenhouse gas emission scenario, and one without the QBO in the tropical stratosphere. In comparison with reanalysis, the model simulates a realistic frequency and characteristics of FrIACs, which occur under an abrupt and early winter‐to‐summer stratospheric circulation transition, driven by enhanced planetary wave activity. Furthermore, the model results support the suggestion that the development of FrIACs is favored by an easterly QBO in the middle stratosphere and by the absence of mSSWs during the preceding winter. The lower stratospheric persistence of background dynamical state anomalies induced by deep mSSWs leads to less favorable conditions for planetary waves to enter the high‐latitude stratosphere in April, which in turn decreases the probability of FrIAC development. Our model results do not suggest that climate change conditions (RCP8.5 scenario) influence FrIAC occurrences.

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The large‐scale frozen‐in anticyclone in the 2011 Arctic summer stratosphere

2013

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The 2011 Arctic stratospheric final warming was characterized by a large‐scale frozen‐in anticyclone (FrIAC) that rapidly displaced the winter polar vortex, establishing unusually strong polar easterlies. A comprehensive overview of the 2011 FrIAC is provided using meteorological analyses, Microwave Limb Sounder (MLS) N2O observations, and N2O simulations from the Global Modeling Initiative (GMI) 3‐D chemistry and transport model and the Van Leer Icosahedral Triangular Advection (VITA) 2‐D (latitude × longitude) isentropic transport model. A vortex edge diagnostic is used to determine the FrIAC boundary, allowing quantification of several FrIAC properties. The 2011 FrIAC originated over North Africa in late March and traveled eastward and poleward over 2 weeks, forming a strong anticyclone that extended from ~580–2100 K potential temperature (~25–50 km). Low potential vorticity (PV) was transported to the pole with the FrIAC in early April; during May, most of the PV signature decayed due to diabatic processes. A small remnant negative PV anomaly persisted near the pole until mid‐June. Tracer equivalent latitude was low initially and remained low throughout the summer. GMI, VITA, and MLS showed elevated N2O in the FrIAC, although the peak value was smaller in GMI due to a subtropical low bias. The high‐resolution (~20 km) VITA filamentary structure quantitatively matched most of the features observed by MLS when smoothed to match the MLS resolution. The high‐N2O anomaly persisted in the middle stratosphere over 4 months until late August, when it was destroyed by horizontal and vertical shearing, combined with photochemical processes.

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Tracer transport during the Arctic stratospheric final warming based on a 33‐year (1979‐2011) tracer equivalent latitude simulation

Cited by 8 publications

References 31 publications

A climatology of frozen‐in anticyclones in the spring arctic stratosphere over the period 1960–2011

A climatology of frozen‐in anticyclones in the spring arctic stratosphere over the period 1960–2011

Poleward transport variability in the Northern Hemisphere during final stratospheric warmings simulated by CESM(WACCM)

The large‐scale frozen‐in anticyclone in the 2011 Arctic summer stratosphere

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