scholarly journals On the Identification of the Downward Propagation of Arctic Stratospheric Climate Change over Recent Decades*

2014 ◽  
Vol 27 (8) ◽  
pp. 2789-2799 ◽  
Author(s):  
Diane J. Ivy ◽  
Susan Solomon ◽  
David W. J. Thompson
Keyword(s):  
Time Scales ◽  
Geopotential Height ◽  
Polar Vortex ◽  
Early Spring ◽  
The Arctic ◽  
Late Winter ◽  
Downward Propagation ◽  
Dynamical Coupling ◽  
Arctic Temperature ◽  
The Antarctic

Abstract Dynamical coupling between the stratospheric and tropospheric circumpolar circulations in the Arctic has been widely documented on month-to-month and interannual time scales, but not on longer time scales. In the Antarctic, both short- and long-term coupling extending from the stratosphere to the surface has been identified. In this study, changes in Arctic temperature, geopotential height, and ozone observed since the satellite era began in 1979 are examined, comparing dynamically quiescent years in which major sudden stratospheric warmings did not occur to all years. It is shown that this approach clarifies the behavior for years without major warmings and that dynamically quiescent years are marked by a strengthening of the Arctic polar vortex over the past 30 years. The associated declines in stratospheric temperatures, geopotential height, and ozone are qualitatively similar to those obtained in the Antarctic (albeit weaker), and propagate downward into the Arctic lowermost stratosphere during late winter and early spring. In sharp contrast to the Antarctic, the strengthening of the Arctic stratospheric vortex appears to originate at a higher altitude, and the propagation to the Arctic troposphere is both very limited and confined to the uppermost troposphere, even when only dynamically quiescent years are considered in the analysis.

scholarly journals Comparison of Inorganic Chlorine in the Southern Hemispheric lowermost stratosphere during Late Winter 2019

2021 ◽  
Author(s):  
Markus Jesswein ◽  
Heiko Bozem ◽  
Hans-Christoph Lachnitt ◽  
Peter Hoor ◽  
Thomas Wagenhäuser ◽  
...  
Keyword(s):  
Degradation Products ◽  
Polar Vortex ◽  
Boundary Region ◽  
Early Spring ◽  
Active Chlorine ◽  
The Arctic ◽  
Late Winter ◽  
Annual Variations ◽  
The Difference ◽  
The Antarctic

Abstract. Inorganic chlorine (Cly) is the sum of the degradation products of long-lived chlorinated source gases. These include the reservoir species (HCl and ClONO2) and active chlorine species (i.e. ClOx). The active chlorine species drive catalytic cycles that deplete ozone in the polar winter stratosphere. This work presents calculations of inorganic chlorine (Cly) derived from chlorinated source gas measurements on board the High Altitude and Long Range Research Aircraft (HALO) during the Southern hemisphere Transport, Dynamic and Chemistry (SouthTRAC) campaign in late winter and early spring 2019. Results are compared to Cly of the Northern Hemisphere derived from measurements of the POLSTRACC-GW-LCYCLE-SALSA (PGS) campaign in the Arctic winter of 2015/2016. A scaled correlation was used for PGS data, since not all source gases were measured. Cly from a scaled correlation was compared to directly determined Cly and agreed well. An air mass classification based on in situ N2O measurements allocates the measurements to the vortex, the vortex boundary region, and mid-latitudes. Although the Antarctic vortex was weakened in 2019 compared to previous years, Cly reached 1687 ± 20 ppt at 385 K, therefore up to around 50 % of total chlorine could be found in inorganic form inside the Antarctic vortex, whereas only 15 % of total chlorine could be found in inorganic form in the southern mid-latitudes. In contrast, only 40 % of total chlorine could be found in inorganic form in the Arctic vortex during PGS and roughly 20 % in the northern mid-latitudes. Differences inside the respective vortex reaches up to 565 ppt more Cly in the Antarctic vortex 2019 than in the Arctic vortex 2016 (at comparable distance to the local tropopause). As far as is known, this is the first comparison of inorganic chlorine within the respective polar vortex. Based on the results of these two campaigns, the difference of Cly inside the respective vortex is significant and larger than reported inter annual variations.

scholarly journals Analysis of Arctic Spring Ozone Anomaly in the Phases of QBO and 11-year Solar Cycle for 1979–2011

2021 ◽  
Author(s):  
Yousuke Yamashita ◽  
Hideharu Akiyoshi ◽  
Masaaki Takahashi
Keyword(s):  
Solar Cycle ◽  
Climate Model ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Early Spring ◽  
The Arctic ◽  
Negative Anomaly ◽  
Late Winter ◽  
Quasi Biennial Oscillation ◽  
Biennial Oscillation

Arctic ozone amount in winter to spring shows large year-to-year variation. This study investigates Arctic spring ozone in relation to the phase of quasi-biennial oscillation (QBO)/the 11-year solar cycle, using satellite observations, reanalysis data, and outputs of a chemistry climate model (CCM) during the period of 1979–2011. For this duration, we found that the composite mean of the Northern Hemisphere high-latitude total ozone in the QBO-westerly (QBO-W)/solar minimum (Smin) phase is slightly smaller than those averaged for the QBO-W/Smax and QBO-E/Smax years in March. An analysis of a passive ozone tracer in the CCM simulation indicates that this negative anomaly is primarily caused by transport. The negative anomaly is consistent with a weakening of the residual mean downward motion in the polar lower stratosphere. The contribution of chemical processes estimated using the column amount difference between ozone and the passive ozone tracer is between 10–20% of the total anomaly in March. The lower ozone levels in the Arctic spring during the QBO-W/Smin years are associated with a stronger Arctic polar vortex from late winter to early spring, which is linked to the reduced occurrence of sudden stratospheric warming in the winter during the QBO-W/Smin years.

Lagrangian analysis of the northern polar vortex split in April 2020 during development of the Arctic ozone hole

2021 ◽  
Author(s):  
Jezabel Curbelo ◽  
Gang Chen ◽  
Carlos R. Mechoso
Keyword(s):  
Wave Train ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Early Spring ◽  
Ozone Hole ◽  
The Arctic ◽  
Late Winter ◽  
Lagrangian Analysis ◽  
The North ◽  
Vortex Split

<div>The evolution of the Northern Hemisphere stratosphere during late winter and early spring of 2020 was punctuated by outstanding events both in dynamics and tracer evolution. It provides an ideal case for study of the Lagrangian properties of the evolving flow and its connections with the troposphere. The events ranged from an episode of polar warming at upper levels in March, a polar vortex split into two cyclonic vortices at middle and lower levels in April, and a remarkably deep and persistent mass of ozone poor air within the westerly circulation throughout the period. The latter feature was particularly remarkable during 2020, which showed the lowest values of stratospheric ozone on record.</div><div> </div><div>We focus on the vortex split in April 2020 and we examine this split at middle as well as lower stratospheric levels, and the interactions that occurred between the resulting two vortices which determined the distribution of ozone among them. We also examine the connections among stratospheric and tropospheric events during the period.</div><div> </div><div>Our approach for analysis will be based on the application of Lagrangian tools to the flow field, based on following air parcels trajectories, examining barriers to the flow, and the activity and propagation of planetary waves. Our findings confirm the key role for the split played by a flow configuration with a polar hyperbolic trajectory and associated manifolds. A trajectory analysis illustrates the transport of ozone between the vortices during the split. We argue that these stratospheric events were linked to strong synoptic scale disturbances in the troposphere forming a wave train from the north Pacific to North America and Eurasia.</div><div><strong> </strong></div><div><strong>Reference:</strong><strong> </strong>J. Curbelo, G. Chen,  C. R. Mechoso. Multi-level analysis of the northern polar vortex split in April 2020 during development of the Arctic ozone hole. Earth and Space Science Open Archive. doi: 10.1002/essoar.10505516.1</div><div> </div><div><strong>Acknowledgements:</strong> NSF Grant AGS-1832842, RYC2018-025169 and EIN2019-103087.</div>

Recent Extreme Arctic Temperatures are due to a Split Polar Vortex

2016 ◽  
Vol 29 (15) ◽  
pp. 5609-5616 ◽  
Author(s):  
James E. Overland ◽  
Muyin Wang
Keyword(s):  
Atmospheric Circulation ◽  
Geopotential Height ◽  
Polar Vortex ◽  
Circulation Pattern ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Arctic Amplification ◽  
The North ◽  
Central Eurasia ◽  
Arctic Temperature

Abstract There were extensive regions of Arctic temperature extremes in January and February 2016 that continued into April. For January, the Arctic-wide averaged temperature anomaly was 2.0°C above the previous record of 3.0°C based on four reanalysis products. Midlatitude atmospheric circulation played a major role in producing such extreme temperatures. Extensive low geopotential heights at 700 hPa extended over the southeastern United States, across the Atlantic, and well into the Arctic. Low geopotential heights along the Aleutian Islands and a ridge along northwestern North America contributed southerly wind flow. These two regions of low geopotential height were seen as a major split in the tropospheric polar vortex over the Arctic. Warm air advection north of central Eurasia reinforced the ridge that split the flow near the North Pole. Winter 2015 and 2016 geopotential height fields represented an eastward shift in the longwave atmospheric circulation pattern compared to earlier in the decade (2010–13). Certainly Arctic amplification will continue, and 2016 shows that there can be major Arctic contributions from midlatitudes. Whether Arctic amplification feedbacks are accelerated by the combination of recent thinner, more mobile Arctic sea ice and occasional extreme atmospheric circulation events from midlatitudes is an interesting conjecture.

scholarly journals Dynamical Elliptical Diagnostics of the Antarctic Polar Vortex

2019 ◽  
Vol 77 (3) ◽  
pp. 1167-1180
Author(s):  
M. Mester ◽  
J. G. Esler
Keyword(s):  
Data Assimilation ◽  
Polar Vortex ◽  
The Arctic ◽  
Late Winter ◽  
Phase Plane Analysis ◽  
Background Flow ◽  
Planetary Scale ◽  
Plane Analysis ◽  
Antarctic Polar Vortex ◽  
The Antarctic

Abstract Elliptical diagnostics provide dynamical and climatological information about the behavior of the Arctic and Antarctic stratospheric polar vortices. Here Kida’s model, describing the evolution of a uniform vortex in a linear, but possibly unsteady, background flow, is used to interpret the observed evolution of the Antarctic vortex in late winter during 1999–2018. Kida’s model has oscillatory solutions that can undergo an amplitude bifurcation, which serves as a simple model for the onset of vortex-splitting stratospheric sudden warmings (SSWs). A data assimilation method is used to find solutions of Kida’s equations consistent with the observations. A phase-plane analysis reveals large interannual variability in the amplitude of oscillations of the vortex. In 2002, the year of the only observed vortex-splitting Antarctic SSW, the system is found to cross a separatrix in phase space, associated with the SSW amplitude bifurcation, in late September. An output of the data assimilation is the linear background flow experienced by the vortex. The rotational component of this linear flow is consistent with the vortex being embedded in an anticyclonic background. The time-mean strain flow is weak but has a clear orientation, consistent with the presence of stationary forcing due to planetary-scale topography and land–sea contrast. The time-varying strain flow is comparatively large in magnitude, illustrating the relative importance of the planetary-scale component of the turbulent dynamics occurring at tropopause level. Unlike in the Northern Hemisphere, therefore, the direction of future Antarctic vortex splits will not necessarily align with the direction of the 2002 split.

scholarly journals Analysis of Arctic Spring Ozone Anomaly in the Phases of QBO and 11-Year Solar Cycle for 1979–2017

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 582
Author(s):  
Yousuke Yamashita ◽  
Hideharu Akiyoshi ◽  
Masaaki Takahashi
Keyword(s):  
Solar Cycle ◽  
Climate Model ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Early Spring ◽  
The Arctic ◽  
Negative Anomaly ◽  
Late Winter ◽  
Quasi Biennial Oscillation ◽  
Biennial Oscillation

Arctic ozone amount in winter to spring shows large year-to-year variation. This study investigates Arctic spring ozone in relation to the phase of quasi-biennial oscillation (QBO)/the 11-year solar cycle, using satellite observations, reanalysis data, and outputs of a chemistry climate model (CCM) during the period of 1979–2017. For this duration, we found that the composite mean of the Northern Hemisphere high-latitude total ozone in the QBO-westerly (QBO-W)/solar minimum (Smin) phase is slightly smaller than those averaged for the QBO-W/Smax and QBO-E/Smax years in March. An analysis of a passive ozone tracer in the CCM simulation indicates that this negative anomaly is primarily caused by transport. The negative anomaly is consistent with a weakening of the residual mean downward motion in the polar lower stratosphere. The contribution of chemical processes estimated using the column amount difference between ozone and the passive ozone tracer is between 10–20% of the total anomaly in March. The lower ozone levels in the Arctic spring during the QBO-W/Smin years are associated with a stronger Arctic polar vortex from late winter to early spring, which is linked to the reduced occurrence of sudden stratospheric warming in the winter during the QBO-W/Smin years.

scholarly journals Comparison of inorganic chlorine in the Antarctic and Arctic lowermost stratosphere by separate late winter aircraft measurements

2021 ◽  
Vol 21 (23) ◽  
pp. 17225-17241
Author(s):  
Markus Jesswein ◽  
Heiko Bozem ◽  
Hans-Christoph Lachnitt ◽  
Peter Hoor ◽  
Thomas Wagenhäuser ◽  
...  
Keyword(s):  
Boundary Region ◽  
Early Spring ◽  
Active Chlorine ◽  
The Arctic ◽  
Late Winter ◽  
Annual Variations ◽  
Research Aircraft ◽  
Gas Measurements ◽  
Catalytic Cycles ◽  
The Antarctic

Abstract. Stratospheric inorganic chlorine (Cly) is predominantly released from long-lived chlorinated source gases and, to a small extent, very short-lived chlorinated substances. Cly includes the reservoir species (HCl and ClONO2) and active chlorine species (i.e., ClOx). The active chlorine species drive catalytic cycles that deplete ozone in the polar winter stratosphere. This work presents calculations of inorganic chlorine (Cly) derived from chlorinated source gas measurements on board the High Altitude and Long Range Research Aircraft (HALO) during the Southern Hemisphere Transport, Dynamic and Chemistry (SouthTRAC) campaign in austral late winter and early spring 2019. Results are compared to Cly in the Northern Hemisphere derived from measurements of the POLSTRACC-GW-LCYCLE-SALSA (PGS) campaign in the Arctic winter of 2015/2016. A scaled correlation was used for PGS data, since not all source gases were measured. Using the SouthTRAC data, Cly from a scaled correlation was compared to directly determined Cly and agreed well. An air mass classification based on in situ N2O measurements allocates the measurements to the vortex, the vortex boundary region, and midlatitudes. Although the Antarctic vortex was weakened in 2019 compared to previous years, Cly reached 1687±19 ppt at 385 K; therefore, up to around 50 % of total chlorine was found in inorganic form inside the Antarctic vortex, whereas only 15 % of total chlorine was found in inorganic form in the southern midlatitudes. In contrast, only 40 % of total chlorine was found in inorganic form in the Arctic vortex during PGS, and roughly 20 % was found in inorganic form in the northern midlatitudes. Differences inside the two vortices reach as much as 540 ppt, with more Cly in the Antarctic vortex in 2019 than in the Arctic vortex in 2016 (at comparable distance to the local tropopause). To our knowledge, this is the first comparison of inorganic chlorine within the Antarctic and Arctic polar vortices. Based on the results of these two campaigns, the differences in Cly inside the two vortices are substantial and larger than the inter-annual variations previously reported for the Antarctic.

scholarly journals On the discrepancy of HCl processing in the core of the wintertime polar vortices

2018 ◽  
Vol 18 (12) ◽  
pp. 8647-8666 ◽  
Author(s):  
Jens-Uwe Grooß ◽  
Rolf Müller ◽  
Reinhold Spang ◽  
Ines Tritscher ◽  
Tobias Wegner ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Polar Vortex ◽  
Galactic Cosmic Rays ◽  
Lagrangian Model ◽  
The Arctic ◽  
Late Winter ◽  
Model Simulations ◽  
Ozone Loss ◽  
The Antarctic ◽  
Eulerian Models

Abstract. More than 3 decades after the discovery of the ozone hole, the processes involved in its formation are believed to be understood in great detail. Current state-of-the-art models can reproduce the observed chemical composition in the springtime polar stratosphere, especially regarding the quantification of halogen-catalysed ozone loss. However, we report here on a discrepancy between simulations and observations during the less-well-studied period of the onset of chlorine activation. During this period, which in the Antarctic is between May and July, model simulations significantly overestimate HCl, one of the key chemical species, inside the polar vortex during polar night. This HCl discrepancy is also observed in the Arctic. The discrepancy exists in different models to varying extents; here, we discuss three independent ones, the Chemical Lagrangian Model of the Stratosphere (CLaMS) as well as the Eulerian models SD-WACCM (the specified dynamics version of the Whole Atmosphere Community Climate Model) and TOMCAT/SLIMCAT. The HCl discrepancy points to some unknown process in the formulation of stratospheric chemistry that is currently not represented in the models. We characterise the HCl discrepancy in space and time for the Lagrangian chemistry–transport model CLaMS, in which HCl in the polar vortex core stays about constant from June to August in the Antarctic, while the observations indicate a continuous HCl decrease over this period. The somewhat smaller discrepancies in the Eulerian models SD-WACCM and TOMCAT/SLIMCAT are also presented. Numerical diffusion in the transport scheme of the Eulerian models is identified to be a likely cause for the inter-model differences. Although the missing process has not yet been identified, we investigate different hypotheses on the basis of the characteristics of the discrepancy. An underestimated HCl uptake into the polar stratospheric cloud (PSC) particles that consist mainly of H2O and HNO3 cannot explain it due to the temperature correlation of the discrepancy. Also, a direct photolysis of particulate HNO3 does not resolve the discrepancy since it would also cause changes in chlorine chemistry in late winter which are not observed. The ionisation caused by galactic cosmic rays provides an additional NOx and HOx source that can explain only about 20 % of the discrepancy. However, the model simulations show that a hypothetical decomposition of particulate HNO3 by some other process not dependent on the solar elevation, e.g. involving galactic cosmic rays, may be a possible mechanism to resolve the HCl discrepancy. Since the discrepancy reported here occurs during the beginning of the chlorine activation period, where the ozone loss rates are small, there is only a minor impact of about 2 % on the overall ozone column loss over the course of Antarctic winter and spring.

scholarly journals On the discrepancy of HCl processing in the dark polar vortices

2018 ◽  
Author(s):  
Jens-Uwe Grooß ◽  
Rolf Müller ◽  
Reinhold Spang ◽  
Ines Tritscher ◽  
Tobias Wegner ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Transport Model ◽  
Polar Vortex ◽  
Galactic Cosmic Rays ◽  
The Arctic ◽  
Late Winter ◽  
Chemistry Transport Model ◽  
Ozone Loss ◽  
The Antarctic ◽  
Eulerian Models

Abstract. More than three decades after the discovery of the ozone hole, the processes involved in its formation are believed to be understood in great detail. Current state-of-the-art models are able to reproduce the observed chemical composition in the springtime polar stratosphere, especially regarding the quantification of halogen-catalysed ozone loss. However, here we report on a discrepancy between simulations and observations during the less-well studied period of the onset of chlorine activation. During this period, which in the Antarctic is between May and July, model simulations significantly overestimate HCl, one of the key chemical species, inside the polar vortex during polar night. This HCl discrepancy is also observed in the Arctic and present, to varying extents, in three independent models, the Lagrangian chemistry transport model CLaMS as well as the Eulerian models WACCM and TOMCAT/SLIMCAT. The HCl discrepancy points to some unknown process in the formulation of stratospheric chemistry that is currently not represented in the models. Here we characterise the HCl discrepancy in space and time for the Lagrangian Chemistry Transport Model CLaMS, in which HCl in the polar vortex core stays about constant from June to August in the Antarctic while the observations indicate a continuous HCl decrease over this period. The somewhat smaller discrepancies in the models WACCM and TOMCAT/SLIMCAT are also presented. Numerical diffusion in the Eulerian models is identified to be a likely cause for the inter-model differences. Although the missing process has not yet been identified, we investigate different hypotheses on the basis of the characteristics of the discrepancy. An under-estimated uptake of HCl into the PSC particles that consist mainly of H2O and HNO3 cannot explain the discrepancy due to the temperature correlation of the discrepancy. Also, a direct photolysis of particulate HNO3 does not explain the discrepancy since it would also cause changes in late winter which are not observed. The ionisation caused by Galactic Cosmic Rays provides an additional NOx and HOx source that can explain only around 20 % of the discrepancy. A hypothetical decomposition of particulate HNO3 by some other process not dependent on the solar elevation, e.g. involving Galactic Cosmic Rays, may be a possible mechanism to resolve the HCl discrepancy. Since the discrepancy reported here occurs during the beginning of the chlorine activation period, where the ozone loss rates are slow, there is only a minor impact of about 2 % on the overall ozone column loss over the course of Antarctic winter and spring.

scholarly journals Chemical ozone loss and ozone mini-hole event during the Arctic winter 2010/2011 as observed by SCIAMACHY and GOME-2

2014 ◽  
Vol 14 (7) ◽  
pp. 3247-3276 ◽  
Author(s):  
R. Hommel ◽  
K.-U. Eichmann ◽  
J. Aschmann ◽  
K. Bramstedt ◽  
M. Weber ◽  
...  
Keyword(s):  
Transport Model ◽  
Polar Vortex ◽  
The Arctic ◽  
Optical Absorption Spectroscopy ◽  
Late Winter ◽  
Total Column Ozone ◽  
Bromine Oxide ◽  
Ozone Loss ◽  
Catalytic Cycles ◽  
Total Column

Abstract. Record breaking loss of ozone (O3) in the Arctic stratosphere has been reported in winter–spring 2010/2011. We examine in detail the composition and transformations occurring in the Arctic polar vortex using total column and vertical profile data products for O3, bromine oxide (BrO), nitrogen dioxide (NO2), chlorine dioxide (OClO), and polar stratospheric clouds (PSC) retrieved from measurements made by SCIAMACHY (Scanning Imaging Absorption SpectroMeter for Atmospheric CHartography) on-board Envisat (Environmental Satellite), as well as total column ozone amount, retrieved from the measurements of GOME-2 (Global Ozone Monitoring Experiment) on MetOp-A (Meteorological Experimental Satellite). Similarly we use the retrieved data from DOAS (Differential Optical Absorption Spectroscopy) measurements made in Ny-Ålesund (78.55° N, 11.55° E). A chemical transport model (CTM) has been used to relate and compare Arctic winter–spring conditions in 2011 with those in the previous year. In late winter–spring 2010/2011 the chemical ozone loss in the polar vortex derived from SCIAMACHY observations confirms findings reported elsewhere. More than 70% of O3 was depleted by halogen catalytic cycles between the 425 and 525 K isentropic surfaces, i.e. in the altitude range ~16–20 km. In contrast, during the same period in the previous winter 2009/2010, a typical warm Arctic winter, only slightly more than 20% depletion occurred below 20 km, while 40% of O3 was removed above the 575 K isentrope (~23 km). This loss above 575 K is explained by the catalytic destruction by NOx descending from the mesosphere. In both Arctic winters 2009/2010 and 2010/2011, calculated O3 losses from the CTM are in good agreement to our observations and other model studies. The mid-winter 2011 conditions, prior to the catalytic cycles being fully effective, are also investigated. Surprisingly, a significant loss of O3 around 60%, previously not discussed in detail, is observed in mid-January 2011 below 500 K (~19 km) and sustained for approximately 1 week. The low O3 region had an exceptionally large spatial extent. The situation was caused by two independently evolving tropopause elevations over the Asian continent. Induced adiabatic cooling of the stratosphere favoured the formation of PSC, increased the amount of active chlorine for a short time, and potentially contributed to higher polar ozone loss later in spring.

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