Temperature variability in the upper polar stratosphere depending on the polar vortex strength

2020 ◽  
Author(s):  
Vladimir V. Zuev ◽  
Nina E. Zueva ◽  
Ekaterina S. Savelieva ◽  
Alexey V. Pavlinskiy
Keyword(s):  
Polar Vortex ◽  
Temperature Variability ◽  
Vortex Strength ◽  
Polar Stratosphere

The Life Cycle and Variability of Antarctic Weak Polar Vortex Events

2022 ◽  
pp. 1-63
Keyword(s):  
Life Cycle ◽  
Polar Vortex ◽  
Southern Annular Mode ◽  
Austral Spring ◽  
Stratospheric Polar Vortex ◽  
Temperature And Precipitation ◽  
Scale Temperature ◽  
Precipitation Anomalies ◽  
Polar Stratosphere ◽  
The Antarctic

Abstract Motivated by the strong Antarctic sudden stratospheric warming (SSW) in 2019, a survey on the similar Antarctic weak polar events (WPV) is presented, including their life cycle, dynamics, seasonality, and climatic impacts. The Antarctic WPVs have a frequency of about four events per decade, with the 2002 event being the only major SSW. They show a similar life cycle to the SSWs in the Northern Hemisphere but have a longer duration. They are primarily driven by enhanced upward-propagating wavenumber 1 in the presence of a preconditioned polar stratosphere, i.e., a weaker and more contracted Antarctic stratospheric polar vortex. Antarctic WPVs occur mainly in the austral spring. Their early occurrence is preceded by an easterly anomaly in the middle and upper equatorial stratosphere besides the preconditioned polar stratosphere. The Antarctic WPVs increase the ozone concentration in the polar region and are associated with an advanced seasonal transition of the stratospheric polar vortex by about one week. Their frequency doubles after 2000 and is closely related to the advanced Antarctic stratospheric final warming in recent decades. The WPV-resultant negative phase of the southern annular mode descends to the troposphere and persists for about three months, leading to persistent hemispheric scale temperature and precipitation anomalies.

scholarly journals Extending the Modular Earth Submodel System (MESSy v2.54) model hierarchy: the ECHAM/MESSy IdeaLized (EMIL) model setup

2020 ◽  
Vol 13 (11) ◽  
pp. 5229-5257
Author(s):  
Hella Garny ◽  
Roland Walz ◽  
Matthias Nützel ◽  
Thomas Birner
Keyword(s):  
Climate Model ◽  
Polar Vortex ◽  
Equilibrium Temperature ◽  
Earth System ◽  
Tracer Transport ◽  
Dynamical Core ◽  
Vortex Strength ◽  
Model Hierarchy ◽  
Model Setup ◽  
The Impact

Abstract. As models of the Earth system grow in complexity, a need emerges to connect them with simplified systems through model hierarchies in order to improve process understanding. The Modular Earth Submodel System (MESSy) was developed to incorporate chemical processes into an Earth System model. It provides an environment to allow for model configurations and setups of varying complexity, and as of now the hierarchy ranges from a chemical box model to a fully coupled chemistry–climate model. Here, we present a newly implemented dry dynamical core model setup within the MESSy framework, denoted as ECHAM/MESSy IdeaLized (EMIL) model setup. EMIL is developed with the aim to provide an easily accessible idealized model setup that is consistently integrated in the MESSy model hierarchy. The implementation in MESSy further enables the utilization of diagnostic chemical tracers. The setup is achieved by the implementation of a new submodel for relaxation of temperature and horizontal winds to given background values, which replaces all other “physics” submodels in the EMIL setup. The submodel incorporates options to set the needed parameters (e.g., equilibrium temperature, relaxation time and damping coefficient) to functions used frequently in the past. This study consists of three parts. In the first part, test simulations with the EMIL model setup are shown to reproduce benchmarks provided by earlier dry dynamical core studies. In the second part, the sensitivity of the coupled troposphere–stratosphere dynamics to various modifications of the setup is studied. We find a non-linear response of the polar vortex strength to the prescribed meridional temperature gradient in the extratropical stratosphere that is indicative of a regime transition. In agreement with earlier studies, we find that the tropospheric jet moves poleward in response to the increase in the polar vortex strength but at a rate that strongly depends on the specifics of the setup. When replacing the idealized topography to generate planetary waves by mid-tropospheric wave-like heating, the response of the tropospheric jet to changes in the polar vortex is strongly damped in the free troposphere. However, near the surface, the jet shifts poleward at a higher rate than in the topographically forced simulations. Those results indicate that the wave-like heating might have to be used with care when studying troposphere–stratosphere coupling. In the third part, examples for possible applications of the model system are presented. The first example involves simulations with simplified chemistry to study the impact of dynamical variability and idealized changes on tracer transport, and the second example involves simulations of idealized monsoon circulations forced by localized heating. The ability to incorporate passive and chemically active tracers in the EMIL setup demonstrates the potential for future studies of tracer transport in the idealized dynamical model.

scholarly journals The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength

2004 ◽  
Vol 4 (5) ◽  
pp. 6127-6148 ◽  
Author(s):  
K. Walter ◽  
H.-F. Graf
Keyword(s):  
North Atlantic ◽  
Storm Track ◽  
Polar Vortex ◽  
The State ◽  
Storm Tracks ◽  
The Arctic ◽  
Ample Evidence ◽  
Vortex Strength ◽  
The North ◽  
The North Atlantic

Abstract. There is ample evidence that the state of the northern polar stratospheric vortex in boreal winter influences tropospheric variability. Therefore, the main teleconnection patterns over the North Atlantic are defined separately for winter episodes in which the zonal mean wind at 50 hPa and 65° N is above or below the critical Rossby velocity for zonal planetary wave one. It turns out that the teleconnection structure in the middle and upper troposphere differs considerably between the two regimes of the polar vortex, while this is not the case at sea level. If the "polar vortex is strong", there exists "one" meridional dipole structure of geopotential height in the upper and middle troposphere, which is situated in the central North Atlantic. If the "polar vortex is weak", there exist "two" such dipoles, one over the western and one over the eastern North Atlantic. Storm tracks (and precipitation related with these) are determined by mid and upper tropospheric conditions and we find significant differences of these parameters between the stratospheric regimes. For the strong polar vortex regime, in case of a negative upper tropospheric "NAO" index we find a blocking height situation over the Northeast Atlantic and the strongest storm track of all. It is reaching far north into the Arctic Ocean and has a secondary maximum over the Denmark Strait. Such storm track is not found in composites based on a classic NAO defined by surface pressure differences between the Icelandic Low and the Azores High. Our results show that it is essential to include the state of the upper dynamic boundary conditions (the polar vortex strength) in any study of the variability over the North Atlantic. Climate forecast based solely on the forecast of a "classic NAO" and further statistical downscaling may lead to the wrong conclusions if the state of the polar vortex is not considered as well.

scholarly journals Unusually strong nitric oxide descent in the Arctic middle atmosphere in early 2013 as observed by Odin/SMR

2014 ◽  
Vol 14 (3) ◽  
pp. 3563-3581
Author(s):  
K. Pérot ◽  
J. Urban ◽  
D. P. Murtagh
Keyword(s):  
Nitric Oxide ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Polar Vortex ◽  
Meteorological Conditions ◽  
Atmospheric Composition ◽  
The Arctic ◽  
The Reformation ◽  
Polar Stratosphere ◽  
Energetic Particle Precipitation

Abstract. The middle atmosphere has been affected by an exceptionally strong midwinter stratospheric sudden warming (SSW) during the Arctic winter 2012/2013. These unusual meteorological conditions led to a breakdown of the polar vortex, followed by the reformation of a strong upper stratospheric vortex associated with particularly efficient descent of air. Measurements by the Sub-Millimetre Radiometer (SMR), on board the Odin satellite, show that very large amounts of nitric oxide (NO), produced by Energetic Particle Precipitation (EPP) in the mesosphere/lower thermosphere (MLT), could thus enter the polar stratosphere in early 2013. The mechanism referring to the downward transport of EPP generated-NOx during winter is generally called the EPP indirect effect. SMR observed up to 20 times more NO in the upper stratosphere than the average NO measured at the same latitude, pressure and time during three previous winters where no mixing between mesospheric and stratospheric air was noticeable. This event turned out to be an unprecedently strong case of this effect. Our study is based on a comparison with the Arctic winter 2008/2009, when a similar situation was observed and which was so far considered as a record-breaking winter for this kind of events. This outstanding situation is the result of the combination between a relatively high geomagnetic activity and an unusually high dynamical activity, which makes this case a prime example to study the EPP impacts on the atmospheric composition.

scholarly journals Simulation of the record Arctic stratospheric ozone depletion in 2020

2021 ◽  
Author(s):  
Jens-Uwe Grooß ◽  
Rolf Müller
Keyword(s):  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Potential Temperature ◽  
Polar Vortex ◽  
Lagrangian Model ◽  
Polar Regions ◽  
Ozone Monitoring Instrument ◽  
Polar Stratosphere ◽  
Year 2000

<p>In Arctic winter/spring 2019/2020, the stratospheric temperatures  were exceptionally low until early April and the polar vortex was  very stable.  As a consequence, significant chemical ozone depletion  occurred in Northern polar regions in spring 2020.  Here, we present  simulations by the Chemical Lagrangian Model of the Stratosphere  (CLaMS) that address the development of chlorine compounds and  ozone in the polar stratosphere in 2020.  The simulation reproduces  relevant observations of ozone and chlorine compounds, as shown by  comparisons with data from Microwave Limb Sounder (MLS), Atmospheric  Chemistry Experiment - Fourier Transform Spectrometer (ACE-FTS),  in-situ ozone sondes and the Ozone Monitoring Instrument (OMI).  Although the concentration of chlorine and bromine compounds in the  polar stratosphere has decreased by more than 10% compared to the  peak values around the year 2000, the meteorological conditions in  winter/spring 2019/2020 caused an unprecedented ozone depletion. The  simulated lowest ozone mixing ratio was around 0.05 ppmv and the  calculated partial ozone column depletion in the vortex core in the  lower stratosphere reached 141 Dobson Units between 350 and 600 K  potential temperature, which is more than the  loss in the years 2011 and 2016 which until 2020 had seen the  largest Arctic ozone depletion on record.</p>

scholarly journals Sub 500 nm refractory carbonaceous particles in the polar stratosphere

2017 ◽  
Author(s):  
Katharina Schütze ◽  
James C. Wilson ◽  
Stephan Weinbruch ◽  
Nathalie Benker ◽  
Martin Ebert ◽  
...  
Keyword(s):  
Standard Deviation ◽  
High Resolution ◽  
Polar Vortex ◽  
Dust Particles ◽  
Interplanetary Dust Particles ◽  
Particle Volume ◽  
Carbonaceous Particles ◽  
Minor Elements ◽  
Validation Experiment ◽  
Polar Stratosphere

Abstract. Eleven particle samples collected in the polar stratosphere during SOLVE (SAGE III Ozone loss and validation experiment) from January until March 2000 were characterized in detail by high-resolution transmission and scanning electron microscopy (TEM/SEM) combined with energy-dispersive X-ray microanalysis. A total number of 4175 particles (TEM = 3845; SEM = 330) was analyzed from these samples which were collected mostly inside the polar vortex in the altitude range between 17.3 and 19.9 km. By particle volume, all samples are dominated by volatile particles (ammonium sulfates/hydrogen sulfates). By number, approximately 28–82 % of the particles are refractory carbonaceous with sizes between 20–830 nm. Internal mixtures of refractory carbonaceous and volatile particles comprise up to 16 %, individual volatile particles about 9 to 72 %. Most of the refractory carbonaceous particles are completely amorphous, a few of the particles are partly ordered with a graphene sheet separation distance of 0.37 ± 0.06 nm (mean value ± standard deviation). Carbon and oxygen are the only detected major elements with an atomic O / C ratio of 0.11 ± 0.07. Minor elements observed include Si, S, Fe, Cr and Ni with the following atomic ratios relative to C: Si / C: 0.010 ± 0.011; S / C: 0.0007 ± 0.0015; Fe / C: 0.0052 ± 0.0074; Cr / C: 0.0012 ± 0.0017; Ni / C: 0.0006 ± 0.0011 (all mean values ± standard deviation). High resolution element distribution images reveal that the minor elements are distributed within the carbonaceous matrix, i.e., heterogeneous inclusions are not observed. No difference in size, nanostructure and elemental composition was found between particles collected inside and outside the polar vortex. Based on chemistry and nanostructure, aircraft exhaust, volcanic emissions and biomass burning can certainly be excluded as source. The same is true for the less probable, but globally important sources: wood burning, coal burning, diesel engines and ship emissions. Rocket exhaust and carbonaceous material from interplanetary dust particles remain as possible sources of the refractory carbonaceous particles studied. However, additional work is required in order to identify the sources unequivocally.

scholarly journals The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength

2005 ◽  
Vol 5 (1) ◽  
pp. 239-248 ◽  
Author(s):  
K. Walter ◽  
H.-F. Graf
Keyword(s):  
North Atlantic ◽  
Storm Track ◽  
Polar Vortex ◽  
The State ◽  
Storm Tracks ◽  
The Arctic ◽  
Boreal Winter ◽  
Vortex Strength ◽  
The North ◽  
The North Atlantic

Abstract. Motivated by the strong evidence that the state of the northern hemisphere vortex in boreal winter influences tropospheric variability, teleconnection patterns over the North Atlantic are defined separately for winter episodes where the zonal wind at 50hPa and 65° N is above or below the critical velocity for vertical propagation of zonal planetary wave 1. We argue that the teleconnection structure in the middle and upper troposphere differs considerably between the two regimes of the polar vortex, while this is not the case at sea level. If the polar vortex is strong, there exists one meridional dipole structure of geopotential height in the upper and middle troposphere, which is situated in the central North Atlantic. If the polar vortex is weak, there exist two such dipoles, one over the western and one over the eastern North Atlantic. Storm tracks (and precipitation related with these) are determined by mid and upper tropospheric conditions and we find significant differences of these parameters between the stratospheric regimes. For the strong polar vortex regime, in case of a negative upper tropospheric "NAO" index we find a blocking height situation over the Northeast Atlantic and the strongest storm track of all. It is reaching far north into the Arctic Ocean and has a secondary maximum over the Denmark Strait. Such storm track is not found in composites based on a classic NAO defined by surface pressure differences between the Icelandic Low and the Azores High. Our results suggest that it is important to include the state of the polar vortex strength in any study of the variability over the North Atlantic.

scholarly journals A quantitative measure of polar vortex strength using the functionM

2014 ◽  
Vol 119 (10) ◽  
pp. 5966-5985 ◽  
Author(s):  
Madeleine L. Smith ◽  
Adrian J. McDonald
Keyword(s):  
Polar Vortex ◽  
Quantitative Measure ◽  
Vortex Strength
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