scholarly journals Stratospheric warming influence on the mesosphere/lower thermosphere as seen by the extended CMAM

2014 ◽  
Vol 32 (6) ◽  
pp. 589-608 ◽  
Author(s):  
M. G. Shepherd ◽  
S. R. Beagley ◽  
V. I. Fomichev
Keyword(s):  
Atmospheric Chemistry ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Lower Atmosphere ◽  
Fourier Transform Spectrometer ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
New Information ◽  
The Impact ◽  
Chemistry Experiment

Abstract. The response of the upper mesosphere/lower thermosphere region to major sudden stratospheric warming (SSW) is examined employing temperature, winds, NOX and CO constituents from the extended Canadian Middle Atmosphere Model (CMAM) with continuous incremental nudging below 10 hPa (~ 30 km). The model results considered cover high latitudes (60–85° N) from 10 to 150 km height for the December–March period of 2003/2004, 2005/2006 and 2008/2009, when some of the strongest SSWs in recent years were observed. NOX and CO are used as proxies for examining transport. Comparisons with ACE-FTS (Atmospheric Chemistry Experiment–Fourier Transform Spectrometer) satellite observations show that the model represents well the dynamics of the upper mesosphere/lower thermosphere region, the coupling of the stratosphere–mesosphere, and the NOX and CO transport. New information is obtained on the upper mesosphere/lower thermosphere up to 150 km showing that the NOX volume mixing ratio in the 2003/2004 winter was very perturbed indicating transport from the lower atmosphere and intense mixing with large NOX influx from the thermosphere compared to 2006 and 2009. These results, together with those from other models and observations, clearly show the impact of stratospheric warmings on the thermosphere.

scholarly journals Propagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming event

2020 ◽  
Vol 20 (12) ◽  
pp. 7617-7644
Author(s):  
In-Sun Song ◽  
Changsup Lee ◽  
Hye-Yeong Chun ◽  
Jeong-Han Kim ◽  
Geonhwa Jee ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Waves ◽  
Lower Thermosphere ◽  
Upper Atmosphere ◽  
Lower Atmosphere ◽  
Wave Number ◽  
Horizontal Wind ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Curvature Effects

Abstract. Effects of realistic propagation of gravity waves (GWs) on distribution of GW pseudomomentum fluxes are explored using a global ray-tracing model for the 2009 sudden stratospheric warming (SSW) event. Four-dimensional (4D; x–z and t) and two-dimensional (2D; z and t) results are compared for various parameterized pseudomomentum fluxes. In ray-tracing equations, refraction due to horizontal wind shear and curvature effects are found important and comparable to one another in magnitude. In the 4D, westward pseudomomentum fluxes are enhanced in the upper troposphere and northern stratosphere due to refraction and curvature effects around fluctuating jet flows. In the northern polar upper mesosphere and lower thermosphere, eastward pseudomomentum fluxes are increased in the 4D. GWs are found to propagate more to the upper atmosphere in the 4D, since horizontal propagation and change in wave numbers due to refraction and curvature effects can make it more possible that GWs elude critical level filtering and saturation in the lower atmosphere. GW focusing effects occur around jet cores, and ray-tube effects appear where the polar stratospheric jets vary substantially in space and time. Enhancement of the structure of zonal wave number 2 in pseudomomentum fluxes in the middle stratosphere begins from the early stage of the SSW evolution. An increase in pseudomomentum fluxes in the upper atmosphere is present even after the onset in the 4D. Significantly enhanced pseudomomentum fluxes, when the polar vortex is disturbed, are related to GWs with small intrinsic group velocity (wave capture), and they would change nonlocally nearby large-scale vortex structures without substantially changing local mean flows.

Propagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming event

2021 ◽  
Author(s):  
In-Sun Song ◽  
Changsup Lee ◽  
Hye-Yeong Chun ◽  
Jeong-Han Kim ◽  
Geonhwa Jee ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Waves ◽  
Lower Thermosphere ◽  
Upper Atmosphere ◽  
Lower Atmosphere ◽  
Horizontal Wind ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Curvature Effects ◽  
Zonal Wavenumber

<p>Effects of realistic propagation of gravity waves (GWs) on distribution of GW pseudomomentum fluxes are explored using a global ray-tracing model for the 2009 sudden stratospheric warming (SSW) event. Four-dimensional (4D; <span><em>x</em></span>–<span><em>z</em></span> and <span><em>t</em></span>) and two-dimensional (2D; <span><em>z</em></span> and <span><em>t</em></span>) results are compared for various parameterized pseudomomentum fluxes. In ray-tracing equations, refraction due to horizontal wind shear and curvature effects are found important and comparable to one another in magnitude. In the 4D, westward pseudomomentum fluxes are enhanced in the upper troposphere and northern stratosphere due to refraction and curvature effects around fluctuating jet flows. In the northern polar upper mesosphere and lower thermosphere, eastward pseudomomentum fluxes are increased in the 4D. GWs are found to propagate more to the upper atmosphere in the 4D, since horizontal propagation and change in wave numbers due to refraction and curvature effects can make it more possible that GWs elude critical level filtering and saturation in the lower atmosphere. GW focusing effects occur around jet cores, and ray-tube effects appear where the polar stratospheric jets vary substantially in space and time. Enhancement of the structure of zonal wavenumber 2 in pseudomomentum fluxes in the middle stratosphere begins from the early stage of the SSW evolution. An increase in pseudomomentum fluxes in the upper atmosphere is present even after the onset in the 4D. Significantly enhanced pseudomomentum fluxes, when the polar vortex is disturbed, are related to GWs with small intrinsic group velocity (wave capture), and they would change nonlocally nearby large-scale vortex structures without substantially changing local mean flows.</p>

Vertical Atmospheric Coupling during the September 2019 Antarctic Sudden Stratospheric Warming

2020 ◽  
Author(s):  
Yosuke Yamazaki ◽  
Vivien Matthias ◽  
Yasunobu Miyoshi ◽  
Claudia Stolle ◽  
Tarique Siddiqui ◽  
...  
Keyword(s):  
Large Scale ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Upper Atmosphere ◽  
The Arctic ◽  
Electron Content ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Total Electron ◽  
Zonal Wavenumber

<p>A sudden stratospheric warming (SSW) is an extreme wintertime meteorological phenomenon occurring mostly over the Arctic region. Studies have shown that an Arctic SSW can influence the whole atmosphere including the ionosphere. In September 2019, a rare SSW event occurred in the Antarctic region, following strong wave-1 planetary wave activity. The event provides an opportunity to investigate its broader impact on the upper atmosphere, which has been largely unexplored in previous studies. Ionospheric data from ESA's Swarm satellite constellation mission show prominent 6-day variations in the dayside low-latitude region during the SSW, including 20-70% variations in the equatorial zonal electric field, 20-40% variations in the electron density, and 5-10% variations in the top-side total electron content. These ionospheric variations have characteristics of a westward-propagating wave with zonal wavenumber 1, and can be attributed to forcing from the middle atmosphere by the Rossby normal mode “quasi-6-day wave” (Q6DW). Geopotential height measurements by the Microwave Limb Sounder aboard NASA's Aura satellite reveal a burst of global Q6DW activity in the mesosphere and lower thermosphere at this time, which is one of the strongest in the record. These results suggest that an Antarctic SSW can lead to ionospheric variability by altering middle atmosphere dynamics and propagation characteristics of large-scale waves from the middle atmosphere to the upper atmosphere.</p>

Dynamical-Chemical Feedbacks in General Circulation Models and Their Influence on Sudden Stratospheric Warming Events

2020 ◽  
Author(s):  
Oscar Dimdore-Miles ◽  
Lesley Gray ◽  
Scott Osprey
Keyword(s):  
Atmospheric Chemistry ◽  
General Circulation ◽  
General Circulation Models ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Quasi Biennial Oscillation ◽  
Stratospheric Polar Vortex ◽  
Feedback Mechanisms ◽  
Surface Climate ◽  
The Impact

<p>Sudden Stratospheric Warming events (SSWs) are rapid disruptions of the Northern Hemisphere (NH) winter stratospheric polar vortex and represent the largest source of inter-annual variability in the NH winter stratosphere. They have been linked to winter surface climate anomalies such as cold snaps over North America and Eurasia. Representing these events accurately in large scale GCMs as well as developing a greater understanding of them is key to improving predictability of winter surface climate. A key component of a GCM is its representation of atmospheric chemistry. Chemical distributions are either prescribed or calculated interactively by coupling an atmospheric chemistry model to radiation and dynamical components, thus capturing any chemical dynamical feedback mechanisms but incurring significant running cost.</p><p>This work evaluates the impact of interactive chemistry when modelling SSW events and explores the feedback mechanisms between chemical distributions and stratospheric dynamical variability. Pre-industrial control runs from the MetOffice HadGEMGC3.1 model which prescribes chemical fields and UKESM1 which calculates trace gas concentration interactively are utilised. Over the whole season - The Earth System Model appears to suppress warmings while the model with prescribed physics overestimates their occurrence compared to reanalysis. The differing representation of the equatorial stratosphere appears to be partially responsible for this difference. Additionally we find that middle stratosphere equatorial ozone concentration in late NH summer is closely associated with SSW probability in the ensuing winter in UKESM1. Anomalously low ozone is generally associated with an elevated SSW rate. This implies a chemical-dynamical coupling between the equator and the vortex in this model which preliminary results suggest could be driven by chemical feedbacks influencing the state of the early winter Quasi Biennial Oscillation (QBO) and Semi-Annual Oscillation (SAO) in zonal winds which can alter the distribution of planetary wave propagation and breaking (the primary cause of SSWs). Further work will assess whether this phenomenon is observed in other GCMs and further explore the physical mechanisms responsible.</p>

scholarly journals Observations of peroxyacetyl nitrate (PAN) in the upper troposphere by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS)

2013 ◽  
Vol 13 (1) ◽  
pp. 1575-1607 ◽  
Author(s):  
K. A. Tereszchuk ◽  
D. P. Moore ◽  
J. J. Harrison ◽  
C. D. Boone ◽  
M. Park ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
Fourier Transform Spectrometer ◽  
Data Set ◽  
Upper Troposphere ◽  
Volatile Organic ◽  
The Impact ◽  
Chemistry Experiment

Abstract. Peroxyacetyl nitrate (CH3CO·O2NO2, abbreviated as PAN) is a trace molecular species present in the troposphere and lower stratosphere due primarily to pollution from fuel combustion and the pyrogenic outflows from biomass burning. In the lower troposphere, PAN has a relatively short life-time and is principally destroyed within a few hours through thermolysis, but it can act as a reservoir and carrier of NOx in the colder temperatures of the upper troposphere where UV photolysis becomes the dominant loss mechanism. Pyroconvective updrafts from large biomass burning events can inject PAN into the upper troposphere and lower stratosphere (UTLS), providing a means for the long-range transport of NOx. Given the extended lifetimes at these higher altitudes, PAN is readily detectable via satellite remote sensing. A new PAN data product is now available for the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) Version 3.0 data set. We report measurements of PAN in Boreal biomass burning plumes recorded during the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) campaign. The retrieval method employed and errors analysis are described in full detail. The retrieved volume mixing ratio (VMR) profiles are compared to coincident measurements made by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument on the European Space Agency (ESA) ENVIronmental SATellite (ENVISAT). Three ACE-FTS occultations containing measurements of Boreal biomass burning outflows, recorded during BORTAS, were identified as having coincident measurements with MIPAS. In each case, the MIPAS measurements demonstrated good agreement with the ACE-FTS VMR profiles for PAN. The ACE-FTS PAN data set is used to obtain zonal mean distributions of seasonal averages from ~5 to 20 km. A strong seasonality is clearly observed for PAN concentrations in the global UTLS. Since the principal source of PAN in the UTLS is due to lofted biomass burning emissions from the pyroconvective updrafts created by large fires, the observed seasonality in enhanced PAN coincides with fire activity in different geographical regions throughout the year. This work is part of an in-depth investigation that is being conducted in an effort to study the aging and chemical evolution of biomass burning emissions in the UTLS by remote, space-borne measurements made by ACE-FTS to further our understanding of the impact of pyrogenic emissions on atmospheric chemistry. Included in this study will be the addition of new, pyrogenic, volatile organic hydrocarbons (VOCs) and oxygenated volatile organic compounds (OVOCs) to expand upon the already extensive suite of molecules retrieved by ACE-FTS to aid in elucidating biomass burning plume chemistry in the free troposphere.

scholarly journals Propagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming event

2020 ◽  
Author(s):  
In-Sun Song ◽  
Changsup Lee ◽  
Hye-Yeong Chun ◽  
Jeong-Han Kim ◽  
Geonhwa Jee ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Waves ◽  
Large Scale ◽  
Early Stage ◽  
Lower Thermosphere ◽  
Lower Atmosphere ◽  
Horizontal Wind ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Curvature Effects

Abstract. Effects of realistic propagation of gravity waves (GWs) on distribution of GW pseudomomentum fluxes (Fps) are explored using a global ray-tracing model for the 2009 sudden stratospheric warming (SSW). Four-dimensional (4D) (x–z, t) and two-dimensional (2D) (z, t) results are compared for various parameterized Fps. In ray-tracing equations, refraction due to horizontal wind shear and curvature effects are found important and comparable to one another in magnitude. In the 4D, westward Fps are enhanced in the upper troposphere and northern stratosphere, due to refraction and curvature effects around fluctuating jet flows associated with large-scale waves. In the northern polar upper mesosphere and lower thermosphere, eastward Fps are increased in the 4D. GWs are found to propagate more to the upper atmosphere in the 4D, since horizontal propagation and change in wavenumbers due to refraction and curvature effects can make it more possible that GWs elude critical-level filtering and saturation in the lower atmosphere. GW focusing and ray-tube effects have some impacts on changes in Fps. Focusing effects occur around jet cores, and ray-tube effects appear where the polar stratospheric jets vary substantially in space and time. Increase in the Fps in the northern upper stratosphere and the lower thermosphere begins from the early stage of the SSW evolution, and it is present even after the onset in the 4D. Significantly enhanced Fps in the northern stratosphere are likely related to GWs with small intrinsic group velocity (wave capture), and they would change nonlocally nearby large-scale vortex structure without changing substantially local mean flows.

scholarly journals On the formation of the F1 layer during sudden stratospheric warming events

2019 ◽  
Vol 5 (3) ◽  
pp. 117-127 ◽  
Author(s):  
Неля Полех ◽  
Nelya Polekh ◽  
Марина Черниговская ◽  
Marina Chernigovskaya ◽  
Ольга Яковлева ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Magnetic Activity ◽  
Frequency Of Occurrence ◽  
Neutral Atmosphere ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Global Dynamic ◽  
Wave Disturbances ◽  
Thermodynamic Processes

Using vertical sounding data obtained by the Irkutsk digisonde DPS-4 from 2003 to 2016, we have studied the frequency of occurrence of the F1 layer in winter conditions. The frequency of occurrence of the F1 layer in December–January is shown to be more than twice lower than that in February at any level of magnetic activity. At moderate and low solar activity under quiet geomagnetic conditions, the appearance of F1 layer in midlatitudes of the Northern Hemisphere may be caused by active thermodynamic processes, which lead to transformation or destruction of the circumpolar vortex at heights of the middle atmosphere. Such global dynamic changes occurring in the winter strato-mesosphere are often associated with sudden stratospheric warming events, which are accompanied by increased generation of atmospheric waves of various scales. These wave disturbances can propagate upward to the heights of the lower thermosphere and ionosphere, carrying a significant vertical flow of energy and causing variations in the composition, thermodynamic parameters of the neutral atmosphere and ionosphere.

scholarly journals On the formation of the F1 layer during sudden stratospheric warming events

2019 ◽  
Vol 5 (3) ◽  
pp. 140-152
Author(s):  
Неля Полех ◽  
Nelya Polekh ◽  
Марина Черниговская ◽  
Marina Chernigovskaya ◽  
Ольга Яковлева ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Magnetic Activity ◽  
Frequency Of Occurrence ◽  
Neutral Atmosphere ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Global Dynamic ◽  
Wave Disturbances ◽  
Thermodynamic Processes

Using vertical sounding data obtained by the Irkutsk digisonde DPS-4 from 2003 to 2016, we have studied the frequency of occurrence of the F1 layer in winter conditions. The frequency of occurrence of the F1 layer in December–January is shown to be more than twice lower than that in February at any level of magnetic activity. At moderate and low solar activity under quiet geomagnetic conditions, the appearance of F1 layer in midlatitudes of the Northern Hemisphere may be caused by active thermodynamic processes, which lead to transformation or destruction of the circumpolar vortex at heights of the middle atmosphere. Such global dynamic changes occurring in the winter strato-mesosphere are often associated with sudden stratospheric warming events, which are accompanied by increased generation of atmospheric waves of various scales. These wave disturbances can propagate upward to the heights of the lower thermosphere and ionosphere, carrying a significant vertical flow of energy and causing variations in the composition, thermodynamic parameters of the neutral atmosphere and ionosphere.

scholarly journals An empirical infrared transit spectrum of Earth: opacity windows and biosignatures

2019 ◽  
Vol 489 (1) ◽  
pp. 196-204 ◽  
Author(s):  
Evelyn J R Macdonald ◽  
Nicolas B Cowan
Keyword(s):  
Atmospheric Chemistry ◽  
Lower Atmosphere ◽  
High Dispersion ◽  
Fourier Transform Spectrometer ◽  
Transmission Spectra ◽  
Near Ir ◽  
James Webb Space Telescope ◽  
Ir Transmission ◽  
Chemistry Experiment

Abstract The Atmospheric Chemistry Experiment Fourier Transform Spectrometer on the SCISAT satellite has been measuring infrared (IR) transmission spectra of Earth during Solar occultations since 2004. We use these data to build an IR transit spectrum of Earth. Regions of low atmospheric opacity, known as windows, are of particular interest, as they permit observations of the planet’s lower atmosphere. Even in the absence of clouds or refraction, imperfect transmittance leads to a minimum effective thickness of hmin ≈ 4 km in the 10–12 $\mu \mathrm{m}$ opacity window at a spectral resolution of R = 103. None the less, at R = 105, the maximum transmittance at the surface is around ${70}{{{\ \rm per\ cent}}}$. In principle, one can probe the troposphere of an Earth-like planet via high-dispersion transit spectroscopy in the mid-IR; in practice aerosols and/or refraction likely make this impossible. We simulate the transit spectrum of an Earth-like planet in the TRAPPIST-1 system. We find that a long-term near-IR (NIR) campaign with the James Webb Space Telescope(JWST) could readily detect CO2, establishing the presence of an atmosphere. A mid-IR campaign or longer NIR campaign would be more challenging, but in principle could detect H2O and the biosignatures O3 and CH4.

scholarly journals Identification of the mechanisms responsible for anomalies in the tropical lower thermosphere/ionosphere caused by the January 2009 sudden stratospheric warming

2019 ◽  
Vol 9 ◽  
pp. A39 ◽  
Author(s):  
Maxim V. Klimenko ◽  
Vladimir V. Klimenko ◽  
Fedor S. Bessarab ◽  
Timofei V. Sukhodolov ◽  
Pavel A. Vasilev ◽  
...  
Keyword(s):  
Electric Field ◽  
Phase Change ◽  
Lower Thermosphere ◽  
Upper Atmosphere ◽  
Electron Content ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Low Latitude ◽  
Plasma Drift ◽  
Solar Tide

We apply the Entire Atmosphere GLobal (EAGLE) model to investigate the upper atmosphere response to the January 2009 sudden stratospheric warming (SSW) event. The model successfully reproduces neutral temperature and total electron content (TEC) observations. Using both model and observational data, we identify a cooling in the tropical lower thermosphere caused by the SSW. This cooling affects the zonal electric field close to the equator, leading to an enhanced vertical plasma drift. We demonstrate that along with a SSW-related wind disturbance, which is the main source to form a dynamo electric field in the ionosphere, perturbations of the ionospheric conductivity also make a significant contribution to the formation of the electric field response to SSW. The post-sunset TEC enhancement and pre-sunrise electron content reduction are revealed as a response to the 2009 SSW. We show that at post-sunset hours the SSW affects low-latitude TEC via a disturbance of the meridional electric field. We also show that the phase change of the semidiurnal migrating solar tide (SW2) in the neutral wind caused by the 2009 SSW at the altitude of the dynamo electric field generation has a crucial importance for the SW2 phase change in the zonal electric field. Such changes lead to the appearance of anomalous diurnal variability of the equatorial electromagnetic plasma drift and subsequent low-latitudinal TEC disturbances in agreement with available observations. Plain Language Summary – Entire Atmosphere GLobal model (EAGLE) interactively calculates the troposphere, stratosphere, mesosphere, thermosphere, and plasmasphere–ionosphere system states and their response to various natural and anthropogenic forcing. In this paper, we study the upper atmosphere response to the major sudden stratospheric warming that occurred in January 2009. Our results agree well with the observed evolution of the neutral temperature in the upper atmosphere and with low-latitude ionospheric disturbances over America. For the first time, we identify an SSW-related cooling in the tropical lower thermosphere that, in turn, could provide additional information for understanding the mechanisms for the generation of electric field disturbances observed at low latitudes. We show that the SSW-related vertical electromagnetic drift due to electric field disturbances is a key mechanism for interpretation of an observed anomalous diurnal development of the equatorial ionization anomaly during the 2009 SSW event. We demonstrate that the link between thermospheric winds and the ionospheric dynamo electric field during the SSW is attained through the modulation of the semidiurnal migrating solar tide.

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