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>

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.

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.

Whole Atmosphere Coupling during the September 2019 Antarctic Sudden Stratospheric Warming

2021 ◽  
Author(s):  
Yosuke Yamazaki ◽  
Yasunobu Miyoshi
Keyword(s):  
Large Scale ◽  
Lower Thermosphere ◽  
Upper Atmosphere ◽  
The Arctic ◽  
Electron Content ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Total Electron ◽  
Total Electron Content Data ◽  
Zonal Wavenumber

<p>A sudden stratospheric warming (SSW) is a large-scale meteorological phenomenon, which is most commonly observed in the Arctic region during winter months. In September 2019, a rare SSW occurred in the Antarctic region, providing a unique opportunity to study its impact on the middle and upper atmosphere. Geopotential height measurements by the Microwave Limb Sounder aboard NASA's Aura satellite reveal a burst of westward-propagating quasi-6-day wave (Q6DW) with zonal wavenumber 1 in the mesosphere and lower thermosphere following the SSW. At this time, ionospheric data from ESA's Swarm satellite constellation mission show prominent 6-day variations in the daytime equatorial electrojet intensity and low-latitude plasma densities. The whole atmosphere model GAIA reproduces salient features of the middle and upper atmosphere response to the SSW. GAIA results suggest that the observed ionospheric 6-day variations are not directly driven by the Q6DW but driven indirectly through tidal modulations by the Q6DW. An analysis of global total electron content data reveals signatures of secondary waves arising from the nonlinear interaction between the Q6DW and tides.</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>

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.

Modeling of the effect of internal gravity waves on upper atmospheric conditions during sudden stratospheric warming

2016 ◽  
Vol 2 (3) ◽  
pp. 99-105 ◽  
Author(s):  
Павел Васильев ◽  
Pavel Vasilyev ◽  
Иван Карпов ◽  
Ivan Karpov ◽  
Сергей Кшевецкий ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Internal Gravity Waves ◽  
Upper Atmosphere ◽  
Stratospheric Warming ◽  
Atmospheric Conditions ◽  
Dimensional Model ◽  
Sudden Stratospheric Warming ◽  
Temperature Changes ◽  
Ionospheric Effects ◽  
Charged Component

We present results of modeling of the effect of internal gravity waves (IGW), excited in the region of development of a sudden stratospheric warming (SSW), on upper atmospheric conditions. In the numerical experiment, we use a two-dimensional model of propagation of atmospheric waves, taking into account dissipative and nonlinear processes accompanying wave propagation. As a source of disturbances we consider temperature and density disturbances in the stratosphere during SSWs. Amplitude and frequency characteristics of the source of disturbances are estimated from observations and IGW theory. Numerical calculations showed that waves generated at stratospheric heights during SSW can cause temperature changes in the upper atmosphere. Maximum relative disturbances, caused by such waves, with respect to quiet conditions are observed at 100–200 km. Disturbances of the upper atmosphere in turn have an effect on the dynamics of charged component in the ionosphere and can contribute to observable ionospheric effects of SSW.

Role of Gravity Waves in a Vortex-Split Sudden Stratospheric Warming in January 2009

2020 ◽  
Vol 77 (10) ◽  
pp. 3321-3342
Author(s):  
Byeong-Gwon Song ◽  
Hye-Yeong Chun ◽  
In-Sun Song
Keyword(s):  
Gravity Waves ◽  
Significant Positive Correlation ◽  
Source Term ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Flux Divergence ◽  
Zonal Wavenumber ◽  
The Relationship ◽  
Vortex Split

AbstractThe role of gravity waves (GWs) in a sudden stratospheric warming (SSW) event that occurred in January 2009 (SSW09) is investigated using the MERRA-2 dataset. Nearly 2 weeks prior to the central date (lag = 0), at which the zonal-mean zonal wind at 10 hPa and 60°N first becomes negative, westward GW drag (GWD) is significantly enhanced in the lower mesosphere and stratosphere. At 5 days before lag = 0, planetary waves (PWs) of zonal wavenumber 2 (ZWN-2) in the stratosphere are enhanced, while PWs of ZWN-1 are weakened, which are evident from the amplitudes of the PWs and their Eliassen–Palm flux divergence (EPD). To examine the relationship between PWs and GWs, a nonconservative GWD (NCGWD) source term of the linearized quasigeostrophic potential vorticity equation is considered. A ZWN-2 pattern of the NCGWD forcing is developed around z = 55–60 km with a secondary peak around z = 40 km just before the PWs of ZWN-2 in the stratosphere began to enhance. A significant positive correlation between the NCGWD forcing in the upper stratosphere and lower mesosphere (USLM; 0.3–0.1 hPa in the present data) and the PWs of ZWN-2 in the stratosphere (5–1 hPa) exists. This result demonstrates that the amplification of the PWs of ZWN-2 in the stratosphere before the onset of SSW09 is likely related to the generation of PWs by GWD in the USLM, which is revealed by the enhanced downward-propagating PWs of ZWN-2 into the stratosphere from above.

Error Growth in a Whole Atmosphere Climate Model

2009 ◽  
Vol 66 (1) ◽  
pp. 173-186 ◽  
Author(s):  
H-L. Liu ◽  
F. Sassi ◽  
R. R. Garcia
Keyword(s):  
Gravity Waves ◽  
Growth Rates ◽  
Climate Model ◽  
Initial Conditions ◽  
Lower Thermosphere ◽  
Physical Nature ◽  
Upper Atmosphere ◽  
Lower Atmosphere ◽  
Finite Limit ◽  
Mesosphere And Lower Thermosphere

Abstract It has been well established that the atmosphere is chaotic by nature and thus has a finite limit of predictability. The chaotic divergence of initial conditions and the predictability are explored here in the context of the whole atmosphere (from the ground to the thermosphere) using the NCAR Whole Atmosphere Community Climate Model (WACCM). From ensemble WACCM simulations, it is found that the early growth of differences in initial conditions is associated with gravity waves and it becomes apparent first in the upper atmosphere and progresses downward. The differences later become more profound on increasingly larger scales, and the growth rates of the differences change in various atmospheric regions and with seasons—corresponding closely with the strength of planetary waves. For example, in December–February the growth rates are largest in the northern and southern mesosphere and lower thermosphere and in the northern stratosphere, while smallest in the southern stratosphere. The growth rates, on the other hand, are not sensitive to the altitude where the small differences are introduced in the initial conditions or the physical nature of the differences. Furthermore, the growth rates in the middle and upper atmosphere are significantly reduced if the lower atmosphere is regularly reinitialized, and the reduction depends on the frequency and the altitude range of the reinitialization.

scholarly journals Modeling of the effect of internal gravity waves on upper atmospheric conditions during sudden stratospheric warming

2016 ◽  
Vol 2 (3) ◽  
pp. 69-73
Author(s):  
Павел Васильев ◽  
Pavel Vasilyev ◽  
Иван Карпов ◽  
Ivan Karpov ◽  
Сергей Кшевецкий ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Internal Gravity Waves ◽  
Upper Atmosphere ◽  
Stratospheric Warming ◽  
Atmospheric Conditions ◽  
Dimensional Model ◽  
Sudden Stratospheric Warming ◽  
Temperature Changes ◽  
Ionospheric Effects ◽  
Charged Component

We present results of modeling of the effect of internal gravity waves (IGW), excited in the region of development of a sudden stratospheric warming (SSW), on upper atmospheric conditions. In the numerical experiment, we use a two-dimensional model of propagation of atmospheric waves, taking into account dissipative and nonlinear processes accompanying wave propagation. As a source of disturbances we consider temperature and density disturbances in the stratosphere during SSWs. Amplitude and frequency characteristics of the source of disturbances are estimated from observations and IGW theory. Numerical calculations showed that waves generated at stratospheric heights during SSW can cause temperature changes in the upper atmosphere. Maximum relative disturbances, generated by such waves, with respect to quiet conditions are observed at 100–200 km. Disturbances of the upper atmosphere in turn have an effect on dynamics of a charged component in the ionosphere and can contribute to observable ionospheric effects of SSW.

scholarly journals Climatologies and long-term changes of mesospheric wind and wave measurements based on radar observations at high and mid-latitudes

2019 ◽  
Author(s):  
Sven Wilhelm ◽  
Gunter Stober ◽  
Peter Brown
Keyword(s):  
Kinetic Energy ◽  
Gravity Waves ◽  
Lower Thermosphere ◽  
Stratospheric Warming ◽  
Atmospheric Parameters ◽  
Sudden Stratospheric Warming ◽  
Wave Measurements ◽  
South West ◽  
Mesosphere And Lower Thermosphere

Abstract. We report long-term observations of atmospheric parameters in the mesosphere and lower thermosphere (MLT) made over the last two decades. Within this study, we show based on meteor wind measurement, the long-term variability of winds, tides, and kinetic energy of planetary and gravity waves. These measurements were done between the years 2002 and 2018 for the high latitude location of Andenes (69.3° N, 16° E) and the mid-latitude locations of Juliusruh (54.6° N, 13.4° E) and Tavistock (43.3° N, 80.8° W). While the climatologies for each location show a similar pattern, the locations differ strongly with respect to altitude and season of several parameters. Our results show annual wind tendencies for Andenes which are toward the south-west, with changes of up to 3 m/s per decade, while the mid-latitude locations showing smaller opposite tendencies to negligible changes. The diurnal and semidiurnal tides also show different results for each location. Furthermore, the kinetic energy for planetary waves showed strong peak values during winters which also featured the occurrence of sudden stratospheric warming. The influence of the 11-year solar cycle on the winds and tides is presented.

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