Two Day Wave Traveling Westward With Wave Number 1 During the Sudden Stratospheric Warming in January 2017

2018 ◽  
Vol 123 (4) ◽  
pp. 3005-3013 ◽  
Author(s):  
Jiangang Xiong ◽  
Weixing Wan ◽  
Feng Ding ◽  
Libo Liu ◽  
Lianhuan Hu ◽  
...  
Keyword(s):  
Wave Number ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming

scholarly journals Influence of the sudden stratospheric warming on quasi-2-day waves

2016 ◽  
Vol 16 (8) ◽  
pp. 4885-4896 ◽  
Author(s):  
Sheng-Yang Gu ◽  
Han-Li Liu ◽  
Xiankang Dou ◽  
Tao Li
Keyword(s):  
General Circulation ◽  
Phase Speed ◽  
Circulation Model ◽  
Meridional Wind ◽  
Equatorial Region ◽  
Wave Number ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Middle Latitudes ◽  
Zonal Wave Number

Abstract. The influence of the sudden stratospheric warming (SSW) on a quasi-2-day wave (QTDW) with westward zonal wave number 3 (W3) is investigated using the Thermosphere–Ionosphere–Mesosphere Electrodynamics General Circulation Model (TIME-GCM). The summer easterly jet below 90 km is strengthened during an SSW, which results in a larger refractive index and thus more favorable conditions for the propagation of W3. In the winter hemisphere, the Eliassen–Palm (EP) flux diagnostics indicate that the strong instabilities at middle and high latitudes in the mesopause region are important for the amplification of W3, which is weakened during SSW periods due to the deceleration or even reversal of the winter westerly winds. Nonlinear interactions between the W3 and the wave number 1 stationary planetary wave produce QTDW with westward zonal wave number 2 (W2). The meridional wind perturbations of the W2 peak in the equatorial region, while the zonal wind and temperature components maximize at middle latitudes. The EP flux diagnostics indicate that the W2 is capable of propagating upward in both winter and summer hemispheres, whereas the propagation of W3 is mostly confined to the summer hemisphere. This characteristic is likely due to the fact that the phase speed of W2 is larger, and therefore its waveguide has a broader latitudinal extension. The larger phase speed also makes W2 less vulnerable to dissipation and critical layer filtering by the background wind when propagating upward.

scholarly journals Investigation on the abnormal quasi-two day wave activities during sudden stratospheric warming period of January 2006

2017 ◽  
Author(s):  
Sheng-Yang Gu ◽  
Xiankang Dou ◽  
Dora Pancheva
Keyword(s):  
Planetary Wave ◽  
Phase Speed ◽  
Dominant Mode ◽  
Wave Number ◽  
Stratospheric Warming ◽  
Mean Flow ◽  
Sudden Stratospheric Warming ◽  
Reanalysis Dataset ◽  
Short Period ◽  
Zonal Wave Number

Abstract. The quasi-two day wave (QTDW) during austral summer period usually coincides with sudden stratospheric warming (SSW) event in the winter hemisphere, while the influences of SSW on QTDW are not totally understood. In this work, the anomalous QTDW activities during the major SSW period of January 2006 are further investigated on the basis of hourly Navy Operational Global Atmospheric Prediction System-Advanced Level Physics High Altitude (NOGAPS-ALPHA) reanalysis dataset. Strong westward QTDW with zonal wave number 2 (W2) is identified besides the conventionally dominant mode of zonal wave number 3 (W3). Meanwhile, the W3 peaks with an extremely short period of ~ 42 hours. Compared with January 2005 with no evident SSW, we found that the zonal mean zonal wind in the summer mesosphere is enhanced during 2006. The enhanced summer easterly sustains critical layers for W2 and short-period W3 QTDWs with larger phase speed, which facilitate their amplification through wave-mean flow interaction. The stronger summer easterly also provides stronger barotropic/baroclinic instabilities and thus larger forcing for the amplification of QTDW. The inter-hemispheric coupling induced by strong winter stratospheric planetary wave activities during SSW period is most likely responsible for the enhancement of summer easterly. Besides, we found that the nonlinear interaction between W3 QTDW and the wave number 1 stationary planetary wave (SPW1) may also contribute to the source of W2 at middle and low latitudes in the mesosphere.

scholarly journals A Study of False Alarms of a Major Sudden Stratospheric Warming by Real-Time Subseasonal-to-Seasonal Forecasts for the 2017/2018 Northern Winter

Atmosphere ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 875
Author(s):  
Masakazu Taguchi
Keyword(s):  
False Alarm ◽  
Real Time ◽  
Winter Season ◽  
Wave Activity ◽  
Wave Number ◽  
False Alarms ◽  
Stratospheric Warming ◽  
Seasonal Forecasts ◽  
Sudden Stratospheric Warming ◽  
First Case

This study investigates false alarms of a major sudden stratospheric warming (MSSW) by real-time subseasonal-to-seasonal forecast data of the European Centre for Medium-Range Weather Forecasts system for the 2017/2018 Northern Hemisphere winter season. The analysis reveals two false alarm cases in the season, one in early December and the other in early February. Each case is characterized by ensembles of which a considerable part of the members (MSSW members) show an MSSW, that is, reversal of the zonal mean zonal wind in the extratropical stratosphere on similar calendar dates. Ensemble forecasts that are initialized earlier or later basically lack an MSSW, demonstrating clear intraseasonal variability in the frequency of forecasted MSSWs. For each false alarm case, the MSSW member mean field shows equatorward displacement of the polar vortex around the onset date. For both cases, the MSSW members accompany stronger wave activity in the lower stratosphere than other non-MSSW members and reanalysis data. They are further associated with higher geopotential height than the non-MSSW members, in the upper troposphere over northeastern Canada and Greenland before the first case, and lower height over northeastern Eurasia before the second case. These are located over the ridge and trough, respectively, of the climatological planetary wave of zonal wave number one, and are consistent with the increased wave activity.

scholarly journals The Role of Eddy-Eddy Interactions in Sudden Stratospheric Warming Formation

2019 ◽  
Author(s):  
Erik Anders Lindgren ◽  
Aditi Sheshadri
Keyword(s):  
General Circulation ◽  
Lower Stratosphere ◽  
Circulation Model ◽  
Wave Number ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Wave Forcing ◽  
Wave Numbers ◽  
Tropospheric Heating ◽  
Wave Flux

Abstract. The effects of eddy-eddy interactions on sudden stratospheric warming formation are investigated using an idealized atmospheric general circulation model, in which tropospheric heating perturbations of zonal wave numbers 1 and 2 are used to produce planetary scale wave activity. Eddy-eddy interactions are removed at different vertical extents of the atmosphere in order to examine the sensitivity of stratospheric circulation to local changes in eddy-eddy interactions. We show that the effects of eddy-eddy interactions on sudden warming formation, including sudden warming frequencies, are strongly dependent on the wave number of the tropospheric forcing and the vertical levels where eddy-eddy interactions are removed. Significant changes in sudden warming frequencies are evident when eddy-eddy interactions are removed even when the lower stratospheric wave forcing does not change, highlighting the fact that the upper stratosphere is not a passive recipient of wave forcing from below. We find that while eddy-eddy interactions are required in the troposphere and lower stratosphere to produce displacements when wave number 2 heating is used, both splits and displacements can be produced without eddy-eddy interactions in the troposphere and lower stratosphere when the model is forced by wave number 1 heating. We suggest that the relative strengths of wave numbers 1 and 2 vertical wave flux entering the stratosphere largely determine the split and displacement ratios when wave number 2 forcing is used, but not wave number 1.

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 INVESTIGATION OF NORTHERN HEMISPHERE STRATOSPHERE VARIABILITY IN XXI CENTURY IN INM CM5 CLIMATE MODEL SIMULATIONS

2020 ◽  
Vol 1 (5) ◽  
pp. 27-34
Author(s):  
P. N. Vargin ◽  
◽  
E. M. Volodin ◽  
Keyword(s):  
Planetary Wave ◽  
Climate Model ◽  
Meridional Circulation ◽  
Wave Activity ◽  
Wave Number ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Stratospheric Polar Vortex ◽  
Spring Break ◽  
Break Up

Simulations of 5th version of INM RAS (Institute of Numerical Mathematics of the Russian Academy of Science) climate model performed in the framework of CMIP6 project for the future climate under ssp2–4.5 (moderate) and ssp5–8.5 (business as usual or hard) scenarios of green house gases (GHG) increase are employed to analyze temperature, zonal mean wind, stratospheric polar vortex, planetary wave activity, meridional circulation, sudden stratospheric warming (SSW) events, and stratospheric circulation spring break-up date changes during boreal winters from 2015 to 2100. Comparison of averages over two periods of 2080–2100 and 2015–2035 revealed that temperature will decrease from 1° in the lower stratosphere to 4° in the upper stratosphere under moderate scenario and up to 11° under hard scenario. Cooling of stratosphere will be accompanied by strengthening of zonal circulation and planetary wave activity propagation in the middle – upper stratosphere that in turn leads to increase (stronger under hard scenario) of planetary wave with zonal wave number 1 amplitude (wavenumber 1). 13 major sudden stratospheric warming events and 16 very cold stratospheric winter seasons were revealed under hard scenario. Under both scenarios early spring break-up dates will be accompanied by stronger wavenumber 1 in comparison with winter seasons with later spring break-up dates. Strengthening of zonal mean meridional circulation is expected in the late XXI century

scholarly journals The role of wave–wave interactions in sudden stratospheric warming formation

2020 ◽  
Vol 1 (1) ◽  
pp. 93-109 ◽  
Author(s):  
Erik A. Lindgren ◽  
Aditi Sheshadri
Keyword(s):  
General Circulation ◽  
Lower Stratosphere ◽  
Circulation Model ◽  
Wave Number ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Wave Interactions ◽  
Wave Forcing ◽  
Tropospheric Heating ◽  
Wave Flux

Abstract. The effects of wave–wave interactions on sudden stratospheric warming formation are investigated using an idealized atmospheric general circulation model, in which tropospheric heating perturbations of zonal wave numbers 1 and 2 are used to produce planetary-scale wave activity. Zonal wave–wave interactions are removed at different vertical extents of the atmosphere in order to examine the sensitivity of stratospheric circulation to local changes in wave–wave interactions. We show that the effects of wave–wave interactions on sudden warming formation, including sudden warming frequencies, are strongly dependent on the wave number of the tropospheric forcing and the vertical levels where wave–wave interactions are removed. Significant changes in sudden warming frequencies are evident when wave–wave interactions are removed even when the lower-stratospheric wave forcing does not change, highlighting the fact that the upper stratosphere is not a passive recipient of wave forcing from below. We find that while wave–wave interactions are required in the troposphere and lower stratosphere to produce displacements when wave number 2 heating is used, both splits and displacements can be produced without wave–wave interactions in the troposphere and lower stratosphere when the model is forced by wave number 1 heating. We suggest that the relative strengths of wave number 1 and 2 vertical wave flux entering the stratosphere largely determine the split and displacement ratios when wave number 2 forcing is used but not wave number 1.

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.

Sign in / Sign up

Export Citation Format

Share Document