scholarly journals Planetary wave coupling from the stratosphere to the thermosphere during the 2002 Southern Hemisphere pre-stratwarm period

2005 ◽  
Vol 32 (23) ◽  
Author(s):  
S. E. Palo ◽  
J. M. Forbes ◽  
X. Zhang ◽  
J. M. Russell ◽  
C. J. Mertens ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Planetary Wave ◽  
Wave Coupling

Observed Decadal Changes in Downward Wave Coupling between the Stratosphere and Troposphere in the Southern Hemisphere

2011 ◽  
Vol 24 (17) ◽  
pp. 4558-4569 ◽  
Author(s):  
Nili Harnik ◽  
Judith Perlwitz ◽  
Tiffany A. Shaw
Keyword(s):  
Southern Hemisphere ◽  
Planetary Wave ◽  
Late Winter ◽  
Spectral Correlation ◽  
Dynamical Mechanism ◽  
Wave Coupling ◽  
Reflected Waves ◽  
Dynamical Coupling ◽  
Height Fields ◽  
Reflecting Surface

Downward wave coupling dominates the intraseasonal dynamical coupling between the stratosphere and troposphere in the Southern Hemisphere. The coupling occurs during late winter and spring when the stratospheric basic state forms a well-defined meridional waveguide, which is bounded above by a reflecting surface. This basic-state configuration is favorable for planetary wave reflection and guides the reflected waves back down to the troposphere, where they impact wave structures. In this study decadal changes in downward wave coupling are analyzed using the Modern Era Retrospective-Analysis for Research and Applications (MERRA) dataset. A cross-spectral correlation analysis, applied to geopotential height fields, and a wave geometry diagnostic, applied to zonal-mean zonal wind and temperature data, are used to understand decadal changes in planetary wave propagation. It is found that downward wave 1 coupling from September to December has increased over the last three decades, owing to significant increases at the beginning and end of this 4-month period. The increased downward wave coupling is caused by both an earlier onset of the vertically bounded meridional waveguide configuration and a persistence of this configuration into December. The latter is associated with the observed delay in vortex breakup. The results point to an additional dynamical mechanism whereby the stratosphere has influenced the tropospheric climate in the Southern Hemisphere.

scholarly journals Quasi-10 d wave modulation of an equatorial ionization anomaly during the Southern Hemisphere stratospheric warming of 2002

2020 ◽  
Vol 38 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Xiaohua Mo ◽  
Donghe Zhang
Keyword(s):  
Southern Hemisphere ◽  
Planetary Wave ◽  
Lower Thermosphere ◽  
Periodic Oscillation ◽  
Electron Content ◽  
Stratospheric Warming ◽  
Total Electron ◽  
Equatorial Ionization Anomaly ◽  
E Region ◽  
D Wave

Abstract. The present paper studies the perturbations in an equatorial ionization anomaly (EIA) region during the Southern Hemisphere (SH) sudden stratospheric warming (SSW) of 2002, using the location of EIA crests derived from global positioning system (GPS) station observations, the total electron content (TEC) obtained by the International GNSS (global navigation satellite system) Service (IGS) global ionospheric TEC map (GIMs) and the equatorial electrojet (EEJ) estimated by the geomagnetic field in the Asian sector. The results indicate the existence of an obvious quasi-10 d periodic oscillation in the location and TEC of the northern and southern EIA crest. An eastward phase progression of the quasi-10 d wave producing the SH SSW of 2002 is also identified in polar stratospheric temperature. Previous studies have shown that a strong quasi-10 d planetary wave with zonal wave numbers s=1 extended from the lower stratosphere to the mesosphere and lower thermosphere during the SH SSW of 2002 (Palo et al., 2005). Moreover, the EEJ driven by the equatorial zonal electric field exhibits quasi-10 d oscillation, suggesting the enhanced quasi-10 d planetary wave associated with SSW penetrates into the ionosphere E region and produces oscillation in the EIA region through modulating the E-region electric fields. Our results reveal some newer features of ionospheric variation that have not been reported during Northern Hemisphere (NH) SSWs.

Burst of Unusual Quasi-10 day Wave During the 2019 Southern Sudden Stratospheric Warming

2021 ◽  
Author(s):  
Jack Wang ◽  
Scott Palo ◽  
Jeffrey Forbes ◽  
John Marino ◽  
Tracy Moffat-Griffin
Keyword(s):  
Southern Hemisphere ◽  
Planetary Wave ◽  
Wave Activity ◽  
Stratospheric Warming ◽  
Atmospheric Conditions ◽  
Meteor Radar ◽  
Sudden Stratospheric Warming ◽  
Zonal Wavenumber ◽  
Wind Measurements ◽  
Mlt Region

<div> <p>An unusual sudden stratospheric warming (SSW) occurred in the Southern hemisphere in September 2019. Ground-based and satellite observations show the presence of a transient westward-propagating quasi-10 day planetary wave with zonal wavenumber one during the SSW. The planetary wave activity maximizes in the MLT region approximately 10 days after the SSW onset. Analysis indicates the quasi-10 day planetary wave is symmetric about the equator which is contrary to theory for such planetary waves. </p> </div><div> <p>Observations from MLS and SABER provide a unique opportunity to study the global structure and evolution of the symmetric quasi-10 day wave with observations of both geopotential height and temperature during these unusual atmospheric conditions. The space-based measurements are combined with meteor radar wind measurements from Antarctica, providing a comprehensive view of the quasi-10 day wave activity in the southern hemisphere during this SSW. We will also present the results of our mesospheric and lower thermospheric analysis along with a preliminary analysis of the ionospheric response to these wave perturbations.</p> </div>

scholarly journals Hemispheric ozone variability indices derived from satellite observations and comparison to a coupled chemistry-climate model

2006 ◽  
Vol 6 (12) ◽  
pp. 5105-5120 ◽  
Author(s):  
T. Erbertseder ◽  
V. Eyring ◽  
M. Bittner ◽  
M. Dameris ◽  
V. Grewe
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Total Ozone ◽  
Planetary Wave ◽  
Climate Model ◽  
Model Simulation ◽  
Wave Activity ◽  
Satellite Observations ◽  
Ozone Hole ◽  
Total Column Ozone

Abstract. Total column ozone is used to trace the dynamics of the lower and middle stratosphere which is governed by planetary waves. In order to analyse the planetary wave activity a Harmonic Analysis is applied to global multi-year total ozone observations from the Total Ozone Monitoring Spectrometer (TOMS). As diagnostic variables we introduce the hemispheric ozone variability indices one and two. They are defined as the hemispheric means of the amplitudes of the zonal waves number one and two, respectively, as traced by the total ozone field. The application of these indices as a simple diagnostic for the evaluation of coupled chemistry-climate models (CCMs) is demonstrated by comparing results of the CCM ECHAM4.L39(DLR)/CHEM (hereafter: E39/C) against satellite observations. It is quantified to what extent a multi-year model simulation of E39/C (representing "2000" climate conditions) is able to reproduce the zonal and hemispheric planetary wave activity derived from TOMS data (1996–2004, Version 8). Compared to the reference observations the hemispheric ozone variability indices one and two of E39/C are too high in the Northern Hemisphere and too low in the Southern Hemisphere. In the Northern Hemisphere, where the agreement is generally better, E39/C produces too strong a planetary wave one activity in winter and spring and too high an interannual variability. For the Southern Hemisphere we reveal that the indices from observations and model differ significantly during the ozone hole season. The indices are used to give reasons for the late formation of the Antarctic ozone hole, the insufficient vortex elongation and eventually the delayed final warming in E39/C. In general, the hemispheric ozone variability indices can be regarded as a simple and robust diagnostic to quantify model-observation differences concerning planetary wave activity. It allows a first-guess on how the dynamics is represented in a model simulation before applying costly and more specific diagnostics.

scholarly journals Interhemispheric structure and variability of the 5-day planetary wave from meteor radar wind measurements

2015 ◽  
Vol 33 (11) ◽  
pp. 1349-1359 ◽  
Author(s):  
H. Iimura ◽  
D. C. Fritts ◽  
D. Janches ◽  
W. Singer ◽  
N. J. Mitchell
Keyword(s):  
Interannual Variability ◽  
Southern Hemisphere ◽  
Planetary Wave ◽  
Tierra Del Fuego ◽  
Meteor Radar ◽  
Short Term ◽  
Simultaneous Measurements ◽  
Wind Measurements ◽  
Using Data ◽  
Northern And Southern Hemispheres

Abstract. A study of the quasi-5-day wave (5DW) was performed using meteor radars at conjugate latitudes in the Northern and Southern hemispheres. These radars are located at Esrange, Sweden (68° N) and Juliusruh, Germany (55° N) in the Northern Hemisphere, and at Tierra del Fuego, Argentina (54° S) and Rothera Station, Antarctica (68° S) in the Southern Hemisphere. The analysis was performed using data collected during simultaneous measurements by the four radars from June 2010 to December 2012 at altitudes from 84 to 96 km. The 5DW was found to exhibit significant short-term, seasonal, and interannual variability at all sites. Typical events had planetary wave periods that ranged between 4 and 7 days, durations of only a few cycles, and infrequent strongly peaked variances and covariances. Winds exhibited rotary structures that varied strongly among sites and between events, and maximum amplitudes up to ~ 20 m s−1. Mean horizontal velocity covariances tended to be largely negative at all sites throughout the interval studied.

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