scholarly journals A model of mid-latitude E-region plasma convergence inside a planetary wave cyclonic vortex

2002 ◽  
Vol 20 (8) ◽  
pp. 1193-1201 ◽  
Author(s):  
S. Shalimov ◽  
C. Haldoupis
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Planetary Wave ◽  
Numerical Solutions ◽  
Lower Thermosphere ◽  
Plasma Transport ◽  
Neutral Wind ◽  
Prevailing Wind Direction ◽  
E Region ◽  
Region Plasma

Abstract. Recently, Shalimov et al. (1999) proposed a new mechanism for large-scale accumulation of long-lived metallic ions in the mid-latitude ionosphere driven by planetary waves in the lower thermosphere. In this mechanism, the combined action of frictional and horizontal magnetic field forces at E-region altitudes causes the plasma to converge and accumulate in large areas of positive neutral wind vorticity within a propagating planetary wave. The present paper provides a theoretical formulation for this mechanism by modelling both horizontal and vertical plasma transport effects within a planetary wave vortex, of cyclonic neutral wind. Non-steady-state numerical solutions of the ion continuity equation show that the proposed accumulation process can enhance the ionization significantly inside the planetary wave vortex but its efficiency depends strongly on altitude, whereas on the other hand, it can be complicated by vertical plasma motions. The latter, which are driven by the same planetary wave wind field under the action of the vertical Lorentz force and meridional wind forcing along the magnetic field lines, can lead to either plasma compressions or depletions, depending on the prevailing wind direction. We conclude that, for shorter times, vertical plasma transport may act constructively to the horizontal gathering process to produce considerable E-region plasma accumulation over large sectors of a planetary wave vortex of cyclonic winds.Key words. Ionosphere (ionosphere-atmosphere interactions; mid-latitude ionosphere; sporadic E-layers) – Meteorology and atmospheric dynamics (waves and tides)

scholarly journals Numerical Modeling of the Influence of Solar Activity on the Global Circulation in the Earth’s Mesosphere and Lower Thermosphere

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Igor Mingalev ◽  
Victor Mingalev
Keyword(s):  
Solar Activity ◽  
Large Scale ◽  
Input Parameter ◽  
Lower Thermosphere ◽  
Vertical Component ◽  
Neutral Wind ◽  
Wind System ◽  
Model Calculations ◽  
Global Circulation ◽  
Mesosphere And Lower Thermosphere

The nonhydrostatic model of the global neutral wind system of the earth’s atmosphere, developed earlier in the Polar Geophysical Institute, is utilized to investigate how solar activity affects the formation of the large-scale global circulation of the mesosphere and lower thermosphere. The peculiarity of the utilized model consists in that the internal energy equation for the neutral gas is not solved in the model calculations. Instead, the global temperature field is assumed to be a given distribution, that is, the input parameter of the model. Moreover, in the model calculations, not only the horizontal components but also the vertical component of the neutral wind velocity is obtained by means of a numerical solution of a generalized Navier-Stokes equation for compressible gas, so the hydrostatic equation is not applied. The simulation results indicate that solar activity ought to influence considerably on the formation of global neutral wind system in the mesosphere and lower thermosphere. The influence is conditioned by the vertical transport of air from the lower thermosphere to the mesosphere and stratosphere. This transport may be rather different under distinct solar activity conditions.

scholarly journals More evidence for a planetary wave link with midlatitude <i>E</i> region coherent backscatter and sporadic <i>E</i> layers

2000 ◽  
Vol 18 (9) ◽  
pp. 1182-1196 ◽  
Author(s):  
M. Voiculescu ◽  
C. Haldoupis ◽  
D. Pancheva ◽  
M. Ignat ◽  
K. Schlegel ◽  
...  
Keyword(s):  
Planetary Wave ◽  
Close Relation ◽  
Planetary Waves ◽  
Neutral Wind ◽  
Spectral Peaks ◽  
Direct Indication ◽  
E Region ◽  
Waves And Tides ◽  
Coherent Backscatter

Abstract. Measurements of midlatitude E region coherent backscatter obtained during four summers with SESCAT, a 50 MHz Doppler system operating in Crete, Greece, and concurrent ionosonde recordings from the same ionospheric volume obtained with a CADI for one of these summers, are used to analyse the long-term variability in echo and Es occurrence. Echo and Es layer occurrences, computed in percent of time over a 12-h nighttime interval, take the form of time sequences. Linear power spectrum analysis shows that there are dominant spectral peaks in the range of 2–9 days, the most commonly observed periods appearing in two preferential bands, of 2–3 days and 4–7 days. No connection with geomagnetic activity was found. The characteristics of these periodicities compare well with similar properties of planetary waves, which suggests the possibility that planetary waves are responsible for the observed long-term periodicities. These findings indicate also a likely close relation between planetary wave (PW) activity and the well known but not well understood seasonal Es dependence. To test the PW postulation, we used simultaneous neutral wind data from the mesopause region around 95 km, measured from Collm, Germany. Direct comparison of the long-term periodicities in echo and Es layer occurrence with those in the neutral wind show some reasonable agreement. This new evidence, although not fully conclusive, is the first direct indication in favour of a planetary wave role on the unstable midlatitude E region ionosphere. Our results suggest that planetary waves observation is a viable option and a new element into the physics of midlatitude Es layers that needs to be considered and investigated.Key words: Ionosphere (ionosphere irregularities; mid-latitude ionosphere) – Meteorology and atmospheric dynamics (waves and tides)

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.

The upper atmospheric responses to tidal and planetary waves

2020 ◽  
Author(s):  
Sheng-Yang Gu
Keyword(s):  
Planetary Wave ◽  
Lower Thermosphere ◽  
Satellite System ◽  
Planetary Waves ◽  
Spatial Structures ◽  
Ionospheric Effect ◽  
Ion Drift ◽  
E Region ◽  
Mesosphere And Lower Thermosphere ◽  
Tide Interaction

&lt;p&gt;Tidal and planetary waves (PWs) in the mesosphere and lower thermosphere region could have significant impact on the upper thermosphere/ionosphere system through direct propagations, E region wind dynamo, and the change of residual circulations. We would like to show some results from BeiDou and COSMIC observations, as well as TIME-GCM simulations, to illustrate the lower/upper atmospheric couplings through different mechanisms. Generally, the spatial structures of the ionospheric responses to planetary waves agree with the ionospheric fountain effect, which indicates the important roles of equatorial wind dynamos in transmitting planetary wave signals to the ionosphere. The TIME-GCM simulations show that the zonal and meridional components of the planetary waves could result in evident vertical ion drift perturbations, while the net ionospheric effect is related to both their latitudinal structures and phases. The simulations also show that the change of tidal amplitudes and secondary PWs generated by PW-tide interaction are also important to the ionospheric variabilities. Besides, the couplings through PW-induced residual circulations are exhibited by both model simulations and TEC observations from BeiDou satellite system.&lt;/p&gt;

scholarly journals Sequential observations of the local neutral wind field structure associated with E region plasma layers

2005 ◽  
Vol 110 (A4) ◽  
Author(s):  
R. L. Bishop ◽  
G. D. Earle ◽  
M. F. Larsen ◽  
C. M. Swenson ◽  
C. G. Carlson ◽  
...  
Keyword(s):  
Wind Field ◽  
Field Structure ◽  
Neutral Wind ◽  
E Region ◽  
Region Plasma

scholarly journals The MaCWAVE program to study gravity wave influences on the polar mesosphere

2006 ◽  
Vol 24 (4) ◽  
pp. 1159-1173 ◽  
Author(s):  
R. A. Goldberg ◽  
D. C. Fritts ◽  
F. J. Schmidlin ◽  
B. P. Williams ◽  
C. L. Croskey ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Large Scale ◽  
Planetary Wave ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Wave Structure ◽  
Wave Activity ◽  
Small Scale ◽  
Mountain Waves ◽  
The Mean

Abstract. MaCWAVE (Mountain and Convective Waves Ascending VErtically) was a highly coordinated rocket, ground-based, and satellite program designed to address gravity wave forcing of the mesosphere and lower thermosphere (MLT). The MaCWAVE program was conducted at the Norwegian Andøya Rocket Range (ARR, 69.3° N) in July 2002, and continued at the Swedish Rocket Range (Esrange, 67.9° N) during January 2003. Correlative instrumentation included the ALOMAR MF and MST radars and RMR and Na lidars, Esrange MST and meteor radars and RMR lidar, radiosondes, and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) satellite measurements of thermal structures. The data have been used to define both the mean fields and the wave field structures and turbulence generation leading to forcing of the large-scale flow. In summer, launch sequences coupled with ground-based measurements at ARR addressed the forcing of the summer mesopause environment by anticipated convective and shear generated gravity waves. These motions were measured with two 12-h rocket sequences, each involving one Terrier-Orion payload accompanied by a mix of MET rockets, all at ARR in Norway. The MET rockets were used to define the temperature and wind structure of the stratosphere and mesosphere. The Terrier-Orions were designed to measure small-scale plasma fluctuations and turbulence that might be induced by wave breaking in the mesosphere. For the summer series, three European MIDAS (Middle Atmosphere Dynamics and Structure) rockets were also launched from ARR in coordination with the MaCWAVE payloads. These were designed to measure plasma and neutral turbulence within the MLT. The summer program exhibited a number of indications of significant departures of the mean wind and temperature structures from ``normal" polar summer conditions, including an unusually warm mesopause and a slowing of the formation of polar mesospheric summer echoes (PMSE) and noctilucent clouds (NLC). This was suggested to be due to enhanced planetary wave activity in the Southern Hemisphere and a surprising degree of inter-hemispheric coupling. The winter program was designed to study the upward propagation and penetration of mountain waves from northern Scandinavia into the MLT at a site favored for such penetration. As the major response was expected to be downstream (east) of Norway, these motions were measured with similar rocket sequences to those used in the summer campaign, but this time at Esrange. However, a major polar stratospheric warming just prior to the rocket launch window induced small or reversed stratospheric zonal winds, which prevented mountain wave penetration into the mesosphere. Instead, mountain waves encountered critical levels at lower altitudes and the observed wave structure in the mesosphere originated from other sources. For example, a large-amplitude semidiurnal tide was observed in the mesosphere on 28 and 29 January, and appears to have contributed to significant instability and small-scale structures at higher altitudes. The resulting energy deposition was found to be competitive with summertime values. Hence, our MaCWAVE measurements as a whole are the first to characterize influences in the MLT region of planetary wave activity and related stratospheric warmings during both winter and summer.

scholarly journals Tracing Primordial Magnetic Fields with 21 cm Line Observations

Galaxies ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 37 ◽  
Author(s):  
Kerstin Kunze
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Cosmic Microwave Background ◽  
Large Scale ◽  
Numerical Solutions ◽  
Gaussian Random Field ◽  
Microwave Background ◽  
Matter Power Spectrum ◽  
Primordial Magnetic Fields ◽  
The Universe

Magnetic fields are observed on a large range of scales in the universe. Up until recently, the evidence always pointed to magnetic fields associated with some kind of structure, from planets to clusters of galaxies. Blazar observations have been used to posit the first evidence of truly cosmological magnetic fields or void magnetic fields. A cosmological magnetic field generated in the very early universe before recombination has implications for the cosmic microwave background (CMB), large scale structure as well as the 21 cm line signal. In particular, the Lorentz term causes a change in the linear matter power spectrum. Its implication on the 21 cm line signal was the focus of our recent simulations which will be summarised here. Modelling the cosmological magnetic field as a gaussian random field numerical solutions were found for magnetic fields with present day amplitudes of 5 nG and negative spectral indices which are within the range of observational constraints imposed by the cosmic microwave background (CMB).

Plasma and magnetic field conditions during radar blackouts at Mars.

2021 ◽  
Author(s):  
Mark Lester ◽  
Beatriz Sanchez-Cano ◽  
Hermann Opgenoorth
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Solar Zenith Angle ◽  
Field Conditions ◽  
Local Times ◽  
Plasma Transport ◽  
Interplanetary Coronal Mass Ejections ◽  
Plasma System ◽  
Operational Frequency ◽  
Using Data

&lt;p&gt;Large scale solar wind disturbances such as Interplanetary Coronal Mass Ejections (ICMEs) have a major impact on planetary systems.&amp;#160; At Mars, for example, Solar Energetic Particles released during the process that creates the ICME cause large scale radar blackouts as a result of enhanced ionisation at lower altitudes than normal.&amp;#160; The increased absorption of the radar signals can last for up to 10 &amp;#8211; 12 days, depending on the operational frequency of the radar.&amp;#160; These events occur at all latitudes and local times but there does appear to be a peak in occurrence at a solar zenith angle of about 160o, i.e. deep in the tail of the Martian plasma system. Using data from MAVEN, Mars Express and Mars Reconnaissance Orbiter we investigate the background plasma&amp;#160; and magnetic field conditions, which occur at the same time as these events to investigate how the SEP impact on the nightside atmosphere.&amp;#160; This will provide crucial evidence for plasma transport in the Martian system, in particular during the passage of ICMEs.&lt;/p&gt;

scholarly journals Magnetohydrodynamic stability of large scale liquid metal batteries

2018 ◽  
Vol 852 ◽  
pp. 453-483 ◽  
Author(s):  
A. Tucs ◽  
V. Bojarevics ◽  
K. Pericleous
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Numerical Solutions ◽  
Practical Interest ◽  
Electrolysis Cell ◽  
Stability Estimates ◽  
Vertical Magnetic Field ◽  
Regular Perturbation ◽  
Conductive Liquid ◽  
Coupled Equations

The aim of this paper is to develop a stability theory and a numerical model for three density-stratified electrically conductive liquid layers. Using regular perturbation methods to reduce the full three-dimensional problem to the shallow layer model, the coupled wave and electric current equations are derived. The problem set-up allows for weakly nonlinear velocity field action and an arbitrary vertical magnetic field. Further linearisation of the coupled equations is used for the linear stability analysis in the case of a uniform vertical magnetic field. New analytical stability criteria accounting for the viscous damping are derived for particular cases of practical interest and compared to the numerical solutions for a variety of materials used in batteries. These new criteria are equally applicable to the aluminium electrolysis cell magnetohydrodynamic (MHD) stability estimates.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

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