The role of neutral winds and ionospheric electric field in forming stable sporadic E-layers

1976 ◽  
Vol 24 (5) ◽  
pp. 475-478 ◽  
Author(s):  
D. Rees ◽  
E.B. Dorling ◽  
K.H. Lloyd ◽  
C. Low
Keyword(s):  
Electric Field ◽  
Neutral Winds ◽  
Sporadic E Layers ◽  
Sporadic E ◽  
Ionospheric Electric Field

scholarly journals High resolution observations of sporadic-E layers within the polar cap ionosphere using a new incoherent scatter radar experiment

2002 ◽  
Vol 20 (9) ◽  
pp. 1429-1438 ◽  
Author(s):  
B. Damtie ◽  
T. Nygrén ◽  
M. S. Lehtinen ◽  
A. Huuskonen
Keyword(s):  
High Resolution ◽  
Electric Field ◽  
Single Layer ◽  
Meridional Wind ◽  
Two Phase ◽  
Range Resolution ◽  
Incoherent Scatter ◽  
Sporadic E Layers ◽  
Sporadic E ◽  
Ionospheric Electric Field

Abstract. High resolution observations of sporadic-E layers using a new experiment with the EISCAT (European Incoherent SCATter) Svalbard radar (ESR) are presented. The observations were made by means of a new type of hardware, which was connected in parallel with the standard receiver. The radar beam was aligned with the geomagnetic field. The experiment applies a new modulation principle. Two phase codes, one with 22 bits and the other with 5 bits, were transmitted at separate frequencies. Each bit was further modulated by a 5-bit Barker code. The basic bit length of both transmissions was 6 µs. Instead of storing the lagged products of the ionospheric echoes in the traditional way, samples of both the transmitted pulses and the ionospheric echoes were taken at intervals of 1 µs and stored on hard disk. The lagged products were calculated later in an off-line analysis. In the analysis a sidelobe-free Barker decoding technique was used. The experiment produces range ambiguities, which were removed by mathematical inversion. Sporadic-E layers were observed at 105–115 km altitudes, and they are displayed with a 150-m range resolution and a 10-s time resolution. The layers show sometimes complex shapes, including triple peaked structures. The thickness of these sublayers is of the order of 1–2 km and they may be separated by 5 km in range. While drifting downwards, the sublayers merge together to form a single layer. The plasma inside a layer is found to have a longer correlation length than that of the surrounding plasma. This may be an indication of heavy ions inside the layer. The field-aligned ion velocity is also calculated. It reveals shears in the meridional wind, which suggests that shears probably also exist in the zonal wind. Hence the wind shear mechanism is a possible generation mechanism of the layer. However, observations from the coherent SuperDARN radar indicate the presence of an ionospheric electric field pointing in the sector between west and north. Thus, the layer could also be produced by the electric field mechanism. This means that both mechanisms may be active simultaneously. Their relative importance could not be determined in this study.Key words. Ionosphere; polar ionosphere, instruments and techniques

scholarly journals <i>E</i>-region wind-driven electrical coupling of patchy sporadic-<i>E</i> and spread-<i>F</i> at midlatitude

2005 ◽  
Vol 23 (6) ◽  
pp. 2095-2105 ◽  
Author(s):  
S. Shalimov ◽  
C. Haldoupis
Keyword(s):  
Electric Fields ◽  
Electrical Coupling ◽  
Neutral Winds ◽  
Medium Scale ◽  
F Region ◽  
Sporadic E Layers ◽  
Spread F ◽  
Sporadic E ◽  
Electric Fields And Currents

Abstract. This paper investigates the role of neutral winds in the generation of relatively large polarization electric fields across patchy sporadic-E layers, which then map upward to the F region, to create conditions for medium-scale spread-F. The calculations are based on an analytical model that uses the current continuity equation and field-aligned current closures to the F region in order to describe quantitatively a Hall polarization process inside sporadic-E plasma patches during nighttime. In applying this model we use experimentally known values for E and F region, conductances, the ambient electric fields and prevailing neutral winds, in order to estimate the polarization fields that build up inside sporadic-E. It is found that the relatively strong west-southwest neutral winds during summer nighttime can provide the free energy for the generation of sizable polarization electric fields, which have comparable eastward and north-upward components and reach values of several mV/m. Given that the sporadic-E patches have sizes from a few to several tens of kilometers, the polarization fields can map easily to the F region bottomside where they impact ExB plasma uplifts and westward bulk motions, in line with key observational properties of medium-scale spread-F. However, the present simple model needs further development to also include wind forcing of the F region plasma and possible polarization processes inside spread-F. Keywords. Ionosphere (Electric fields and currents; Ionospheric irregularities; Mid-latitude ionosphere)

scholarly journals The role of electric field and neutral wind in the generation of polar cap sporadic E

2008 ◽  
Vol 26 (12) ◽  
pp. 3757-3763 ◽  
Author(s):  
T. Nygrén ◽  
M. Voiculescu ◽  
A. T. Aikio
Keyword(s):  
Electric Field ◽  
Driving Forces ◽  
Neutral Wind ◽  
Polar Cap ◽  
Sporadic E Layers ◽  
Sporadic E ◽  
In The Beginning ◽  
Model Formation ◽  
Good Agreement

Abstract. This paper investigates the roles of electric field and neutral wind in the generation of sporadic-E layers within the polar cap. Two Es layers above Svalbard, observed by the EISCAT Svalbard Radar (ESR), were chosen for investigation. The radar experiment contains four beam directions, and this was used for determining the electric field. The neutral wind was obtained from the HWM93 model. Formation of Es layers was calculated by integrating the continuity equation under the action of driving forces due to neutral wind and electric field. A flat height profile of metal ions was assumed in the beginning. The calculation gives the time variation of the layer, which can be compared with observations. In one case the electric field was shown to be the main driving agent in layer generation. In the other case the electric field was weak and the layer was produced mainly by the neutral wind, but the electric field had influence on the height of the layer. A fairly good agreement between the variations of the observed and calculated layer altitudes was obtained and some agreement between the intensity variations was also found.

scholarly journals The role of total wind in the vertical dynamics of ions in the E-region at high latitudes

2005 ◽  
Vol 23 (4) ◽  
pp. 1191-1197
Author(s):  
M. Voiculescu ◽  
M. Ignat
Keyword(s):  
Electric Field ◽  
Diurnal Variation ◽  
High Latitudes ◽  
Ion Dynamics ◽  
Convergence Conditions ◽  
Sporadic E Layers ◽  
E Region ◽  
Sporadic E ◽  
Spatial Locations

Abstract. A seasonally dependent total neutral wind model obtained from experimental data is used to evaluate the diurnal variation of the vertical ion velocity in the E-region at a high-latitude location (Tromsø), for each season, in the presence of an electric field with a typical diurnal variation for quiet auroral days. The diurnal variation and spatial locations of the vertical convergence of ions are analyzed and the effect of the total wind on the occurrence of sporadic E-layers is inferred. The results show that the structure of the wind is an important factor in controlling the vertical velocities of ions, favoring or hindering the sporadic E-layer formation. The ion convergence conditions are improved when the permanent wind is removed, which suggests that sporadic E-layers occur when the mean wind has small values, thus allowing the electric field and/or the semidiurnal tide to control the ion dynamics. We conclude that for quiet days the formation of the sporadic layers is initiated by the electric field, while their evolution and dynamics is controlled by the wind. We also find that the seasonal variation of the Es layers cannot be related to the seasonally dependent wind shear. Although we focus on sporadic E-layers, our results can be used in the analysis of other processes involving the vertical dynamics of ions in the E-region at high latitudes.

Investigation on the role of E-F region coupling processes on the generation of nighttime MSTIDs: Case studies over northern Germany

2021 ◽  
Author(s):  
Mani Sivakandan ◽  
Jorge L Chau ◽  
Carlos Martinis ◽  
Yuichi Otsuka ◽  
Jens Mielich ◽  
...  
Keyword(s):  
Gps Tec ◽  
F Region ◽  
Perkins Instability ◽  
Sporadic E Layers ◽  
Spread F ◽  
E Region ◽  
Sporadic E ◽  
Low Latitude Ionosphere ◽  
Atmospheric Gravity

&lt;p&gt;Northwest to southeast phase fronts with southwestward moving features are commonly observed in the nighttime midlatitude ionosphere during the solstice months at low solar activity. These features are identified as nighttime MSTIDs (medium scale traveling ionospheric disturbances). Initially, they were considered to be a manifestation of neutral atmospheric gravity waves. Later on, investigations showed that the nighttime MSTIDs are electrified in nature and mostly confined to the mid and low latitude ionosphere. Although the overall characteristics of the nighttime MSTIDs are mostly well understood, the causative mechanisms are not well known. Perkins instability mechanism was believed to be the cause of nighttime MSTIDs, however, the growth rate of the instability is too small to explain the perturbations observed. Recently, model simulations and observational studies suggest that coupling between sporadic-E layers and other type of E-region instabilities, and the F region may be relevant to explain the generation of the MSTIDs.&lt;/p&gt;&lt;p&gt;In the present study simultaneous observation from OI 630 nm all-sky airglow imager, GPS-TEC, ionosonde and Meteor radars, are used to investigate the role of E and F region coupling on the generation of MSTIDs .Nighttime MSTIDs observed on three nights (14 March 2020, 23 March 2020 and 28 May 2020) in the OI 630 nm airglow images over Kuehlungsborn (54&amp;#176;07'N; 11&amp;#176;46'E, 53.79N&amp;#160; mag latitude), Germany, are presented. Simultaneous detrended GPS-TEC measurements also shows presence of MSTIDs on these nights. In addition, simultaneous ionosonde observations over Juliusruh (54&amp;#176;37.7'N 13&amp;#176;22.5'E) show spread-F in the ionograms as well as sporadic-E layer occurrence.&amp;#160; Furthermore, we also investigate the MLT region wind variations during these nights. The role of Es-layers and the interplay between the winds and Es-layers role on the generation of the MSTIDs will be discussed in detail in this presentation.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Role of filament plasma remnants in ICMEs leading to geomagnetic storms

2013 ◽  
Vol 8 (S300) ◽  
pp. 493-494 ◽  
Author(s):  
Rahul Sharma ◽  
Nandita Srivastava ◽  
D. Chakrabarty
Keyword(s):  
Electric Field ◽  
Geomagnetic Storms ◽  
Interplanetary Coronal Mass Ejections ◽  
Plasma Dynamics ◽  
Terrestrial Magnetosphere ◽  
Auroral Substorms ◽  
Polarity Reversals ◽  
Ionospheric Electric Field ◽  
Filament Plasma

AbstractWe studied three interplanetary coronal mass ejections associated with solar eruptive filaments. Filament plasma remnants embedded in these structures were identified using plasma, magnetic and compositional signatures. These features when impacted the Earth's terrestrial magnetosphere - ionosphere system, resulted in geomagnetic storms. During the main phase of associated storms, along with high density plasma structures, polarity reversals in the Y-component (dawn-to-dusk) of the interplanetary electric field seem to trigger major auroral substorms with concomitant changes in the polar ionospheric electric field. Here, we examine the cases where plasma dynamics and magnetic structuring in the presence of the prompt penetration of the electric field into the equatorial ionosphere affected the space weather while highlighting the complex geomagnetic storm-substorm relationship.

scholarly journals Ionospheric conductivity effects on electrostatic field penetration into the ionosphere

2008 ◽  
Vol 8 (5) ◽  
pp. 1009-1017 ◽  
Author(s):  
V. V. Denisenko ◽  
M. Y. Boudjada ◽  
M. Horn ◽  
E. V. Pomozov ◽  
H. K. Biernat ◽  
...  
Keyword(s):  
Electric Field ◽  
Electrostatic Field ◽  
Night Time ◽  
Ionospheric Conductivity ◽  
Demeter Satellite ◽  
Classic Approach ◽  
Ionospheric Electric Field ◽  
Orbital Height ◽  
Field Penetration

Abstract. The classic approach to calculate the electrostatic field penetration, from the Earth's surface into the ionosphere, is to consider the following equation ∇·(σ·∇Φ)=0 where σ and Φ are the electric conductivity and the potential of the electric field, respectively. The penetration characteristics strongly depend on the conductivities of atmosphere and ionosphere. To estimate the electrostatic field penetration up to the orbital height of DEMETER satellite (about 700 km) the role of the ionosphere must be analyzed. It is done with help of a special upper boundary condition for the atmospheric electric field. In this paper, we investigate the influence of the ionospheric conductivity on the electrostatic field penetration from the Earth's surface into the ionosphere. We show that the magnitude of the ionospheric electric field penetrated from the ground is inverse proportional to the value of the ionospheric Pedersen conductance. So its typical value in day-time is about hundred times less than in night-time.

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