scholarly journals Interaction of plasma cloud with external electric field in lower ionosphere

2010 ◽  
Vol 28 (3) ◽  
pp. 719-736 ◽  
Author(s):  
Y. S. Dimant ◽  
M. M. Oppenheim
Keyword(s):  
Electric Fields ◽  
Large Scale ◽  
Three Dimensional ◽  
Lower Ionosphere ◽  
Ionosphere Plasma ◽  
Sporadic E Layers ◽  
D Region ◽  
Mhd Modeling ◽  
Sporadic E ◽  
Meteor Plasma

Abstract. In the auroral lower-E and upper-D region of the ionosphere, plasma clouds, such as sporadic-E layers and meteor plasma trails, occur daily. Large-scale electric fields, created by the magnetospheric dynamo, will polarize these highly conducting clouds, redistributing the electrostatic potential and generating anisotropic currents both within and around the cloud. Using a simplified model of the cloud and the background ionosphere, we develop the first self-consistent three-dimensional analytical theory of these phenomena. For dense clouds, this theory predicts highly amplified electric fields around the cloud, along with strong currents collected from the ionosphere and circulated through the cloud. This has implications for the generation of plasma instabilities, electron heating, and global MHD modeling of magnetosphere-ionosphere coupling via modifications of conductances induced by sporadic-E clouds.

scholarly journals Wavelength dependence of the linear growth rate of the <I>E<sub>s</sub></I> layer instability

2007 ◽  
Vol 25 (6) ◽  
pp. 1311-1322 ◽  
Author(s):  
R. B. Cosgrove
Keyword(s):  
Growth Rate ◽  
Electric Fields ◽  
Large Scale ◽  
Linear Growth ◽  
Three Dimensional ◽  
Generalized Derivation ◽  
Wavelength Dependence ◽  
Meridional Wind ◽  
Linear Growth Rate ◽  
Significant Wavelength

Abstract. It has recently been shown, by computation of the linear growth rate, that midlatitude sporadic-E (Es) layers are subject to a large scale electrodynamic instability. This instability is a logical candidate to explain certain frontal structuring events, and polarization electric fields, which have been observed in Es layers by ionosondes, by coherent scatter radars, and by rockets. However, the original growth rate derivation assumed an infinitely thin Es layer, and therefore did not address the short wavelength cutoff. Also, the same derivation ignored the effects of F region loading, which is a significant wavelength dependent effect. Herein is given a generalized derivation that remedies both these short comings, and thereby allows a computation of the wavelength dependence of the linear growth rate, as well as computations of various threshold conditions. The wavelength dependence of the linear growth rate is compared with observed periodicities, and the role of the zeroth order meridional wind is explored. A three-dimensional paper model is used to explain the instability geometry, which has been defined formally in previous works.

scholarly journals 50 MHz continuous wave interferometer observations of the unstable mid-latitude E-region ionosphere

2003 ◽  
Vol 21 (7) ◽  
pp. 1589-1600 ◽  
Author(s):  
C. Haldoupis ◽  
A. Bourdillon ◽  
A. Kamburelis ◽  
G. C. Hussey ◽  
J. A. Koehler
Keyword(s):  
Electric Fields ◽  
Continuous Wave ◽  
Isotropic Turbulence ◽  
Doppler Radar ◽  
Active Regions ◽  
Field Of View ◽  
Ionosphere Plasma ◽  
First Results ◽  
Sporadic E

Abstract. In this paper we describe the conversion of SESCAT (Sporadic-E SCATter experiment), a bistatic 50 MHz continuous wave (CW) Doppler radar located on the island of Crete, Greece, to a single (east-west) baseline interferometer. The first results show that SESCAT, which provides high quality Doppler spectra and excellent temporal resolution, has its measurement capabilities enhanced significantly when operated as an interferometer, as it can also study short-term dynamics of localized scattering regions within mid-latitude sporadic E-layers. The interferometric observations reveal that the aspect sensitive area viewed by the radar often contains a few zonally located backscatter regions, presumably blobs or patches of unstable metallic ion plasma, which drift across the radar field-of-view with the neutral wind. On average, these active regions of backscatter have mean zonal scales ranging from a few kilometers to several tens of kilometers and drift with westward speeds from ~ 20 m/s to 100 m/s, and occasionally up to 150 m/s. The cross-spectral analysis shows that mid-latitude type 1 echoes occur much more frequently than has been previously assumed and they originate in single and rather localized areas of elevated electric fields. On the other hand, typical bursts of type 2 echoes are often found to result from two adjacent regions in azimuth undergoing the same bulk motion westwards but producing scatter of opposite Doppler polarity, a fact that contradicts the notion of isotropic turbulence to which type 2 echoes are attributed. Finally, quasi-periodic (QP) echoes are observed simply to be due to sequential unstable plasma patches or blobs which traverse across the radar field-of-view, sometimes in a wave-like fashion.Key words. Ionosphere (ionospheric irregularities; mid-latitude ionosphere; plasma waves and instabilities)

scholarly journals Long term trends in sporadic E layers and electric fields over Fortaleza, Brazil

1996 ◽  
Vol 23 (7) ◽  
pp. 757-760 ◽  
Author(s):  
M. A. Abdu ◽  
I. S. Batista ◽  
P. Muralikrishna ◽  
J. H. A Sobral
Keyword(s):  
Electric Fields ◽  
Sporadic E Layers ◽  
Long Term Trends ◽  
Sporadic E

scholarly journals Interhemispheric transport of metallic ions within ionospheric sporadic E layers by the lower thermospheric meridional circulation

2020 ◽  
Author(s):  
Bingkun Yu ◽  
Xianghui Xue ◽  
Christopher J. Scott ◽  
Jianfei Wu ◽  
Xinan Yue ◽  
...  
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Meridional Circulation ◽  
Strong Support ◽  
Metallic Ions ◽  
Meridional Transport ◽  
Summer Circulation ◽  
Sporadic E Layers ◽  
Sporadic E ◽  
Interhemispheric Transport

Abstract. Long-lived metallic ions in the Earth's atmosphere/ionosphere have been investigated for many decades. Although the seasonal variation in ionospheric sporadic E layers was first observed in the 1960s, the mechanism driving the variation remains a long-standing mystery. Here we report a study of ionospheric irregularities using scintillation data from COSMIC satellites and identify a large-scale horizontal transport of long-lived metallic ions, combined with the simulations of the Whole Atmosphere Community Climate Model with the chemistry of metals and ground-based observations from two meridional chains of stations from 1975–2016. We find that the lower thermospheric meridional circulation influences the meridional transport and seasonal variations of metallic ions within sporadic E layers. The winter-to-summer, meridional velocity of ions is estimated to vary between −1.08 and 7.45 m/s at altitudes of 107–118 km between 10°–60° N latitude. Our results not only provide strong support for the lower thermospheric meridional circulation predicted by a whole atmosphere chemistry-climate model, but also emphasise the influences of this winter-to-summer circulation on the large-scale interhemispheric transport of composition in the thermosphere/ionosphere.

scholarly journals Competition between winds and electric fields in the formation of blanketing sporadic E layers at equatorial regions

2016 ◽  
Vol 68 (1) ◽  
Author(s):  
Laysa Cristina Araújo Resende ◽  
Inez Staciarini Batista ◽  
Clezio Marcos Denardini ◽  
Alexander José Carrasco ◽  
Vânia de Fátima Andrioli ◽  
...  
Keyword(s):  
Electric Fields ◽  
Sporadic E Layers ◽  
Sporadic E

scholarly journals First simulations of day-to-day variability of mid-latitude sporadic E layer structures

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Satoshi Andoh ◽  
Akinori Saito ◽  
Hiroyuki Shinagawa ◽  
Mitsumu K. Ejiri
Keyword(s):  
Three Dimensional ◽  
Lower Ionosphere ◽  
Atmospheric Tides ◽  
Ionospheric Model ◽  
Radio Waves ◽  
Metallic Ions ◽  
Long Distance ◽  
Distance Communication ◽  
Sporadic E ◽  
Realistic Information

Abstract We present the first simulations that successfully reproduce the day-to-day variability of the mid-latitude sporadic E ($$E_s$$ E s ) layers. $$E_s$$ E s layers appearing in the lower ionosphere have been extensively investigated to monitor and forecast their effects on long-distance communication by radio waves. Although it is widely accepted that the atmospheric tides are important in generating the $$E_s$$ E s layers, no simulations to date have reproduced the $$E_s$$ E s layers observed on a certain day. This is due to the lack of the combination of realistic information on the atmospheric tides in the lower ionosphere and a three-dimensional numerical ionospheric model that can simulate the precise transport of metallic ions. We developed a numerical ionospheric model coupled with the neutral winds from the GAIA (Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy). The fundamental structures and the day-to-day variations of the $$E_s$$ E s layers observed by a $$\hbox {Ca}^+$$ Ca + lidar are well-reproduced in the simulations.

scholarly journals Observation of electron biteout regions below sporadic E layers at polar latitudes

2015 ◽  
Vol 33 (3) ◽  
pp. 371-380 ◽  
Author(s):  
G. A. Lehmacher ◽  
M. F. Larsen ◽  
C. L. Croskey
Keyword(s):  
Electric Fields ◽  
Sounding Rockets ◽  
Ion Drift ◽  
Sporadic E Layers ◽  
New Process ◽  
Combined Action ◽  
Sporadic E Layer ◽  
Sporadic E ◽  
Chemical Releases ◽  
Trimethyl Aluminum

Abstract. The descent of a narrow sporadic E layer near 95 km altitude over Poker Flat Research Range in Alaska was observed with electron probes on two consecutive sounding rockets and with incoherent scatter radar during a 2 h period near magnetic midnight. A series of four trimethyl aluminum chemical releases demonstrated that the Es layer remained just slightly above the zonal wind node, which was slowly descending due to propagating long-period gravity waves. The location of the layer is consistent with the equilibrium position due to combined action of the wind shear and electric fields. Although the horizontal electric field could not be measured directly, we estimate that it was ~ 2 mV m−1 southward, consistent with modeling the vertical ion drift, and compatible with extremely quiet conditions. Both electron probes observed deep biteout regions just below the Es enhancements, which also descended with the sporadic layers. We discuss several possibilities for the cause of these depletions; one possibility is the presence of negatively charged, nanometer-sized mesospheric smoke particles. Such particles have recently been detected in the upper mesosphere, but not yet in immediate connection with sporadic E. Our observations of electron depletions suggest a new process associated with sporadic E.

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)

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