scholarly journals E- and F-region coupling between an intense sporadic E layer and a mesoscale traveling ionospheric disturbance

2009 ◽  
Vol 27 (6) ◽  
pp. 2475-2482 ◽  
Author(s):  
W. E. Swartz ◽  
M. C. Kelley ◽  
N. Aponte
Keyword(s):  
Electric Fields ◽  
Ionospheric Disturbance ◽  
Type I ◽  
Data Set ◽  
Coherent Scatter ◽  
F Region ◽  
Scatter Radar ◽  
Considerable Controversy ◽  
Sporadic E Layer ◽  
Sporadic E

Abstract. Considerable controversy exists concerning the relative roles of the E- and F-regions in controlling irregularity formation in the mid-latitude ionosphere, largely because electric fields due to a plasma instability in one region may map to the other if the perpendicular scales are sufficiently large. In this paper we look at a particularly fortuitous data set in which both E- and F-region observations were made using incoherent scatter radar, GPS, lidar, and coherent scatter radar. In this event, a dense, patchy sporadic E layer was detected that exhibited type I (two-stream) coherent echoes while, at the same time, the F-layer plasma was highly structured with plasma drifts of hundreds of m/s. We examine this event in the context of a mesoscale traveling ionospheric disturbance. The data presentation will be followed by comparison with current theories for coupling between these two regions.

scholarly journals Equatorial E Region Electric Fields and Sporadic E Layer Responses to the Recovery Phase of the November 2004 Geomagnetic Storm

2017 ◽  
Vol 122 (12) ◽  
pp. 12,517-12,533 ◽  
Author(s):  
J. Moro ◽  
L. C. A. Resende ◽  
C. M. Denardini ◽  
J. Xu ◽  
I. S. Batista ◽  
...  
Keyword(s):  
Geomagnetic Storm ◽  
Electric Fields ◽  
Recovery Phase ◽  
E Region ◽  
Sporadic E Layer ◽  
Sporadic E

scholarly journals Morphological aspects of a new type of counter electrojet event

1999 ◽  
Vol 17 (2) ◽  
pp. 210-219 ◽  
Author(s):  
R. G. Rastogi
Keyword(s):  
Electric Fields ◽  
Current System ◽  
Equatorial Ionosphere ◽  
Geomagnetic Disturbances ◽  
Counter Electrojet ◽  
F Region ◽  
New Type ◽  
Northern Winter ◽  
Sporadic E ◽  
Electric Fields And Currents

Abstract. The study describes the time and space morphologies of a rather new type of counter electrojet event on the basis of data from the excellent chain of magnetic and ionospheric observatories along the Indo-Russian longitude sector. Abnormally large westward currents are observed during almost the whole of the daytime hours on a series of days. These events do not form any vortices in the current system and do not apparently seem to be associated with tidal effects or any solar magnetosphere events or geomagnetic disturbances. The existence of a westward electric field over the equatorial ionosphere has been confirmed by the absence of an equatorial type of sporadic E in the ionograms at Thumba precisely during the periods when ∆H at Trivandrum minus ∆H at Alibag is negative. The equatorial F region anomaly was also absent on the counter electrojet day. Such counter electrojet events during the northern winter months of low solar activity years are suggested to be the result of the modified wind system in the ionosphere associated with stratospheric warming events.Key words. Geomagnetism and paleomagnetism (time variations · diurnal to secular) · Ionosphere (electric fields and currents; equatorial ionosphere)

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)

scholarly journals Artificial E-region field-aligned plasma irregularities generated at pump frequencies near the second electron gyroharmonic

2009 ◽  
Vol 27 (7) ◽  
pp. 2711-2720 ◽  
Author(s):  
D. L. Hysell ◽  
E. Nossa
Keyword(s):  
Plasma Density ◽  
Hybrid Wave ◽  
Pump Frequency ◽  
Coherent Scatter ◽  
Wave Trapping ◽  
Plasma Irregularities ◽  
Ionospheric Modification ◽  
E Region ◽  
Sporadic E Layer ◽  
Sporadic E

Abstract. E region ionospheric modification experiments have been performed at HAARP using pump frequencies about 50 kHz above and below the second electron gyroharmonic frequency. Artificial E region field-aligned plasma density irregularities (FAIs) were created and observed using the imaging coherent scatter radar near Homer, Alaska. Echoes from FAIs generated with pump frequencies above and below 2Ωe did not appear to differ significantly in experiments conducted on summer afternoons in 2008, and the resonance instability seemed to be at work in either case. We argue that upper hybrid wave trapping and resonance instability at pump frequencies below the second electron gyroharmonic frequency are permitted theoretically when the effects of finite parallel wavenumbers are considered. Echoes from a sporadic E layer were observed to be somewhat weaker when the pump frequency was 50 kHz below the second electron gyroharmonic frequency. This may indicate that finite parallel wavenumbers are inconsistent with wave trapping in thin sporadic E ionization layers.

scholarly journals Tidal variations in the high-latitude E- and F-region observed by EISCAT

1996 ◽  
Vol 14 (2) ◽  
pp. 201-210 ◽  
Author(s):  
Klemens Hocke
Keyword(s):  
Electron Density ◽  
Electric Fields ◽  
Lower Thermosphere ◽  
Data Set ◽  
Density Spectrum ◽  
F Region ◽  
Temperature Oscillations ◽  
Long Time ◽  
E Region ◽  
Tidal Variations

Abstract. During the MLTCS (Mesosphere-Lower Thermosphere Coupling Study) campaign the EISCAT UHF radar was continuously operated over 7 days (30 July–5 August 1992) in the CP-1 mode. The long time series obtained of the fundamental ionospheric parameters field-aligned ion velocity (Vi), ion and electron temperature (T and Te), and electron density (Ne) are useful in investigating tidal variations in the E- and F-region since the geomagnetic activity was particularly low during the time of measurement. Maximum entropy spectra of the parameters were calculated for the relatively quiet interval from 1 August to 4 August 1992 and indicated dominant variations with harmonics of 24 hours. In the electron density spectrum especially, harmonics up to the sixth order (4-h period) are clearly visible. The phase and amplitude height profiles (100–450 km) of the diurnal, semidiurnal, and terdiurnal variations were determined by Fourier transform for a 24-h data set beginning at 12:00 UT on 3 August 1992 when the contaminating influences of electric fields were negligible. The tidal variations of the ion temperatures are compared with the corresponding variations of the neutral temperature predicted by the MSISE-90 model. A remarkable result is the dominance of terdiurnal temperature oscillations at E-region heights on 3–4 August 1992, while the measured diurnal and semidiurnal variations were negligible. The finding was confirmed by the analysis of further EISCAT data (2–3 August 1989, 2–3 July 1990, 31 March–1 April 1992) which also showed a dominant terdiurnal temperature tide in the E-region. This is different from numerous observations of tides in the E-region at mid-latitudes where the diurnal and especially the semidiurnal temperature oscillations were dominant.

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