Sporadic E-Region Ionization, ‘Spread F’, and the Twinkling of Radio Stars

Nature ◽  
1959 ◽  
Vol 183 (4672) ◽  
pp. 1382-1383 ◽  
Author(s):  
D. F. MARTYN
Keyword(s):  
Spread F ◽  
E Region ◽  
Sporadic E ◽  
Radio Stars

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

<p>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.</p><p>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°07'N; 11°46'E, 53.79N  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°37.7'N 13°22.5'E) show spread-F in the ionograms as well as sporadic-E layer occurrence.  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.</p><p> </p>

scholarly journals Multistation digisonde observations of equatorial spread F in South America

2004 ◽  
Vol 22 (9) ◽  
pp. 3145-3153 ◽  
Author(s):  
B. W. Reinisch ◽  
M. Abdu ◽  
I. Batista ◽  
G. S. Sales ◽  
G. Khmyrov ◽  
...  
Keyword(s):  
South America ◽  
Field Line ◽  
Magnetic Equator ◽  
Simple Correlation ◽  
Equatorial Spread F ◽  
F Region ◽  
Sporadic E Layers ◽  
Spread F ◽  
E Region ◽  
Sporadic E

Abstract. Directional ionogram and F-region drift observations were conducted at seven digisonde stations in South America during the COPEX campaign from October to December 2002. Five stations in Brazil, one in Argentina, and one in Peru, monitored the ionosphere across the continent to study the onset and development of F-region density depletions that cause equatorial spread F (ESF). New ionosonde techniques quantitatively describe the prereversal uplifting of the F layer at the magnetic equator and the eastward motion of the depletions over the stations. Three of the Brazilian stations were located along a field line with a 350-km apex over the equator to investigate the relation of the occurrence of ESF and the presence of sporadic E-layers at the two E-region intersections of the field line. No simple correlation was found.

scholarly journals Observational evidence for new instabilities in the midlatitude <i>E</i> and <i>F</i> region

2016 ◽  
Vol 34 (11) ◽  
pp. 927-941 ◽  
Author(s):  
David L. Hysell ◽  
Miguel Larsen ◽  
Michael Sulzer
Keyword(s):  
Dynamic Instability ◽  
Lower Thermosphere ◽  
Growth Time ◽  
F Region ◽  
Stable Conditions ◽  
Spread F ◽  
E Region ◽  
Sporadic E ◽  
The One ◽  
Arecibo Observatory

Abstract. Radar observations of the E- and F-region ionosphere from the Arecibo Observatory made during moderately disturbed conditions are presented. The observations indicate the presence of patchy sporadic E (Es) layers, medium-scale traveling ionospheric disturbances (MSTIDs), and depletion plumes associated with spread F conditions. New analysis techniques are applied to the dataset to infer the vector plasma drifts in the F region as well as vector neutral wind and temperature profiles in the E region. Instability mechanisms in both regions are evaluated. The mesosphere–lower-thermosphere (MLT) region is found to meet the conditions for neutral dynamic instability in the vicinity of the patchy Es layers even though the wind shear was relatively modest. An inversion in the MLT temperature profile contributed significantly to instability in the vicinity of one patchy layer. Of particular interest is the evidence for the conditions required for neutral convective instability in the lower-thermosphere region (which is usually associated with highly stable conditions) due to the rapid increase in temperature with altitude. A localized F-region plasma density enhancement associated with a sudden ascent up the magnetic field is shown to create the conditions necessary for convective plasma instability leading to the depletion plume and spread F. The growth time for the instability is short compared to the one described by [Perkins(1973)]. This instability does not offer a simple analytic solution but is clearly present in numerical simulations. The instability mode has not been described previously but appears to be more viable than the various mechanisms that have been suggested previously as an explanation for the occurrence of midlatitude spread F.

scholarly journals Eastward traverse of equatorial plasma plumes observed with the Equatorial Atmosphere Radar in Indonesia

2006 ◽  
Vol 24 (5) ◽  
pp. 1411-1418 ◽  
Author(s):  
S. Fukao ◽  
T. Yokoyama ◽  
T. Tayama ◽  
M. Yamamoto ◽  
T. Maruyama ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Time Modulation ◽  
West Sumatra ◽  
Plasma Plumes ◽  
Long Time ◽  
Spread F ◽  
E Region ◽  
Sporadic E ◽  
Magnetic Meridian ◽  
Atmospheric Gravity

Abstract. The zonal structure of radar backscatter plumes associated with Equatorial Spread F (ESF), probably modulated by atmospheric gravity waves, has been investigated with the Equatorial Atmosphere Radar (EAR) in West Sumatra, Indonesia (0.20° S, 100.32° E; dip latitude 10.1° S) and the FM-CW ionospheric sounders on the same magnetic meridian as the EAR. The occurrence locations and zonal distances of the ESF plumes were determined with multi-beam observations with the EAR. The ESF plumes drifted eastward while keeping distances of several hundred to a thousand kilometers. Comparing the occurrence of the plumes and the F-layer uplift measured by the FM-CW sounders, plumes were initiated within the scanned area around sunset only, when the F-layer altitude rapidly increased. Therefore, the PreReversal Enhancement (PRE) is considered as having a zonal variation with the scales mentioned above, and this variation causes day-to-day variability, which has been studied for a long time. Modulation of the underlying E-region conductivity by gravity waves, which causes inhomogeneous sporadic-E layers, for example, is a likely mechanism to determine the scale of the PRE.

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 Energetics and structure of the lower E region associated with sporadic E layer

2008 ◽  
Vol 26 (9) ◽  
pp. 2929-2936 ◽  
Author(s):  
K.-I. Oyama ◽  
K. Hibino ◽  
T. Abe ◽  
R. Pfaff ◽  
T. Yokoyama ◽  
...  
Keyword(s):  
Electric Field ◽  
Field Data ◽  
Magnetic Line ◽  
Height Range ◽  
Sounding Rockets ◽  
Main Structure ◽  
Irregular Structures ◽  
E Region ◽  
Sporadic E Layer ◽  
Sporadic E

Abstract. The electron temperature (Te), electron density (Ne), and two components of the electric field were measured from the height of 90 km to 150 km by one of the sounding rockets launched during the SEEK-2 campaign. The rocket went through sporadic E layer (Es) at the height of 102 km–109 km during ascent and 99 km–108 km during decent, respectively. The energy density of thermal electrons calculated from Ne and Te shows the broad maximum in the height range of 100–110 km, and it decreases towards the lower and higher altitudes, which implies that a heat source exists in the height region of 100 km–110 km. A 3-D picture of Es, that was drawn by using Te, Ne, and the electric field data, corresponded to the computer simulation; the main structure of Es is projected to a higher altitude along the magnetic line of force, thus producing irregular structures of Te, Ne and electric field in higher altitude.

scholarly journals Some Aspects of Gyro?Splitting in the Ionosphere

1962 ◽  
Vol 15 (1) ◽  
pp. 25 ◽  
Author(s):  
GG Bowman
Keyword(s):  
Geomagnetic Latitude ◽  
Mode Propagation ◽  
E Region ◽  
Sporadic E

Ionograms for Hobart (geomagnetic latitude 52 oS.), showing x-mode propagation below the electron gyro frequency, were examined. Detailed analyses of some ionograms were made. Strong reflections for this particular propagation seem dependent on the amount of ionization, between the sporadic E level and 180 km, being reduced to a sufficiently low value. It is suggested that this can be achieved, in the sporadic E region, by the concentration of existing ionization; this concentration producing the sporadic E reflections.

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