On the Necessity of Using foμEs Instead of Foes in Estimating The Intensity and Variability of Sporadic E Layers

2020 ◽  
Author(s):  
Christos Haldoupis ◽  
Haris Haralambous ◽  
Chris Meek
Keyword(s):  
Sporadic E Layers ◽  
Sporadic E

scholarly journals Midnight variations of spreading of ionospheric sporadic E-layers before earthquakes

2012 ◽  
Vol 55 (1) ◽  
Author(s):  
Elena V. ◽  
Alexandra S. ◽  
Victor A. ◽  
Claudia-Veronika Meister ◽  
Dieter H.H. ◽  
...  
Keyword(s):  
Sporadic E Layers ◽  
Sporadic E

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 Coincident extremely large sporadic sodium and sporadic E layers observed in the lower thermosphere over Colorado and Utah

2007 ◽  
Vol 25 (1) ◽  
pp. 3-8 ◽  
Author(s):  
B. P. Williams ◽  
F. T. Berkey ◽  
J. Sherman ◽  
C. Y. She
Keyword(s):  
North America ◽  
Layer Structure ◽  
Lower Thermosphere ◽  
Ion Density ◽  
Bear Lake ◽  
Sodium Layer ◽  
Sporadic E Layers ◽  
Fort Collins ◽  
Sporadic E ◽  
Wind Shears

Abstract. On the night of 2 June 2002, the sodium lidar in Fort Collins, CO (40.6 N, 105 W) measured an extremely strong sporadic sodium layer lasting from 03:30 to 05:00 UT with several weaker layers later in the night at 06:00 and 09:00 UT. There is a double layer structure with peaks at 101 and 104 km. The peak sodium density was 21 000 atoms/cm3 with a column abundance of up to twice that of the normal sodium layer. The peak density was 500 times greater than the typical density at that altitude. The sporadic layer abundance and strength factor were higher than any reported in the literature. The two lidar beams, separated by 70 km at this altitude, both measured 0.6 h periodicities in the abundance, but out of phase with each other by 0.3 h. There is also evidence for strong wave activity in the lidar temperatures and winds. The NOAA ionosonde in Boulder, CO (40.0 N, 105 W) measured a critical frequency (foEs) of 14.3 MHz at 03:00 UT on this night, the highest value anytime during 2002. The high values of total ion density inferred means that Na+ fraction must have been only a few percent to explain the neutral Na layer abundances. The Bear Lake, Utah (41.9 N, 111.4 W) dynasonde also measured intense Es between 02:00 and 05:00 UT and again from 06:00 to 08:00 UT about 700 km west of the lidar, with most of the ionograms during these intervals measuring Es up to 12 MHz, the limit of the ionosonde sweep. Other ionosondes around North America on the NGDC database measured normal foEs values that night, so it was a localized event within North America. The peak of Es activity observed in Europe during the summer of 2002 occurred on 4 June. The observations are consistent with the current theories where a combination of wind shears and long period waves form and push downward a concentrated layer of ions, which then chemically react and form a narrow layer of sodium atoms.

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

Density profiles of sporadic E-layers containing two metal ion species

1984 ◽  
Vol 46 (10) ◽  
pp. 885-893 ◽  
Author(s):  
T Nygrén ◽  
L Jalonen ◽  
A Huuskonen ◽  
T Turunen
Keyword(s):  
Metal Ion ◽  
Density Profiles ◽  
Sporadic E Layers ◽  
Sporadic E ◽  
Ion Species

scholarly journals Type-1 echoes from the mid-latitude E-Region ionosphere

1997 ◽  
Vol 15 (7) ◽  
pp. 908-917 ◽  
Author(s):  
C. Haldoupis ◽  
D. T. Farley ◽  
K. Schlegel
Keyword(s):  
Doppler Radar ◽  
Spectral Component ◽  
Equatorial Electrojet ◽  
Metallic Ions ◽  
Sporadic E Layers ◽  
E Region ◽  
Sporadic E ◽  
The Right

Abstract. This paper presents more data on the properties of type-1 irregularities in the nighttime mid-latitude E-region ionosphere. The measurements were made with a 50-MHz Doppler radar system operating in Crete, Greece. The type-1 echoes last from several seconds to a few minutes and are characterized by narrow Doppler spectra with peaks corresponding to wave phase velocities of 250–350 m/s. The average velocity of 285 m/s is about 20% lower than nominal E-region ion-acoustic speeds, probably because of the presence of heavy metallic ions in the sporadic-E-layers that appear to be associated with the mid-latitude plasma instabilities. Sometimes the type-1 echoes are combined with a broad spectrum of type-2 echoes; at other times they dominate the spectrum or may appear in the absence of any type-2 spectral component. We believe these echoes are due to the modified two-stream plasma instability driven by a polarization electric field that must be larger than 10 mV/m. This field is similar in nature to the equatorial electrojet polarization field and can arise when patchy nighttime sporadic-E-layers have the right geometry.

scholarly journals Seasonal variability and descent of mid-latitude sporadic E layers at Arecibo

2009 ◽  
Vol 27 (3) ◽  
pp. 923-931 ◽  
Author(s):  
N. Christakis ◽  
C. Haldoupis ◽  
Q. Zhou ◽  
C. Meek
Keyword(s):  
Lower Thermosphere ◽  
Time Base ◽  
Large Set ◽  
Seasonal Behavior ◽  
Incoherent Scatter ◽  
Electron Density Gradient ◽  
Sporadic E Layers ◽  
Sporadic E Layer ◽  
Sporadic E ◽  
Wind Shears

Abstract. Sporadic E layers (Es) follow regular daily patterns in variability and altitude descent, which are determined primarily by the vertical tidal wind shears in the lower thermosphere. In the present study a large set of sporadic E layer incoherent scatter radar (ISR) measurements are analyzed. These were made at Arecibo (Geog. Lat. ~18° N; Magnetic Dip ~50°) over many years with ISR runs lasting from several hours to several days, covering evenly all seasons. A new methodology is applied, in which both weak and strong layers are clearly traced by using the vertical electron density gradient as a function of altitude and time. Taking a time base equal to the 24-h local day, statistics were obtained on the seasonal behavior of the diurnal and semidiurnal tidal variability and altitude descent patterns of sporadic E at Arecibo. The diurnal tide, most likely the S(1,1) tide with a vertical wavelength around 25 km, controls fully the formation and descent of the metallic Es layers at low altitudes below 110 km. At higher altitudes, there are two prevailing layers formed presumably by vertical wind shears associated mainly with semidiurnal tides. These include: 1) a daytime layer starting at ~130 km around midday and descending down to 105 km by local midnight, and 2) a less frequent and weaker nighttime layer which starts prior to midnight at ~130 km, descending downwards at somewhat faster rate to reach 110 km by sunrise. The diurnal and semidiurnal-like pattern prevails, with some differences, in all seasons. The differences in occurrence, strength and descending speeds between the daytime and nighttime upper layers are not well understood from the present data alone and require further study.

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