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 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 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 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.

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 SEEK-2 (Sporadic-<i>E</i> Experiment over Kyushu 2) − Project Outline, and Significance

2005 ◽  
Vol 23 (7) ◽  
pp. 2295-2305 ◽  
Author(s):  
M. Yamamoto ◽  
S. Fukao ◽  
R. T. Tsunoda ◽  
R. Pfaff ◽  
H. Hayakawa
Keyword(s):  
Electric Field ◽  
Spatial Structure ◽  
Electric Fields ◽  
Density Profiles ◽  
Sounding Rockets ◽  
Optical Instruments ◽  
Observation Network ◽  
E Region ◽  
Sporadic E ◽  
Electron Density Profiles

Abstract. SEEK-2 (Sporadic-E Experiment over Kyushu 2) is an observation campaign to study the spatial structure of the field-aligned irregularity (FAI) and sporadic-E(Es)-layer by means of two sounding rockets and a ground-based observation network with radars and optical instruments. The experiment was successfully conducted on 3 August 2002, with successive launches of two sounding rockets from the Uchinoura Space Center (USC) of the Japan Aerospace Exploration Agency (JAXA). The timing of the experiment was carefully selected, while intense quasi-periodic (QP) echoes were observed with two radars in Tanegashima. The main Es-layer, with its double-layered structure, was observed at altitudes of 103–105 km, the presence of which was well accounted for by the ion accumulation due to neutral-wind shear. Several minor peaks were detected in the electron density profiles at altitudes of up to 130 km. The intensity of the electric field was 5–10 mV/m and showed intense fluctuations below 110 km. Wave-like variation of the electric field was seen above 110 km. From radar experiments, we found that QP echoes appeared around 105 km, which agreed well with the main Es-layer height. The QP echoes propagated to the west-northwest, with frontal structures elongated from north-northeast to south-southwest. Radar observations conduced throughout the SEEK-2 period, on the other hand, showed that frontal structures of the QP echoes were most frequently propagated to the southeast. This result was consistent with the direction of gravity-wave propagation observed with the OH imager during the same period. The rocket beacon experiment with the Es-layers revealed the spatial structure of the plasma densities. On the basis of these results and those from SEEK-1 in 1996, we examined the structures of the nighttime mid-latitude E-region. We concluded that the QP echoes reflect the horizontal structures of the main Es-layers. The source of the structures was not clearly determined from the experiments, but the candidates are gravity waves and the Kelvin-Helmholtz instability. The azimuth-dependent Es-instability may have contributed to enhance structures of the QP echoes, although this instability may not be a major source of the QP structure in SEEK-2. Polarization electric fields were induced from the Es-layer with QP echoes, mapped upward along the geomagnetic field, and played an important role in determining the structures of the whole ionospheric E-region. Keywords. Mid-latitude ionosphere – Ionospheric irregularities – Ionosphere-atmosphere interactions

scholarly journals Numerical prediction of sporadic E layer occurrence using GAIA

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Hiroyuki Shinagawa ◽  
Chihiro Tao ◽  
Hidekatsu Jin ◽  
Yasunobu Miyoshi ◽  
Hitoshi Fujiwara
Keyword(s):  
Space Weather ◽  
Coupled Model ◽  
Weather Forecast ◽  
Temporal Variations ◽  
Radio Communications ◽  
Prediction Scheme ◽  
Experimental Prediction ◽  
Sporadic E Layers ◽  
Sporadic E Layer ◽  
Sporadic E

AbstractA sporadic E layer has significant influence on radio communications and broadcasting, and predicting the occurrence of sporadic E layers is one of the most important issues in space weather forecast. While sporadic E layer occurrence and the magnitude of the critical sporadic E frequency (foEs) have clear seasonal variations, significant day-to-day variations as well as regional and temporal variations also occur. Because of the highly complex behavior of sporadic E layers, the prediction of sporadic E layer occurrence has been one of the most difficult issues in space weather forecast. To explore the possibility of numerically predicting sporadic E layer occurrence, we employed the whole atmosphere–ionosphere coupled model GAIA, examining parameters related to the formation of sporadic E layer such as vertical ions velocities and vertical ion convergences at different altitudes between 90 and 150 km. Those parameters in GAIA were compared with the observed foEs data obtained by ionosonde observations in Japan. Although the agreement is not very good in the present version of GAIA, the results suggest a possibility that sporadic E layer occurrence can be numerically predicted using the parameters derived from GAIA. We have recently developed a real-time GAIA simulation system that can predict atmosphere–ionosphere conditions for a few days ahead. We present an experimental prediction scheme and a preliminary result for predicting sporadic E layer occurrence.

scholarly journals Numerical prediction of sporadic E layer occurrence using GAIA

2020 ◽  
Author(s):  
Hiroyuki Shinagawa ◽  
Chihiro Tao ◽  
Hidekatsu Jin ◽  
Yasunobu Miyoshi ◽  
Hitoshi Fujiwara
Keyword(s):  
Space Weather ◽  
Coupled Model ◽  
Weather Forecast ◽  
Temporal Variations ◽  
Radio Communications ◽  
Prediction Scheme ◽  
Experimental Prediction ◽  
Sporadic E Layers ◽  
Sporadic E Layer ◽  
Sporadic E

Abstract A sporadic E layer has significant influence on radio communications and broadcasting, and predicting the occurrence of sporadic E layers is one of the most important issues in space weather forecast. While sporadic E layer occurrence and the magnitude of the critical sporadic E frequency ( foEs ) have clear seasonal variations, significant day-to-day variations as well as regional and temporal variations also occur. Because of the highly complex behavior of sporadic E layers, the prediction of sporadic E layer occurrence has been one of the most difficult issues in space weather forecast. To explore the possibility of numerically predicting sporadic E layer occurrence, we employed the whole atmosphere–ionosphere coupled model GAIA, examining parameters related to the formation of sporadic E layer such as vertical ions velocities and vertical ion convergences at different altitudes between 90 km and 150 km. By comparing those parameters in GAIA with observed foEs data obtained by ionosonde observations in Japan, we found that variations in the vertical ion convergence at 120 km altitude agree fairly well with variations in foEs . This result suggests that sporadic E layer occurrence can be numerically predicted using the parameters derived from GAIA. We have recently developed a real-time GAIA simulation system that can predict atmosphere–ionosphere conditions for a few days ahead. We present an experimental prediction scheme and a preliminary result for predicting sporadic E layer occurrence.

scholarly journals Modulation of sporadic E layers by small-scale atmospheric waves in Earth’s high-latitude ionosphere

2019 ◽  
Vol 5 (3) ◽  
pp. 116-129
Author(s):  
Владимир Губенко ◽  
Vladimir Gubenko ◽  
Иван Кириллович ◽  
Ivan Kirillovich
Keyword(s):  
High Latitude ◽  
Radio Occultation ◽  
Small Scale ◽  
Polar Cap ◽  
Atmospheric Waves ◽  
Sporadic E Layers ◽  
High Latitude Ionosphere ◽  
Sporadic E Layer ◽  
Sporadic E ◽  
Good Agreement

We have used radio occultation measurements of the satellite CHAMP (Challenging Minisatellite Payload) to examine sporadic E layers (altitudes 90–130 km) in Earth’s high-latitude ionosphere. We have developed a new method for determining characteristics of internal atmospheric waves based on the use of inclined sporadic E layers of Earth’s ionosphere as a detector. The method relies on the fact that an internal wave propagating through the initially horizontal sporadic E layer causes the plasma density gradient to rotate in the direction of the wave vector, which leads to the fact that the layer ionization plane is set parallel to the phase wave front. The developed method enables us to study the interrelations between small-scale internal waves and sporadic E layers in Earth’s ionosphere and significantly expands the capabilities of traditional radio occultation monitoring of the atmosphere. We have found that the internal atmospheric waves under study have periods from 35 to 46 min and vertical phase speeds from 1.2 to 2.0 m/s, which are in good agreement with the results of independent experiments and simulation data on sporadic E layers at a height of ~100 km in Earth’s polar cap.

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