Global distribution of neutral wind shear associated with sporadic E layers derived from GAIA

2017 ◽  
Vol 122 (4) ◽  
pp. 4450-4465 ◽  
Author(s):  
H. Shinagawa ◽  
Y. Miyoshi ◽  
H. Jin ◽  
H. Fujiwara
Keyword(s):  
Wind Shear ◽  
Global Distribution ◽  
Neutral Wind ◽  
Sporadic E Layers ◽  
Sporadic E

scholarly journals Sporadic E morphology based on COSMIC radio occultation data and its relationship with wind shear theory

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Jia Luo ◽  
Haifeng Liu ◽  
Xiaohua Xu
Keyword(s):  
Magnetic Field ◽  
Wind Shear ◽  
Radio Occultation ◽  
Field Model ◽  
Global Distribution ◽  
Cosmic Radio ◽  
Neutral Wind ◽  
Earth’S Magnetic Field ◽  
Low Altitude ◽  
Sporadic E

AbstractThe S4max data retrieved from the Constellation Observing System for the Meteorology, Ionosphere, and Climate (COSMIC) radio occultation (RO) measurements during 2007 to 2015 is adopted to investigate the global distribution and seasonal variation of the sporadic E (Es) layers in the present work. The long-term and short-term global Es occurrence maps are presented and the spatial and temporal distributions of Es occurrence rates (ORs) are further confirmed and studied. The International Geomagnetic Reference Field model (IGRF12) is used to calculate the horizontal intensity and inclination of the Earth’s magnetic field. The analysis shows that the Earth’s magnetic field is one of the fundamental reasons for the global distribution of the Es layers. In addition, the Horizontal Wind Field model HWM14 and the IGRF12 model were employed to calculate the vertical ion convergence (VIC) to examine the role of neutral wind shear in the global distribution of the Es ORs. The results reveal that the middle latitude distribution of simulated vertical concentration of Fe+ is similar to that of Es ORs, which indicates that the VIC induced by the neutral wind shear is an important factor in determining the geographical distribution, summer maximum (or winter minimum) and diurnal characteristics of Es ORs in middle latitudes. The new findings mainly include the following two aspects: (1) in summer over mid-latitudes, VIC peaks in the morning and afternoon to evening, which explains the semidiurnal behavior of Es ORs; (2) VIC reaches its minimum value in low-altitude (100 km) areas, which is the reason for the significant decrease in Es ORs in low-altitude areas. The disagreements between the VIC and Es ORs indicate that other processes, such as the meteor influx rate, the ionospheric electric fields and atmospheric tides, should also be considered as they may have an important impact on the variation of Es layers. Graphical Abstract

Tidal signatures in sporadic E occurrence rates - migrating and nonmigrating components, and comparison with neutral wind shear

2021 ◽  
Author(s):  
Christoph Jacobi ◽  
Kanykei Kandieva ◽  
Christina Arras
Keyword(s):  
Wind Shear ◽  
Signal To Noise Ratio ◽  
Ion Concentration ◽  
Vertical Shear ◽  
Neutral Wind ◽  
High Electron ◽  
Phase Measurements ◽  
Middle Latitudes ◽  
E Region ◽  
Sporadic E

<p>In the lower ionospheric E region, shallow regions of high electron density are found, which are called sporadic E (ES) layers. ES layers consist of thin clouds of accumulated ions. They occur mainly at middle latitudes, and they are most frequently found during the summer season. ES are generally formed at heights between 90 and 120 km. At midlatitudes, their occurrence can be described through the wind shear theory. According to this theory, ES formation is due to interaction between the metallic ion concentration, the Earth’s magnetic field, and the vertical shear of the neutral wind. Here, we analyze ES occurrence rates (OR) obtained from ionospheric radio occultation measurements by the FORMOSAT-3/COSMIC constellation. To derive information on ES from RO, we use the Signal-to-Noise ratio (SNR) profiles of the GPS L1 phase measurements. If large SNR standard deviation values occur that are concentrated within a layer of less than 10 km thickness, we assume that the respective SNR profile disturbance is owing to an ES layer.</p><p>Midlatitude ES are found to be mainly connected with a migrating diurnal and semidiurnal component. Especially at high latitudes of the southern hemisphere, nonmigrating components such as a diurnal westward wave 2 and a semidiurnal westward wave 1 are also visible. Near the equator, a strong diurnal eastward wavenumber 3 component and a semidiurnal eastward wavenumber 2 component are found in summer and autumn. Terdiurnal and quarterdiurnal components are weaker than the diurnal and semidiurnal ones. We discuss seasonal and global distributions of migrating and nonmigrating components, and their relation to neutral wind shear derived from ground-based observations and numerical modeling.</p>

scholarly journals Mid-latitude <i>E</i>-region bulk motions inferred from digital ionosonde and HF radar measurements

2004 ◽  
Vol 22 (11) ◽  
pp. 3789-3798 ◽  
Author(s):  
G. C. Hussey ◽  
C. Haldoupis ◽  
A. Bourdillon ◽  
J. Delloue ◽  
J. T. Wiensz
Keyword(s):  
Hf Radar ◽  
Neutral Wind ◽  
Angle Of Arrival ◽  
Neutral Winds ◽  
Sporadic E Layers ◽  
E Region ◽  
Radar Measurements ◽  
Sporadic E ◽  
Coherent Radar ◽  
Coherent Backscatter

Abstract. In the mid-latitude E-region there is now evidence suggesting that neutral winds play a significant role in driving the local plasma instabilities and electrodynamics inside sporadicE layers. Neutral winds can be inferred from coherent radar backscatter measurements of the range-/azimuth-time-intensity (RTI/ATI) striations of quasi-periodic (QP) echoes, or from radar interferometer/imaging observations. In addition, neutral winds in the E-region can be estimated from angle-of-arrival ionosonde measurements of sporadic-E layers. In the present paper we analyse concurrent ionosonde and HF coherent backscatter observations obtained when a Canadian Advanced Digital Ionosonde (CADI) was operated under a portion of the field-of-view of the Valensole high frequency (HF) radar. The Valensole radar, a mid-latitude radar located in the south of France with a large azimuthal scanning capability of 82° (24° E to 58° W), was used to deduce zonal bulk motions of QP echoing regions using ATI analysis. The CADI was used to measure angle-of-arrival information in two orthogonal horizontal directions and thus derive the motion of sporadic-E patches drifting with the neutral wind. This paper compares the neutral wind drifts of the unstable sporadic-E patches as determined by the two instruments. The CADI measurements show a predominantly westward aligned motion, but the measured zonal drifts are underestimated relative to those observed with the Valensole radar.

scholarly journals The role of electric field and neutral wind in the generation of polar cap sporadic E

2008 ◽  
Vol 26 (12) ◽  
pp. 3757-3763 ◽  
Author(s):  
T. Nygrén ◽  
M. Voiculescu ◽  
A. T. Aikio
Keyword(s):  
Electric Field ◽  
Driving Forces ◽  
Neutral Wind ◽  
Polar Cap ◽  
Sporadic E Layers ◽  
Sporadic E ◽  
In The Beginning ◽  
Model Formation ◽  
Good Agreement

Abstract. This paper investigates the roles of electric field and neutral wind in the generation of sporadic-E layers within the polar cap. Two Es layers above Svalbard, observed by the EISCAT Svalbard Radar (ESR), were chosen for investigation. The radar experiment contains four beam directions, and this was used for determining the electric field. The neutral wind was obtained from the HWM93 model. Formation of Es layers was calculated by integrating the continuity equation under the action of driving forces due to neutral wind and electric field. A flat height profile of metal ions was assumed in the beginning. The calculation gives the time variation of the layer, which can be compared with observations. In one case the electric field was shown to be the main driving agent in layer generation. In the other case the electric field was weak and the layer was produced mainly by the neutral wind, but the electric field had influence on the height of the layer. A fairly good agreement between the variations of the observed and calculated layer altitudes was obtained and some agreement between the intensity variations was also found.

Ion-acoustic instability caused by neutral wind action on sporadic E-layers

1998 ◽  
Vol 21 (6) ◽  
pp. 911-914 ◽  
Author(s):  
C.-V Meister ◽  
V.A Liperovsky ◽  
S.A Senchenkov
Keyword(s):  
Neutral Wind ◽  
Wind Action ◽  
Acoustic Instability ◽  
Sporadic E Layers ◽  
Ion Acoustic ◽  
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
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