scholarly journals Day-to-day Variability of Field-Aligned Irregularities Occurrence in Nighttime F-region Ionosphere over the Equatorial Atmosphere Radar: A Combinatorics Analysis

2020 ◽  
Author(s):  
Dyah Rahayu Martiningrum ◽  
Mamoru Yamamoto ◽  
Rezy Pradipta
Keyword(s):  
F Region ◽  
Field Aligned Irregularities

scholarly journals Predicted and observed characteristics of small-scale field-aligned irregularities generated in the F-region by low power HF heating

2002 ◽  
Vol 20 (5) ◽  
pp. 647-653 ◽  
Author(s):  
E. Kolesnikova ◽  
T. R. Robinson ◽  
J. A. Davies
Keyword(s):  
Low Power ◽  
Decay Rate ◽  
Parametric Instability ◽  
Small Scale ◽  
F Region ◽  
Scale Field ◽  
Thermal Parametric Instability ◽  
Hf Heating ◽  
Heated Volume ◽  
Field Aligned Irregularities

Abstract. Simultaneous HF scattering from the different regions of the heated volume is used to investigate characteristics of the small-scale field-aligned irregularities in the F-region. Time of growth, decay rate and saturation level for different pump powers are deduced from the observations and are compared with their behaviour predicted by the thermal parametric instability model. As a result, the estimates of the density and of the temperature modifications inside of the irregularities are obtained.Key words. Ionosphere (ionospheric irregularities)

scholarly journals Multi-frequency HF radar measurements of artificial F-region field-aligned irregularities

2004 ◽  
Vol 22 (10) ◽  
pp. 3503-3511 ◽  
Author(s):  
A. Senior ◽  
N. D. Borisov ◽  
M. J. Kosch ◽  
T. K. Yeoman ◽  
F. Honary ◽  
...  
Keyword(s):  
Wave Interaction ◽  
Operating Mode ◽  
Hf Radar ◽  
Heating Facility ◽  
F Region ◽  
Density Perturbations ◽  
Radar Measurements ◽  
The Mean ◽  
Power Measurements ◽  
Field Aligned Irregularities

Abstract. We present radar backscatter power measurements using the CUTLASS HF radar at Hankasalmi, Finland from F-region field-aligned irregularities induced by HF radio pumping with the EISCAT Heating facility. A novel radar operating mode is used in which the radar frequency is rapidly swept through a number of bands, making use of the varying ionospheric refraction to probe different heights within the heated region. We obtain height profiles of backscatter power which correspond to e-folding scale lengths of around 20km for the mean-square electron density perturbations for pump wave interaction heights in the region of 240-250km in daytime conditions. The results are in agreement with previous measurements made by other techniques. We discuss some problems with the method and suggest improvements for future experiments.

scholarly journals Comparison of the orientation of small-scale electron density irregularities and F region plasma flow direction

2000 ◽  
Vol 18 (8) ◽  
pp. 918-926 ◽  
Author(s):  
E. D. Tereshchenko ◽  
B. Z. Khudukon ◽  
M. O. Kozlova ◽  
O. V. Evstafiev ◽  
T. Nygrén ◽  
...  
Keyword(s):  
Plasma Flow ◽  
Flow Direction ◽  
Small Scale ◽  
Incoherent Scatter ◽  
F Region ◽  
Anisotropy Parameters ◽  
Electron Density Irregularities ◽  
Region Plasma ◽  
Good Agreement ◽  
Field Aligned Irregularities

Abstract. Results are shown from an experimental campaign where satellite scintillation was observed at three sites at high latitudes and, simultaneously, the F region plasma flow was measured by the nearby EISCAT incoherent scatter radar. The anisotropy parameters of field-aligned irregularities are determined from amplitude scintillation using a method based on the variance of the relative logarithmic amplitude. The orientation of the anisotropy in a plane perpendicular to the geomagnetic field is compared with the direction of F region plasma flow. The results indicate that in most cases a good agreement between the two directions is obtained.Key words: Ionosphere (auroral ionosphere; ionospheric irregularities)

Artificial Small-scale Field-aligned Irregularities in the High Latitude Ionospheric F-region

2018 ◽  
Author(s):  
Nataly Blagoveshchenskaya ◽  
Tatiana Borisova ◽  
Alexey Kalishin ◽  
Timothy Yeoman
Keyword(s):  
High Latitude ◽  
Small Scale ◽  
F Region ◽  
Scale Field ◽  
Field Aligned Irregularities

Artificial small-scale field-aligned irregularities in the high latitude F region of the ionosphere induced by an X-mode HF heater wave

2011 ◽  
Vol 38 (8) ◽  
pp. n/a-n/a ◽  
Author(s):  
N. F. Blagoveshchenskaya ◽  
T. D. Borisova ◽  
T. K. Yeoman ◽  
M. T. Rietveld ◽  
I. M. Ivanova ◽  
...  
Keyword(s):  
High Latitude ◽  
Small Scale ◽  
F Region ◽  
Scale Field ◽  
Field Aligned Irregularities

Wavelike Structure of Magnetic Field-Aligned Irregularities Detected by Phase Interferometry

1972 ◽  
Vol 50 (21) ◽  
pp. 2654-2661 ◽  
Author(s):  
L. A. Hajkowicz
Keyword(s):  
Magnetic Field ◽  
Wave Structure ◽  
Auroral Zone ◽  
Angle Of Arrival ◽  
Angular Structure ◽  
F Region ◽  
The Difference ◽  
Satellite Beacon ◽  
Hydromagnetic Waves ◽  
Field Aligned Irregularities

Recordings of scintillations in the angle of arrival of satellite beacon transmissions at 136.410 MHz, by means of a modified phase interferometer, show relatively slow, periodic increases in angular variations. These increases are associated with occurrences of magnetic field-aligned irregularities at the height of the F region. The periodic component of scintillations is thought to arise from a wavelike form of distribution of irregularities. The wavelength most frequently found is in a 3–4 km range. No similar wave structure was found in simultaneous recordings of amplitude scintillations, possibly because of the difference between amplitude and phase scale sizes of irregularities. The existence of magnetic field-aligned irregularities, characterized by the periodic angular structure, could be evidence of a ducted mode of propagation of hydromagnetic waves originating in the auroral zone.

scholarly journals Imaging observations of nighttime mid-latitude F-region field-aligned irregularities by an MU radar ultra-multi-channel system

2008 ◽  
Vol 26 (8) ◽  
pp. 2345-2352 ◽  
Author(s):  
S. Saito ◽  
M. Yamamoto ◽  
H. Hashiguchi
Keyword(s):  
Radar Imaging ◽  
Doppler Velocity ◽  
Electron Content ◽  
Imaging Analysis ◽  
Channel System ◽  
Total Electron ◽  
F Region ◽  
Mu Radar ◽  
Scale Structures ◽  
Field Aligned Irregularities

Abstract. Mid-latitude F-region field-aligned irregularities (FAIs) were studied by using the middle-and-upper atmosphere (MU) radar ultra-multi-channel system with the radar imaging technique. On 12 June 2006, F-region FAI echoes with a period of about one hour were observed intermittently. These echoes were found to be embedded in medium-scale traveling ionospheric disturbances (MSTIDs) observed as variations of total electron content (TEC). The echoes drifting away from (toward) the radar were observed in the depletion (enhancement) phase of the MSTID. The Doppler velocity of the echoes is consistent with the range rates in the the range-time-intensity (RTI) maps. Fine scale structures with a spatial scale of 10 km or less were found by the radar imaging analysis. Those structures with positive Doppler velocities (moving away from the radar) appeared to drift north- (up-) westward, and those with negative Doppler velocities south- (down-) eastward approximately along the wavefronts of the MSTID. FAIs with positive Doppler velocities filling TEC depletion regions were observed.

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