First VHF radar observation of midlatitude F-region field-aligned irregularities

1988 ◽  
Vol 15 (8) ◽  
pp. 768-771 ◽  
Author(s):  
S. Fukao ◽  
J. P. McClure ◽  
A. Ito ◽  
T. Sato ◽  
I. Kimura ◽  
...  
Keyword(s):  
Radar Observation ◽  
Vhf Radar ◽  
F Region ◽  
Field Aligned Irregularities

scholarly journals Characteristics of the E- and F-region field-aligned irregularities in middle latitudes: Initial results obtained from the Daejeon 40.8 MHz VHF radar in South Korea

2014 ◽  
Vol 31 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Young-Sil Kwak ◽  
Tae-Yong Yang ◽  
Hoysub Kil ◽  
Devulapalli Venkata Phanikumar ◽  
Bok-Haeng Heo ◽  
...  
Keyword(s):  
South Korea ◽  
Vhf Radar ◽  
Middle Latitudes ◽  
F Region ◽  
Initial Results ◽  
Field Aligned Irregularities

scholarly journals Statistical characteristics of low-latitude ionospheric field-aligned irregularities obtained with the Piura VHF radar

2002 ◽  
Vol 20 (8) ◽  
pp. 1203-1212 ◽  
Author(s):  
J. L. Chau ◽  
R. F. Woodman ◽  
L. A. Flores
Keyword(s):  
Signal To Noise Ratio ◽  
Equatorial Electrojet ◽  
Meridional Wind ◽  
Statistical Characteristics ◽  
Doppler Velocity ◽  
Vhf Radar ◽  
F Region ◽  
Seasonal Characteristics ◽  
E Region ◽  
Field Aligned Irregularities

Abstract. We present a summary of the statistical characteristics of echoes from ionospheric (E- and F-region) field-aligned irregularities obtained with the Piura VHF radar. This radar is located at ~ 7.0° dip latitude, just outside the equatorial electrojet (EEJ) region. Our results are based on (1) intermittent observations made between 1991 and 1999 just few days a year, and (2) continuous observations made between January 2000 and June 2001. During most of the intermittent observations, simultaneous measurements of EEJ and equatorial spread F (ESF) irregularities were performed with the Jicamarca VHF radar. From the continuous measurements, we have obtained the diurnal and seasonal characteristics of a variety of parameters (percentage of occurrence, signal-to-noise ratio and/or Doppler velocities) from the lower and upper E-region irregularities and also from F-region irregularities over Piura. For example, we have found that (1) the E-region echoes are stronger and occur more frequently during local summer (i.e. between December and March); (2) between May and June, the E-region echoes are weaker and occur less frequently; moreover, during these months, a semidiurnal wave with large amplitudes is observed in the meridional wind (> 100 ms- 1); (3) there is vertical wavelength of about 20 km in the Doppler velocity, particularly after midnight; (4) the lower (upper) E-region Doppler velocities are influenced mainly by meridional winds (equatorial F-region vertical drifts). In addition, we have observed that the seasonal and daily occurrences of Piura F-region irregularities are similar to the occurrence of topside ESF irregularities over Jicamarca. The likelihood of occurrence of F-region irregularities over Piura and, therefore, topside ESF over Jicamarca is greater when there are no E-region irregularities over Piura. On the other hand, there is more probability of observing bottomtype/bottomside ESF irregularities over Jicamarca when E-region irregularities are observed over Piura.Key words. Ionosphere (ionospheric irregularities; equatorial ionosphere; instruments and techniques)

scholarly journals Simultaneous VHF radar backscatter and ionosonde observations of low-latitude E region

2005 ◽  
Vol 23 (3) ◽  
pp. 773-779 ◽  
Author(s):  
A. K. Patra ◽  
S. Sripathi ◽  
P. B. Rao ◽  
K. S. V. Subbarao
Keyword(s):  
Low Latitude ◽  
Vhf Radar ◽  
Radar Echoes ◽  
First Results ◽  
E Region ◽  
Gradient Drift ◽  
Drift Instability ◽  
Relationship Of ◽  
The Relationship ◽  
Field Aligned Irregularities

Abstract. The first results of simultaneous observations made on the low-latitude field-aligned irregularities (FAI) using the MST radar located at Gadanki (13.5° N, 79.2° E, dip 12.5°) and the Es parameters using an ionosonde at a nearby station Sriharikota (13.7° N, 80.1° E, dip 12.6°) are presented. The observations show that while the height of the most intense radar echoes is below the virtual height of Es (h'Es) during daytime, it is found to be either below or above during nighttime. The strength of the FAI is better correlated with the top penetration frequency (ftEs) and the blanketing frequency (fbEs) during the night (r=0.4 in both cases) as compared to the day (r=0.35 and -0.04, respectively). Furthermore, the signal strength of FAI is reasonably correlated with (ftEs-fbEs) during daytime (r=0.59) while very poorly correlated during nighttime (r=0.18). While the radar observations in general appear to have characteristics close to that of mid-latitudes, the relationship of these with the Es parameters are poorer than that of mid-latitudes. The observations reported here, nevertheless, are quite consistent with the expectations based on the gradient drift instability mechanism.

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
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