The dependence of the relative backscatter cross section of 1-m density fluctuations in the auroral electrojet on the angle between electron drift and radar wave vector

1983 ◽  
Vol 88 (A10) ◽  
pp. 8043 ◽  
Author(s):  
Dieter André
Keyword(s):  
Cross Section ◽  
Wave Vector ◽  
Density Fluctuations ◽  
Auroral Electrojet ◽  
Electron Drift ◽  
Radar Wave ◽  
Backscatter Cross Section

scholarly journals Volume cross section of auroral radar backscatter and RMS plasma fluctuations inferred from coherent and incoherent scatter data: a response on backscatter volume parameters

2011 ◽  
Vol 29 (6) ◽  
pp. 1081-1092 ◽  
Author(s):  
M. V. Uspensky ◽  
P. Janhunen ◽  
A. V. Koustov ◽  
K. Kauristie
Keyword(s):  
Electron Density ◽  
Cross Section ◽  
Drift Velocity ◽  
Density Fluctuations ◽  
Electron Drift Velocity ◽  
Electron Drift ◽  
Data Set ◽  
Flow Angle ◽  
Effective Electron ◽  
Rate Of Increase

Abstract. Norway and Finland STARE radar measurements in the eastward auroral electrojet are combined with EISCAT CP-1 measurements of the electron density and electric field vector in the common scattering volume to investigate the variation of the auroral radar volume cross section (VCS) with the flow angle of observations (radar look direction with respect to the E×B electron drift). The data set available consists of ~6000 points for flow angles of 40–85° and electron drifts between 500 and 2000 m s−1. The EISCAT electron density N(h)-profile data are used to estimate the effective electron density, aspect angle and thickness of the backscattering layer. It is shown that the flow angle variation of the VCS is rather weak, only ~5 dB within the range of the considered flow angles. The VCS values themselves respond almost linearly to the square of both the electron drift velocity magnitude and the effective electron density. By adopting the inferred shape of the VCS variation with the flow angle and the VCS dependence upon wavelength, the relative amplitude of electrostatic electron density fluctuations over all scales is estimated. Inferred values of 2–4 percent react nearly linearly to the electron drift velocity in the range of 500–1000 m s−1 but the rate of increase slows down at electron drifts >1000 m s−1 and density fluctuations of ~5.5 percent due to, perhaps, progressively growing nonlinear wave losses.

Scattering of electromagnetic waves by anomalous fluctuations of a magnetized plasma

1990 ◽  
Vol 43 (2) ◽  
pp. 165-172 ◽  
Author(s):  
V. N. Pavlenko ◽  
V. G. Panchenko
Keyword(s):  
Cross Section ◽  
Electromagnetic Waves ◽  
Pump Wave ◽  
Density Fluctuations ◽  
Scattering Cross Section ◽  
Magnetized Plasma ◽  
Lower Hybrid ◽  
Scattering Cross ◽  
Parametric Decay ◽  
Ion Acoustic

Fluctuations and scattering of transverse electromagnetic waves by density fluctuations in a magnetized plasma in the presence of parametric decay of the pump wave are investigated. The spectral density of electron-density fluctuations is calculated. It is shown that the differential scattering cross-section has sharp maxima at the ion-acoustic and lower-hybrid frequencies when parametric decay of the lower-hybrid pump wave occurs. We note that scattering at the ion-acoustic frequency is dominant. When the pump-wave amplitude tends to the threshold strength of the electric field the scattering cross-section increases anomalously, i.e. there is critical opalescence.

scholarly journals Radar efficiency and the calculation of decade-long PMSE backscatter cross-section for the Resolute Bay VHF radar

2009 ◽  
Vol 27 (4) ◽  
pp. 1643-1656 ◽  
Author(s):  
N. Swarnalingam ◽  
W. K. Hocking ◽  
P. S. Argall
Keyword(s):  
Cross Section ◽  
Great Level ◽  
Vhf Radar ◽  
Radar Echoes ◽  
Summer Echoes ◽  
Resolute Bay ◽  
Absolute Measurements ◽  
Coherent Radar ◽  
Backscatter Cross Section

Abstract. The Resolute Bay VHF radar, located in Nunavut, Canada (75.0° N, 95.0° W) and operating at 51.5 MHz, has been used to investigate Polar Mesosphere Summer Echoes (PMSE) since 1997. PMSE are a unique form of strong coherent radar echoes, and their understanding has been a challenge to the scientific community since their discovery more than three decades ago. While other high latitude radars have recorded strong levels of PMSE activities, the Resolute Bay radar has observed relatively lower levels of PMSE strengths. In order to derive absolute measurements of PMSE strength at this site, a technique is developed to determine the radar efficiency using cosmic (sky) noise variations along with the help of a calibrated noise source. VHF radars are only rarely calibrated, but determination of efficiency is even less common. Here we emphasize the importance of efficiency for determination of cross-section measurements. The significant advantage of this method is that it can be directly applied to any MST radar system anywhere in the world as long as the sky noise variations are known. The radar efficiencies for two on-site radars at Resolute Bay are determined. PMSE backscatter cross-section is estimated, and decade-long PMSE strength variations at this location are investigated. It was noticed that the median of the backscatter cross-section distribution remains relatively unchanged, but over the years a great level of variability occurs in the high power tail of the distribution.

3D Wavelet Multiresolution of Multiphase Flow CT Images

2002 ◽  
Author(s):  
Masahiro Takei ◽  
Hui Li ◽  
Mitsuaki Ochi ◽  
Yoshifuru Saito ◽  
Kiyoshi Horii
Keyword(s):  
Cross Section ◽  
Density Fluctuation ◽  
Particle Density ◽  
Three Dimensional ◽  
Density Fluctuations ◽  
Time Space ◽  
Bent Pipe ◽  
Space Frequency ◽  
Pass Through ◽  
Discrete Wavelets

The extraction of dominant particle density fluctuation in various time-space frequency levels on a pipeline cross section was performed using capacitance-computed tomography and three-dimensional discrete wavelets transform. As a result, particle density fluctuation downstream of a bent pipe is decomposed into the time-space levels in a non-choking state and a pseudo-choking state. The proposed method enables realization of the time and position at which particle density fluctuations with respect to dominant time-space levels pass through the pipeline.

Regularizing method for the determination of the backscatter cross section in lidar data

2009 ◽  
Vol 26 (5) ◽  
pp. 1071 ◽  
Author(s):  
Yanfei Wang ◽  
Jianzhong Zhang ◽  
Andreas Roncat ◽  
Claudia Künzer ◽  
Wolfgang Wagner
Keyword(s):  
Cross Section ◽  
Lidar Data ◽  
Backscatter Cross Section
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