scholarly journals An Improved Meteor Echo Recognition Algorithm for SuperDARN HF Radar

Electronics ◽  
2021 ◽  
Vol 10 (16) ◽  
pp. 1971
Author(s):  
Guangming Li ◽  
Jingye Yan ◽  
Ailan Lan
Keyword(s):  
Power Distribution ◽  
Power Doppler ◽  
Spectral Width ◽  
Hf Radar ◽  
Integration Time ◽  
Doppler Velocity ◽  
Neutral Wind ◽  
Extraction Algorithm ◽  
Radar Meteor ◽  
Improved Algorithm

The SuperDARN HF radars can be used for meteor observation and inversion of mid-upper atmosphere neutral wind using observed meteor echo Doppler velocities. Aiming at the problem that the extraction of meteor echo based on echo power, Doppler velocity and spectral width is rough and contains ionospheric echo, this paper optimizes the extraction algorithm of meteor echo. Based on the AgileDARN HF radar’s digital characteristics, the observation method of meteor echo was improved, and we designed a meteor observation mode without changing the hardware system: using a meteor observation with a 7.5 km range resolution and a 2 s integration time, we extracted the Doppler characteristics of different echo types at meteor echo ranges; according to these features, the extraction algorithm of meteor echo was optimized. By analyzing the measured data, the characteristics of diurnal variation, power distribution, Doppler velocity distribution and spectral width distribution of meteor echo extracted by the optimization algorithm were obtained. The meteor echo characteristics obtained by the improved algorithm are more consistent with the theoretical analysis; thus, the improved algorithm is better than the SuperDARN high frequency radar meteor echo extraction algorithm and has good performance. The meteor echo extraction algorithm presented in this paper can extract the meteor echo more accurately, so that the atmospheric neutral wind can be retrieved more accurately. At the same time, the proposed algorithm is not only applicable to AgileDARN HF radar meteor observation mode data, but also to AgileDARN and SuperDARN normal mode data, which is beneficial to expand the data application of SuperDARN radars.

scholarly journals CUTLASS HF radar observations of high-velocity E-region echoes

2001 ◽  
Vol 19 (4) ◽  
pp. 411-424 ◽  
Author(s):  
M. V. Uspensky ◽  
A. V. Koustov ◽  
P. Eglitis ◽  
A. Huuskonen ◽  
S. E. Milan ◽  
...  
Keyword(s):  
Electric Fields ◽  
High Velocity ◽  
Power Doppler ◽  
Spectral Width ◽  
Plasma Instability ◽  
Hf Radar ◽  
Doppler Velocity ◽  
Classical Type ◽  
E Region

Abstract. A short event of high-velocity E-region echo observations by the Pykkvibaer HF radar is analysed to study echo parameters and the echo relation to the Farley-Buneman plasma instability. The echoes were detected in several beams aligned closely to the magnetic L-shell direction. Two echo groups were identified: one group corresponded to the classical type 1 echoes with velocities close to the nominal ion-acoustic speed of 400 ms–1 , while the other group had significantly larger velocities, of the order of 700 ms–1 . The mutual relationship between the echo power, Doppler velocity, spectral width and elevation angles for these two groups was studied. Plotting of echo parameters versus slant range showed that all ~700 ms–1 echoes originated from larger heights and distances of 500–700 km, while all ~400 ms–1 echoes came from lower heights and from farther distances; 700–1000 km. We argue that both observed groups of echoes occurred due to the Farley-Buneman plasma instability excited by strong ( ~70 mVm–1 ) and uniformly distributed electric fields. We show that the echo velocities for the two groups were different because the echoes were received from different heights. Such a separation of echo heights occurred due to the differing amounts of ionospheric refraction at short and large ranges. Thus, the ionospheric refraction and related altitude modulation of ionospheric parameters are the most important factors to consider, when various characteristics of E-region decametre irregularities are derived from HF radar measurements.Key words. Ionosphere (ionospheric irregularities; plasma waves and instabilities; polar ionosphere)

scholarly journals Dynamical critical scaling of electric field fluctuations in the greater cusp and magnetotail implied by HF radar observations of F-region Doppler velocity

2006 ◽  
Vol 24 (2) ◽  
pp. 689-705 ◽  
Author(s):  
M. L. Parkinson
Keyword(s):  
Solar Wind ◽  
Open Field ◽  
Electric Fields ◽  
Spectral Width ◽  
Hf Radar ◽  
Doppler Velocity ◽  
Closed Field ◽  
Scaling Exponent ◽  
Central Plasma ◽  
Field Lines

Abstract. Akasofu's solar wind ε parameter describes the coupling of solar wind energy to the magnetosphere and ionosphere. Analysis of fluctuations in ε using model independent scaling techniques including the peaks of probability density functions (PDFs) and generalised structure function (GSF) analysis show the fluctuations were self-affine (mono-fractal, single exponent scaling) over 9 octaves of time scale from ~46 s to ~9.1 h. However, the peak scaling exponent α0 was a function of the fluctuation bin size, so caution is required when comparing the exponents for different data sets sampled in different ways. The same generic scaling techniques revealed the organisation and functional form of concurrent fluctuations in azimuthal magnetospheric electric fields implied by SuperDARN HF radar measurements of line-of-sight Doppler velocity, vLOS, made in the high-latitude austral ionosphere. The PDFs of vLOS fluctuation were calculated for time scales between 1 min and 256 min, and were sorted into noon sector results obtained with the Halley radar, and midnight sector results obtained with the TIGER radar. The PDFs were further sorted according to the orientation of the interplanetary magnetic field, as well as ionospheric regions of high and low Doppler spectral width. High spectral widths tend to occur at higher latitude, mostly on open field lines but also on closed field lines just equatorward of the open-closed boundary, whereas low spectral widths are concentrated on closed field lines deeper inside the magnetosphere. The vLOS fluctuations were most self-affine (i.e. like the solar wind ε parameter) on the high spectral width field lines in the noon sector ionosphere (i.e. the greater cusp), but suggested multi-fractal behaviour on closed field lines in the midnight sector (i.e. the central plasma sheet). Long tails in the PDFs imply that "microbursts" in ionospheric convection occur far more frequently, especially on open field lines, than can be captured using the effective Nyquist frequency and volume resolution of SuperDARN radars.

scholarly journals Finland HF and Esrange MST radar observations of polar mesosphere summer echoes

2003 ◽  
Vol 21 (4) ◽  
pp. 1047-1055 ◽  
Author(s):  
T. Ogawa ◽  
N. F. Arnold ◽  
S. Kirkwood ◽  
N. Nishitani ◽  
M. Lester
Keyword(s):  
Middle Atmosphere ◽  
Spectral Width ◽  
Hf Radar ◽  
Doppler Velocity ◽  
Short Period ◽  
Mst Radar ◽  
Summer Echoes ◽  
Polar Mesosphere Summer Echoes ◽  
Thermospheric Dynamics ◽  
Atmospheric Gravity

Abstract. Peculiar near range echoes observed in summer with the SuperDARN HF radar in Finland are presented. The echoes were detected at four frequencies of 9, 11, 13 and 15 MHz at slant ranges of 105–250 km for about 100 min. Interferometer measurements indicate that the echoes are returned from 80–100 km altitudes with elevation angles of 20°–60°. Echo power (< 16 dB), Doppler velocity (between –30 and + 30 ms-1) and spectral width (< 60 ms-1) fluctuate with periods of several to 20 min, perhaps due to short–period atmospheric gravity waves. When the HF radar detected the echoes, a vertical incidence MST radar, located at Esrange in Sweden (650 km north of the HF radar site), observed polar mesosphere summer echoes (PMSE) at altitudes of 80–90 km. This fact suggests that the near range HF echoes are PMSE at HF band, although both radars did not probe a common volume. With increasing radar frequency, HF echo ranges are closer to the radar site and echo power becomes weaker. Possible mechanisms to explain these features are discussed.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves and tides; instruments and techniques)

scholarly journals High resolution observations of spectral width features associatedwith ULF wave signatures in artificial HF radar backscatter

2004 ◽  
Vol 22 (1) ◽  
pp. 169-182 ◽  
Author(s):  
D. M. Wright ◽  
T. K. Yeoman ◽  
L. J. Baddeley ◽  
J. A. Davies ◽  
R. S. Dhillon ◽  
...  
Keyword(s):  
High Resolution ◽  
Plasma Source ◽  
Spectral Width ◽  
Hf Radar ◽  
Mhd Waves ◽  
Small Scale ◽  
Ulf Waves ◽  
Source Population ◽  
Radar Backscatter ◽  
Field Lines

Abstract. The EISCAT high power heating facility at Tromsø, northern Norway, has been utilised to generate artificial radar backscatter in the fields of view of the CUTLASS HF radars. It has been demonstrated that this technique offers a means of making very accurate and high resolution observations of naturally occurring ULF waves. During such experiments, the usually narrow radar spectral widths associated with artificial irregularities increase at times when small scale-sized (high m-number) ULF waves are observed. Possible mechanisms by which these particle-driven high-m waves may modify the observed spectral widths have been investigated. The results are found to be consistent with Pc1 (ion-cyclotron) wave activity, causing aliasing of the radar spectra, in agreement with previous modelling work. The observations also support recent suggestions that Pc1 waves may be modulated by the action of longer period ULF standing waves, which are simultaneously detected on the magnetospheric field lines. Drifting ring current protons with energies of ∼ 10keV are indicated as a common plasma source population for both wave types. Key words. Magnetospheric physics (MHD waves and instabilities) – Space plasma physics (wave-particle interactions) – Ionosphere (active experiments)

scholarly journals High-Range Resolution Spectral Analysis of Precipitation Through Range Imaging of the Chung-Li VHF Radar

2017 ◽  
Author(s):  
Shih-Chiao Tsai ◽  
Jenn-Shyong Chen ◽  
Yen-Hsyang Chu ◽  
Ching-Lun Su ◽  
Jui-Hsiang Chen
Keyword(s):  
Weighting Function ◽  
Power Doppler ◽  
Power Spectra ◽  
Doppler Frequency ◽  
Doppler Velocity ◽  
Small Scale ◽  
Range Imaging ◽  
Very High Frequency ◽  
Vhf Radar ◽  
Range Resolution

Abstract. Multi-frequency range imaging (RIM) has been implemented in the Chung-Li very-high-frequency (VHF) radar, located on the campus of National Central University, Taiwan, since 2008. RIM processes the echo signals with a group of closely spaced transmitting frequencies through appropriate inversion methods to obtain high-resolution distribution of echo power in the range direction. This is beneficial to the investigation of the small scale structure embedded in dynamic atmosphere. Five transmitting frequencies were employed in the radar experiment for observation of the precipitating atmosphere during the period between 21 and 23 Aug, 2013. Using the Capon and Fourier methods, the radar echoes were synthesized to retrieve the temporal signals at a smaller range step than the original range resolution defined by the pulse width, and such retrieved temporal signals were then processed in the Doppler frequency domain to identify the atmosphere and precipitation echoes. An analysis called conditional averaging was further executed for echo power, Doppler velocity, and spectral width to verify the potential capabilities of the retrieval processing in resolving small-scale precipitation and atmosphere structures. Point-by-point correction of range delay combined with compensation of range weighting function effect has been performed during the retrieval of temporal signals to improve the continuity of power spectra at gate boundaries, making the small-scale structures in the power spectra more natural and reasonable. We examined stratiform and convective precipitations and demonstrated their different structured characteristics by means of the Capon-processed results.

scholarly journals Simultaneous HF measurements of E- and F-region Doppler velocities at large flow angles

2004 ◽  
Vol 22 (4) ◽  
pp. 1177-1185 ◽  
Author(s):  
R. A. Makarevitch ◽  
F. Honary ◽  
A. V. Koustov
Keyword(s):  
Hf Radar ◽  
Doppler Velocity ◽  
Plasma Convection ◽  
Aspect Angle ◽  
F Region ◽  
Significant Difference ◽  
E Region ◽  
The Difference ◽  
New Feature ◽  
Large Flow

Abstract. Data collected by the CUTLASS Finland HF radar are used to illustrate the significant difference between the cosine component of the plasma convection in the F-region and the Doppler velocity of the E-region coherent echoes observed at large flow angles. We show that the E-region velocity is ~5 times smaller in magnitude and rotated by ~30° clockwise with respect to convection in the F-region. Also, measurements at flow angles larger than 90° exhibit a completely new feature: Doppler velocity increase with the expected aspect angle and spatial anticorrelation with the backscatter power. By considering DMSP drift-meter measurements we argue that the difference between F- and E-region velocities cannot be interpreted in terms of the convection change with latitude. The observed features in the velocity of the E-region echoes can be explained by taking into account the ion drift contribution to the irregularity phase velocity as predicted by the linear fluid theory. Key words. Ionosphere (auroral ionosphere; ionospheric irregularities; plasma convection)

scholarly journals Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp

2004 ◽  
Vol 22 (2) ◽  
pp. 511-525 ◽  
Author(s):  
K. Oksavik ◽  
F. Søraas ◽  
J. Moen ◽  
R. Pfaff ◽  
J. A. Davies ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Broad Band ◽  
Spectral Width ◽  
Hf Radar ◽  
Optical Data ◽  
Low Energy Electrons ◽  
Field Lines ◽  
Auroral Phenomena ◽  
Electric Fields And Currents

Abstract. In this paper we discuss counterstreaming electrons, electric field turbulence, HF radar spectral width enhancements, and field-aligned currents in the southward IMF cusp region. Electric field and particle observations from the FAST spacecraft are compared with CUTLASS Finland spectral width enhancements and ground-based optical data from Svalbard during a meridional crossing of the cusp. The observed 630nm rayed arc (Type-1 cusp aurora) is associated with stepped cusp ion signatures. Simultaneous counterstreaming low-energy electrons on open magnetic field lines lead us to propose that such electrons may be an important source for rayed red arcs through pitch angle scattering in collisions with the upper atmosphere. The observed particle precipitation and electric field turbulence are found to be nearly collocated with the equatorward edge of the optical cusp, in a region where CUTLASS Finland also observed enhanced spectral width. The electric field turbulence is observed to extend far poleward of the optical cusp. The broad-band electric field turbulence corresponds to spatial scale lengths down to 5m. Therefore, we suggest that electric field irregularities are directly responsible for the formation of HF radar backscatter targets and may also explain the observed wide spectra. FAST also encountered two narrow highly structured field-aligned current pairs flowing near the edges of cusp ion steps. Key words. Ionosphere (electric fields and currents). Magnetosphere physics (magnetopause, cusp, and boundary layers; auroral phenomena)

Research on Fire Power Distribution Model of Shore Support Based on PSGA

2014 ◽  
Vol 543-547 ◽  
pp. 747-750
Author(s):  
Xiang Yang Li ◽  
Wan Feng Ji ◽  
Hai Feng Xu ◽  
Chang Peng Pan
Keyword(s):  
Genetic Algorithms ◽  
Power Distribution ◽  
Distribution Model ◽  
Model Based ◽  
Improved Algorithm

As for the two main limitations as partial constringency and convergence hysteresis of Genetic Algorithms (GA), predatory search is introduced and Predatory Search Genetic Algorithms (PSGA) based on GA is designed to enhance the integrate ability of hunting. The concepts of fire support platform and target fitness are introduced, and fire power distribution model based on fire support fitness coefficient is built. The improved PSGA is applied to fire power and emulation experiment is done. The result of emulation shows the validity of the improved algorithm.

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