Detection of the height of maximum ionization in a meteor trail

1979 ◽  
Vol 2 (2) ◽  
pp. 235-245
Author(s):  
G. C. Rumi
Keyword(s):  
Meteor Trail ◽  
Maximum Ionization

Method of meteor trail impulsive interference suppression in OTHR

2009 ◽  
Vol 2009 (10) ◽  
pp. 67-72 ◽  
Author(s):  
Jie Wang ◽  
Tao Liu ◽  
Xiaoxu Chen ◽  
Yaohuan Gong
Keyword(s):  
Interference Suppression ◽  
Impulsive Interference ◽  
Meteor Trail

scholarly journals Maximum Ionization in Restricted and Unrestricted Hartree-Fock Theory

Atoms ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 13
Author(s):  
Hazel Cox ◽  
Michael Melgaard ◽  
Ville J. J. Syrjanen
Keyword(s):  
Upper Bound ◽  
Detailed Account ◽  
Hartree Fock ◽  
Bound Theorem ◽  
Maximum Ionization

In this paper, we investigate the maximum number of electrons that can be bound to a system of nuclei modelled by Hartree-Fock theory. We consider both the Restricted and Unrestricted Hartree-Fock models. We are taking a non-existence approach (necessary but not sufficient), in other words we are finding an upper bound on the maximum number of electrons. In giving a detailed account of the proof of Lieb’s bound [Theorem 1, Phys. Rev. A 29 (1984), 3018] for the Hartree-Fock models we establish several new auxiliary results, furthermore we propose a condition that, if satisfied, will give an improved upper bound on the maximum number of electrons within the Restricted Hartree-Fock model. For two-electron atoms we show that the latter condition holds.

scholarly journals Day to night variation in meteor trail measurements: Evidence for a new theory of plasma trail evolution

2008 ◽  
Vol 35 (3) ◽  
Author(s):  
Meers M. Oppenheim ◽  
Glenn Sugar ◽  
Elizabeth Bass ◽  
Yakov S. Dimant ◽  
Jorge Chau
Keyword(s):  
Meteor Trail

MF radar interferometer measurements of meteor trail motions

Radio Science ◽  
1990 ◽  
Vol 25 (4) ◽  
pp. 649-655 ◽  
Author(s):  
C. E. Meek ◽  
A. H. Manson
Keyword(s):  
Meteor Trail ◽  
Mf Radar

Meteor trail footprint statistics

2002 ◽  
Author(s):  
S.Y. Mui ◽  
R.C. Ellicott
Keyword(s):  
Meteor Trail

scholarly journals Probabilistic analysis of ambiguities in radar echo direction of arrival from meteors

2020 ◽  
Author(s):  
Daniel Kastinen ◽  
Johan Kero
Keyword(s):  
Bayesian Method ◽  
Direction Of Arrival ◽  
Radar System ◽  
Stable Region ◽  
Radar Signal ◽  
Ambient Atmosphere ◽  
Radar Systems ◽  
Mu Radar ◽  
Meteor Trail ◽  
The Antarctic

Abstract. Meteors and hard targets produce coherent radar echoes. If measured with an interferometric radar system, these echoes can be used to determine the position of the target through finding the Direction Of Arrival (DOA) of the incoming echo onto the radar. If the DOA of meteor trail plasma drifting with the ambient atmosphere is determined, the neutral wind at the observation altitude can be calculated. Specular meteor trail radars have become widespread scientific instruments to study atmospheric dynamics. Meteor head echo measurements also contribute to studies of the atmosphere as the meteoroid input of extraterrestrial material is relevant for a plethora of atmospheric phenomena. Depending on the spatial configuration of radar receiving antennas and their individual gain patterns, there may be an ambiguity problem when determining the DOA of an echo. Radars that are theoretically ambiguity free are known to still have ambiguities that depend on the total radar Signal to Noise Ratio (SNR). In this study we investigate robust methods which are easy to implement to determine the effect of ambiguities on any hard target DOA determination by interferometric radar systems. We apply these methods specifically to simulate four different radar systems measuring meteor head and trail echoes using the multiple signal classification (MUSIC) DOA determination algorithm. The four radar systems are the middle and upper atmosphere (MU) radar in Japan, a generic Jones 2.5λ specular meteor trail radar configuration, the Middle Atmosphere Alomar Radar System (MAARSY) radar in Norway and the The Program of the Antarctic Syowa Mesosphere Stratosphere Troposphere Incoherent Scatter (PANSY) radar in the Antarctic. We also examined a slightly perturbed Jones 2.5λ configuration used as a meteor trail echo receiver for the PANSY radar. All the results are derived from simulations and their purpose is to grant understanding of the behaviour of DOA determination. General results are: there may be a region of SNRs where ambiguities are relevant; Monte Carlo simulation determines this region and if it exists; the MUSIC function peak value is directly correlated with the ambiguous region; a Bayesian method is presented that may be able to analyse echoes from this region; the DOA of echoes with SNRs larger then this region are perfectly determined; the DOA of echoes with SNRs smaller then this region completely fail to be determined; the location of this region is shifted based on the total SNR versus the channel SNR in the direction of the target; asymmetric subgroups can cause ambiguities even for ambiguity free radars. For a DOA located at the zenith, the end of the ambiguous region is located at 17 dB SNR for the MU radar and 3 dB SNR for the PANSY radar. The Jones radars are usually used to measure specular trail echoes far from zenith. The ambiguous region for a DOA at 75.5° elevation and 0° azimuth ends at 12 dB SNR. Using the Bayesian method it may be possible to analyse echoes down to 4 dB SNR for the Jones configuration, given enough data points from the same target. The PANSY meteor trail echo receiver did not deviate significantly from the generic Jones configuration. The MAARSY radar could not resolve arbitrary DOAs sufficiently well to determine a stable region. However, if the DOA search is restricted to 70° elevation or above by assumption, stable DOA determination occurs above 15 dB SNR.

VARIATION OF METEOR ECHO RATES WITH RADAR SYSTEM PARAMETERS

1951 ◽  
Vol 29 (5) ◽  
pp. 403-426 ◽  
Author(s):  
D. W. R. McKinley
Keyword(s):  
Radio Wave ◽  
Wave Length ◽  
Radar System ◽  
Antenna Gain ◽  
Scattering Pattern ◽  
Magnitude Distribution ◽  
System Parameters ◽  
Transmitter Power ◽  
Meteor Trail ◽  
Strong Filter

Observations made with crossed-polarization radar system systems do not support the suggestion that the ionized meteor trail may act as a strong filter–polarizer of the incident radio wave. Experiments have been carried out to determine the variation of normal meteor echo rates with transmitter power, antenna gain, and radio wave length, and all confirm Lovell's scattering formula, provided that account is taken of the effective broadening of the scattering pattern of the meteor trail with increasing wave length. The limiting sensitivity of the 9.22 m. 200 kw. radar is determined to be about 9th magnitude. During a strong visual shower the observed increase in visual rates and low-power radar rates, compared to high-power radar rates, is explained by assuming that the magnitude distribution of the shower meteors differs from the normal nonshower distribution.

scholarly journals Change in turbopause altitude at 52 and 70° N

2016 ◽  
Vol 16 (4) ◽  
pp. 2299-2308 ◽  
Author(s):  
Chris M. Hall ◽  
Silje E. Holmen ◽  
Chris E. Meek ◽  
Alan H. Manson ◽  
Satonori Nozawa
Keyword(s):  
Time Series ◽  
Atomic Oxygen ◽  
Molecular Diffusion ◽  
Temporal Evolution ◽  
Molecular Mixing ◽  
Trace Species ◽  
Term Change ◽  
Meteor Trail ◽  
Altitude Estimation

Abstract. The turbopause is the demarcation between atmospheric mixing by turbulence (below) and molecular diffusion (above). When studying concentrations of trace species in the atmosphere, and particularly long-term change, it may be important to understand processes present, together with their temporal evolution that may be responsible for redistribution of atmospheric constituents. The general region of transition between turbulent and molecular mixing coincides with the base of the ionosphere, the lower region in which molecular oxygen is dissociated, and, at high latitude in summer, the coldest part of the whole atmosphere. This study updates previous reports of turbopause altitude, extending the time series by half a decade, and thus shedding new light on the nature of change over solar-cycle timescales. Assuming there is no trend in temperature, at 70° N there is evidence for a summer trend of  ∼  1.6 km decade−1, but for winter and at 52° N there is no significant evidence for change at all. If the temperature at 90 km is estimated using meteor trail data, it is possible to estimate a cooling rate, which, if applied to the turbopause altitude estimation, fails to alter the trend significantly irrespective of season. The observed increase in turbopause height supports a hypothesis of corresponding negative trends in atomic oxygen density, [O]. This supports independent studies of atomic oxygen density, [O], using mid-latitude time series dating from 1975, which show negative trends since 2002.

scholarly journals A comparison of northern hemisphere winds using SuperDARN meteor trail and MF radar wind measurements

2000 ◽  
Vol 105 (D14) ◽  
pp. 18053-18066 ◽  
Author(s):  
G. C. Hussey ◽  
C. E. Meek ◽  
D. André ◽  
A. H. Manson ◽  
G. J. Sofko ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Meteor Trail ◽  
Wind Measurements ◽  
Mf Radar
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