scholarly journals 33. Meteor shower mass distribution from radar echo counts

1968 ◽  
Vol 33 ◽  
pp. 352-361
Author(s):  
W. G. Elford
Keyword(s):  
Mass Distribution ◽  
Meteor Shower ◽  
Inverse Power ◽  
Meteor Showers ◽  
Power Flux ◽  
Wide Aperture ◽  
Radar Echoes ◽  
Radar Echo

Theoretical hourly rates of radar echoes from meteor showers observed with narrow- and wide-aperture systems are calculated in terms of equipment parameters and the distribution of the number of meteors as a function of mass. From a comparison of the echo rates in selected range intervals, it is shown that it is possible to determine the value of the exponent in a simple inverse power flux law.The effect on the echo rate of a change in the value of the exponent in the flux law with magnitude is described and the probability of detecting showers at different stations is discussed.It is suggested that simple radar echo counts in several range intervals can be used to determine the mass distribution of meteor showers over a range of two or three magnitudes above the limiting magnitude of the system. The analysis is applied to some observations made at Christchurch and Ottawa.

THE DETERMINATION OF METEOR MASS DISTRIBUTION FROM RADAR ECHO COUNTS

1966 ◽  
Vol 44 (11) ◽  
pp. 2729-2748 ◽  
Author(s):  
B. A. McIntosh
Keyword(s):  
Mass Distribution ◽  
Electron Attachment ◽  
Meteor Radar ◽  
Low Velocity ◽  
Wide Beam ◽  
Radar Echoes ◽  
Long Duration ◽  
Radar Echo ◽  
Meteor Trails

In relating the frequency distribution of the durations of radar echoes from meteor trails to the mass distribution of the meteoroid flux, two major effects must be taken into account. Because bright meteors tend to be observable by radar from any angle, the rate of long-duration echoes is enhanced relative to short-duration echoes. This effect is particularly pronounced for the Ottawa radar which has wide-beam antennas. On the other hand, the effect of electron attachment is to suppress the long-duration echo count, particularly for low-velocity meteors, which produce ionized trails at lower altitudes.The influence of both these effects on the observational results from the Ottawa meteor radar is examined quantitatively.

scholarly journals 32. Meteor mass distribution from radar observations

1968 ◽  
Vol 33 ◽  
pp. 343-351
Author(s):  
B.A. McIntosh
Keyword(s):  
Mass Distribution ◽  
Electron Attachment ◽  
Radar Observations ◽  
Long Duration ◽  
Radar Echo

There are many problems in deducing the meteor mass distribution from radar echo observations. Some of these are reviewed in this paper, particular emphasis being placed on the effects of electron attachment and of equipment parameters on the statistics of long-duration echoes.

Simulation of Stepped-Frequency LFM Radar Echo Based on FPGA

2012 ◽  
Vol 198-199 ◽  
pp. 948-953
Author(s):  
Jian Ping Ou ◽  
Sheng Qi Liu ◽  
Wei Niu
Keyword(s):  
Moving Target ◽  
Direct Digital Synthesis ◽  
Implementation Framework ◽  
Radar Echoes ◽  
Radar Echo ◽  
Digital Synthesis ◽  
Physical Simulations ◽  
Stepped Frequency ◽  
Logic Resource

An implementation framework of stepped-frequency LFM (SF-LFM) radar echoes simulator is presented in the paper based on the decomposition and calculation of SF-LFM radar echoes of a moving target. The proposed method can be implemented conveniently with direct digital synthesis (DDS) logic resource. The feasibility of this resolution is verified with computer and semi-physical simulations experiments.

scholarly journals Improving The Accuracy Of Selection Of Bird Radar Echoes Against A Background Of Atomized Clouds And Atmospheric Inhomogeneities

The Ring ◽  
2015 ◽  
Vol 37 (1) ◽  
pp. 3-18
Author(s):  
Leonid Dinevich
Keyword(s):  
Bird Migration ◽  
Meteorological Conditions ◽  
Flight Safety ◽  
Selection Algorithm ◽  
Radar Echoes ◽  
Military Aviation ◽  
Radar Echo ◽  
Reflected Signal ◽  
Selection Of ◽  
Polarization Fluctuation

Abstract The algorithm for bird radar echo selection was developed in Israel and has been successfully used for many years to monitor birds in periods of massive intercontinental migration in order to ensure flight safety in civil and military aviation. However, it has been found that under certain meteorological conditions the bird echo selection algorithm does not filter out false signals formed by atomized clouds and atmospheric inhomogeneities. Although the algorithm is designed to identify and sift false signals, some useful echoes from smaller birds are erroneously sifted as well. This paper presents some additional features of radar echoes reflected from atmospheric formations that can be taken into account to prevent the loss of useful bird echoes. These additional features are based on the use of polarization, fluctuation and Doppler characteristics of a reflected signal. By taking these features into account we can reduce the number of false signals and increase the accuracy of the bird echo selection algorithm. The paper presents methods for using radar echoes to identify species and sizes of birds, together with recommendations on using the data to ensure flight safety during periods of massive intercontinental bird migration.

associations between aircraft measurements of turbulence and weather radar measurements1

1965 ◽  
Vol 46 (8) ◽  
pp. 443-447 ◽  
Author(s):  
Edwin Kessler ◽  
Jean T. Lee ◽  
Kenneth E. Wilk
Keyword(s):  
Weather Radar ◽  
Radar Data ◽  
Time Dependent ◽  
Aircraft Measurements ◽  
Radar Echoes ◽  
Radar Echo

Aircraft have been guided with the aid of radar data to measure turbulence in thunderstorm areas. Although turbulence is frequently encountered in areas containing highly reflective and sharp-edged echoes, no unique correspondence has been discovered between single-echo parameters and collocated within-storm turbulence. A theory embracing some of the time-dependent relationships between fields of wind and precipitation suggests that the correspondence between instantaneous distributions of radar echoes and turbulence is statistical rather than precise. Statistical bases for study of radar echo-turbulence relationships are outlined.

scholarly journals Investigation of the Motion of Periodic Comet Giacobini-Zinner and the Origin of the Draconid Meteor Showers of 1926, 1933 and 1946

1972 ◽  
Vol 45 ◽  
pp. 173-180
Author(s):  
Yu. V. Evdokimov
Keyword(s):  
Meteor Shower ◽  
Meteor Showers ◽  
Orbital Elements ◽  
Periodic Comet

Orbital elements of P/Giacobini-Zinner have been obtained from 577 observations at the eight apparitions 1900 to 1965 by linking apparitions in pairs. By this technique we established that the comet has a nongravitational secular deceleration amounting, on the average, to 0.081 day/(period)2. As a result of the comet's approach to Jupiter in 1969, a return of the Draconid meteor shower is possible on 1972 October 8d15h45m UT. The 1946 meteor shower was due to meteoroids ejected forward along the orbit of the comet in 1940 with velocities of 14 m s- 1. The meteor showers of 1933 and 1926 were apparently produced by meteoroids ejected in 1900 with velocities of 15.0 m s- 1 forward and 14.5 m s- 1 backward, respectively.

scholarly journals Metal concentrations in the upper atmosphere during meteor showers

2010 ◽  
Vol 10 (3) ◽  
pp. 909-917 ◽  
Author(s):  
J. Correira ◽  
A. C. Aikin ◽  
J. M. Grebowsky ◽  
J. P. Burrows
Keyword(s):  
Mass Flux ◽  
Mass Density ◽  
Meteor Shower ◽  
Meteor Showers ◽  
Vertical Column ◽  
Metal Concentrations ◽  
Theoretical Mass ◽  
Measuring Experiment ◽  
Dependent Mass ◽  
Temporal Profiles

Abstract. Using the nadir-viewing Global Ozone Measuring Experiment (GOME) UV/VIS spectrometer on the ERS-2 satellite, we investigate short term variations in the vertical magnesium column densities in the atmosphere and any connection to possible enhanced mass deposition during a meteor shower. Time-dependent mass influx rates are derived for all the major meteor showers using published estimates of mass density and temporal profiles of meteor showers. An average daily sporadic background mass flux rate is also calculated and used as a baseline against which calculated shower mass flux rates are compared. These theoretical mass flux rates are then compared with GOME derived metal vertical column densities of Mg and Mg+ from the years 1996–2001. There is no correlation between theoretical mass flux rates and changes in the Mg and Mg+ metal column densities. A possible explanation for the lack of a shower related increase in metal concentrations may be differences in the mass regimes dominating the average background mass flux and shower mass flux.

scholarly journals Metal concentrations in the upper atmosphere during meteor showers

2009 ◽  
Vol 9 (5) ◽  
pp. 18705-18726
Author(s):  
J. Correira ◽  
A. C. Aikin ◽  
J. M. Grebowsky ◽  
J. P. Burrows
Keyword(s):  
Mass Flux ◽  
Mass Density ◽  
Meteor Shower ◽  
Meteor Showers ◽  
Vertical Column ◽  
Metal Concentrations ◽  
Theoretical Mass ◽  
Measuring Experiment ◽  
Dependent Mass ◽  
Temporal Profiles

Abstract. Using the nadir-viewing Global Ozone Measuring Experiment (GOME) UV/VIS spectrometer on the ERS-2 satellite, we investigate short term variations in the vertical magnesium column densities in the atmosphere and any connection to possible enhanced mass deposition during a meteor shower. Time-dependent mass influx rates are derived for all the major meteor showers using published estimates of mass density and temporal profiles of meteor showers. An average daily sporadic background mass flux rate is also calculated and used as a baseline against which calculated shower mass flux rates are compared. These theoretical mass flux rates are then compared with GOME derived metal vertical column densities of Mg and Mg+ from the years 1996–2001. There is no correlation between theoretical mass flux rates and changes in the Mg and Mg+ metal column densities. A possible explanation for the lack of a shower related increase in metal concentrations may be differences in the mass regimes dominating the average background mass flux and shower mass flux.

A Study of Extrapolation Nowcasting Based on IVAP-Retrieved Wind

2021 ◽  
Vol 38 (4) ◽  
pp. 885-895
Author(s):  
Yi Luo ◽  
Xudong Liang ◽  
Gang Wang ◽  
Zheng Cao
Keyword(s):  
Radial Velocity ◽  
Traditional Method ◽  
Large Scale ◽  
Wind Profile ◽  
Method Comparison ◽  
The Past ◽  
Radar Echoes ◽  
Radar Echo ◽  
Similar Accuracy ◽  
Tracking Radar

AbstractIn this study, we propose a new way to obtain motion vectors using the integrating velocity–azimuth process (IVAP) method for extrapolation nowcasting. Traditional tracking methods rely on tracking radar echoes of a few time slices. In contrast, the IVAP method does not depend on the past variation of radar echoes; it only needs the radar echo and radial velocity observations at the latest time. To demonstrate it is practical to use IVAP-retrieved winds to extrapolate radar echoes, we carried out nowcasting experiments using the IVAP method, and compared these results with the results using a traditional method, namely, the tracking radar echoes by correlation (TREC) method. Comparison based on a series of large-scale mature rainfall cases showed that the IVAP method has similar accuracy to that of the TREC method. In addition, the IVAP method provides the vertical wind profile that can be used to anticipate storm type and motion deviations.

The variational echo tracking method and its application in convective storm nowcasting

2020 ◽  
Author(s):  
Jiankun Wu ◽  
Mingxuan Chen ◽  
Rui Qin ◽  
Feng Gao ◽  
Linye Song
Keyword(s):  
Motion Vector ◽  
Correlation Method ◽  
Convective Precipitation ◽  
Convective Storm ◽  
Tracking Method ◽  
Radar Echoes ◽  
Radar Echo ◽  
Echo Tracking ◽  
Tracking Radar ◽  
Precipitation Events

<p>The objective extrapolation forecast is the main method for 0-1 hour convective storm nowcasting. Radar echo extrapolation was performed by using the 6 minute interval radar mosaics obtained from the radar images of 8 multi-radars in Beijing-Tianjin-Hebei region. A comparative study of two extrapolated forecasts of eighteen typical convective precipitation events occurred in Beijing-Tianjin-Hebei region from 2016 to 2018 was conducted. Compared with the tracking radar echoes by correlation method, the variational echo tracking method utilizes variational technique to compute the motion vector fields, and uses two strict constraints to get a better motion vector field. The results indicated that the variational echo tracking method performed better in prediction of the radar echo pattern, echo location, and echo intensity at 30- and 60-min forecast lead times: 1) A comparative study of the two extrapolated forecasts of four precipitation events in Beijing-Tianjin-Hebei region was conducted. The result indicated that the radar echo location, the echo pattern and echo intensity produced by the variational echo tracking method were closer to the real observation within one hour. 2) Quantitative evaluation for the two extrapolated forecasts of the eighteen typical convective precipitation events was conducted. Compared with the tracking radar echoes by correlation method, the probability of detection and the critical success index of the 30- or 60-min extrapolated forecast produced by the variational echo tracking method were higher, meanwhile the false alarm rate was lower when the radar echo threshold was 35dBz and 45dBz. Also, a quantitative evaluation classified by the weather type indicated that the variational echo tracking method performed better than the tracking radar echoes by correlation method in most weather types.</p>

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