Comparison of location accuracy of the Japanese lightning detection network with large scale lightning detection networks

2015 ◽  
Author(s):  
M. Matsui ◽  
K. Michishita ◽  
S. Kurihara
Keyword(s):  
Large Scale ◽  
Location Accuracy ◽  
Lightning Detection

scholarly journals Evaluation of the performance characteristics of the North American Lightning Detection Network based on extensive CN Tower lightning data

2021 ◽  
Author(s):  
Savdulla Kazazi
Keyword(s):  
North American ◽  
Detection Efficiency ◽  
Performance Characteristics ◽  
Enhancement Effect ◽  
Return Stroke ◽  
Location Accuracy ◽  
Peak Current ◽  
The North ◽  
Current Estimation ◽  
Lightning Detection

The North American Lightning Detection Network (NALDN) has been providing lightning data since 1998. Important applications, such as detection of lightning-caused forest fires, power line fault locations and aviation safety procedures, have triggered a number of hardware and software upgrades for improving the network performance characteristics, including its detection efficiency and location accuracy. The NALDN performance characteristics are here evaluated based on the lightning currents measured at the CN Tower during three major storms (2005, 2011 and 2014). Each of these three storms followed one of the network’s substantial upgrades that took place in 2003-2004, 2010-2011 and 2013-2014. The major contribution of this extensive investigation is the determination of the network’s performance characteristics following each of the three major upgrades, which is expected to lead to additional upgrades. Since 1990, the lightning current derivatives of return strokes have been measured at the CN Tower. Its 553-m height has allowed the recording of the current derivative signals of many hundreds of return strokes. Also, imaging systems have been used to record trajectories of flashes to the tower. The evaluated performance characteristics of the network include return-stroke detection efficiency, location accuracy, and return-stroke polarity and peak current estimation. The 2013 NALDN deployment of LS7002 digital sensors with enhanced embedded software has substantially improved the sensitivity of the sensors leading to a greater return-stroke detection efficiency. Furthermore, the 2014 total lightning processor (TLP100) –designed with new algorithm - provides smaller time-of-arrival errors, leading to better location accuracy. Based on the 2014 storm evaluation, the numbers and polarities of NALDN-detected return strokes were perfectly matched with those recorded at the tower. Furthermore, based on the 2014 storm evaluation, the NALDN is found, as expected, to overestimate the current peak measured at the tower by a factor of 3.89, which is due to the field enhancement effect resulting from the high-speed of propagation of the current within the tall tower. The presented analysis shows that the latest NALDN upgrades (2013-2014), following the 2003-2004 and 2010-2011 upgrades, have substantially improved the NALDN performance characteristics, especially in terms of stroke-detection efficiency and location accuracy. Keywords: Tall-structure lightning; lightning detection; detection efficiency; location accuracy; peak current estimation.

scholarly journals Assessment of the mapping potential of Pléiades stereo and triplet data

2014 ◽  
Vol II-3 ◽  
pp. 103-109 ◽  
Author(s):  
R. Perko ◽  
H. Raggam ◽  
K. Gutjahr ◽  
M. Schardt
Keyword(s):  
Large Scale ◽  
Optical Data ◽  
Model Optimization ◽  
Location Accuracy ◽  
Sensor Model ◽  
Forest Assessment ◽  
Stereo Data ◽  
Surface Models ◽  
High Level ◽  
Very High

The Pléiades satellites provide very high resolution optical data at a swath width of 20 km and a ground sampling distance of about 0.7 m at nadir direction. The sensors are remarkable agile as their pointing angle can be changed in a range of ±47 degrees. Thus, they are able to collect three images in one over flight representing tri-stereo data. In the presented work the mapping potential of Pléiades stereo and tri-stereo data is assessed in detail. The assessment is performed on two test sites and contains discussions on 2D initial geo-location accuracy, sensor model optimization, 3D geo-location accuracy, and a novel workflow for dense reconstruction of digital surface models (DSMs). The main outcomes are that the sensor accuracy is within the range as defined by Astrium, however a sensor model optimization is obligatory when it comes to highly accurate 3D mapping. The derived DSMs show a high level of detail thus enabling varying applications on a large scale, like change detection or forest assessment.

scholarly journals Evaluation of the performance characteristics of the North American Lightning Detection Network based on extensive CN Tower lightning data

2021 ◽  
Author(s):  
Savdulla Kazazi
Keyword(s):  
North American ◽  
Detection Efficiency ◽  
Performance Characteristics ◽  
Enhancement Effect ◽  
Return Stroke ◽  
Location Accuracy ◽  
Peak Current ◽  
The North ◽  
Current Estimation ◽  
Lightning Detection

The North American Lightning Detection Network (NALDN) has been providing lightning data since 1998. Important applications, such as detection of lightning-caused forest fires, power line fault locations and aviation safety procedures, have triggered a number of hardware and software upgrades for improving the network performance characteristics, including its detection efficiency and location accuracy. The NALDN performance characteristics are here evaluated based on the lightning currents measured at the CN Tower during three major storms (2005, 2011 and 2014). Each of these three storms followed one of the network’s substantial upgrades that took place in 2003-2004, 2010-2011 and 2013-2014. The major contribution of this extensive investigation is the determination of the network’s performance characteristics following each of the three major upgrades, which is expected to lead to additional upgrades. Since 1990, the lightning current derivatives of return strokes have been measured at the CN Tower. Its 553-m height has allowed the recording of the current derivative signals of many hundreds of return strokes. Also, imaging systems have been used to record trajectories of flashes to the tower. The evaluated performance characteristics of the network include return-stroke detection efficiency, location accuracy, and return-stroke polarity and peak current estimation. The 2013 NALDN deployment of LS7002 digital sensors with enhanced embedded software has substantially improved the sensitivity of the sensors leading to a greater return-stroke detection efficiency. Furthermore, the 2014 total lightning processor (TLP100) –designed with new algorithm - provides smaller time-of-arrival errors, leading to better location accuracy. Based on the 2014 storm evaluation, the numbers and polarities of NALDN-detected return strokes were perfectly matched with those recorded at the tower. Furthermore, based on the 2014 storm evaluation, the NALDN is found, as expected, to overestimate the current peak measured at the tower by a factor of 3.89, which is due to the field enhancement effect resulting from the high-speed of propagation of the current within the tall tower. The presented analysis shows that the latest NALDN upgrades (2013-2014), following the 2003-2004 and 2010-2011 upgrades, have substantially improved the NALDN performance characteristics, especially in terms of stroke-detection efficiency and location accuracy. Keywords: Tall-structure lightning; lightning detection; detection efficiency; location accuracy; peak current estimation.

scholarly journals Performance Characteristics of Distinct Lightning Detection Networks Covering Belgium

2013 ◽  
Vol 30 (5) ◽  
pp. 942-951 ◽  
Author(s):  
Dieter R. Poelman ◽  
Wolfgang Schulz ◽  
Christian Vergeiner
Keyword(s):  
High Speed ◽  
Detection Efficiency ◽  
Field Measurements ◽  
Ground Truth ◽  
Location Accuracy ◽  
Lightning Detection ◽  
Cloud To Ground Lightning ◽  
The Individual ◽  
Electric Field Measurements ◽  
Meteorological Institute

Abstract This study reports results from electric field measurements coupled to high-speed camera observations of cloud-to-ground lightning to test the performance of lightning location networks in terms of its detection efficiency and location accuracy. The measurements were carried out in August 2011 in Belgium, during which 57 negative cloud-to-ground flashes, with a total of 210 strokes, were recorded. One of these flashes was followed by a continuing current of over 1 s—one of the longest ever observed in natural negative cloud-to-ground lightning. Lightning data gathered from the lightning detection network operated by the Royal Meteorological Institute of Belgium [consisting of a network employing solely Surveillance et Alerte Foudre par Interférométrie Radioélectrique (SAFIR) sensors and a network combining SAFIR and LS sensors], the European Cooperation for Lightning Detection (EUCLID), Vaisala’s Global Lightning Detection network GLD360, and the Met Office’s long-range Arrival Time Difference network (ATDnet) are evaluated against this ground-truth dataset. It is found that all networks are capable of detecting over 90% of the observed flashes, but a larger spread is observed at the level of the individual strokes. The median location accuracy varies between 0.6 and 1 km, except for the SAFIR network, locating the ground contacts with 6.1-km median accuracy. The same holds for the reported peak currents, where a good correlation is found among the networks that provide peak current estimates, apart from the SAFIR network being off by a factor of 3.

Towards improved damage location using acoustic emission

2012 ◽  
Vol 226 (9) ◽  
pp. 2141-2153 ◽  
Author(s):  
Mark J Eaton ◽  
Rhys Pullin ◽  
Karen M Holford
Keyword(s):  
Acoustic Emission ◽  
Large Scale ◽  
Mapping Technique ◽  
Complex Materials ◽  
Acoustic Emission Technique ◽  
Destructive Testing ◽  
Location Accuracy ◽  
Aircraft Landing ◽  
Aircraft Landing Gear ◽  
Calculation Algorithms

The acoustic emission technique is a passive non-destructive testing technique that has significant potential for use as a structural health monitoring technique for many large-scale structures, allowing continuous global monitoring. The location capability of the acoustic emission technique is its most beneficial attribute; however, the location accuracy can often be limited in complex materials and structures. This article discusses recent advances in the location of acoustic emission signals. The key sources of errors are identified as signal arrival time measurement and processing algorithm limitations. A series of strategies for reducing the effects of both causes of error are presented. Additionally, the results of a case study are used to demonstrate a novel mapping technique for acoustic emission source location of fatigue crack signals in an aircraft landing gear component. Improvements in location accuracy of up to 87.5% were observed when compared with standard location calculation algorithms.

Performance evaluation of the U.S. National Lightning Detection Network in eastern New York: 2. Location accuracy

1998 ◽  
Vol 103 (D8) ◽  
pp. 9057-9069 ◽  
Author(s):  
Vincent P. Idone ◽  
Daniel A. Davis ◽  
Paul K. Moore ◽  
Yan Wang ◽  
Ronald W. Henderson ◽  
...  
Keyword(s):  
New York ◽  
Performance Evaluation ◽  
Location Accuracy ◽  
Lightning Detection ◽  
The U.S

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Large-scale Motion of Solar Filaments

2000 ◽  
Vol 179 ◽  
pp. 205-208
Author(s):  
Pavel Ambrož ◽  
Alfred Schroll
Keyword(s):  
Magnetic Flux ◽  
Proper Motion ◽  
Time Scale ◽  
Large Scale ◽  
Accuracy Of Measurements ◽  
Solar Filaments ◽  
General Movement ◽  
Scale Motion ◽  
Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

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