scholarly journals Lightning environment in the vicinity of the CN tower during major storms

2021 ◽  
Author(s):  
Norhan Mansour
Keyword(s):  
Measurement System ◽  
North American ◽  
Electromagnetic Interference ◽  
Current Measurement ◽  
Average Multiplicity ◽  
Network Data ◽  
Return Stroke ◽  
The North ◽  
Lightning Detection ◽  
Intense Storm

Based on the North American Lightning Detection Network data and the return-stroke currents recorded at the CN Tower, the lightning environment within 100 km from the CN Tower is thoroughly investigated, especially while the tower was struck with major storms in 2011 and 2005. On Aug 24, 2011, video records showed that the tower was struck with 52 flashes within about 84 minutes, pointing out to the most intense storm that has ever been observed at the tower. During this most intense storm, the tower’s current measurement system recorded 32 flashes, containing 161 return strokes, resulting in an average flash multiplicity of 5, which is 80% higher than the average multiplicity of flashes occurring in the vicinity of the tower. Since the tower is repeatedly hit by lightning and its flashes produce markedly higher number of strokes, then it definitely poses an electromagnetic interference risk to nearby sensitive installations, including those in downtown Toronto.

scholarly journals Lightning environment in the vicinity of the CN tower during major storms

2021 ◽  
Author(s):  
Norhan Mansour
Keyword(s):  
Measurement System ◽  
North American ◽  
Electromagnetic Interference ◽  
Current Measurement ◽  
Average Multiplicity ◽  
Network Data ◽  
Return Stroke ◽  
The North ◽  
Lightning Detection ◽  
Intense Storm

Based on the North American Lightning Detection Network data and the return-stroke currents recorded at the CN Tower, the lightning environment within 100 km from the CN Tower is thoroughly investigated, especially while the tower was struck with major storms in 2011 and 2005. On Aug 24, 2011, video records showed that the tower was struck with 52 flashes within about 84 minutes, pointing out to the most intense storm that has ever been observed at the tower. During this most intense storm, the tower’s current measurement system recorded 32 flashes, containing 161 return strokes, resulting in an average flash multiplicity of 5, which is 80% higher than the average multiplicity of flashes occurring in the vicinity of the tower. Since the tower is repeatedly hit by lightning and its flashes produce markedly higher number of strokes, then it definitely poses an electromagnetic interference risk to nearby sensitive installations, including those in downtown Toronto.

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 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 Effects of lightning and other meteorological factors on fire activity in the North American boreal forest: implications for fire weather forecasting

2010 ◽  
Vol 10 (14) ◽  
pp. 6873-6888 ◽  
Author(s):  
D. Peterson ◽  
J. Wang ◽  
C. Ichoku ◽  
L. A. Remer
Keyword(s):  
Boreal Forest ◽  
North American ◽  
Meteorological Factors ◽  
Convective Available Potential Energy ◽  
Fire Weather ◽  
Lightning Strikes ◽  
The North ◽  
Lightning Detection ◽  
Western Boreal Forest ◽  
Consecutive Dry Days

Abstract. The effects of lightning and other meteorological factors on wildfire activity in the North American boreal forest are statistically analyzed during the fire seasons of 2000–2006 through an integration of the following data sets: the MODerate Resolution Imaging Spectroradiometer (MODIS) level 2 fire products, the 3-hourly 32-km gridded meteorological data from North American Regional Reanalysis (NARR), and the lightning data collected by the Canadian Lightning Detection Network (CLDN) and the Alaska Lightning Detection Network (ALDN). Positive anomalies of the 500 hPa geopotential height field, convective available potential energy (CAPE), number of cloud-to-ground lightning strikes, and the number of consecutive dry days are found to be statistically important to the seasonal variation of MODIS fire counts in a large portion of Canada and the entirety of Alaska. Analysis of fire occurrence patterns in the eastern and western boreal forest regions shows that dry (in the absence of precipitation) lightning strikes account for only 20% of the total lightning strikes, but are associated with (and likely cause) 40% of the MODIS observed fire counts in these regions. The chance for ignition increases when a threshold of at least 10 dry strikes per NARR grid box and at least 10 consecutive dry days is reached. Due to the orientation of the large-scale pattern, complex differences in fire and lightning occurrence and variability were also found between the eastern and western sub-regions. Locations with a high percentage of dry strikes commonly experience an increased number of fire counts, but the mean number of fire counts per dry strike is more than 50% higher in western boreal forest sub-region, suggesting a geographic and possible topographic influence. While wet lightning events are found to occur with a large range of CAPE values, a high probability for dry lightning occurs only when 500 hPa geopotential heights are above ~5700 m and CAPE values are near the maximum observed level, underscoring the importance of low-level instability to boreal fire weather forecasts.

INVESTIGATION OF RADAR AND ELECTRICAL CHARACTERISTICS OF THUNDERCLOUDS SEEDED WITH A GLACIOGENIC REAGENT IN KARNATAKA, INDIA

2021 ◽  
pp. 112-122
Author(s):  
A.A. SIN'KEVICH ◽  
◽  
B. BOE ◽  
S. PAWAR ◽  
YU. P. MIKHAILOVSKII ◽  
...  
Keyword(s):  
Network Data ◽  
Lightning Flash ◽  
Electrical Characteristics ◽  
North Caucasus ◽  
Flash Rate ◽  
Convective Clouds ◽  
The North ◽  
Lightning Detection ◽  
Karnataka State ◽  
Order Of Magnitude

Characteristics of developing convective clouds (Cu) in Karnataka state (India) during the thunderstorm formation are analyzed using weather radar and lightning detection network data. It is noted that radar characteristics of Cu which produced lightning, exceed those where lightning does not form. The study has shown that the number of negative cloud-to-ground strokes exceeds the number of positive ones by an order of magnitude. The radar characteristics of clouds in India and the North Caucasus are compared. Significant differences in lightning flash rates over the mentioned regions are registered. A low correlation is found between the supercooled volume and the flash rate of negative lightning. The paper also presents the results of studying the dynamic characteristics of four Cu seeded with a glaciogenic reagent. The thunderstorm risk is estimated for the clouds. It is shown that the seeding increases a probability of lightning events.

scholarly journals The North American Lightning Detection Network (NALDN)—Analysis of Flash Data: 2001–09

2011 ◽  
Vol 139 (5) ◽  
pp. 1305-1322 ◽  
Author(s):  
Richard E. Orville ◽  
Gary R. Huffines ◽  
William R. Burrows ◽  
Kenneth L. Cummins
Keyword(s):  
United States ◽  
North America ◽  
North American ◽  
The United States ◽  
The North ◽  
Lightning Detection ◽  
Geographical Regions ◽  
Positive Peak ◽  
The U.S ◽  
Cg Lightning

Cloud-to-ground (CG) lightning data have been analyzed for the years 2001–09 for North America, which includes Alaska, Canada, and the lower 48 U.S. states. Flashes recorded within the North American Lightning Detection Network (NALDN) are examined. No corrections for detection efficiency variability are made over the 9 yr of the dataset or over the large geographical area comprising North America. There were network changes in the NALDN during the 9 yr, but these changes have not been corrected for nor have the recorded data been altered in any way with the exception that all positive lightning reports with peak currents less than 15 kA have been deleted. Thus, the reader should be aware that secular changes are not just climatological in nature. All data were analyzed with a spatial resolution of 20 km. The analyses presented in this work provide a synoptic view of the interannual variability of lightning observations in North America, including the impacts of physical changes in the network during the 9 yr of study. These data complement and extend previous analyses that evaluate the U.S. NLDN during periods of upgrade. The total (negative and positive) flashes for ground flash density, the percentage of positive lightning, and the positive flash density have been analyzed. Furthermore, the negative and positive first stroke peak currents and the flash multiplicity have been examined. The highest flash densities in Canada are along the U.S.–Canadian border (1–2 flashes per square kilometer) and in the United States along the Gulf of Mexico coast from Texas through Florida (exceeding 14 flashes per square kilometer in Florida). The Gulf Stream is “outlined” by higher flash densities off the east coast of the United States. Maximum annual positive flash densities in Canada range primarily from 0.01 to 0.3 flashes per square kilometer, and in the United States to over 0.5 flashes per square kilometer in the Midwest and in the states of Louisiana and Mississippi. The annual percentage of positive lightning to ground varies from less than 2% over Florida to values exceeding 25% off the West Coast, Alaska, and the Yukon. A localized maximum in the percentage of positive lightning in the NALDN occurs in Manitoba and western Ontario, just north of North Dakota and Minnesota. When averaged over North America, first stroke negative median peak currents range from 19.8 kA in 2001 to 16.0 kA in 2009 and for all years, average 16.1 kA. First stroke positive median peak currents range from a high of 29.0 kA in 2008 and 2009 to a low of 23.3 kA in 2003 with a median of 25.7 kA for all years. There is a relatively sharp transition from low to high median negative peak currents along the Gulf and Atlantic coasts of the United States. No sharp transitions are observed for the median positive peak currents. Relatively lower positive peak currents occur throughout the southeastern United States. The highest values of mean negative multiplicity exceed 3.0 strokes per flash in the NALDN with some variation over the 9 yr. Lower values of mean negative multiplicity occur in the western United States. Positive flash mean multiplicity is slightly higher than 1.1, with the highest values of 1.7 observed in the southwestern states. As has been noted in prior research, CG lightning has significant variations from storm to storm as well as between geographical regions and/or seasons and, consequently, a single distribution for any lightning parameter, such as multiplicity or peak current, may not be sufficient to represent or describe the parameter.

scholarly journals A performance analysis of the North American Lightning Detection Network using CN Tower lightning data

2021 ◽  
Author(s):  
Alexandru Lafkovici
Keyword(s):  
North American ◽  
Detection Efficiency ◽  
Lightning Discharge ◽  
Location Error ◽  
Error Ellipse ◽  
Semi Major Axis ◽  
North East ◽  
The North ◽  
Lightning Detection ◽  
Triggered Lightning

The North American Lightning Detection Network (NALDN) is a commercial lightning detection network operated by Vaisala Inc., and is composed of the U.S. National Lightning Detection Network (NLDN) and the Environment Canada owned Canadian Lightning Detection Network (CLDN). The CN Tower is one of the best sites in the world to observe the lightning phenomenon and provides an excellent opportunity to evaluate the performance of the NALDN in the Toronto area. Using CN Tower lightning data acquired during 2005, the performance characteristics of the NALDN were thoroughly evaluated, including the flash detection efficiency (DE), stroke DE, absolute location error, peak current estimation and location accuracy model (50%, 90% and 99% error ellipses) error. Although a similar test was performed using rocket-triggered lightning in Florida at Camp Blanding, this test evaluated a completely different region of the NALDN. Moreover, rocket-triggered lightning artificially initiates a lightning discharge, whereas lightning events to the CN Tower occur naturally and are similar to discharges that occur to tall structures or objects at high altitude or mountainous areas. Excluding two flashes understood to be composed of M-components, the NALDN detected 7 out of 7 flashes recorded at the CN Tower, resulting in a 100% flash DE. Furthermore, the NALDN detected 22 out of 39 strokes recorded at the CN Tower, resulting in a stroke DE of 56%. Relative to the CN Tower, the NALDN was found to have a median absolute location error of 0.356 km and a mean error of 0.390 km for the 22 strokes it detected. It was also demonstrated that the NALDN stroke location error seems to have a large bias towards the north of the CN Tower and a slight bias towards the east, with 19 of the 22 strokes predicted north-east of the CN Tower. The 50%, 90% and 99% error ellipses provided by the NALDN were also evaluated. It was found that 73% (16 out of the 22) detected strokes were enclosed by the 50% error ellipse, 91% (20 out of the 22) detected strokes were enclosed by the 90% error ellipse and 95% (21 out of the 22) detected strokes were enclosed by the 99% error ellipse. The minimum value for the 50% error ellipse axes is set at 0.4 km by Vaisala, and 21 out of the 22 detected strokes had a semi-major axis length of 0.4 km, suggesting that the median location error for CN Tower strokes is 0.4 or less. The 0.356 km median location error obtained for the 22 detected strokes appears to support this.

NAD83 SECONDARY INTEGRATION

CISM journal ◽  
1988 ◽  
Vol 42 (4) ◽  
pp. 331-340
Author(s):  
C. Parent ◽  
M.C. Pinch
Keyword(s):  
North American ◽  
Geodetic Network ◽  
Network Data ◽  
The North ◽  
Secondary Network ◽  
Control Survey ◽  
Cooperative Project ◽  
Integration Project ◽  
Simultaneous Adjustment ◽  
Secondary Networks

The Canadian geodetic network that was adjusted with networks of other North American countries, in the July 1986 Continental Adjustment, included only the 8000-station national primary framework. There still remains many thousands of stations contained in regional and local secondary networks to integrate into the North American Datum of 1983 (NAD83). Secondary Integration is a cooperative project organized by member agencies of the Canadian Control Survey Committee (CCSC) which first met in 1982. Since then, members have automated and evaluated secondary network data for approximately 100 000 stations established by conventional, inertial and satellite surveying methods. The task of compiling and testing Helmert blocks for input to the simultaneous adjustment of primary and secondary networks is now underway. This paper describes the plans and progress, and some of the problems that challenge us in the NAD83 Secondary Integration Project.

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