scholarly journals Seasonal Variability of Lightning Activity in Yakutia in 2009–2019

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 918
Author(s):  
Lena Tarabukina ◽  
Vladimir Kozlov
Keyword(s):  
Moving Average ◽  
Single Point ◽  
Low Frequency ◽  
Lightning Activity ◽  
Entire Area ◽  
Direction Finder ◽  
Seasonal And Diurnal Variations ◽  
Number Variation ◽  
Lightning Discharges ◽  
Total Lightning

The instrumental continuous monitoring of lightning activity in Yakutia has been carried by the lightning direction finder since the 2000s. Devices for detection of sferic (very low frequency radio pulses emitted by lightning discharges) in Yakutia were supplemented in 2009 with relatively short-range (effective detection radius up to 480 km) single-point Stormtracker and LD-250 direction finders from Boltek Corporation (Welland, ON, Canada). The Stormtracker gives a slightly overestimated ratio of CG strokes due to the amplitude threshold of a single-point direction finder, but the device has not changed over the years, which allows for the consideration of the annual dynamics of parameters. In 2009, a sensor in Yakutsk was included in the World Wide Lightning Location Network (WWLLN). The seasonal and diurnal variations of the total lightning stroke number in the central part and the entire area of Yakutia were obtained (up to 1200 km in radius and limited by latitude–longitude boundaries of 105–150° E, 55–75° N). The longest thunderstorm seasons are often observed in the southern part of Yakutia. There was a slight increase in the duration of the thunderstorm season until 2015 in the central part of Yakutia. The interannual variations in the total number of lightning strokes showed periodic fluctuations (with a period of about three years) over the whole area of Yakutia. The periods of high lightning activity shifted within a season from year to year, as revealed by the monthly stroke number variation. Thus, the maximum lightning rate occurred at the beginning of summer, in the middle or at the beginning of August, and had a period of about three years. Every summer, there were 2–3 periods of high lightning activity, resulting from the moving average with a two-week window (according to the longest duration of cyclones). If the periods of high lightning activity shifted toward the beginning of summer, a decrease in the number of days between seasonal peaks was observed. If the maximum shifted to the beginning of August, the number of days between peaks increased. The ratio of cloud-to-ground (CG) lightning strokes and the ratio of negative CG strokes was slightly decreasing by 2015 in the central part of Yakutia.

CORRELATION OF LOCAL LIGHTNING ACTIVITY WITH EXTRA LOW FREQUENCY DETECTOR FOR SCHUMANN RESONANCE MEASUREMENTS

2021 ◽  
pp. 147671
Author(s):  
G. Tatsis ◽  
A. Sakkas ◽  
V. Christofilakis ◽  
G. Baldoumas ◽  
S.K. Chronopoulos ◽  
...  
Keyword(s):  
Low Frequency ◽  
Lightning Activity ◽  
Schumann Resonance ◽  
Frequency Detector

scholarly journals The Three-Dimensional Locating of VHF Broadband Lightning Interferometers

Atmosphere ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 317 ◽  
Author(s):  
Hengyi Liu ◽  
Shi Qiu ◽  
Wansheng Dong
Keyword(s):  
Time Resolution ◽  
High Frequency ◽  
Three Dimensional ◽  
High Time Resolution ◽  
Very High Frequency ◽  
Time Difference Of Arrival ◽  
Lightning Discharges ◽  
Total Lightning ◽  
Locating Information ◽  
Very High

VHF (Very High Frequency) lightning interferometers can locate and observe lightning discharges with a high time resolution. Especially the appearance of continuous interferometers makes the 2-D location of interferometers further improve in time resolution and completeness. However, there is uncertainty in the conclusion obtained by simply analyzing the 2-D locating information. Without the support of other 3-D total lightning locating networks, the 2-station interferometer becomes an option to obtain 3-D information. This paper introduces a 3-D lightning location method of a 2-station broadband interferometer, which uses the theodolite wind measurement method for reference, and gives the simulation results of the location accuracy. Finally, using the multi-baseline continuous 2-D locating method and the 3-D locating method, the locating results of one intra-cloud flash and the statistical results of the initiation heights of 61 cloud-to-ground flashes and 80 intra-cloud flashes are given. The results show that the two-station interferometer has high observation accuracy on both sides of the connection between the two sites. The locating accuracy will deteriorate as the distance between the radiation source and the two stations increases or the height decreases. The actual locating results are similar to those of the existing VHF TDOA (Time Difference of Arrival) lightning locating network.

scholarly journals Location accuracy of VLF World-Wide Lightning Location (WWLL) network: Post-algorithm upgrade

2005 ◽  
Vol 23 (2) ◽  
pp. 277-290 ◽  
Author(s):  
C. J. Rodger ◽  
J. B. Brundell ◽  
R. L. Dowden
Keyword(s):  
Real Time ◽  
World Wide ◽  
Detection Efficiency ◽  
Activity Levels ◽  
Operational Mode ◽  
Current Form ◽  
Location Accuracy ◽  
Central Processing ◽  
Lightning Discharges ◽  
Total Lightning

Abstract. An experimental VLF World-Wide Lightning Location (WWLL) network has been developed through collaborations with research institutions across the globe. The aim of the WWLL is to provide global real-time locations of lightning discharges, with >50% CG flash detection efficiency and mean location accuracy of <10km. While these goals are essentially arbitrary, they do define a point where the WWLL network development can be judged a success, providing a breakpoint for a more stable operational mode. The current network includes 18 stations which cover much of the globe. As part of the initial testing phase of the WWLL the network operated in a simple mode, sending the station trigger times into a central processing point rather than making use of the sferic Time of Group Arrival (TOGA). In this paper the location accuracy of the post-TOGA algorithm WWLL network (after 1 August 2003) is characterised, providing estimates of the globally varying location accuracy for this network configuration which range over 1.9-19km, with the global median being 2.9km, and the global mean 3.4km. The introduction of the TOGA algorithm has significantly improved the location accuracies. The detection efficiency of the WWLL is also considered. In the selected region the WWLL detected ~13% of the total lightning, suggesting a ~26% CG detection efficiency and a ~10% IC detection efficiency. Based on a comparison between all WWLL good lightning locations in February-April 2004, and the activity levels expected from satellite observations we estimate that the WWLL is currently detecting ~2% of the global total lightning, providing good locations for ~5% of global CG activity. The existing WWLL network is capable of providing real-time positions of global thunderstorm locations in its current form.

scholarly journals Electrical characteristics and environmental conditions of lightning-ignited fires in the Iberian Peninsula and Mediterranean France between 2009 and 2015

2020 ◽  
Author(s):  
Francisco J. Pérez-Invernón ◽  
Heidi Huntrieser ◽  
Sergio Soler Lopez ◽  
Francisco J. Gordillo-Vázquez ◽  
Javier Navarro-Gonzalez ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Forest Fires ◽  
Environmental Conditions ◽  
Climate Model ◽  
Wildland Fire ◽  
Current Phase ◽  
Electrical Characteristics ◽  
Geophysical Research ◽  
Lightning Discharges ◽  
Total Lightning

&lt;p&gt;About 5% of the wildfires in the Mediterranean basin are produced by lightning [1]. Lightning-ignited fires tend to occur in remote areas and can spread significantly before suppression. The occurrence of lightning-caused fires is closely related with intense drought periods and high temperatures [2]. Therefore, drier conditions and higher temperatures in a changing climate are expected to lead to a future increase in lightning-ignited fires occurrence. The development of a lightning-ignited fire parameterization for Earth system models arises as a necessary tool to predict the future occurrence of these extreme events and to study their impact on atmospheric chemistry.&lt;/p&gt;&lt;p&gt;Long Continuing Current lightning (LCC-lightning), preferable taking place in dry thunderstorms, is believed to be the main precursor of lightning-ignited fires. This was originally proposed by McEachron and Itagenguth in 1942 [3] working with laboratory sparks, which suggested that ignition by natural lightning is usually caused by a discharge having an unusual long-continuing current phase. Later in 1967 this hypothesis was confirmed by Fuquay &lt;em&gt;et al.&lt;/em&gt; [4].&lt;/p&gt;&lt;p&gt;In this work, we analyse three fire databases of lightning-ignited fires in Spain, Portugal and Southern France between 2009 and 2015. Furthermore lightning measurements from the World Wide Lightning Location Network (WWLLN) and the Earth Networks Total Lightning Network (ENTLN), and land and atmospheric variables from the new ERA-5 reanalysis are combined to investigate the electrical characteristics and environmental conditions of the fires. This preliminary data analysis will be useful to set new relationships between the characteristics of thunderstorms and the initiation of wildfires. It is the first step towards the development of a detailed lightning-ignited fire parameterization for the atmospheric chemistry-climate model EMAC.&lt;/p&gt;&lt;p&gt;[1] V&amp;#225;zquez, A., and Moreno, J. M. (1998). Patterns of lightning-, and people-caused fires in peninsular Spain. International Journal of Wildland Fire, 8(2), 103-115.&lt;/p&gt;&lt;p&gt;[2] Pineda, N., and Rigo, T. (2017). The rainfall factor in lightning-ignited wildfires in Catalonia. Agricultural and Forest Meteorology, 239, 249-263.&lt;/p&gt;&lt;p&gt;[3] McEachron, K. B., and Itagenguth, J. It (1942), Effect of lightning on thin metal surfaces, AIEE Trans., 61, 559-564, 1942.&lt;/p&gt;&lt;p&gt;[4] Fuquay, D. M., Baughman R. G, Taylor, A. R. and Hawe, R. G. (1967). Characteristics of seven lightning discharges that caused forest fires. Journal of Geophysical Research, 72 (24).&lt;/p&gt;

scholarly journals Magnetic Field due to the Radiation of High Altitude Lightning

2020 ◽  
Vol 8 (2S12) ◽  
pp. 49-50
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Radiation ◽  
High Altitude ◽  
Low Frequency ◽  
Frequency Region ◽  
Middle Region ◽  
Very Low Frequency ◽  
Lightning Discharges ◽  
Cloud To Ground Lightning ◽  
Frequency Radiation

High altitude optical discharges generated by extreme cloud-to-ground lightning strokes, which occur in the middle region of the atmosphere known as sprites. Streamer formation in sprites has been well stated to be existing by several previous workers. These streamers are not only responsible for the initiation of sprites but also they are composed of these streamers. It causes the production of electromagnetic radiation upto or below the ELF (very low frequency) region which have been reported earlier through various research theories. Thus, we are reporting out for the formulation of the model by using an earlier model used to estimate higher frequency radiation from cloud and ground lightning discharges through these positive corona streamers. Taking it into account, other terms like radiation magnetic field has been evaluated with the studied observations.

Use of seismoscope records to determine ML and peak velocities

1984 ◽  
Vol 74 (1) ◽  
pp. 315-324
Author(s):  
David M. Boore
Keyword(s):  
Lower Bound ◽  
San Francisco ◽  
Peak Velocity ◽  
Response Spectrum ◽  
Single Point ◽  
Empirical Relation ◽  
Low Frequency ◽  
Simulation Method ◽  
Horizontal Velocity ◽  
Earthquake Moment

Abstract More information about ground motion can be extracted from seismoscope records than a single point on a response spectrum. To demonstrate this, the relation between seismoscope response and Wood-Anderson instrument output and peak horizontal ground velocity has been studied by simulating the various responses for a range of distances and magnitudes. The simulations show that the relation used by Jennings and Kanamori (1979) to convert from peak seismoscope readings to the peak response of a Wood-Anderson instrument has a distance- and magnitude-dependent systematic error. The error is negligible, however, for modern seismoscopes at distances of a few tens of kilometers. At several hundred kilometers, the relation underestimates the Wood-Anderson response by as much as a factor of two. The spread in Jennings and Kanamori's estimate of ML for the 1906 San Francisco earthquake, recorded on seismoscopes having relatively low natural frequencies (0.26 and 0.5 Hz), is reduced by the results in this paper—the upper value, from a seismoscope in Carson City, Nevada, at 290 km from the fault, going from ML = 7.2 to ML = 7.0 and the lower value, from Yountville, California (R ≈ 60 km), going from about 6.3 to 6.4. About 0.3 units of the remaining spread may be due to local geologic site conditions. If the 0.3 units is distributed equally between the Yountville and Carson City recordings, the estimates of ML for the San Francisco earthquake then become 6.5 and 6.8, somewhat lower than Jennings and Kanamori's final estimates of 634 to 7. Although the error in using the relation of Jennings and Kanamori to estimate Wood-Anderson response was at most a factor of 1.6 for the 1906 earthquake, the error can be substantially larger for smaller earthquakes recorded on similar low frequency seismoscopes. The relation between Wood-Anderson and seismoscope response used by Jennings and Kanamori can be combined with an empirical relation between peak horizontal velocity and Wood-Anderson response to predict peak velocity from seismocope recordings. The simulations show that this relation (vmax = 8.1Awa, where vmax is the peak horizontal velocity in centimeters/second and Awa is one-half the range of the Wood-Anderson motion in meters) forms a lower bound for estimates of peak velocity from seismoscope recordings. The relation is good for stations within about 100 km of earthquakes with moment magnitudes of about 4.5 to 6.5, and it underestimates peak velocity by factors up to 2 or 3 for larger earthquakes at distances within 100 km. An application of the simulation method to the 1976 Guatemala earthquake (moment magnitude = 7.6) results in 37 cm/sec as a lower bound to vmax, with 66 cm/sec as a more likely value, from the seismocope recording in Guatemala City (approximately 25 km from the Motagua fault).

scholarly journals The Effects of Hydraulic Jumps Instability on a Natural River Confluence: The Case Study of the Chiaravagna River (Italy)

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 2027 ◽  
Author(s):  
Annalisa De Leo ◽  
Alessia Ruffini ◽  
Matteo Postacchini ◽  
Marco Colombini ◽  
Alessandro Stocchino
Keyword(s):  
Physical Model ◽  
Hydraulic Jump ◽  
Low Frequency ◽  
Water Levels ◽  
Entire Area ◽  
Hydraulic Conditions ◽  
River Confluence ◽  
Series Of Experiments ◽  
Small River Basin

The occurrence and the effects of hydraulic jump instabilities on a natural river confluence in a small river basin in Liguria (Italy) is here investigated. Hydraulic jump instability has been extensively studied in controlled and simplified laboratory rectangular flumes. In the present study, a scaled physical model of the Chiaravagna River and Ruscarolo Creek confluence has been used, retaining the realistic geometry of the reaches. This reach has been subject to frequent floods in the last twenty years and the entire area of the confluence has been redesigned to decrease the flood risk. A series of experiments has been performed varying the discharge on the two reaches and the geometrical configurations. Free surface levels and two dimensional horizontal velocities have been measured in several positions along the physical model. The analysis of the water levels and velocities reveals that oscillations characterised by large amplitude and low frequency occur under particular hydraulic conditions. These oscillations have been found to be triggered by the hydraulic jump toe instability of the smallest reach of the confluence. Aiming at reducing the amplitude of the oscillations, which can be of the order of the flow depth, possible constructive solutions have been tested to control or damp the oscillations. Indeed, the insertion of a longitudinal dyke at the confluence has proven to be an effective solution to limit the amplitude of the transversal oscillations.

scholarly journals Removal of ECG Baseline Wander using Savitzky-Golay Filter Based Method

2017 ◽  
Vol 8 (1) ◽  
pp. 32-45 ◽  
Author(s):  
KM Talha Nahiyan ◽  
Abdullah Al Amin
Keyword(s):  
Body Surface ◽  
Medical Physics ◽  
Moving Average ◽  
Low Frequency ◽  
The Body ◽  
Ecg Signal ◽  
Fitting Method ◽  
Baseline Wander ◽  
Moving Averaging ◽  
Average Filter

ECG (Electrocardiogram) is a measure of heart’s electrical activity. As the body is a volume conductor, ECG signal can be recorded from the body surface. The signal while being recorded from the body surface gets corrupted by various types of noise or artifact. Among these, baseline wander is a type of noise that severely hampers the ECG signal. Baseline wander is particularly of very low frequency; it causes the ECG signal to deviate from its isoelectric line and causes the signal to ride on the lower frequency artifact. The proposed method is based on Savitzky-Golay filter, which is a moving average filter that takes into consideration the polynomial order along with moving averaging when approximating the signal. It enables to approximate the baseline wander quite efficiently. Though in some cases it distorts the ECG signal to some extent, when compared with usual polynomial fitting method, it demonstrates superiority in terms of accuracy, simplicity and generalization.Bangladesh Journal of Medical Physics Vol.8 No.1 2015 32-45

Exploiting the characteristics of volcanic lightning for volcano monitoring

2020 ◽  
Author(s):  
Sonja Behnke ◽  
Harald Edens ◽  
Seda Senay ◽  
Diana Swanson ◽  
Alexa Van Eaton ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Long Range ◽  
Detection Efficiency ◽  
Low Frequency ◽  
Volcano Monitoring ◽  
Volcanic Plume ◽  
Very High Frequency ◽  
New Information ◽  
Lightning Discharges ◽  
Volcanic Lightning

&lt;p&gt;Volcanic lightning measurements are gaining momentum in the volcano monitoring community as a tool to identify when an ash producing eruption has occurred. As a volcanic plume develops from an ash-laden jet to a convective plume, the electrical discharges also evolve, ranging from small &amp;#8220;vent discharges&amp;#8221; (a few meters in length) and near-vent lightning (tens of meters to kilometers in length) to thunderstorm-like plume lightning (tens of kilometers in length). Currently, volcanic lightning monitoring capabilities for volcano observatories are mainly limited to using long-range lightning sensor networks, which do not detect the full gamut of volcanic lightning due to the networks&amp;#8217; detection efficiency and the radio frequency band that they use (very low frequency or low frequency). This biases the sensors towards detecting only the larger volcanic lightning discharges that occur at later stages in plume development, which can result in detection delays of minutes to tens of minutes from the onset of eruption. In addition to the latency, there is no way to know if the lightning picked up by long range networks is from a volcanic or meteorological source without some other additional source measurement. Both the latency and the source ambiguity could be reduced by using lightning sensors at close range that can detect the very small vent discharges associated with volcanic explosions. Vent discharges occur within the gas thrust region in a plume, starting simultaneously with the onset of an eruption and persisting continually for seconds or tens of seconds, depending on the duration of an eruption. They produce a distinctive &amp;#8216;continual radio frequency&amp;#8217; signal, of which there is no analogous signature in meteorological lightning. Thus, the characteristics of the radio frequency signature of vent discharges could be exploited to innovate a new sensor design that is both low power and transmits information (i.e., a useful derived data product) at rates low enough to be used at remote volcanoes where volcano monitoring is often sparse. To meet this goal, a new experiment at Sakurajima Volcano in Japan is underway to learn more about the physical characteristics and signal characteristics of vent discharges. We use broadband very high frequency sensors to record time series measurements of the vent discharges and other volcanic lightning discharges that occur from explosions of the Minamidake crater of Sakurajima. These measurements reveal new information about vent discharges, such as their duration and spectral features, that can be used to help identify when explosive eruptions are occurring.&lt;/p&gt;

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