Reconstructing the propagation of Whistlers observed in ELF during ASM burst sessions from the lightning strikes to their detection and validation of IRI model

2020 ◽  
Author(s):  
Pierdavide Coïsson ◽  
Vladimir Truhlik ◽  
Janusz Mlynarczyk ◽  
Gauthier Hulot ◽  
Rémi Madelon ◽  
...  
Keyword(s):  
Spectral Band ◽  
Lightning Discharge ◽  
Geomagnetic Latitude ◽  
Propagation Path ◽  
Topside Ionosphere ◽  
Iri Model ◽  
Experimental Conditions ◽  
Lightning Strikes ◽  
Swarm Satellites ◽  
The World

<p>New sessions of burst-mode acquisition of the Absolute Scalar Magnetometers (ASM) onboard Swarm satellites have been conducted during 2019 , with the aim of acquiring events covering various geophysical conditions, in terms of geomagnetic latitude, spacecraft Local Time and season, to better understand the conditions under which the ELF component of whistlers is excited and can be detected at satellite altitude and to provide an additional ionospheric monitoring.</p><p>Among all candidate events detected using an automatic algorithm specifically designed for that purpose, a selection of remarkable whistler events have been further studied. Firstly, from the estimation of the whistler dispersions, the origin times of the lightning discharge have been estimated and validated with ground data from the World ELF Radiolocation Array (WERA), providing the locations of the lightning strikes and their intensity in the ELF spectral band. These locations have also been validated using data from the World Wide Lightning Location Network (WWLLN) providing measurements.</p><p>Subsequently, to reconstruct the propagation path inside the ionosphere of the ELF component of the whistler, a dedicated ray-tracing algorithm has been designed. It uses a background ionosphere model of electron and ions based on the International Reference Ionosphere. For the purposes of producing a ionospheric representation as close as possible to the experimental conditions, the update of the main ionospheric parameters based on worldwide ionosonde data IRTAM has been applied, validating it by using ionosonde data available in the vicinity of specific whistler events. The in-situ electron density measurements of the Electric Field Instrument (EFI) of Swarm satellite have also been used to constrain the model in the topside ionosphere.</p><p>We present the recent results obtained during some of these burst sessions, and discuss the possibility offered by this new dataset to validate global ionospheric models and provide a new avenue in ionospheric research, that could be also pursued by the NanoMagSat mission.</p>

Observation and modelling of whistlers in the ELF as observed by Swarm satellites during regular ASM burst sessions

2021 ◽  
Author(s):  
Pierdavide Coïsson ◽  
Vladimir Truhlik ◽  
Janusz Mlynarczyk ◽  
Gauthier Hulot ◽  
Laura Brocco ◽  
...  
Keyword(s):  
Spectral Band ◽  
Neutral Atmosphere ◽  
Iri Model ◽  
Low Frequencies ◽  
Lightning Strikes ◽  
Ionospheric Models ◽  
Swarm Satellites ◽  
Burst Data ◽  
Low Earth Orbits ◽  
Electromagnetic Signals

<p>The magnetic component of electromagnetic signals in the Extremely Low Frequencies (ELF) has been rarely observed from space. The Swarm satellites have the capability of observing part of this spectral band during burst sessions of the Absolute Scalar Magnetometer (ASM), when the sampling frequency of the instrument is raised to 250 Hz. Burst sessions of one week duration have been acquired regularly since 2019. Swarm satellites drift slowly in local time, therefore it has been possible to progressively acquire burst data to cover all hours at all latitudes. This is a unique opportunity at Low Earth Orbits (LEO) in recent years.</p><p>This study focuses on whistlers excited by lightning strikes generated by strong storm systems in the troposphere. The ELF component of the lightning signal propagates in the neutral atmosphere at very long distances. We used data from the ground stations of the World ELF Radiolocation Array (WERA) in order to estimate lightning locations and intensity for remarkable events. Part of the lightning signal penetrates into the ionosphere, where the ionospheric plasma produces its dispersion, depending on the spatial distribution of the plasma and the direction of the magnetic field.</p><p>We selected events to simulate their propagation through the ionosphere, using ionosonde data, IRI Real-Time Assimilative Mapping (IRTAM) and International Reference Ionosphere (IRI) model as backgrounds, along with the latest version of the International Geomagnetic Reference Field (IGRF). This technique allows to use these signals to sound the ionosphere and validate ionospheric models.</p><p>A database of whistler occurrences and parameters has been constructed and a new Swarm L2 product has been defined to make this data accessible to the scientific community.</p>

scholarly journals On the Electron Temperature in the Topside Ionosphere as Seen by Swarm Satellites, Incoherent Scatter Radars, and the International Reference Ionosphere Model

2021 ◽  
Vol 13 (20) ◽  
pp. 4077
Author(s):  
Alessio Pignalberi ◽  
Fabio Giannattasio ◽  
Vladimir Truhlik ◽  
Igino Coco ◽  
Michael Pezzopane ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Time Window ◽  
European Space Agency ◽  
International Reference Ionosphere ◽  
Topside Ionosphere ◽  
Iri Model ◽  
International Reference ◽  
Incoherent Scatter ◽  
Swarm Satellites ◽  
Incoherent Scatter Radars

The global statistical median behavior of the electron temperature (Te) in the topside ionosphere was investigated through in-situ data collected by Langmuir Probes on-board the European Space Agency Swarm satellites constellation from the beginning of 2014 to the end of 2020. This is the first time that such an analysis, based on such a large time window, has been carried out globally, encompassing more than half a solar cycle, from the activity peak of 2014 to the minimum of 2020. The results show that Swarm data can help in understanding the main features of Te in the topside ionosphere in a way never achieved before. Te data measured by Swarm satellites were also compared to data modeled by the empirical climatological International Reference Ionosphere (IRI) model and data measured by Jicamarca (12.0°S, 76.8°W), Arecibo (18.2°N, 66.4°W), and Millstone Hill (42.6°N, 71.5°W) Incoherent Scatter Radars (ISRs). Moreover, the correction of Swarm Te data recently proposed by Lomidze was applied and evaluated. These analyses were performed for two main reasons: (1) to understand how the IRI model deviates from the measurements; and (2) to test the reliability of the Swarm dataset as a new possible dataset to be included in the underlying empirical dataset layer of the IRI model. The results show that the application of the Lomidze correction improved the agreement with ISR data above all at mid latitudes and during daytime, and it was effective in reducing the mismatch between Swarm and IRI Te values. This suggests that future developments of the IRI Te model should include the Swarm dataset with the Lomidze correction. However, the existence of a quasi-linear relation between measured and modeled Te values was well verified only below about 2200 K, while for higher values it was completely lost. This is an important result that IRI Te model developers should properly consider when using the Swarm dataset.

scholarly journals Topside Ionosphere and Plasmasphere Modelling Using GNSS Radio Occultation and POD Data

2021 ◽  
Vol 13 (8) ◽  
pp. 1559
Author(s):  
Fabricio S. Prol ◽  
M. Mainul Hoque
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Radio Occultation ◽  
Geomagnetic Latitude ◽  
Low Earth Orbit ◽  
Activity Level ◽  
Topside Ionosphere ◽  
Electron Content ◽  
Total Electron ◽  
Solar Activity Level

A 3D-model approach has been developed to describe the electron density of the topside ionosphere and plasmasphere based on Global Navigation Satellite System (GNSS) measurements onboard low Earth orbit satellites. Electron density profiles derived from ionospheric Radio Occultation (RO) data are extrapolated to the upper ionosphere and plasmasphere based on a linear Vary-Chap function and Total Electron Content (TEC) measurements. A final update is then obtained by applying tomographic algorithms to the slant TEC measurements. Since the background specification is created with RO data, the proposed approach does not require using any external ionospheric/plasmaspheric model to adapt to the most recent data distributions. We assessed the model accuracy in 2013 and 2018 using independent TEC data, in situ electron density measurements, and ionosondes. A systematic better specification was obtained in comparison to NeQuick, with improvements around 15% in terms of electron density at 800 km, 26% at the top-most region (above 10,000 km) and 26% to 55% in terms of TEC, depending on the solar activity level. Our investigation shows that the developed model follows a known variation of electron density with respect to geographic/geomagnetic latitude, altitude, solar activity level, season, and local time, revealing the approach as a practical and useful tool for describing topside ionosphere and plasmasphere using satellite-based GNSS data.

Study of the influence of overvoltage on the quality of electricity in energy systems.

2020 ◽  
Vol 23 (2) ◽  
pp. 52-58
Author(s):  
S. SKRYPNYK ◽  
Keyword(s):  
Power Supply ◽  
Fire Hazard ◽  
Lightning Discharge ◽  
Quality Standard ◽  
Normal Operation ◽  
Electrical Network ◽  
Modern World ◽  
Electrical Networks ◽  
The World

Our world with its high technologies has long been deeply dependent on the quality of electricity supply. In most countries of the world there are national power grids that combine the entire set of generating capacity and loads. This network provides the operation of household appliances, lighting, heating, refrigeration, air conditioning and transport, as well as the functioning of the state apparatus, industry, finance, trade, health services and utilities across the country. Without this utility, namely electricity, the modern world simply could not live at its current pace. Sophisticated technological improvements are firmly rooted in our lives and workplaces, and with the advent of e-commerce began the process of continuous transformation of the way individuals interact with the rest of the world. But with the achievement of intelligent technologies, an uninterrupted power supply is required, the parameters of which exactly meet the established standards. These standards maintain our energy security and create a reliable power system, that is maintaining the system in a trouble-free state. Overvoltage is the deviation of the rated voltage from the value of the corresponding quality standard (frequency, sinusoidal voltage and compliance of harmonics). Overvoltage in terms of fire hazard is one of the most dangerous emergency modes of electrical equipment, which causes conditions that in most cases are sufficient for the occurrence of fire hazards (exceeding the allowable voltage leads to disruption of normal operation or possible ignition). Against the background of deteriorating engineering systems, increased power consumption and poor maintenance, power supply of electrical installations, the main causes of overvoltage in electrical networks are thunderstorms (atmospheric overvoltage), switching switches, uneven phase load in electrical networks, etc. The physical picture of internal overvoltage is due to oscillatory transients from the initial to the established voltage distributions in the conductive sections due to the different situation in the electrical circuit. In the conditions of operation of electric networks planned, mode or emergency situations are possible. Therefore, the ranges of overvoltage are determined by the range from several hundred volts to tens and hundreds of kilovolts, and depend on the types of overvoltage. Atmospheric overvoltage is considered to be one of the most dangerous types of emergency modes of operation of the electrical network. This overvoltage occurs as a result of lightning discharge during precipitation by concentrating electricity on the surface of the object, the introduction of potential through engineering networks and

scholarly journals First ground-based observations of sprites over southern Africa

2018 ◽  
Vol 114 (9/10) ◽  
Author(s):  
Stanislaus Nnadih ◽  
Mike Kosch ◽  
Peter Martinez ◽  
Jozsef Bor
Keyword(s):  
South Africa ◽  
Southern Africa ◽  
Dielectric Breakdown ◽  
Electrical Discharges ◽  
Lightning Strikes ◽  
The World ◽  
Lightning Discharges ◽  
Northern Cape ◽  
Cloud To Ground Lightning ◽  
Peak Value

Sprites are the optical signatures of electrical discharges in the mesosphere triggered by large lightning strikes associated with thunderstorms. Since their discovery in the late 1980s, sprites have been observed extensively around the world, although very few observations of sprites from Africa have been documented in the literature. In this paper, we report the first ground-based recorded observations of sprites from South Africa. In 2 out of the 22 nights of observations (11 January and 2 February 2016), about 100 sprite elements were recorded from Sutherland in the Northern Cape, comprising different morphologies (carrot (55%), carrot/column (11%), unclassified (21%), column (13%)). The sprites were triggered by positive cloud-to-ground lightning strikes, which had an average peak value of ~74 kA and were observed at distances from ~400 km to 800 km. The estimated charge moment change of the lightning discharges associated with these events was in agreement with the threshold for dielectric breakdown of the mesosphere and correlates well with the observed sprite brightness.

Introducing fire

2018 ◽  
Author(s):  
Andrew C. Scott
Keyword(s):  
Volcanic Activity ◽  
Burning Surface ◽  
Lightning Strikes ◽  
World Today ◽  
The World ◽  
Surface Vegetation

Fire has a bad reputation. Wildfires raging across parts of California and Australia make headlines. In the news bulletins, it is a destructive force that has to be quenched. But that is far from the whole story. Fire has a long history. In our deep past, wildfire helped shape aspects of our planet, and plants and animals have adapted to it in a variety of ways. In this book, we will follow the story of fire through time. But we begin with the present, with the fires that occur around the world today, and how satellites are changing our view of wildfire. Most of us have little or no experience of a wildfire, apart from those dramatic scenes shown on our television sets from time to time. Almost invariably, two questions are asked: who started the fire, and how quickly can it be put out? Reasonable though they seem, these two questions betray a potential misunderstanding of how fire works on our planet. We assume that the fire was started by humans, either accidentally or deliberately. This may indeed be true, but more than half of the fires started across the globe have a natural cause—mostly lightning strikes, but also other causes such as volcanic activity. Every moment of every day, a fire is burning somewhere in the world. The second assumption is that a fire should always be suppressed. But should we always be rushing to put out a vegetation fire? Wildfire is one of nature’s most frightening manifestations. Winds and storms may die down, and we can seek shelter from them, but fire can be difficult to outrun and escape. Many who are killed by wildfire have underestimated this force of nature, and even those with experience in putting out fires can find themselves cut off, and succumbing to the flames. As we shall discover, not all vegetation burns in the same way, and there are many different kinds of fire, from those burning surface vegetation to those moving through the crowns of trees. Their consequences may also be very different.

scholarly journals Atmospheric Electricity Studies at the Pierre Auger Observatory: Signal Comparisons between Lightning and Cosmic Ray Events

2019 ◽  
Vol 210 ◽  
pp. 05007
Author(s):  
Kevin-Druis Merenda ◽  
Keyword(s):  
Task Force ◽  
Atmospheric Electricity ◽  
Cosmic Ray ◽  
Pierre Auger Observatory ◽  
Fluorescence Detector ◽  
Lightning Strikes ◽  
Transient Luminous Events ◽  
The World ◽  
Surface Detector ◽  
Atmospheric Phenomena

The research horizons of the Pierre Auger Cosmic-Ray Observatory widened when the collaboration found exotic (atmospheric) phenomena in both its Fluorescence Detector (FD) and Surface Detector (SD). The Cosmology and Geophysics task force of the Auger Collaboration focused some of its attention on these highly energetic events, which are correlated to some of the most intense convective thunderstorm systems in the world. In this proceeding, we compare the signal of these exotic events and the signal of cosmic rays, as seen in the FD and the SD. The FD has triggered on numerous transient luminous events, dubbed “elves" since their first observation in 2005. The SD observed peculiar events with radially expanding footprints, which are correlated with lightning strikes reconstructed by the World Wide Lightning Location Network (WWLLN). The traced signals of both of these atmospheric events last longer in time than cosmic ray signals. The footprints are much larger; typically more SD stations (or more FD pixels) contribute to the observations.

Studies on milk yield and calf suckling behaviour in Kenyan camels (Camelus dromedarius)

1996 ◽  
Vol 1996 ◽  
pp. 105-105 ◽  
Author(s):  
S.P. Simpkin ◽  
P. Rowlinson
Keyword(s):  
Milk Yield ◽  
Literature Survey ◽  
Camel Milk ◽  
Human Consumption ◽  
Milk Secretion ◽  
Experimental Conditions ◽  
Short Period ◽  
The World ◽  
Total Milk ◽  
Milking Frequency

Estimates of camel lactation yields in the literature vary from less than 1000kg to more than 12000 kg, with mean daily yields from 0.1 to 35kg (Simpkin 1985). Suckling or milking frequency and strength of the milk letdown reflex are just two of many factors that affect milk secretion rate in camels. Most of the 18 million camels in the world are kept in nomadic pastoral herds where estimation of milk yield is particularly difficult and the large variation in reported camel milk yields could be attributed to the methodology used to estimate yields. A literature survey shows most articles are based on infrequent observations on small numbers of animals over a short period of lactation and fail to state the experimental conditions or whether figures represent milk offtake for human consumption or total milk yield.

scholarly journals Magnetic Field and Electron Density Data Analysis from Swarm Satellites Searching for Ionospheric Effects by Great Earthquakes: 12 Case Studies from 2014 to 2016

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 371 ◽  
Author(s):  
Angelo De Santis ◽  
Dedalo Marchetti ◽  
Luca Spogli ◽  
Gianfranco Cianchini ◽  
F. Javier Pavón-Carrasco ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Geomagnetic Latitude ◽  
Statistical Correlation ◽  
Satellite Mission ◽  
Strong Earthquakes ◽  
Density Data ◽  
Ionospheric Effects ◽  
Swarm Satellites ◽  
Swarm Satellite

We analyse Swarm satellite magnetic field and electron density data one month before and one month after 12 strong earthquakes that have occurred in the first 2.5 years of Swarm satellite mission lifetime in the Mediterranean region (magnitude M6.1+) or in the rest of the world (M6.7+). The search for anomalies was limited to the area centred at each earthquake epicentre and bounded by a circle that scales with magnitude according to the Dobrovolsky’s radius. We define the magnetic and electron density anomalies statistically in terms of specific thresholds with respect to the same statistical quantity along the whole residual satellite track (|geomagnetic latitude| ≤ 50°, quiet geomagnetic conditions). Once normalized by the analysed satellite tracks, the anomalies associated to all earthquakes resemble a linear dependence with earthquake magnitude, so supporting the statistical correlation with earthquakes and excluding a relationship by chance.

Sign in / Sign up

Export Citation Format

Share Document