János Lichtenberger

Eötvös Loránd University · Department of Geophysics and Space Sciences

The Matched Filtering and Parameter Estimation (MFPE) technique developed for the analysis of mid/high latitude whistlers has been extended to analyze whistlers recorded at low latitude ground station Varanasi, India (geomagnetic latitude 148 55 ' N, longitude 1538 59 ' E, L = 1.07). Some of the whistlers recorded at Varanasi are found to have prop...

We present a new method for identifying the source regions of lightning‐generated whistlers observed at a fixed location. In addition to the spatial distribution of causative lightning discharges, we calculate the ratio of lightning discharges transmitted into ground detectable whistlers as a function of location. Our method relies on the time of t...

The Earth’s magnetic field is a dynamic system and varies on a wide spectrum of timescales from microseconds to hundreds of millions of years. The primary source of the field is the self-sustaining geodynamo action of the Earth’s liquid outer core. This creates around 95% of the magnetic field strength at the Earth’s surface. Its average strength a...

The plasmasphere is a torus-like region that encircles the Earth and is mainly populated by plasma of ionospheric origin. The plasmasphere changes its configuration in response to geomagnetic disturbances, and exhibits erosion, emptying and refilling. We present the results of a study of plasmasphere dynamics during selected periods that include a...

A full-halo coronal mass ejection (CME) left the Sun on 21 June 2015 from Active Region (AR) NOAA 12371. It encountered Earth on 22 June 2015 and generated a strong geomagnetic storm whose maximum Dst value was −204 nT. The CME was associated with an M2-class flare observed at 01:42 UT, located near disk center (N12 E16). Using satellite data from...

The Dynamic Global Core Plasma Model (DGCPM) is an empirical dynamical model of the plasmasphere which, despite its simple mathematical form, or perhaps because of its simple mathematical form, has enjoyed wide use in the space physics modeling community. In this paper we present some recent observations from the European quasi-Meridional Magnetome...

Wheat is one of the most important crops in Hungary, which represents approximately 20% of the entire agricultural area of the country, and about 40% of cereals. A robust yield method has been improved for estimating and forecasting wheat yield in Hungary in the period of 2003–2015 using normalized difference vegetation index (NDVI) derived from th...

A full-halo coronal mass ejection left the sun on June 21, 2015 from the active region NOAA 12371 encountering Earth on June 22, 2015, generating a G3 strong geomagnetic storm. The CME was associated with an M2 class flare observed at 01:42 UT, located near the center disk (N12E16). Using satellite data from solar, heliospheric, magnetospheric miss...

We present the method called Automatized Detector Weight Optimization (ADWO). This method searches for non-triggered, short-duration transients in the data-set of the Fermi's Gamma-ray Burst Monitor. The data of all available detectors and energy channels are combined. Therefore, ADWO is ideal to search for electromagnetic counterparts of gravitati...

The lightning localization task is very interested for the meteorologist organizations, airlines, networks operators, military and etc. The electromagnetic properties of lightning can be measured using VLF sensor. The paper deals with some hardware and software of VLF sensors used in IKIR FEB RAS.

The knowledge of the spatial distribution and temporal variation of the concentration and composition of the plasma populating the Earth’s magnetosphere represents an essential information for understanding the dynamic processes which take place in the magnetosphere. Such an information can be efficiently provided through the detection of geomagnet...

The Fermi collaboration identified a possible electromagnetic counterpart of the GW event of September 14, 2015. Our goal is to work out an unsupervised data analysis algorithm to identify similar events in the Fermi's Gamma-ray Burst Monitor CTTE data stream. In a typical case the signal is very weak and can be only found by a careful analysis of...

The Fermi collaboration identified a possible electromagnetic counterpart of the gravitational wave event of September 14, 2015. Our goal is to provide an unsupervised data analysis algorithm to identify similar events in Fermi's Gamma-ray Burst Monitor CTTE data stream. We are looking for signals that are typically weak. Therefore, they can only b...

We present the results of a study of plasmasphere dynamics during a few geomagnetic storms through examination of radial profiles of the equatorial plasma mass density. The plasma mass density is derived from field line resonance (FLR) frequencies observations across EMMA, a meridional network of 25 magnetometer stations extending from Central Ital...

Unconditional and conditional statistics are used for studying the histograms of magnetic field multiscale fluctuations in the solar wind near the solar cycle minimum in 2008. The unconditional statistics involves the magnetic data during the whole year in 2008. The conditional statistics involves the magnetic field time series split into concatena...

We present analysis of more than 2000 lightning-generated whistlers recorded at a low latitude station, located at Allahabad (Geog. lat., 25.40° N; Geog. long. 81.93° E; L=1.081), India, during December 2010 to November 2011. The main focus of this work is on the correlation between observed low latitude whistlers and lightning activity detected by...

AWDANet is a global network for monitoring the plasmasphere. It consists of 15 ground stations automatically detecting VLF whistlers and performing automatic inversion on GPUs. The algorithm yields real-time plasmaspheric electron densities. Another source of data used here is ground based measurements of magnetic field line resonances (FLR), obtai...

Lightning discharges radiate electromagnetic waves in a wide frequency range, with maximum energy in extremely low frequency/very low frequency band. A part of the radiated extremely low frequency/very low frequency wave energy is trapped in the Earth–ionosphere waveguide and travels thousands of kilometers in different modes with lower attenuation...

EMMA is a network of 25 magnetometer stations extending from Central Italy to North Finland (1.5 < L < 6.5) which was established in 2012 with the main purpose to remote sense the plasma mass density from field line resonance (FLR) observations. We present here the results obtained during some selected intervals which include geomagnetic storm even...

Monitoring the state and health of the vegetation is essential to understand causes and severity of environmental change and to prepare for the negative effects of climate change on plant growth and productivity. Satellite remote sensing is the fundamental tool to monitor and study the changes of vegetation activity in general and to understand its...

The main goals of the Chibis-M mission are the testing of a new micro-satellite technology, the study of new physical processes related to lightning activity and the verification of possible monitoring techniques of Space Weather phenomena. In frames of the Chibis-M mission an electromagnetic wave complex MWC is installed on board of the satellite...

The Earth's plasmasphere is a region of dense plasma, originating in the ionosphere, extending nearly to geostationary orbit. The precise extent of the plasmasphere is dynamic, particularly during geomagnetic active conditions. Knowing the exact distribution of plasma in the plasmasphere is important as an input to coupled magnetospheric models. In...

In this study we will present a description of the FP7 Space Weather project PLASMON-developed model of energetic electron precipitation (EEP) fluxes that occur inside and outside of the plasmasphere during space weather events. The aim of the PLASMON EEP model is to identify 3 or 4 MLT zones which are populated by ULF/VLF waves that can generate e...

The equatorial electron density obtained from whistler inversion has long been regarded as an effective tool for monitoring the plasmasphere from ground based measurements. However, as these inversion methods are based on various models, it is essential to validate them through comparison with in-situ density measurements. To date, no such comparis...

Whistlers detected at Dunedin, New Zealand, are unusual: whereas the classical model for whistler generation suggests that the source lightning occurs close to the magnetic conjugate point, the source lightning for Dunedin appears to be on the west coast of Central America, far from the conjugate point. Our aim is to investigate Dunedin whistlers f...

In the frame of the FP7 POPDAT project the Ionosphere Waves Service (IWS) has been developed and opened for public access by ionosphere experts. IWS is forming a database, derived from archived ionospheric wave records to assist the ionosphere and Space Weather research, and to answer the following questions: How can the data of earlier ionospheric...

One-to-one relation with its causative lightning discharges and propagation features of night-time whistlers recorded at low-latitude station, Allahabad (geomag. lat. 16.05�N, L = 1.08), India, from continuous observations made during 1–7 April, 2011 have been studied. The whistler observations were made using the Automatic Whistler Detector (AWD)...

The possibilities of whistler waves registration and analysis in the space project “Ionosat-Micro” are overviewed.

The results of the first 18 months of the PLASMON project are presented. We have extended our three, existing ground-based measuring networks, AWDANet (VLF/whistlers), EMMA/SANSA (ULF/FLRs), and AARDDVARK (VLF/perturbations on transmitters’ signal), by three, eight, and four new stations, respectively. The extended networks will allow us to achieve...

Whistlers are VLF (3-30 kHz) emissions initiated by lightning, propagating along magnetic field lines, observed on ground and in space. Whistler wave analysis is an effective tool for studying the plasmasphere. Whistlers acquire particular frequency-time characteristics while they propagate through the magnetospheric plasma, and in particular throu...

One-to-one relation with its causative lightning discharges and propagation features of night-time whistlers recorded at low-latitude station, Allahabad (geomag. lat. 16.05° N, L=1.08), India, from continuous observations made during 1-7 April, 2011 have been studied. The whistler observations were made using the Automatic Whistler Detector (AWD) s...

On 4 August 2010 a moderate geomagnetic storm occurred with minimum Dst of -65 nT and maximum Kp of 7-. Shortly after the onset of this storm, VLF chorus was observed at Marion Island (L= 2.6). Over time the spectral structure of the chorus transformed into a hiss band spanning the same frequency range. The observation of overlapping chorus and his...

Man and equipment in space are affected by the energetic charged particles in the radiation belts. The degree of exposure is determined by the rate of Relativistic Electron Precipitation (REP), which is driven by wave-particle interactions. The properties of the plasmasphere determine the interaction rate. Current models of the plasmasphere do not...

The matched filtering technique is based on the digital-construction of theoretical whistlers and their comparison with observed whistlers. The parameters estimated from the theoretical and experimental whistler curves are matched to have higher accuracy using digital filters. This yields a resolution ten times better in the time domain. We have te...

VLF and magnetometer observations can be used to remotely sense the plasmasphere. VLF whistler waves can be used to measure the electron density and magnetic Field Line Resonance (FLR) measurements can be used to measure the mass density. In principle it is then possible to remotely map the plasmasphere with a network of ground-based stations which...

We will present the results of data assimilation of density measurements into the Dynamic Global Core Plasma Model (DGCPM) using a Kalman filter approach. Being able to produce accurate maps of plasmaspheric density is important because plasma density gradients are sites of waves which contribute to acceleration or loss of radiation belt particles....

Both the traditional, human assisted methods, and the recently developed automatic whistler inversion method [1,2] need at least an estimate for the time of the initial sferic (t0) and also the nose frequency (fn) for the whistler inversion to work. Failure to provide accurate values for these data will lead to no or useless derivation of whistler...

Man and equipment in space are affected by the energetic charged particles in the radiation belts. The degree of exposure is determined by the rate of Relativistic Electron Precipitation (REP), which is driven by wave-particle interactions. The properties of the plasmasphere de- termine the interaction rate. Current models of the plasmasphere do no...

PLASMON is a European Union FP7 project which will use observations of whistlers and field line resonances to construct a data assimilative model of the plasmasphere. This model will be validated by comparison with electron precipitation data derived from narrowband VLF observations of subionospheric propagation from the AARDDVARK network. A VLF re...

The inner magnetosphere is the area where the physical processes driven by the energetic particles originated from the Sun interact with the waves propagated there in the wave-particle interaction. This phenomenon is called space weather and it plays an important role in the security of space assets. This is why these investigations are in front of...

Explosive volcanic eruptions that eject columns of ash from the crater often generate lightning discharges strong enough to be remotely located by very low frequency radio waves. A fraction of volcanic ash particles can stay and disperse long enough to have an effect on weather phenomena days later such as thunderstorms and lightnings. In this work...

We will present the results of data assimilation of density measurements into the Dynamic Global Core Plasma Model (DGCPM) using a particle filter approach. Being able to produce accurate maps of plasmaspheric density is important because plasma density gradients are sites of waves which contribute to acceleration or loss of radiation belt particle...

There is an increasing `demand' for plasmaspheric electron density data for plasmasphere models in Space Weather related investigations, particularly in modeling charged particle accelerations and losses in Radiation Belts. The global Automatic Whistler Detector and Analyzer (AWDA) system network detects millions of whistlers in a year. But the ana...

We have developed an advanced version of our yield estimation method [Ferencz et al., 2004], that is able to provide reliable forecasts for corn and wheat, several weeks before the harvest. The forecasting method is based on the data of the Advanced Very High Resolution Radiometer (AVHRR) instruments of the National Oceanic and Atmospheric Administ...

The principal source and loss mechanisms in the Earth's radiation belts are currently not completely understood. Loss rates are important since they determine the duration of exposure of satellites to enhanced radiation conditions during a geomagnetic storm. The dominant loss process is relativistic electron precipitation via resonant interactions...

[1] The accepted mechanism for whistler generation implicitly assumes that the causative lightning stroke occurs within reasonable proximity to the conjugate foot point of the guiding magnetic field line and that nighttime whistlers are prevalent because of low transionospheric attenuation. However, these assumptions are not necessarily valid. In t...

The full potential of whistlers for monitoring plasmaspheric electron density variations has not yet been realized. The primary reason is the vast human effort required for the analysis of whistler traces. Recently, the first part of a complete whistler analysis procedure was successfully automated, i.e., the automatic detection of whistler traces...

Accurately modeling the dynamics of the plasmasphere is important because the plasmasphere and in particular density variations in the plasmasphere are the sites of waves which contribute to acceleration and loss of radiation belt particles. The plasmasphere can be largely described in terms of plasma flow out of and into the ionosphere, and a conv...

Plasma-wave experiment on the micro-satellite “Chibis-M” is aimed at the solution of fundamental problem – a study of the interrelation of the plasma- wave processes connected with the manifestation in the ionosphere of solar – magnetosphere – ionosphere – atmosphere connections and the parameters of space weather. Specific fundamental problem is t...

Collier et al. [2009] have shown a correlation between whistlers observed at Tihany, Hungary, and lightning activity within a few hundred km of Tihany's conjugate point. The lightning data were obtained from the World Wide Lightning Location Network (WWLLN). This network currently only detects approximately 10% of global lightning activity, and als...

One of the recent challenges of space physics is the study of processes taking place during lightning discharges. A dedicated microsatellite named Chibis-M («lapwing» in English) is under preparation for launch in 2010. It contains two space instrumentation units, namely, «Thunderstorm» and «Wave Package». A special efficiency of this project is ex...

A type of electromagnetic phenomenon has been found in the electric VLF data measured by the low Earth orbit DEMETER satellite, which was nonidentified earlier as a different class of electromagnetic VLF events. The phenomenon, termed as “swallow-tailed whistler” (STW) after its shape, seems to be similar to a whistler, but following the main trace...

Whistlers observed at Dunedin, New Zealand, are an enigma since they do not conform to the classical model of whistler production developed by Storey (1953). It is generally accepted that the causative lightning stroke for a whistler observed on the ground at a particular location was located in the neighbourhood of the conjugate point, and generat...

The BepiColombo Mercury Magnetospheric Orbiter (MMO) spacecraft includes the plasma and radio wave observation system called Plasma Wave Investigation (PWI). Since the receivers for electric field, plasma waves, and radio waves are not installed in any of the preceding spacecraft to Mercury, the PWI will provide the first opportunity for conducting...

Although the generation and propagation mechanisms for whistlers are fairly well understood, the location and extent of the lightning source region for the whistlers observed at a given station are currently unknown. The correlation of whistler observations against global lightning data allows an estimate of the size and position of the source regi...

A new whistler inversion method has been developed to obtain plasmaspheric electron densities and propagation paths deduced from measured whistler data. It is based on the exact Appleton-Hartree dispersion relation and recent experimental density distribution models, comprising the following components: a longitudinal whistler wave propagation mode...

A whistler is a very low frequency (VLF) phenomenon that acquires its characteristics from dispersive propagation in the magneto- sphere. Whistlers are derived from the intense VLF radiation produced in lightning strikes, which can travel great distances within the Earth-ionosphere waveguide (EIWG) before penetrating the ionosphere, and exciting a...

The Antarctic-Arctic Radiation-belt (Dynamic) Deposition-VLF Atmospheric Research Konsortium (AARDDVARK) provides a network of continuous long-range observations of the lower ionosphere in the polar regions. Our ultimate aim is to develop the network of sensors to detect changes in ionization levels from ∼30–90 km altitude, globally, continuously,...

Signals of naval VLF transmitters, propagating long distances along the Earth-ionosphere waveguide (EIWG) have been widely applied as effective tools for monitoring transient ionization at mesospheric altitudes. Perturbations in recorded amplitude and/or phase data series of stable frequency signals may refer to the effect of transient enhanced ion...

The advanced electromagnetic wave detector and analyzer, Signal Analyzer and Sampler 2, successfully operated on board of Compass-2 satellite (launched May 2006). One of the peculiarities of this experiment was that the efficient sensitivities of both electric and magnetic channels were very close to being identical. Between the interesting events...

Lightning-generated "Whistlers", the strongly dispersed radio wave pulses that have propagated along the Earth's magnetic field from one hemisphere of the Earth to the other, have long been regarded as inexpensive and effective tools for plasmasphere diagnosis. The Eötvös University Automatic Whistler Detector (AWD) system has been operating in Dun...

The Antarctic-Arctic Radiation-belt (Dynamic) Deposition -VLF Atmospheric Research Konsortium (AARDDVARK) provides a network of continuous long-range observations of the lower-ionosphere in the polar regions. Our ultimate aim is to develop the network of sensors to detect changes in ionization levels from ~30-90 km altitude, globally, continuously,...