Disturbances in the ionospheric plasma due to geomagnetic storms and thunderstorms recorded by the DEMETER and Swarm satellites are presented. Lightning and, in particular, transient luminous events (sprites, jets, elves and halos) are associated with the electromagnetic links and interactions between the atmosphere, ionosphere and magnetosphere and with intense thunderstorm activity. DEMETER has clearly shown that thunderstorms and sprites can affect the ionosphere even at its orbital altitude (680 km). Additional information on ionospheric disturbances comes from data collected by the Swarm satellites. The Swarm constellation consists of three identical satellites. Two of them operate in circular polar orbits with an initial altitude of 460 km, while the third satellite has a circular orbit but an altitude of 530 km. The orbits of the first two satellites are almost in the same plane, but the third satellite is almost perpendicular to the first two. The payload, which includes a vector field magnetometer, an absolute scalar magnetometer and an electric field instrument, will make it possible to study the effects of thunderstorms on the ionosphere. Registrations of ionospheric disturbances collected by DEMETER and Swarm during selected strong geomagnetic storms and thunderstorms over Poland and Central Africa are presented, and the similarities and differences are discussed.

THE TERRESTRIAL IONOSPHERE IS MAINLY A PLASMA REGION which is very sensitive to different disturbances. A wide range of plasma instabilities can develop in this region, which are often nonlinear processes and leading to the development of plasma turbulence. Turbulence plays a crucial role in the dynamics of the space plasma processes. The turbulence appears when some physical parameter exceeds a certain level. It can have place during strong thunderstorms. The ionosphere is sometimes treated as plasma physics laboratory with unique possibility to study fundamental plasma processes. The use of ionospheric satellite gives the chance to perform insitu measurements of plasma parameters during dynamic processes. For our analysis we used a set of selected data of the electric and magnetic fields variations in ELF (Extra Low Frequency 10-1250 Hz) and VLF (Very Low Frequency 100-20000 Hz) ranges originated from the French microsatellite DEMETER which was operating on the circular orbit with inclination of about 80 degrees at altitude of 660 km from July 2004 until December 2010. The Fourier, wavelet and bispectral analyses of these signals are given in this paper. Three wave processes have been identified during few very strong strokes. In some cases the nonlinear interactions of whistlers with the VLF signals of ground based transmitters have been registered. The character of spectra suggests the presence of Richardson's cascade. Our conclusion is that in few cases these results are related to whistler turbulence.

It is not new knowledge that whistler are always present in the ionosphere during the thunderstorms. The terrestrial ionosphere is mainly a plasma region which is very sensitive for different disturbances. A wide range of plasma instabilities can develop in this region, which are often nonlinear processes and leading to the development of plasma turbulence. Turbulence is one of the most universal events phenomena in nature. It plays a crucial role in the dynamics of the space plasma processes. The turbulence appears when some physical parameter exceeds a certain level. It can have place during strong thunderstorms. The ionosphere is sometimes treated as plasma physics laboratory with unique possibility to study fundamental plasma processes. The use of ionospheric satellite gives the chance to perform insitu measurement of plasma parameters during dynamic processes. For our analysis we used set of selected data of the electric and magnetic fields variations in ELF and VLF ranges originating from the all French microsatellite DEMETER which was operating on the circular orbit with inclination of about 800 at altitude of 660 km from July 2004 until December 2010.The Fourier, wavelet and bispectral analysis of these signals has been performed. The 3 waves processes has been identified during few very strong strokes. In some cases the nonlinear interactions of whistlers with VLF signals of ground based transmitters. The character of spectra suggests the presence of Richardson’s cascade. Our conclusion is that these results are related to whistler turbulence.

Resonant modes with frequencies 0.02–10 mHz are detected from the bow shock (BS) to the outer magnetosphere, with the nature of the resonances at frequencies 0.02–0.25 mHz being still unexplained. We propose a BS model in the form of a circular plate free along the outer edge that predicts resonant modes at frequencies 0.02–0.3 mHz or lower. We demonstrate the detection of these model resonant modes based on data from five satellites, with the resonance near 0.1 mHz predicted by the model being observed in the magnetosheath continuously for 17 hours downstream of both parallel and perpendicular shocks. Resonant BS modes produce three-wave nonlinear cascades that realize a broadband coherent coupling with resonances both near and inside the magnetopause. In our opinion, it is the coherent nature of the processes in an extended region with different linear resonant eigenmodes that determines the fairly new, nonlinear-cascade, approach to an efficient conversion of the energy of an inflow when interacting with an obstacle. This seems important for the entire nonlinear physics. We also provide arguments suggesting the possibility of resonant mode self-generation in the closed BS/magnetopause loop with a feedback in the form of narrow Poynting vector pulses at the cost of solar wind energy.

Abstract The question of the connection between solar and thunderstorm activity is not new. The discussion among scientists began before the cosmic era. The correlations of the ground-based registration of the cosmic ray flux and meteorological observations have been performed since the 50s of the 20th century. The discussed problem is related to the influence of cosmic rays on the creation of clouds, particularly thunderstorm clouds. The intensity of the galactic cosmic ray flux is controlled by the density and velocity of the solar wind. The increase in the solar wind flux during high solar activity leads to decreasing galactic cosmic ray flux, but on the other hand, the solar activity creates solar cosmic rays. Using data from the PERUN system and the DEMETER satellite, we tried to estimate the connection between the thunderstorm activity in Poland and solar activity during the period of the DEMETER operational activity (2004–2010). The influence of thunderstorms on the ionosphere and its dependence on solar activity is also discussed. However, due to the short time interval of the available data covering an insignificant part of the solar cycle, close to the minimum activity, our findings are not fully conclusive. No correlation was found between the cosmic ray flux and lightning activity given by the number of the discharges. However, some of the most energetic lightning discharges in the analyzed period occurred close to the minimum of the solar activity and their appearance is discussed.

We present results of analysis of lightning observations and satellite measurements of ionospheric magnetic field fluctuations in the ultralow frequency (ULF) range. The fluctuations are measured by Swarm satellites, while the lightning observations are provided by the Geostationary Lightning Mapper (GLM) and the World ELF Radiolocation Array (WERA). We identify spatio‐temporal relationships that demonstrate a leakage of electromagnetic fluctuations caused by lightning into the upper ionosphere. Causal association between the two phenomena is evidenced by investigating relations between lightning and fluctuation properties. The presented results suggest that lightning generate ULF fluctuations in the ionosphere that can be detected by satellites, if the lightning‐satellite geographic distance is less than ∼5°. Typical properties of the fluctuations caused by lightning are described in the paper. To our knowledge, this is the first direct experimental confirmation of a link between lightning and magnetic field fluctuations in the upper ionosphere in the ULF range.

The linear and nonlinear resonances and cascades affecting significantly the interaction of a collisionless plasma flow with a magnetic barrier and the plasma penetration into the barrier are studied using the near-Earth magnetopause as an example. Our linear theory of the membrane instability of the boundary of a magnetic barrier, the magnetopause, explains the structure of the spectra and bi-spectra of fluctuations on different segments of the boundary layers near the magnetopause and the resonances at frequencies 0.05–0.5 mHz. The recorded compressibility of waves under the magnetopause implies that their excitation by Alfv’en resonances alone is impossible. We assume, as a general principle, an approximate coincidence of the frequencies of different harmonics of different resonances as a condition for the amplification of resonances to nonlinear amplitudes and their propagation into the ionosphere. We confirm the presence of resonant waves near the magnetopause and demonstrate a nonlinear three-wave cascade interaction of compressible (0.05–5 mHz) and incompressible waves under the magnetopause that provides the excitation of resonances of magnetic field lines and waveguide resonances at frequencies 1–25 mHz without a close coincidence of the frequencies with linear resonances at the magnetopause and the bow shock. This can also provide a nonlinear coupling of linear and nonlinear resonances in other multilayered media (for example, in the plasma and neutral sheets of the geomagnetic tail and between it and the magnetopause). An example of the excitation of a waveguide mode inside the magnetopause by nonlinear membrane waves is given. We have detected a nonlinear excitation and interaction of most “magic” harmonics under the magnetopause.

Mesoscale convective systems (MCSs) are especially visible in the summertime when there is an advection of warm maritime air from the west. Advection of air masses is enriched by water vapour, the source of which can be found over the Mediterranean Sea. In propitious atmospheric conditions, and thus significant convection, atmospheric instability or strong vertical thermal gradient leads to the development of strong thunderstorm systems. In this paper, we discuss one case of MCSs, which generated a significant amount of +CG (cloud-to-ground), −CG and intracloud (IC) discharges. We have focused on the ELF (extremely low frequency; < 1 kHz) electromagnetic field measurements, since they allow us to compute the charge moments of atmospheric discharges. Identification of the MCSs is a complex process, due to many variables which have to be taken into account. For our research, we took into consideration a few tools, such as cloud reflectivity, atmospheric soundings and data provided by PERUN (Polish system of the discharge localisation system), which operates in a very high frequency (VHF) range (113.5–114.5 MHz). Combining the above-described measurement systems and tools, we identified a MCS which occurred in Poland on 23 July 2009. Furthermore, it fulfilled our requirements since the thunderstorm crossed the path of the DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) overpass.

ELF/VLF waves have been registered in the outer polar cusps simultaneously with high energy electrons fluxes by the satellites Magion 4 (subsatellite to Interball 1), Polar and CLUSTER. Further, we discuss similar observations in the different regions of the ionosphere, where DEMETER registered energetic electrons. The DEMETER satellite operating on the nearly polar orbit at the altitude 650 km crossed different regions in the ionosphere. Registrations of ELF/VLF/HF waves together with the energetic electrons in the polar cusp, in the ionospheric trough and over thunderstorm areas are presented in this paper. The three satellites of ESA's Swarm mission provide additional information on the ELF waves in the mentioned areas together with electron density and temperature. A brief discussion of the generation of these emissions by the so-called "fan instability" (FI) and beam instability is presented.

Abstract. Mesoscale Convective Systems (MCS) are especially visible in the summertime, when there is an advection of warm maritime air from the West. Advection of air masses is enriched by water vapour, which source can be found over the Mediterranean Sea. In propitious atmospheric conditions, thus significant convection, atmospheric instability or strong vertical thermal gradient, lead to the development of strong thunderstorm systems. In this paper we discuss one case of MCS, which generated a significant amount of +CG, -CG and IC discharges. We have focused on the ELF (Extremely Low Frequencies,

The sunward Poynting flux throughout the magnetosheath and foreshock (directly measured by INERBALL-1, CLUSTER-4, and DOUBLE STAR TC1) and its correlation and bi-correlation with the dynamic pressure of the solar plasma flow have been analyzed. It has been demonstrated for the first time that perturbations caused by resonances in the magnetospheric boundary layers propagate upstream towards the bow shock as the short impulses of the sunward Poynting flux, which excite the strongest three-wave resonances. They are initiated in the foreshock and regulate the bow shock surface oscillations. Another interaction zone near the magnetopause assists plasma flow extra deflection and acceleration around the magnetopause. At the outer boundary of stagnant cusp the turbulent barrier can separate the flowing and stagnant plasmas namely by the three-wave cascades. Therefore, both experiment and magnetohydrodynamic simulation demonstrate the leading role of the discovered waves and nonlinear processes in the collisionless interaction of the plasma flow and magnetic barrier.

The JEM-EUSO (Joint Experiment Missions for the Extreme Universe Space Observatory) program aims at developing Ultra-Violet (UV) fluorescence telescopes for efficient detections of Extensive Air Showers (EASs) induced by Ultra-High Energy Cosmic Rays (UHECRs) from satellite orbit. In order to demonstrate key technologies for JEM-EUSO, we constructed the EUSO-Balloon instrument that consists of a similar to 1 m(2) refractive telescope with two Fresnel lenses and an array of multi-anode photo-multiplier tubes at the focus. Distinguishing it from the former balloon-borne experiments, EUSO-Balloon has the capabilities of single photon counting with a gate time of 2.3 mu s and of imaging with a total of 2304 pixels. As a pathfinder mission, the instrument was launched for an 8 h stratospheric flight on a moonless night in August 2014 over Timmins, Canada. In this work, we analyze the count rates over similar to 2.5 h intervals. The measurements are of diffuse light, e.g. of airglow emission, back-scattered from the Earth's atmosphere as well as artificial light sources. Count rates from such diffuse light are a background for EAS detections in future missions and relevant factor for the analysis of EAS events. We also obtain the geographical distribution of the count rates over a similar to 780 km(2) area along the balloon trajectory. In developed areas, light sources such as the airport, mines, and factories are clearly identified. This demonstrates the correct location of signals that will be required for the EAS analysis in future missions. Although a precise determination of count rates is relevant for the existing instruments, the absolute intensity of diffuse light is deduced for the limited conditions by assuming spectra models and considering simulations of the instrument response. Based on the study of diffuse light by EUSO-Balloon, we also discuss the implications for coming pathfinders and future space-based UHECR observation missions. (C) 2018 Published by Elsevier B.V.

Compilation of papers presented by the JEM-EUSO Collaboration at the 36th International Cosmic Ray Conference (ICRC), held July 24 through August 1, 2019 in Madison, Wisconsin.

EUSO-TA is a ground-based telescope, installed at the Telescope Array (TA) site in Black Rock Mesa, Utah, USA. This is the first detector to successfully use a Fresnel lens based optical system and multi-anode photomultipliers (64 channels per tube, 2304 channels encompassing a 10.6 degrees x 10.6 degrees field of view) for detection of Ultra High Energy Cosmic Rays (UHECR). The telescope is located in front of one of the fluorescence detectors of the TA experiment. Since its installation in 2013, the detector has observed several ultra-high energy cosmic ray events and, in addition, meteors. The limiting magnitude of 5.5 on summed frames (similar to 3 ms) has been established. Measurements of the UV night sky emission in different conditions and moon phases and positions have been completed. The performed observations serve as a proof of concept for the future application of this detector technology. (C) 2018 Elsevier B.V. All rights reserved.

To emphasize the relationship between the pre-seismic geomagnetic signals and Vrancea seismicity, in this work it is hypothesized that before an earthquake initiation, the high stress reached into seismogenic volume generates dehydration of the rocks and fracturing processes followed by release of electric charges along the faulting systems, which lead to resistivity changes. These changes were explored on September 2016 by the normalized function Bzn obtained from the geomagnetic data recorded in ULF range (0.001–0.0083 Hz). A statistical analysis was also performed to discriminate on the new Bzn* time series a pre-seismic signature related to the Mw5.7 earthquake. Significant anomalous behavior of Bzn* was identified on September 21, with 3 days prior to the onset of the seismic event. Similar information is provided by registrations of the magnetic and electron concentration variations in the ionosphere over the Vrancea zone, by Swarm satellites, 4 days and 1 day before the earthquake.

EUSO-Balloon is a pathfinder mission for the Extreme Universe Space Observatory onboard the Japanese Experiment Module (JEM-EUSO). It was launched on the moonless night of the 25th of August 2014 from Timmins, Canada. The flight ended successfully after maintaining the target altitude of 38 km for five hours. One part of the mission was a 2.5 hour underflight using a helicopter equipped with three UV light sources (LED, xenon flasher and laser) to perform an inflight calibration and examine the detectors capability to measure tracks moving at the speed of light. We describe the helicopter laser system and details of the underflight as well as how the laser tracks were recorded and found in the data. These are the first recorded laser tracks measured from a fluorescence detector looking down on the atmosphere. Finally, we present a first reconstruction of the direction of the laser tracks relative to the detector.

The paper presents a brief review of the observational facts related to plasma filamentation in astrophysics and the subtle structures of plasma in Transient Luminous Events (TLE’s) and an analysis of the physical mechanism that could contribute to formation of filaments in plasma inside streamers. The values of physical parameters are assumed such as to resemble the physical conditions in streamers of the TLE’s. Estimates of the typical spatial scales of these structures and temporal characteristics of filament formation are given. The analysis concerns a non-magnetic mechanism based on a form of non-relativistic dissipative instability and the electron-nitrogen collisional 2 Π g resonance. It is argued that the influence of the magnetic field is negligible at the leading order at least up to the altitudes of about 65–70 km. Under the conditions related to those in plasma inside the TLE’s, derived based on the current knowledge of physical parameters within the electric discharges, the identified dissipative-resonant instability is demonstrated to be the only/most vigorous linear instability developing in the system. It results in periodic plasma density distribution in the direction transverse to the electric field. The obtained time scales of the instability development are quick and proportional to the inverse of the ion-neutral collision frequency, 1/ ν i , whereas the proposed spatial scale of the density stripes/filaments is proportional to the electron temperature and inversely proportional to the speed of the discharge.

JEM-EUSO is a space mission designed to investigate Ultra-High Energy Cosmic Rays and Neutrinos (E>5⋅1019eV) from the International Space Station (ISS). Looking down from above its wide angle telescope is able to observe their air showers and collect such data from a very wide area. Highly specific trigger algorithms are needed to drastically reduce the data load in the presence of both atmospheric and human activity related background light, yet retain the rare cosmic ray events recorded in the telescope. We report the performance in offline testing of the first level trigger algorithm on data from JEM-EUSO prototypes and laboratory measurements observing different light sources: data taken during a high altitude balloon flight over Canada, laser pulses observed from the ground traversing the real atmosphere, and model landscapes reproducing realistic aspect ratios and light conditions as would be seen from the ISS itself. The first level trigger logic successfully kept the trigger rate within the permissible bounds when challenged with artificially produced as well as naturally encountered night sky background fluctuations and while retaining events with general air-shower characteristics.

The theory of charged current sheets is compared with plasma data of Prognoz-8, Interball-1, Polar, and Cluster satellites. The possibility of momentum and energy transfer into the magnetosphere, irrespective of magnetic field line reconnection, as a specific dynamo effect, is shown. This relates statistical properties of the turbulent boundary layers with the character of the transfer through thin boundaries.