A5029851523- Ionosphere and magnetosphere dynamics
- Lightning and Electromagnetic Phenomena
- Earthquake Detection and Analysis
- Solar and Space Plasma Dynamics
- Astrophysics and Cosmic Phenomena
- High voltage insulation and dielectric phenomena
- GNSS positioning and interference
- Aerosol Filtration and Electrostatic Precipitation
- Seismic Waves and Analysis
- Fire effects on ecosystems
- Gamma-ray bursts and supernovae
- Plasma Diagnostics and Applications
- Power Line Communications and Noise
- Nuclear Physics and Applications
- Atmospheric aerosols and clouds
- Electrostatic Discharge in Electronics
- Plasma Applications and Diagnostics
- Geophysics and Sensor Technology
- Meteorological Phenomena and Simulations
- Electrohydrodynamics and Fluid Dynamics
- Impact of Light on Environment and Health
- Thermal Analysis in Power Transmission
- Laser Design and Applications
- Neutrino Physics Research
- Advanced Fiber Optic Sensors
University of Bergen
2016-2025
Br. Birkeland (Norway)
2015-2024
Instituto de Astrofísica de Andalucía
2022
Stanford University
2005-2015
Hewlett-Packard (United States)
2009
University of Hawaiʻi at Mānoa
2002-2008
University of Hawaii System
2005
Abstract The Atmosphere‐Space Interactions Monitor (ASIM) was launched to the International Space Station on 2 April 2018. ASIM payload consists of two main instruments, Modular X‐ray and Gamma‐ray Sensor (MXGS) for imaging spectral analysis Terrestrial Flashes (TGFs) Multi‐spectral Imaging Array detection, imaging, Transient Luminous Events lightning. is first space mission designed simultaneous observations Events, TGFs, optical During 10 months operation (2 June 2018 1 2019) MXGS has...
A three‐dimensional Monte Carlo model of the uniform relativistic runaway electron breakdown in air presence static electric and magnetic fields is used to calculate distribution functions, avalanche rates, direction velocity propagation. We also derive conditions required for an with a given momentum start absence field. The results are compared previously developed kinetic analytical models our own estimates, it concluded that rates many early [e.g., Lehtinen et al. , 1997; Taranenko...
The FORTE (Fast On-orbit Recording of Transient Events) satellite records bursts electromagnetic waves arising from near the Earth's surface in radio frequency (rf) range 30 to 300 MHz with a dual polarization antenna. We investigate possible rf signature ultrahigh energy cosmic-ray particles form coherent Cherenkov radiation cascades ice. calculate sensitivity neutrino (UHE $\ensuremath{\nu})$ fluxes at different energies beyond Greisen-Zatsepin-Kuzmin cutoff. Some constraints on...
We use a full‐wave finite element approach inspired by the mode calculation method of Wait (1970) to calculate electromagnetic fields in horizontally stratified ionosphere treated as magnetized plasma. The source currents can have arbitrary vertical and horizontal distributions. field is calculated both Earth‐ionosphere waveguide (at distance direction) (as an upward propagating whistler wave). This requires less computational resources than traditional FDFD FDTD methods, while providing...
Terrestrial gamma‐ray flash (TGF) production has been modeled by several emission mechanisms. In spite of extensive studies these mechanisms and the existing satellite data, significant uncertainties exist about nature source. this paper, we present a method to develop approximate production‐mechanism‐independent constraints on TGF basis Monte Carlo simulation propagation through atmosphere. A broad range possible source parameters are simulated, based assumptions simplified with varying...
The full‐wave method (FWM) of N. G. Lehtinen and U. S. Inan (2008) is used to model trans‐ionospheric propagation VLF electromagnetic waves from ground‐based transmitters up satellite altitudes. Direct comparison with observations indicates that the wave intensities measured at altitudes are substantially smaller than predicted. apparent reduction in amplitude attributed presence irregularities ionosphere, which encounter during their traversal lower ionosphere. Linear mode scattering...
The giant γ ‐ray flare from SGR 1806‐20 created a massive disturbance in the daytime lower ionosphere, as evidenced by unusually large changes amplitude/phase of subionospherically propagating VLF signals. perturbations 21.4 kHz NPM (Lualualei, Hawaii) signal observed at PA (Palmer Station, Antarctica) correspond to electron densities increasing factor ∼100 ∼10 3 cm −3 ∼60 km and ≳1000 ∼30 altitude. Enhanced conductivity produced onset endured for >1 hour, time scale determined mutual...
The production of terrestrial gamma ray flashes (TGFs) requires a seed energetic electron source and strong electric field. Lightning leaders naturally provide electrons by cold runaway fields charge accumulation on the channel. We model possible TGF in such simulating charges currents resulting then drive simulations relativistic avalanche photon emission. Photon spectra directional distributions produced agree qualitatively with observations. Simulations variety initial conditions indicate...
Abstract High‐power ordinary mode radio waves produce artificial ionization in the F region ionosphere at European Incoherent Scatter (Tromsø, Norway) and High Frequency Active Auroral Research Program (Gakona, Alaska, USA) facilities. We have summarized features of excited plasma turbulence descending layers freshly ionized (“artificial”) plasma. The concept an ionizing wavefront created by accelerated suprathermal electrons appears to be accordance with data. strong Langmuir (SLT) regime...
During the ALOFT flight campaign, July 2023, a novel type of multi-pulse gamma-ray emission from thunderclouds was systematically recorded. Referred to as flickering flashes (FGFs), this is not linked with lightning leaders and does coincide detectable radio emissions [1].A promising candidate theory for explaining phenomenon relativistic feedback discharge (RFD) developed by Dr. J. Dwyer his group [2]. Fully self-consistent 3D Monte-Carlo calculations RFD [3], which take field quenching...
The European Space Agency's EnVision mission, slated for launch in the next decade, will provide unprecedented insights into geological and atmospheric dynamics of Venus. EnVision's primary objectives include high-resolution subsurface mapping with Subsurface Radar Sounder (SRS), operating 9 MHz as central frequency. This study investigates potential SRS to detect electromagnetic waves generated by lightning Venusian atmosphere, a phenomenon whose existence remains debated.While optical...
During the Airborne Lightning Observatory for FEGS and TGFs (ALOFT) campaign conducted in summer of 2023, hundreds gamma-ray glows were observed. Numerous glow regions, each consisting several individual glows, observed as aircraft passed over active thunderstorms (Marisaldi et al. 2024). We will investigate mechanisms behind termination focusing on whether specific types discharges are responsible or if terminate themselves. combine observations from different instruments onboard aircraft,...
Lightning initiation is one of the top unsolved problems in atmospheric electricity. Runaway electron breakdown air has been suggested to play a key role lightning initiation, by locally enhancing ambient electric field above conventional threshold. The recent results from ALOFT flight campaign have shown tight interconnection between highly convective cores, activity, and high-energy particle acceleration observed as wide range gamma-ray phenomena (gamma-ray glows, Terrestrial Gamma-ray...
Electric fields in thunderclouds can accelerate electrons to relativistic energies, which leads bremsstrahlung production of gamma radiation. This radiation was recently recorded by the ALOFT experimental aircraft campaign [1], and may be classified into various types according their lightcurve shapes, for example, flickering flashes (FGF), single multiple terrestrial (TGF), extended gamma-ray glows (GRG). Electromagnetic field radio optical range also recorded, has different features...
In July 2023, the ALOFT flight campaign deployed an ER-2 research aircraft that flew at 20 km altitude above thunderstorms, carrying extensive suite of instruments. The observed numerous gamma-ray glows exhibiting complex and highly dynamic morphologies (Marisaldi et al. 2024). This study focuses on two specific glow events recorded 29th, between 20:30:20 20:31:40 UTC over Florida. By combining Monte Carlo simulations with observations from hard-radiation instruments ground-based...
Abstract Lightning strokes emit electromagnetic pulses that interact with the lower ionosphere. One manifestation of this interaction are elves: Ring‐shaped light emissions from altitudes around 85 km above ground produced by active thunderstorms. Perturbations to conductivity at those relax time‐scales longer than 10 min and therefore one strong pulse may affect features subsequent pulses. Here we develop a simplified model investigate possibility. We apply thunderstorms copious production...
Terrestrial gamma ray flashes (TGFs) are brief bursts of rays observed by satellites, typically in coincidence with detectable lightning. We incorporate TGF observations and the key physics behind current production theories lightning to produce constraints on mechanisms. The combined naturally suggest a mechanism for pulses leader channels. involves local field enhancements due charge redistribution draws seed energetic particles from cold runaway breakdown processes. can reproduce time...
We consider the possible production of persistent ionization at low altitudes ( h ≤ 70 km) by giant blue jets (GBJ), using a new five constituent model stratospheric/lower‐ionospheric chemistry. Results indicate substantial < 50 km, which exhibits an initially rapid (few seconds) recovery due to electron attachment, followed long enduring (>10 minutes) determined time scale mutual neutralization negative and positive ions. Such signatures may be observable in subionospheric VLF data...
Terrestrial gamma ray flashes (TGFs) are brief bursts of photons with energies up to 20 MeV typically observed in association lightning. Such energetic may undergo photonuclear reactions nontrivial cross section the vicinity giant dipole resonance. Pulses neutrons have been experimentally coincidence lightning, suggesting such observable. We present simulations expected photoneutron production based on initial conditions inferred from observations TGFs. predict an average ∼10 12 produced per...
Accurate models of trans‐ionospheric propagation are needed to assess the role Earth‐originating very low frequency (VLF) electromagnetic waves in radiation belt dynamics. Recent studies have called relatively crude early into question, finding that they underestimate attenuation by 20–100 dB. A full wave model includes all relevant physics has recently become available and experimentally verified within a few decibels via comparison more extensive satellite data. Using this model, we...
[1] Terrestrial gamma ray flashes (TGFs) are bremsstrahlung emissions from relativistic electrons accelerated in electric fields associated with thunder storms, photon energies up to at least 40 MeV, which sets the lowest estimate of total potential MV. The field that produces TGFs will be reflected by initial angular distribution TGF emission. Here we present first constraints on emission cone based accurately geolocated TGFs. source lightning discharges detected RHESSI determined...
Ground based Very Low Frequency (VLF, 3–30 kHz) radio transmitters play a role in precipitation of energetic Van Allen electrons. Initial analyses the contribution VLF to radiation belt losses were on early models trans‐ionospheric propagation known as Helliwell absorption curves, but some recent studies have found that model overestimates (by 20–100 dB) energy reaching magnetosphere. It was subsequently suggested conversion wave into electrostatic modes may be responsible for error. We...
We present 221 Terrestrial Gamma-ray Flashes (TGFs) and associated optical pulses observed by the Atmosphere-Space Interactions Monitor (ASIM) on board International Space Station. The events were detected between end of March 2019 November 2020 consist X- gamma-ray energy detections, as well photometer data (180-230, 337, 777 nm) camera (337 nm). Using available ASIM applying a consistency check based TGF characteristics lightning detections from radio atmospherics close in time, we...