A5074862090- Ionosphere and magnetosphere dynamics
- Lightning and Electromagnetic Phenomena
- Solar and Space Plasma Dynamics
- Earthquake Detection and Analysis
- Atmospheric aerosols and clouds
- Fire effects on ecosystems
- High voltage insulation and dielectric phenomena
- Plasma Diagnostics and Applications
- Meteorological Phenomena and Simulations
- Geomagnetism and Paleomagnetism Studies
- Impact of Light on Environment and Health
- Magnetic confinement fusion research
- Atmospheric Ozone and Climate
- Aerosol Filtration and Electrostatic Precipitation
- Electrostatic Discharge in Electronics
- Gamma-ray bursts and supernovae
- Seismic Waves and Analysis
- Astrophysics and Cosmic Phenomena
- Advanced Optical Sensing Technologies
- Ocular and Laser Science Research
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Dust and Plasma Wave Phenomena
- Tropical and Extratropical Cyclones Research
- Plasma Applications and Diagnostics
Technical University of Denmark
2016-2025
Solarplan (Denmark)
2019-2025
Earth Networks (United States)
2023
Danish Meteorological Institute
1998-2022
DTU Space
2010-2022
Space (Italy)
2018-2022
National Institute for Astrophysics
2022
Universitat de València
2022
University of Science and Technology of China
2022
Institute of Atmospheric Physics
2022
In this paper we report on field‐aligned currents inferred from high‐precision three‐component geomagnetic field observations made board the Danish satellite Ørsted over polar regions. Because of a slow drift in local time orbit through “noon‐midnight” sector, were able to study seasonal dependence dynamic properties dayside and nightside current systems Northern Southern Hemispheres. We find an average over‐the‐pole distance between 32° during summer but 37° winter 36° equinox. The decrease...
The Atmosphere-Space Interactions Monitor (ASIM) is an instrument suite on the International Space Station (ISS) for measurements of lightning, Transient Luminous Events (TLEs) and Terrestrial Gamma-ray Flashes (TGFs). Developed in framework European Agency (ESA), it was launched April 2, 2018 SpaceX CRS-14 flight to ISS. ASIM mounted external platform ESA's Columbus module eleven days later planned take during minimum 3 years.
Terrestrial gamma-ray flashes (TGFs) are transient emissions from thunderstorms, generated by electrons accelerated to relativistic energies in electric fields. Elves ultraviolet and optical excited the lower ionosphere electromagnetic waves radiated lightning current pulses. We observed a TGF an associated elve using Atmosphere-Space Interactions Monitor on International Space Station. The occurred at onset of pulse that elve, early stage flash. Our measurements suggest is fast has high...
The Modular Multispectral Imaging Array (MMIA) is a suite of optical sensors mounted on an external platform the European Space Agency's Columbus Module International Station. MMIA, together with X- and Gamma- ray Sensor (MXGS), are two main instruments forming Atmosphere-Space Interactions Monitor (ASIM). primary scientific objectives ASIM mission to study thunderstorm electrical activity such as lightning, Transient Luminous Emissions (TLEs) Terrestrial Gamma-ray Flashes (TGFs) by...
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 model of field‐aligned currents is derived from high‐precision magnetic field measurements the Ørsted and Magsat satellites, being parameterized by interplanetary strength direction for summer, winter equinox. The data allow to be determined directly a simple 2‐D curl technique combined with fitting spherical harmonic functions. New elements are: (a) FAC patterns are separately both polar regions, resolving seasonal dependence interhemispheric asymmetries, (b) IMF ∼ 0, ground‐state also...
Magnetic measurements taken by the Ørsted satellite during geomagnetic quiet conditions around January 1, 2000 have been used to derive a spherical harmonic model of Earth's magnetic field for epoch 2000.0. The maximum degree and order is 19 internal, 2 external, source fields; however, coefficients above 14 may not be robust. Such detailed exists only one previous epoch, 1980. Achieved rms misfit <2 nT scalar intensity <3 vector components perpendicular field. For scientific purposes...
The paper reviews recent advances in studies of electric discharges the stratosphere and mesosphere above thunderstorms, their effects on atmosphere. primary focus is sprite discharge occurring mesosphere, which most commonly observed high altitude by imaging cameras from ground, but upper atmosphere electromagnetic radiation lightning are also considered. During past few years, co-ordinated observations over Southern Europe have been made a wide range parameters related to sprites causative...
In this paper we estimate the probability that cold electrons can be accelerated by an ambient electric field into runaway regime, and discuss implications for negative streamer formation. The study is motivated discovery of ms duration bursts γ ‐rays from atmosphere above thunderstorms, so‐called Terrestrial Gamma‐Ray Flashes. radiation thought to bremsstrahlung energetic (MeV) in a thunderstorm discharge. observation goes against conventional wisdom discharges air are carried with energies...
Abstract Thunderstorm clouds may reach the lower stratosphere, affecting exchange of greenhouse gases between troposphere and stratosphere. This region atmosphere is difficult to access experimentally, our knowledge processes taking place here incomplete. We recently recorded color video footage thunderstorms over Bay Bengal from International Space Station. The observations show a multitude blue, kilometer‐scale, discharges at cloud top layer ~18 km altitude pulsating blue discharge...
Abstract While narrow bipolar events (NBEs) could be related with lightning initiation, their intrinsic physics remains in question. Here we report on optical measurements by the Atmosphere‐Space Interactions Monitor (ASIM) International Space Station (ISS) of blue flashes associated NBEs. They are observed a band centered at 337 nm, no simultaneous activity 777.4 considered strong emission line. From radio waves measured from ground, find that 7 10 single‐pulse can identified as positive...
We present the results of analytical studies and 2D3V PIC simulations electron-positron plasma cloud collisions. concentrate on problem quasi-static magnetic field generation. It is shown from linear theory, using relativistic two-fluid equations for plasmas, that generation a can be associated with counterstreaming instability. A two-dimensional particle simulation provides good agreement above theory shows that, in nonlinear stage instability, about 5.3% initial flow energy converted into...
Space‐based, high‐precision magnetometry is essential for understanding a variety of phenomena ranging from secular variation the Earth's main field, through signatures crustal magnetism and effects plasma currents flowing externally to Earth. Ørsted, Denmark's first satellite, was launched on February 23, 1999 into polar, low‐Earth orbit provide near‐global set geomagnetic observations since Magsat mission 1979–1980 (see Special Issue Geophysical Research Letters., vol. 9, no. 4 , pp....
During a thunderstorm on 23 July 2003, 15 sprites were captured by LLTV camera mounted at the observatory Pic du Midi in French Pyrénées. Simultaneous observations of cloud‐to‐ground (CG) and intracloud (IC) lightning activity from two independent detection systems broadband ELF/VLF receiver allow detailed study relationship between electrical generated mesosphere above. Results suggest that positive CG IC differ for types most frequently observed, carrot‐ column‐shaped sprites. Column occur...
Abstract. Thermal structure associated with deep convective clouds is investigated using Global Positioning System (GPS) radio occultation measurements. GPS data are insensitive to the presence of clouds, and provide high vertical resolution accuracy measurements identify temperature behavior. Deep systems identified International Satellite Cloud Climatology Project (ISCCP) satellite data, cloud tops accurately measured Cloud-Aerosol Lidar Orthogonal Polarization (CALIPSO) lidar...
Narrow bipolar events (NBEs) are signatures in radio signals from thunderstorms observed by ground-based receivers. NBEs may occur at the onset of lightning, but discharge process is not well understood. Here, we present spectral measurements Atmosphere-Space Interactions Monitor (ASIM) on International Space Station that associated with nine negative and three positive a array We found both polarities emissions 337 nm weak or no detectable 777.4 nm, suggesting streamer breakdown. The rise...
Abstract The accurate determination of tropical cyclone (TC) cloud‐top height and its vertical thermal structure using the GPS radio occultation (RO) technique is demonstrated in this study. Cloud‐top heights are determined by bending angle anomaly temperature profiles during TC events, results compared to near‐coincident Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements. Based on 34 closely located RO‐CALIOP pairs 2006 2009, from RO highly correlated CALIOP ( r = 0.84),...
Abstract A model is proposed capable of accounting for the local electric field increase in front lightning stepped leader up to magnitudes allowing electrons overcome runaway energy threshold and thus initiate relativistic electron avalanches generating X‐ray γ ray bursts observed negative leader. The based on an idea that ionization wave, propagating a preionized channel, being focused, such its remains narrow enhanced. It when space segment, formed ahead leader, connects potential...
Abstract High‐voltage laboratory experiments show that discharges in air, generated over a gap of one meter with maximal voltage 1 MV, may produce X‐rays photon energies up to MeV. It has been suggested the photons are bremsstrahlung from electrons accelerated by impulsive, enhanced field during collisions negative and positive streamers. To explore this process, we have conducted first self‐consistent particle simulations streamer encounters. Our simulation model is 2‐D, cylindrically...
Abstract The Atmosphere‐Space Interactions Monitor measures Terrestrial Gamma‐Ray Flashes (TGFs) simultaneously with optical emissions from associated lightning activity. We analyzed measurements at 180–230, 337, and 777.4 nm related to 69 TGFs observed between June 2018 October 2019. All are 90% of them the onset a large pulse, suggesting that they connected initiation current surges. A model photon delay induced by cloud scattering suggests sources pulses 0.7 ms before 4.4 after TGFs,...