A5067859791- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Geomagnetism and Paleomagnetism Studies
- Dust and Plasma Wave Phenomena
- Earthquake Detection and Analysis
- Laser-induced spectroscopy and plasma
- Magnetic confinement fusion research
- Geophysics and Gravity Measurements
- Particle accelerators and beam dynamics
- GNSS positioning and interference
- Metal and Thin Film Mechanics
- Atomic and Molecular Physics
- Calibration and Measurement Techniques
- Vacuum and Plasma Arcs
- Planetary Science and Exploration
- Geophysics and Sensor Technology
- Atmospheric and Environmental Gas Dynamics
- Advancements in Semiconductor Devices and Circuit Design
- Silicon and Solar Cell Technologies
- Advanced Optical Sensing Technologies
- Atomic and Subatomic Physics Research
- Meteorological Phenomena and Simulations
UiT The Arctic University of Norway
2012-2025
University of Oslo
2007
Abstract The mesosphere/lower thermosphere (MLT, 80–100 km) region is an important boundary between Earth's atmosphere below and space above may act as a sensitive indicator for anthropogenic climate change. Existing observational modeling studies have shown the middle MLT cooling contracting because of increasing greenhouse gas emissions. However, trend analyses are highly to time periods covered, their length, measurement type methodology used. We present first linear 11‐year solar cycle...
Eight years of meridian scanning photometer data from Ny‐Ålesund, Svalbard have been analyzed to study the occurrence F region polar cap patches at night. In total 333 in 43 days were observed hit poleward boundary nighttime auroras which is a unique signature ongoing tail reconnection. The MLT distribution smooth and exhibit bell shaped function symmetric around 23:25 MLT. symmetry patch about midnight indicates that populate morning cell dusk convection same probability. About 60% exit...
Abstract. Meteor radars have become widely used instruments to study atmospheric dynamics, particularly in the 70 110 km altitude region. These systems been proven provide reliable and continuous measurements of horizontal winds mesosphere lower thermosphere. Recently, there many attempts utilize specular and/or transverse scatter meteor estimate vertical wind variability. In this we investigate potential biases estimation that are intrinsic radar observation geometry scattering mechanism,...
Abstract. The Hunga Tonga–Hunga Ha′apai volcano erupted on 15 January 2022, launching Lamb waves and gravity into the atmosphere. In this study, we present results using 13 globally distributed meteor radars identify volcanogenic in mesospheric/lower thermospheric winds. Leveraging High-Altitude Mechanistic general Circulation Model (HIAMCM), compare global propagation of these waves. We observed an eastward-propagating wave packet with phase speed 240 ± 5.7 m s−1 a westward-propagating...
Abstract To investigate physical links between the Earth atmosphere and ionosphere, we present data of medium-scale atmospheric gravity waves (AGWs, periods 25–100 min) observed at auroral latitudes. The AGWs 80–100 km altitude were inferred from wind Nordic meteor radar Cluster with spatial/height/time resolution 90 km/5 km/10 min respectively. At same time, traveling ionospheric disturbances (MSTIDs) detected as variations electron density (critical frequency foF2) height F2 maximum (hmF2,...
Accurate estimation of three-dimensional wind fields in the mesosphere and lower thermosphere (MLT) is crucial for understanding atmospheric dynamics variability, however, it has been a longstanding challenge science. Particularly, retrieval vertical wind, due to inherent biases meteor radar observations resulting from geometric observational limitations. This be addressed as plays key role dynamical processes global atmosphere, such transport momentum energy which incorporates meridional...
Multistatic meteor radar networks have become a valuable tool to study the spatial and temporal variability of mesosphere/lower thermosphere winds. Combined with advanced tomographic analysis such as 3DVAR+DIV or VVP algorithm it is possible infer spectral information related horizontal wavelength spectrum. Here we present statistical almost 5 years observations recorded Nordic Meteor Radar Cluster CONDOR. Our initial results show seasonal slopes for different scales indicating reduced...
Continuous ozone measurements above Ny-Ålesund, Svalbard (79°N, 12°E), using the ground-based microwave radiometer GROMOS-C, effectively capture daily, seasonal, and interannual variability of polar in middle atmosphere. In this study, we analyze observed changes during sudden stratospheric warming (SSW) events compare with Aura/MLS satellite data WACCM-X simulations. Results reveal formation a double-ozone layer stratosphere lower mesosphere following onset SSW...
<title>Abstract</title> We have studied long-term ionospheric variations using data from the Tromsø ionosonde since 1932. To investigate Arctic in relation to warming and cooling before 1970s, we developed a database that makes it possible study daily over about 90 years. During 1940s 1960s, when surface was cooling, gradually increasing trend critical frequency of F2 layer, foF2, observed with rate 0.022 ± 0.011 MHz/year. This can be explained by Earth's atmosphere global energy balance. As...
Abstract. The Hunga Tonga–Hunga Ha′apai volcano eruption was a unique event that caused many atmospheric phenomena around the globe. In this study, we investigate gravity waves in mesosphere/lower-thermosphere (MLT) launched by volcanic explosion Pacific, leveraging multistatic meteor radar observations from Chilean Observation Network De Meteor Radars (CONDOR) and Nordic Radar Cluster Fennoscandia. MLT winds are computed using recently developed 3DVAR+DIV algorithm. We found eastward-...
In the inductively coupled plasma of Njord helicon device we have, for same parameters as which an ion beam exists, measured a downstream population high-energy electrons emerging from source. Separated measurements energetic tail was carried out by Retarding Field Energy Analyzer (RFEA) with grounded entrance grid, operated in electron collection mode. radial scan RFEA pointed toward source, found significant just inside magnetic field line mapping to edge A second peak density observed...
Helicons are efficient plasma sources, capable of producing densities 1019 m−3 with only 100 s W input rf power. There often steep density gradients in both the neutral and density, resulting a fully ionized core few cm wide surrounded by weakly plasma. The ionization profile is usually not well known because typically inferred from indirect spectroscopic measurements or edge pressure gauge measurements. We have developed two photon absorption laser induced fluorescence (TALIF) diagnostic...
Abstract In this paper we examine how polar cap patches, which have been frozen into the antisolar flow over cap, are transported nighttime auroral oval. First present a detailed case study from 12 January 2002, with continuous observations of patches exiting oval in Scandinavian sector. Satellite images and all‐sky camera 630.0 nm airglow superimposed onto Super Dual Auroral Radar Network convection maps. These composite plots reveal that exit on both dusk dawn cells. Then statistics based...
Abstract. Atmospheric gravity waves and traveling ionospheric disturbances can be observed in the neutral atmosphere ionosphere at a wide range of spatial temporal scales. Especially medium scales, these oscillations are often not resolved general circulation models parameterized. We show that forced by upward-propagating atmospheric simultaneously with EISCAT very high frequency incoherent scatter radar Nordic Meteor Radar Cluster. From combined multi-static measurements, both vertical...
Both Laser-Induced Fluorescence (LIF) and Retarding Field Energy Analyzers (RFEA) have been applied to the investigation of beams formed in inductively coupled helicon plasmas. While LIF technique provides a direct measurement velocity distribution plasma, RFEA measures ion flux as function retarding potential. In this paper, we present method compare two techniques, by converting an equivalent measurement. We new measurements different experiments; Hot Helicon Experiment (HELIX) - Large on...
Ion velocity distributions in the vicinity of a spherical object with negative potential respect to collisionless, source-free plasma are studied three-dimensional numerical simulations. The ion dynamics around leads distorted radial presheath and sheath edge region. Far sheath, an increase thermal direction is observed. Different potentials object, temperatures, masses considered, as well role spatial temporal resolutions laboratory measurements distributions. simulations carried out DiP3D,...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation J. Carr, P. A. Cassak, M. Galante, Keesee, G. Lusk, R. Magee, D. McCarren, E. Scime, S. Sears, Vandervort, N. Gulbrandsen, Martin Goldman, David Newman, Eastwood; Spontaneous ion beam formation in the laboratory, space, simulation. Phys. Plasmas 1 July 2013; 20 (7): 072118. https://doi.org/10.1063/1.4817263...
In this study, the neutral density and horizontal wind observed by four meteor radars, as well temperature measured Microwave Limb Sounder (MLS) onboard Aura satellite are used to examine response of density, wind, in MLT region stratospheric sudden warmings (SSWs) during 2005 2021 Northern Hemisphere. The radars include Svalbard (78.3°N, 16°E) Tromsø (69.6°N, 19.2°E) at high latitudes Mohe (53.5°N, 122.3°E) Beijing (40.3°N, 116.2°E) middle latitudes. superposed epoch analysis results...
Abstract A Retarding Field Energy Analyzer (RFEA) with a grounded surface in plasma will be surrounded by sheath. The ion distribution function (IDF) measured at the probe distorted as compared to IDF unaffected In present study we investigate whether practical method can relate undisturbed IDF, thus allowing for derivation of useful parameters from IDFs. We sheath 3D numerical simulations spherical RFEA similar Njord helicon device University Tromsø. By comparison results, critically assess...
Abstract. Following the 38th Annual European Meeting on Atmospheric Studies by Optical Methods in Siuntio Finland, an intercalibration workshop for optical low light calibration sources was held Sodankylä, Finland. The main purpose of this to provide a comparable scale absolute measurements aurora and airglow. All brought were compared Fritz Peak reference source using Lindau Calibration Photometer built Wilhelm Barke Hans Lauche 1984. results several earlier workshops. It found that most...
The importance of an acceptance angle in the plasma diagnostics with ion energy analyzers is investigated by means numerical simulations. It shown that wide angles result low tails measured distribution functions (IDFx). For flowing plasmas or beams, orientation analyzer’s orifice gives different results due to bending trajectories vicinity analyzer. demonstrated maximum IDFx at energies lower than potential. Simulations are done DIP3D, a three-dimensional particle-in-cell code.
Plasma parameters and the subsonic flow from a capacitively coupled, cylindrical plasma source of Njord helicon device are investigated by means Mach probe retarding field energy analyzer (RFEA). 13.56 MHz 600 W RF power is inserted into argon working gas under low-pressure conditions moderate magnetic field. By downstream coil, shaped purely expanding to configuration with more parallel lines. It shown that density along outer rim increases significantly there sudden increase nearly 20 V in...
Abstract. Atmospheric Gravity Waves and Traveling Ionospheric Disturbances can be observed in the neutral atmosphere ionosphere at a wide range of spatial temporal scales. Especially medium scales, these oscillations are often not resolved general circulation models parameterized. We show that ionospheric disturbances forced by upward propagating atmospheric gravity waves simultaneously with EISCAT Very High Frequency incoherent scatter radar Nordic Meteor Radar Cluster. From combined...
Abstract. Following the 38th Annual Meeting on Atmospheric studies by Optical methods at Siuntio in Finland, an intercalibration workshop for optical low-light calibration sources was held Sodankylä, Finland. The main purpose of this to provide a comparable scale absolute measurements aurora and airglow. All brought were compared international standard source (Fritz-Peak) using Lindau Calibration Photometer built Wilhelm Barke Hans Lauche 1984. is loan from Michael Gadsden, Aberdeen. results...