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norskBlar i tittel Artikler, rapporter og annet (fysikk og teknologi)
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The effect of electron bite-outs on artificial electron heating and the PMSE overshoot.
(Journal article; Peer reviewed; Tidsskriftartikkel, 2005-12-23)We have considered the effect that a local reduction in the electron density (an electron bite-out), caused by electron absorption on to dust particles, can have on the artificial electron heating in the height region between 80 to 90 km, where noctilucent clouds (NLC) and the radar phenomenon PMSE (Polar Mesospheric Summer Echoes) are observed. With an electron density profile without ... -
Effect of suprathermal electrons on the intensity and Doppler frequency of electron plasma lines.
(Journal article; Tidsskriftartikkel, 1999)In an incoherent scattering radar experiment, the spectral measurement of the so-called up- and downshifted electron plasma lines provides information about their intensity and their Doppler frequency. These two spectral lines correspond, in the backscatter geom- etry, to two Langmuir waves travelling towards and away from the radar. In the daytime ionosphere, the presence of a small percentage ... -
The effect of vertical mixing on the horizontal drift of oil spills
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-21)Vertical and horizontal transport mechanisms for marine oil spills are investigated using numerical model simulations. To realistically resolve the 3-D development of a spill on the ocean surface and in the water column, recently published parameterizations for the vertical mixing of oil spills are implemented in the open-source trajectory framework OpenDrift (https://doi.org/10.5281/zenodo.1300358, ... -
Effect of Wind Direction and Incidence Angle on Polarimetric SAR Observations of Slicked and Unslicked Sea Surfaces
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-12)The objective of this paper is to investigate the dependency of oil spill observations in polarimetric SAR data on imaging geometry, i.e., on incidence angle and look direction relative to the wind. The study is based on quad-polarization data acquired by the Uninhabited Aerial Vehicle Synthetic Aperture Radar over experimental oil slicks under relatively high winds of 10–12 m/s over an 8-hour period. ... -
Effect on the longitudinal coherence properties of a pseudothermal light source as a function of source size and temporal coherence
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-01)In the present Letter, a synthesized pseudothermal light source having high temporal coherence (TC) and low spatial coherence (SC) properties is used. The longitudinal coherence (LC) properties of the spatially extended monochromatic light source are systematically studied. The pseudothermal light source is generated from two different monochromatic laser sources: He–Ne (at 632 nm) and DPSS (at 532 ... -
Effects of Ocean Acidification and Warming on Sperm Activity and Early Life Stages of the Mediterranean Mussel (Mytilus galloprovincialis)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)Larval stages are among those most vulnerable to ocean acidification (OA). Projected atmospheric CO2 levels for the end of this century may lead to negative impacts on communities dominated by calcifying taxa with planktonic life stages. We exposed Mediterranean mussel (Mytilus galloprovincialis) sperm and early life stages to pHT levels of 8.0 (current pH) and 7.6 (2100 level) by manipulating pCO2 ... -
Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-23)We present the results from investigation of spectra of polar mesospheric summer echoes (PMSE) observed with EISCAT VHF 224 MHz radar during energetic particle precipitation events in the summer of 2019. We used the sudden enhancements in electron densities derived from the VHF observations above 90 km as indicators of particle precipitation. We find that the altitude extent of the PMSE increased ... -
Effects of substorm electrojet on declination along concurrent geomagnetic latitudes in the northern auroral zone
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-02)The geomagnetic field often experiences large fluctuations, especially at high latitudes in the auroral zones. We have found, using simulations, that there are significant differences in the substorm signature, in certain coordinate systems, as a function of longitude. This is confirmed by the analysis of real, measured data from comparable locations. Large geomagnetic fluctuations pose ... -
Effects of the tropospheric large-scale circulation on European winter temperatures during the period of amplified Arctic warming
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-08)We investigate factors influencing European winter (DJFM) air temperatures for the period 1979–2015 with the focus on changes during the recent period of rapid Arctic warming (1998–2015). We employ meteorological reanalyses analysed with a combination of correlation analysis, two pattern clustering techniques, and backtrajectory airmass identification. In all five selected European regions, severe ... -
Efficient photoelectrocatalytic degradation of amoxicillin using nano-TiO<inf>2</inf> photoanode thin films: A comparative study with photocatalytic and electrocatalytic methods
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-24)Excessive utilization of antibiotics in human, animal, and aquaculture poses a substantial threat to human health and the environment. Photoelectrochemical processes are increasingly applied for water remediation because they generate oxidizing species and mineralize organic pollutants, making even small water quantities more amenable for utilization. Thus, this study presents the fabrication of an ... -
Eigen-analysis reveals components supporting super-resolution imaging of blinking fluorophores
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-30)This paper presents eigen-analysis of image stack of blinking fluorophores to identify the components that enable super-resolved imaging of blinking fluorophores. Eigen-analysis reveals that the contributions of spatial distribution of fluorophores and their temporal photon emission characteristics can be completely separated. While cross-emitter cross-pixel information of spatial distribution ... -
EISCAT 3D: the next generation international atmosphere and geospace research radar
(Journal article; Tidsskriftartikkel, 2019)EISCAT_3D is the next generation international atmosphere- and geospace research radar under development in Arctic Europe. Construction have started in September 2017 and the radar system is expected to be operational in the end of 2021. The EISCAT_3D facility will be distributed across three sites in Northern Scandinavia - in Skibotn, Norway, near Kiruna in Sweden, and near Karesuvanto in Finland. ... -
Electron Bulk Heating at Saturn’s Magnetopause
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-25)Magnetic reconnection at the magnetopause (MP) energizes ambient plasma via the release of magnetic energy and produces an “open” magnetosphere allowing solar wind particles to directly enter the system. At Saturn, the nature of MP reconnection remains unclear. The current study examines electron bulk heating at MP crossings, in order to probe the relationship between observed and predicted reconnection ... -
Electron Density Depletion Region Observed in the Polar Cap Ionosphere
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-16)This paper presents and discusses electron density depletion regions observed with the incoherent scatter EISCAT Svalbard Radar (ESR) located at 75.43°N geomagnetic latitude. The data include several decades of measurements, which make them suitable for studying statistical features and characteristics of the ionospheric parameters. Here we focus on the electron density depletions and their dependence ... -
The electron energy distribution during HF pumping, a picture painted with all colors.
(Journal article; Peer reviewed; Tidsskriftartikkel, 2005-07-28)The shape of the electron energy distribution has long been a central question in the field of highfrequency radio-induced optical emission experiments. This report presents estimates of the electron energy distribution function, fe(E), from 0 to 60 eV, based on optical multiwavelength (6300, 5577, 8446, 4278 A° ) data and 930-MHz incoherent scatter radar measurements of ion temperature, electron ... -
Electron Energy Spectrum and Auroral Power Estimation From Incoherent Scatter Radar Measurements
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-23)Differential energy flux of electrons precipitating into the high‐latitude ionosphere can be estimated from incoherent scatter radar observations of the ionospheric electron density profile. We present a method called ELSPEC for electron spectrum estimation from incoherent scatter radar measurements, which is based on integration of the electron continuity equation and spectrum model selection by ... -
Electron fishbones: theory and experimental evidence
(Journal article; Tidsskriftartikkel; Peer reviewed, 2007-07-19)We discuss the processes underlying the excitation of fishbone-like internal kink instabilities driven by supra-thermal electrons generated experimentally by different means: Electron Cyclotron Resonance Heating (ECRH) and by Lower Hybrid (LH) power injection. The peculiarity and interest of exciting these electron fishbones by ECRH only or by LH only is also analyzed. Not only the mode stability ... -
Electron heating by HF pumping of high-latitude ionospheric F-region plasma near magnetic zenith
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-06)High-frequency electromagnetic pumping of ionospheric F-region plasma at high and mid latitudes gives the strongest plasma response in magnetic zenith, antiparallel to the geomagnetic field in the Northern Hemisphere. This has been observed in optical emissions from the pumped plasma turbulence, electron temperature enhancements, filamentary magnetic field-aligned plasma density irregularities, and ... -
Electron velocity distribution function in a plasma with temperature gradient and in the presence of suprathermal electrons: application to incoherent-scatter plasma lines.
(Journal article; Tidsskriftartikkel, 1998-10-31)The plasma dispersion function and the reduced velocity distribution function are calculated numerically for any arbitrary velocity distribution function with cylindrical symmetry along the magnetic field. The electron velocity distribution is separated into two distributions representing the distribution of the ambient electrons and the suprathermal electrons. The velocity distribution function of ... -
Electron-neutral collisions effects on Langmuir probe in the lower E-region ionosphere
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-21)We present the first set of particle-in-cell simulations including Monte Carlo collisions between charged and neutral particles used to simulate a cylindrical Langmuir probe in the electron saturation regime with a collisional electron sheath. We use a setup focused on the E-region ionosphere; however, the results of these simulations are analyzed in a general sense using dimensionless values. We ...
