Blar i tittel Artikler, rapporter og annet (fysikk og teknologi)
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Elemental Abundances in the Fast Solar Wind Emanating from Chromospheric Funnels
(Journal article; Tidsskriftartikkel; Peer reviewed, 2010)We carry out a model study to determine whether a funnel-type flow geometry in the solar wind source region leads to sufficiently fast hydrogen flow to offset heavy element gravitational settling and can thus explain why solar wind abundances are not much smaller than photospheric abundances. We find that high first ionization potential (FIP) elements are more susceptible to gravitational settling ... -
ELM-HTM guided bio-inspired unsupervised learning for anomalous trajectory classification
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-23)Artificial intelligent systems often model the solutions of typical machine learning problems, inspired by biological processes, because of the biological system is faster and much adaptive than deep learning. The utility of bio-inspired learning methods lie in its ability to discover unknown patterns, and its less dependence on mathematical modeling or exhaustive training. In this paper, we propose ... -
Emulating sentinel-1 Doppler radial ice drift measurements using envisat ASAR data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-05)Using data from the Envisat Advanced Synthetic Aperture Radar (ASAR) instrument, this paper demonstrates how the high-precision radial surface velocity product, which will become available with the European Space Agency's Sentinel-1 satellite, can complement the analysis of sea ice motion. High-resolution Doppler frequency measurements are used to estimate the subsecond line-of-sight motion of ... -
Endocytic motif on a biotin-tagged hiv-1 env modulates the co-transfer of env and gag during cell-to-cell transmission
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-31)During HIV-1 transmission through T cell virological synapses, the recruitment of the envelope (Env) glycoprotein to the site of cell–cell contact is important for adhesion and for packaging onto nascent virus particles which assemble at the site. Live imaging studies in CD4 T cells have captured the rapid recruitment of the viral structural protein Gag to VSs. We explored the role of endocytic ... -
Energy budget diagnosis of changing climate feedback
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-21)The climate feedback determines how Earth’s climate responds to anthropogenic forcing. It is thought to have been more negative in recent decades due to a sea surface temperature “pattern effect,” whereby warming is concentrated in the western tropical Pacific, where nonlocal radiative feedbacks are very negative. This phenomenon has however primarily been studied within climate models. We diagnose ... -
Energy conversion in cometary atmospheres - Hybrid modeling of 67P/Churyumov-Gerasimenko
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-08-21)<i>Aims</i>: We wish to investigate the energy conversion between particles and electromagnetic fields and determine the location where it occurs in the plasma environment of comets.<p> <p><i>Methods</i>: We used a hybrid plasma model that included photoionization, and we considered two cases of the solar extreme ultraviolet flux. Other parameters corresponded to the conditions of comet ... -
Enhanced EISCAT UHF backscatter during high-energy auroral electron precipitation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)Natural enhancements in the backscattered power of incoherent scatter radars up to 5 orders of magnitudes above the thermal backscatter are sometimes observed at high latitudes. Recently observations of enhancements in the backscattered power including a feature at zero Doppler shift have been reported. These enhancements are limited in altitude to tens of kilometers. The zero Doppler shift ... -
Enhancement of stratospheric aerosols after solar proton event.
(Journal article; Tidsskriftartikkel, 1996)The lidar measurements at Verhnetulomski observatory (68.6¡N, 31.8¡E) at Kola peninsula detected a considerable increase of stratospheric aerosol concentration after the solar proton event of GLE (ground level event) type on the 16/02/84. This increase was located at precisely the same altitude range where the energetic solar protons lost their energy in the atmosphere. The aerosol layer ... -
Ensemble Conformalized Quantile Regression for Probabilistic Time Series Forecasting
(Journal article; Tidsskriftartikkel, 2022-11-04)This article presents a novel probabilistic forecasting method called ensemble conformalized quantile regression (EnCQR). EnCQR constructs distribution-free and approximately marginally valid prediction intervals (PIs), which are suitable for nonstationary and heteroscedastic time series data. EnCQR can be applied on top of a generic forecasting model, including deep learning architectures. EnCQR ... -
The environment-induced cracking of as-annealed Ni3(Si,Ti) and Ni3(Si,Ti) with 2Mo in sodium chloride solutions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-01)Background The environment-induced cracking (EIC) of as-annealed Ni3(Si,Ti) and Ni3(Si,Ti) with 2Mo has been researched as functions of applied stress, chloride ion concentration, test temperature, and pH. Methods The investigation of EIC was carried out by applying a constant method in NaCl solutions. Results The EIC susceptibility of both intermetallic compounds increased with ... -
Episodically Active Asteroid 6478 Gault
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-06)We present imaging and spectroscopic observations of 6478 Gault, a ~6 km diameter inner main-belt asteroid currently exhibiting strong, comet-like characteristics. Three distinct tails indicate that ultra-slow dust (ejection speed 0.15 ± 0.05 m s−1) was emitted from Gault in separate episodes beginning UT 2018 October 28 ± 5 (Tail A), UT 2018 December 31 ± 5 (Tail B), and UT 2019 February 10 ± 7 ... -
Errors in Simple Climate Model Emulations of Past and Future Global Temperature Change
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-04)Climate model emulators are widely used to generate temperature projections for climate scenarios, including in the recent Intergovernmental Panel on Climate Change Sixth Assessment Report. Here we evaluate the performance of a two-layer energy balance model in emulating historical and future temperature projections from Coupled Model Intercomparison Project Phase 6 models. We find that emulation ... -
Estimates of the size distribution of meteoric smoke particles from rocket-borne impact probes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-26)Ice particles populating noctilucent clouds and being responsible for polar mesosphericsummer echoes exist around the mesopause in the altitude range from 80 to 90 km during polar summer.The particles are observed when temperatures around the mesopause reach a minimum, and it is presumedthat they consist of water ice with inclusions of smaller mesospheric smoke particles (MSPs). This workprovides ... -
Estimating Radiative Forcing With a Nonconstant Feedback Parameter and Linear Response
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-06)A new algorithm is proposed for estimating time-evolving global forcing in climate models. The method is a further development of the work of Forster et al. (2013), <a href=https://doi.org/10.1002/jgrd.50174>https://doi.org/10.1002/jgrd.50174</a>, taking into account the non-constancy of the global feedbacks. We assume that the non-constancy of this global feedback can be explained as a time-scale ... -
Estimating solar irradiation in the Arctic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-08-22)Solar radiation data plays an important role in pre-feasibility studies of solar electricity and/or thermal system installations. Measured solar radiation data is scarcely available due to the high cost of installing and maintaining high quality solar radiation sensors (pyranometers). Indirect measured radiation data received from geostationary satellites is unreliable at latitudes above 60 degrees ... -
Estimating the Space Debris Density Function using Radar Beam Park Measurements
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023)Estimating the density of space debris as a function of orbital elements and size is crucial for determining the risk of collision of spacecraft. For objects 1 cm or larger in diameter, this information can be obtained using beam park observations made with powerful ground based radars. This study presents a novel technique for estimating the density of space debris as a function of orbital elements ... -
Estimation of atmospheric temperature and humidity profiles from MODIS data and radiosond data using artificial neural network
(Journal article; Tidsskriftartikkel; Peer reviewed, 2008)The aim of this study is to test the quality of the neural network for retrieving the temperature and humidity by comparison with the radiosond values and a linear regression method. Remote sensed images give useful information about the atmosphere. In this article, MODIS data is used to retrieve temperature and humidity profiles of the atmosphere. Two methods of linear regression and artificial ... -
Estimation of statistical moments for single point measurements in the Scrape Off Layer
(Conference object; Konferansebidrag, 2014-03-17) -
Evaluating CM-SAF solar radiation CLARA-A1 and CLARA-A2 datasets in Scandinavia
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-26)Estimating/retrieving solar radiation through satellite-based remote sensing provides larger spatial coverage compared to other methods. Accurate estimates of incoming solar radiation is important when planning new solar energy installations. In addition, these estimates are also used in climate studies. Geostationary satellites are ideal for estimating solar radiation but cannot be used for high ... -
Evaluating Landsat-8 and Sentinel-2 Data Consistency for High Spatiotemporal Inland and Coastal Water Quality Monitoring
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-30)The synergy of fine-to-moderate-resolutin (i.e., 10–60 m) satellite data of the Landsat-8 Operational Land Imager (OLI) and the Sentinel-2 Multispectral Instrument (MSI) provides a possibility to monitor the dynamics of sensitive aquatic systems. However, it is imperative to assess the spectral consistency of both sensors before developing new algorithms for their combined use. This study evaluates ...