Viser treff 250-269 av 942

    • Enhancement of stratospheric aerosols after solar proton event. 

      Shumilov, O.I.; Henriksen, K.; Kasatkina, E.A.; Vashenyuk, E.V. (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 

      Jensen, Vilde; Bianchi, Filippo Maria; Anfinsen, Stian Normann (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 

      Priyotomo, Gadang; Wagle, Sanat; Okitsu, Kenji; Iwase, Akihiro; Kaneno, Yasuyuki; Nishimura, Rokuro; Takasugi, Takayuki (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 

      Jewitt, David; Kim, Yoonyoung; Luu, Jane; Rajagopal, Jayadev; Kotulla, Ralf; Ridgway, Susan; Liu, Wilson (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 

      Jackson, Lawrence S.; Maycock, Amanda C.; Andrews, Timothy; Fredriksen, Hege-Beate; Smith, Christopher J.; M. Forster, Piers (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 

      Antonsen, Tarjei; Havnes, Ove; Mann, Ingrid (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 

      Fredriksen, Hege-Beate; Rugenstein, Maria A.A.; Graversen, Rune (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 

      Babar, Bilal; Boström, Tobias (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 

      Vierinen, Juha; Hermann, Frank; Kastinen, Daniel; Kero, Johan; Markkanen, Jussi; Grydeland, Tom (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 

      Akbari, Vahid; Amini, Jalal; Saradjian, Mohammad Reza; Motagh, Mahdi (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 

      Kube, Ralph; Garcia, Odd Erik (Conference object; Konferansebidrag, 2014-03-17)
    • Evaluating CM-SAF solar radiation CLARA-A1 and CLARA-A2 datasets in Scandinavia 

      Babar, Bilal; Graversen, Rune; Boström, Tobias (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 

      Hafeez, Sidrah; Wong, Man Sing; Abbas, Sawaid; Asim, Muhammad (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 ...
    • Evaluation of a method to derive ionospheric conductivities using two auroral emissions (428 and 630 nm) measured with a photometer at Tromsø (69.6°N) 

      Adachi, K; Nozawa, Satonori; Ogawa, Y; Brekke, Asgeir; Hall, Chris; Fujii, Ryochi (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-03)
      This paper mainly aims at evaluating capabilities of derivation of ionospheric conductivities using two principal auroral emissions (427.8 and 630 nm). We have evaluated a photometric method of derivation of ionospheric conductivities based on simultaneous observations of a photometer (feld of view = ~1.2°), a digital camera, and the EISCAT UHF radar (feld of view = ~0.7°) operated at Tromsø, ...
    • Evaluation of a sub-kilometre NWP system in an Arctic fjord-valley system in winter 

      Valkonen, Teresa Maaria; Stoll, Patrick; Batrak, Yurii; Køltzow, Morten Andreas Ødegaard; Schneider, Thea Maria; Stigter, Emmy E.; Aashamar, Ola B.; Støylen, Eivind; Jonassen, Marius Opsanger (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-28)
      Terrain challenges the prediction of near-surface atmospheric conditions, even in kilometre-scale numerical weather prediction (NWP) models. In this study, the ALADIN-HIRLAM NWP system with 0.5 km horizontal grid spacing and an increased number of vertical levels is compared to the 2.5-km model system similar to the currently operational NWP system at the Norwegian Meteorological Institute. The ...
    • Evaluation of adhesive-free focused high-frequency PVDF copolymer transducers fabricated on spherical cavities 

      Habib, Anowarul; Wagle, Sanat; Decharat, Adit; Melandsø, Frank (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-16)
      A layer-by-layer deposition method for fabricating a focused ultrasonic transducer from piezoelectric copolymers has been developed. The fabrication process involves engraving a spherical cavity of 2 mm diameter on polyethyleneimines (PEI) polymer substrate. Surface roughness of the engraved spherical cavity is measured and compared with simulated line scan. Then, the transducer response was ...
    • Evaluation of an emergent feature of sub-shelf melt oscillations from an idealized coupled ice sheet-ocean model using FISOC (v1.1) - ROMSIceShelf (v1.0) - Elmer/Ice (v9.0) 

      Zhao, Chen; Gladstone, Rupert; Galton-Fenzi, Benjamin Keith; Gwyther, David; Hattermann, Tore (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-15)
      Changes in ocean-driven basal melting have a key influence on the stability of ice shelves, the mass loss from the ice sheet, ocean circulation, and global sea level rise. Coupled ice sheet–ocean models play a critical role in understanding future ice sheet evolution and examining the processes governing ice sheet responses to basal melting. However, as a new approach, coupled ice sheet–ocean systems ...
    • Evaluation of crystalline structure quality of Czochralski-silicon using near-infrared tomography 

      Jensen, Mathias Novik; Hellesø, Olav Gaute (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-22)
      In this work, three silicon samples are subject to tomographic scans using a 1.6μm laser. The samples were prematurely terminated due to anomalies during the Czhochralski-process. They are taken as analogues of the in situ crystal, where one sample has known aberrant structure in its lowermost 45 mm. The results of the tomographic scans show a distinct difference in transmission profile between ...
    • Evaluation of feature ranking and regression methods for oceanic chlorophyll-a estimation 

      Blix, Katalin; Eltoft, Torbjørn (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-22)
      This paper evaluates two alternative regression techniques for oceanic chlorophyll-a (Chl-a) content estimation. One of the investigated methodologies is the recently introduced Gaussian process regression (GPR) model. We explore two feature ranking methods derived for the GPR model, namely sensitivity analysis (SA) and automatic relevance determination (ARD). We also investigate a second ...
    • An evaluation of International Reference Ionosphere electron density in the polar cap and cusp using EISCAT Svalbard radar measurements 

      Bjoland, Lindis Merete; Belyey, Vasyl; Løvhaug, Unni Pia; La Hoz, Cesar (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-13)
      Incoherent scatter radar measurements are an important source for studies of ionospheric plasma parameters. In this paper the EISCAT Svalbard radar (ESR) long-term database is used to evaluate the International Reference Ionosphere (IRI) model. The ESR started operations in 1996, and the accumulated database up to 2012 thus covers 16 years, giving an overview of the ionosphere in the polar cap and ...