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norskInstitutt for fysikk og teknologi: Recent submissions
Now showing items 361-380 of 1402
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Spatial variability of nocturnal stability regimes in an operational weather prediction model
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-15)Forecast errors in near-surface temperatures are a persistent issue for numerical weather prediction models. A prominent example is warm biases during cloud-free, snow-covered nights. Many studies attribute these biases to parametrized processes such as turbulence or radiation. Here, we focus on the contribution of physical processes to the nocturnal temperature development. We compare model timestep ... -
Traveling Ionospheric Disturbances in the Vicinity of Storm-Enhanced Density at Midlatitudes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-08)This study provides first storm time observations of the westward-propagating medium-scale traveling ionospheric disturbances (MSTIDs), particularly, associated with characteristic subauroral storm time features, storm-enhanced density (SED), subauroral polarization stream (SAPS), and enhanced thermospheric westward winds over the continental US. In the four recent (2017–2019) geomagnetic storm ... -
Impulse-driven oscillations of the near-Earth's magnetosphere
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-09)It is argued that a simple model based on magnetic image arguments suffices to give a convincing insight into both the basic static as well as some transient dynamic properties of the near-Earth's magnetosphere, particularly accounting for damped oscillations being excited in response to impulsive perturbations. The parameter variations of the frequency are given. Qualitative results can also be ... -
Scalable-resolution structured illumination microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-15)Structured illumination microscopy suffers from the need of sophisticated instrumentation and precise calibration. This makes structured illumination microscopes costly and skill-dependent. We present a novel approach to realize super-resolution structured illumination microscopy using an alignment non-critical illumination system and a reconstruction algorithm that does not need illumination ... -
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 ... -
On the Exploitation of Multimodal Remote Sensing Data Combination for Mesoscale/Submesoscale Eddy Detection in the Marginal Ice Zone
(Journal article; Tidsskriftartikkel, 2022-10-17)The detection and analysis of ocean eddies via remote sensing have become a hot topic in physical oceanography during the last few decades. However, eddy identification and tracking via remote sensing can be a challenging task, since each sensor has some limitations. In order to overcome potential challenges, it is crucial to exploit the complementary information provided by different sensing systems. ... -
Negational symmetry of quantum neural networks for binary pattern classification
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-27)Although quantum neural networks (QNNs) have shown promising results in solving simple machine learning tasks recently, the behavior of QNNs in binary pattern classification is still underexplored. In this work, we find that QNNs have an Achilles’ heel in binary pattern classification. To illustrate this point, we provide a theoretical insight into the properties of QNNs by presenting and analyzing ... -
Reconstruction of precipitating electrons and three-dimensional structure of a pulsating auroral patch from monochromatic auroral images obtained from multiple observation points
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-12)In recent years, aurora observation networks using high-sensitivity cameras have been developed in the polar regions. These networks allow dimmer auroras, such as pulsating auroras (PsAs), to be observed with a high signal-to-noise ratio. We reconstructed the horizontal distribution of precipitating electrons using computed tomography with monochromatic PsA images obtained from three observation ... -
Multi-Year Sea Ice Conditions in the Northwest Passage: 1968–2020
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-21)The Northwest Passage is often referred to as the “Holy Grail” of ship navigation as it provides a shorter route connecting the Atlantic and Pacific Oceans compared to the Northern Sea Route, Panama Canal, Suez Canal, and transiting around Cape Horn. Here, we summarize 52 years of observed multi-year ice (MYI) conditions from 1968 to 2020 in the western Canadian Arctic regions of the Northwest ... -
Ultrasonic image denoising using machine learning in point contact excitation and detection method
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-06)A point contact/Coulomb coupling technique is generally used for visualizing the ultrasonic waves in Lead Zirconate Titanate (PZT) ceramics. The point contact and delta pulse excitation produce a broadband frequency spectrum and wide directional wave vector. In ultrasonic, the signal is corrupted with several types of noises such as speckle, Gaussian, Poisson, and salt and pepper noise. Consequently, ... -
Moon Imaging Technique and Experiments Based on Sanya Incoherent Scatter Radar
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-13)This article introduces the experiment design for Moon imaging based on Sanya incoherent scatter radar (SYISR) and algorithm research in data processing. The peak power of SYISR is 2 MW. The transmitted frequency used for Moon imaging experiments is 430 MHz. We conducted Moon imaging experiments using two types of waveforms, 13-bit Barker code, and linear frequency modulation (LFM) chirp. Considering ... -
This looks more like that: Enhancing Self-Explaining Models by Prototypical Relevance Propagation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-12)Current machine learning models have shown high efficiency in solving a wide variety of real-world problems. However, their black box character poses a major challenge for the comprehensibility and traceability of the underlying decision-making strategies. As a remedy, numerous post-hoc and self-explanation methods have been developed to interpret the models’ behavior. Those methods, in addition, ... -
Probabilistic forecasts of wind power generation in regions with complex topography using deep learning methods: An Arctic case
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-27)The energy market relies on forecasting capabilities of both demand and power generation that need to be kept in dynamic balance. Nowadays, contracts and auctions of renewable energy in a liberalized electricity market heavily rely on forecasting future power generation. The highly intermittent nature of renewable energy sources increases the uncertainty about future power generation. Since point ... -
Pronounced Suppression and X-Pattern Merging of Equatorial Ionization Anomalies After the 2022 Tonga Volcano Eruption
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-27)Following the 2022 Tonga Volcano eruption, dramatic suppression and deformation of the equatorial ionization anomaly (EIA) crests occurred in the American sector ∼14,000 km away from the epicenter. The EIA crests variations and associated ionosphere-thermosphere disturbances were investigated using Global Navigation Satellite System total electron content data, Global-scale Observations of the ... -
Interferometric Study of Ionospheric Plasma Irregularities in Regions of Phase Scintillations and HF Backscatter
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-08)We investigate the nature of small-scale irregularities observed in the cusp by the Twin Rockets to Investigate Cusp Electrodynamics-2 (TRICE-2) in regions of enhanced phase scintillations and high-frequency coherent radar backscatter. We take advantage of the fact that the irregularities were detected by spatially separated probes, and present an interferometric analysis of both the observed electron ... -
Snowfall and snow accumulation during the MOSAiC winter and spring seasons
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-17)Data from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition allowed us to investigate the temporal dynamics of snowfall, snow accumulation and erosion in great detail for almost the whole accumulation season (November 2019 to May 2020). We computed cumulative snow water equivalent (SWE) over the sea ice based on snow depth and density retrievals from a ... -
The Influence of NegEx on ICD-10 Code Prediction in Swedish: How is the Performance of BERT and SVM Models Affected by Negations?
(Journal article; Tidsskriftartikkel, 2022-08-22)Clinical text contains many negated concepts since the physician excludes irrelevant symptoms when reasoning and concluding about the diagnosis. This study investigates the machine interpretation of negated symptoms and diagnoses using a rule-based negation detector and its influence on downstream text classification task. The study focuses on the effect of negated concepts and NegEx preprocessing ... -
Insights into TiO<inf>2</inf>thin film photodegradation from Kelvin Probe AFM maps
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-29)The synthesis of TiO2 thin films by the chemical spray pyrolysis method at different titanium isopropoxide (TTIP) to acetylacetone (AcacH) ratios has been shown to lead to the highest photodegradation at 1 (TTIP):8 (AcacH). These films hold promise in the field of indoor pollution treatment. Carbon incorporation into the surface and into the TiO2 lattice could be responsible for the observed ... -
Multi-instrument observations of the Pajala fireball: origin, characteristics, and atmospheric implications
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-07)Meteor observations provide information about Solar System constituents and their influx onto Earth, their interaction processes in the atmosphere, as well as the neutral dynamics of the upper atmosphere. This study presents optical, radar, and infrasound measurements of a daytime fireball that occurred on 4 December 2020 at 13:30 UTC over Northeast Sweden. The fireball was recorded with two video ... -
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 ...
