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The Role of Clouds in Arctic Climate
(Mastergradsoppgave; Master thesis, 2024-05-14)Anthropogenic climate change is causing the Arctic to warm faster than any other region on Earth, a phenomenon also known as Arctic amplification. The warming and its consequences induce, amongst other things, a change in clouds, impacting their role in the Arctic climate by introducing a feedback. Clouds play an important role in the global radiation budget. They cool the surface by reflecting ... -
Towards seamless environmental prediction–development of Pan-Eurasian EXperiment (PEEX) modelling platform
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-09)The Pan-Eurasian Experiment Modelling Platform (PEEX-MP) is one of the key blocks of the PEEX Research Programme. The PEEX MP has more than 30 models and is directed towards seamless environmental prediction. The main focus area is the Arctic-boreal regions and China. The models used in PEEX-MP cover several main components of the Earth’s system, such as the atmosphere, hydrosphere, pedosphere and ... -
The basics of optical alignment
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-26)Precise optical alignment is critical for high-quality microscopy imaging, especially in custom-built systems. This guide details essential alignment steps, from beam path setup to lens collimation and centering, introduces key tools like pinholes and shearing interferometers, and advocates for a modular construction approach. This article aims to empower microscopy enthusiasts with practical alignment ... -
Impact ionization double peaks analyzed in high temporal resolution on Solar Orbiter
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-05-29)Solar Orbiter is equipped with electrical antennas performing fast measurements of the surrounding electric field. The antennas register high-velocity dust impacts through the electrical signatures of impact ionization. Although the basic principle of the detection has been known for decades, the understanding of the underlying process is not complete, due to the unique mechanical and electrical ... -
Kelvin-Helmholtz versus Gradient drift instability: which one "wins" in the high latitude ionosphere?
(Mastergradsoppgave; Master thesis, 2024-01-14)The high latitude ionosphere is highly irregular, which is caused by plasma patches, flow shears and electron precipitation. These causes are not well understood, but it is thought to be three sources to these irregularities: density gradients, arcs/flow channels and electron precipitation. It is speculated that there are two main mechanisms for the formation of these irregularities. These mechanisms ... -
Cross-population evaluation of cervical cancer risk prediction algorithms
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-24)Background - Cervical cancer is a preventable disease, despite being one of the most common types of female cancers worldwide. Integrating existing programs for cervical cancer screening with personalized risk prediction algorithms can improve population-level cancer prevention by enabling more targeted screening and contrive preventive healthcare innovations. While algorithms developed for cervical ... -
Analysis of time series of polarimetric sea ice signatures observed in fast ice it the Belgica Bank area
(Journal article; Tidsskriftartikkel, 2023-10-20)The CIRFA-Cruise 2022 with <i>RV Kronprins Haakon</i> to the north-eastern coast of Greenland in the period April 22nd to May 9th 2022 was organised to perform measurements and make observations which allow for validation of sea ice remote sensing information and forecast products resulting from work in the Centre for Integrated Remote Sensing and Forecasting for Arctic Operations(CIRFA), a Centre ... -
Distinguishing Mineral Oil Slicks from Low Wind Areas using Rapid Repeat Synthetic Aperture Radar Imagery
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-18)A method for differentiating marine oil slicks from radar-dark, low wind areas in open water using rapid repeat SAR imagery is reported. The study uses data acquired by the airborne UAVSAR L-band SAR instrument, imaging the Coal Oil Point seep field near Santa Barbara, California. Time-series of images from three different days are analyzed, all containing both verified oil slicks and low wind zones. ... -
Correlation between Wettability and Dissolution of Calcite in Ion-Free Water
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-13)Calcite, a prevalent mineral in the earth’s crust, plays a pivotal role in various geological and industrial processes, including carbon sequestration, water treatment, and enhanced oil recovery. Understanding how wettability (a crucial surface property influenced by the interaction between calcite and surrounding fluids) affects calcite’s dissolution is essential for optimizing these processes. We ... -
On the strength of E and F region irregularities for GNSS scintillation in the dayside polar ionosphere
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-02)We present results of the study conducted to quantify the relative contribution of different ionospheric regions to phase scintillation in Global Navigation Satellite Systems (GNSS) at the dayside high latitude ionosphere. By taking advantage of the scanning capability of the 32-m EISCAT radar in Svalbard (ESR) and its recurrent favourable location below the dayside auroral region, we developed ... -
Simultaneous electrochemical determination of benzenediol compounds in environmental samples using nano architectures of hydrogen ammonium zinc molybdate layered double hydroxides integrated with carbon black modified electrode
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-02)Phenolic compounds, such as benzenediol (BD), are toxic and exhibit poor biodegradability, posing a threat to human health and the environment, even at low concentrations. Therefore, the simultaneous detection of BD at low detection limits and a wide detection range is of significant interest for monitoring water quality and environmental remediation efforts. In this study, we developed a novel ... -
Quantification of van der Waals forces in bimodal and trimodal AFM
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-22)The multifrequency formalism is generalized and exploited to quantify attractive forces, i.e., van der Waals interactions, with small amplitudes or gentle forces in bimodal and trimodal atomic force microscopy (AFM). The multifrequency force spectroscopy formalism with higher modes, including trimodal AFM, can outperform bimodal AFM for material property quantification. Bimodal AFM with the second ... -
Quasi Monte Carlo time-frequency analysis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-30)We study signal processing tasks in which the signal is mapped via some generalized time-frequency transform to a higher dimensional time-frequency space, processed there, and synthesized to an output signal. We show how to approximate such methods using a quasi-Monte Carlo (QMC) approach. We consider cases where the time-frequency representation is redundant, having feature axes in addition to the ... -
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 ... -
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 ... -
Radar size inference from statistics of RCS samples
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023)Radar Beam-park experiments have been very successful in characterizing the distribution of space debris objects, both in terms of orbital parameters but also in terms of limiting the estimates of their radar cross section, or RCS. A recent paper \[0\] used observed range and range rates to refine orbit estimates by matching up the observed SNR curve to that predicted by simulations. This gives good ... -
ProtoVAE: A Trustworthy Self-Explainable Prototypical Variational Model
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-15)The need for interpretable models has fostered the development of self-explainable classifiers. Prior approaches are either based on multi-stage optimization schemes, impacting the predictive performance of the model, or produce explanations that are not transparent, trustworthy or do not capture the diversity of the data. To address these shortcomings, we propose ProtoVAE, a variational autoencoder-based ... -
Synthetic wavelength scanning interferometry for 3D surface profilometry with extended range of height measurement using multi-colour LED light sources
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-05)We report three-dimensional surface profilometry with extended range of height measurements using synthetic wavelength scanning interferometry without tunable filters, wavelength-tuning lasers, grating elements. We have used inexpensive multiple colour light emitting diodes (LEDs) and operate them sequentially one by one or combination of two or more colours simultaneously to visualize synthetic ... -
Data Augmentation for SAR Sea Ice and Water Classification Based on Per-Class Backscatter Variation With Incidence Angle
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-03)Monitoring sea ice in polar regions is critical for understanding global climate change and supporting marine navigation. Recently, researchers started to utilize machine/deep learning methodologies to automate the separation of sea ice and open water in synthetic aperture radar imagery. However, this requires a large amount of reliably labeled training data. We here propose an augmentation routine ... -
Airborne Investigation of Quasi-Specular Ku-Band Radar Scattering for Satellite Altimetry Over Snow-Covered Arctic Sea Ice
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-22)Surface-based Ku-band radar altimetry investigations indicate that the radar signal is typically backscattered from well above the snow–sea ice interface. However, this would induce a bias in satellite altimeter sea ice thickness retrievals not reflected by buoy validation. Our study presents a mechanism to potentially explain this paradox: probabilistic quasi-specular radar scattering from the ...
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