Institutt for fysikk og teknologi: Recent submissions
Now showing items 701-720 of 1409
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Two-axis tracking solar irradiance measurements at Tromsø
(Master thesis; Mastergradsoppgave, 2020-06-29)The world is changing towards using more renewable, rather than fossil energy sources in order to reach the 1.5 degrees celsius goal of the Paris agreement (Merchant, 2018). This thesis’ main focus is to investigate the solar irradiance in Tromsø using 2-axis tracking measurements from May 2020. The reduction of global irradiance and direct irradiance is also compared against the values of the other ... -
An investigation of the spatial and temporal distribution of kinetic energy in the mesosphere. The high latitude mesosphere
(Master thesis; Mastergradsoppgave, 2020-06-29)The mesosphere is perhaps the least explored region in the atmosphere with very few methods of observing. This thesis will primarily be exploring a new technique for measuring the distribution of kinetic energy in the mesosphere across a wide range of spatial and temporal scales. The method being used relies on correlation functions between pairs of meteor measurements. These measurements are made ... -
Analysis of the potential of the Ku-band Gamma Portable Radar Interferometer for sea ice information extraction.
(Master thesis; Mastergradsoppgave, 2020-06-29)Radar remote sensing is a key technology for monitoring sea ice. In this regard, passive microwave and Synthetic Aperture Radars (SARs) are the most important sensor types. This technology has been used for sea ice applications for four decades, but there are still many uncertainties related to sea ice monitoring by SAR. Some of these may be solved by multi-sensor observations, in which case other ... -
Determining optical-flow for turbulent motions in the aurora borealis
(Master thesis; Mastergradsoppgave, 2020-06-28)In dynamic aurora there are structures that shows shear-flow and rotations. These flows have a locally varying vorticity-field, which can be observed in small scale aurora. Vorticity in plasma-flows have a direct relation to field-aligned currents. An effective method to determine these flows would be a great tool in research on magnetosphere-ionosphere coupling and auroral physics. With the current ... -
Investigating the viability of lithium-ion battery - fuel cell hybrid systems - A case study for Greenland and Qatar
(Master thesis; Mastergradsoppgave, 2020-06-22)Renewable means of energy production have recently become cost competitive with fossil fuels. However, before they can be completely phased out, the issue of storing renewable energy must be addressed. Two energy storage technologies that have gotten a lot of attention over the past years are lithium ion batteries and hydrogen energy storage. Each of these technologies have their advantages, ... -
Assessment of the Remaining Carbon Budget: Incorporating Arctic Amplification in a Simple Response Model
(Master thesis; Mastergradsoppgave, 2020-06-15)Remaining carbon budgets (RCBs) quantify the total amount of CO2 that can still be emitted into the atmosphere while keeping the global mean surface temperature below a specific target. However, there is significant uncertainty in RCBs estimates. This thesis develops a Simple Response Model (SRM) to explore the uncertainties in RCBs. We use temperature response functions estimated from multi-box ... -
Assessment of the Remaining Carbon Budget: Incorporation of Nonlinear Feedbacks in a Simple Response Model
(Master thesis; Mastergradsoppgave, 2020-06-15)Anthropogenic emission of greenhouse gases is causing an unbalance in the Earth’s climate system, leading to global climate change. The implications of these changes are dramatic, with a need for a global-scale assessment. The remaining carbon budget (RCB) is a measure of the amount of greenhouse gasses (GHGs) that can be emitted if we are to reach a specific temperature target. Traditionally, carbon ... -
Evaluation of a Solar Power Plant at Longyearbyen
(Master thesis; Mastergradsoppgave, 2020-06-15)The world faces one of the greatest challenges by changing the economy in a direction where higher resource productivity and lower greenhouse gas emis- sions are the main focus. The most prominent solution to reduce green house gases is a greater utilisation of renewable energy sources. With a rapid tech- nological advancement, solar energy is now one of the least expensive forms of power in two ... -
Assessment of the Remaining Carbon Budget: A Comparison of a Simple Response Model and the MAGICC Model.
(Master thesis; Mastergradsoppgave, 2020-06-15)We are changing the global climate by altering the Earths energy balance through the emission of greenhouse gasses. The international community aims to prevent dangerous warming with mitigative efforts. A remaining carbon budget (RCB) can roughly quantify an allowable amount of emissions for keeping the temperature below a set target. We have built a simple climate model using impulse response ... -
Deep Learning of Oriented Bounding Box Regression Networks for Ship Detection in Optical Satellite Images
(Master thesis; Mastergradsoppgave, 2020-05-31)Maritime surveillance is important for management of maritime traffic and to prevent activities like illegal fishing, hazardous cargo transportation, piracy, and smuggling of goods and humans. Remote sensing is frequently used for positioning vessels that are not transmitting via the Automatic Identification System (AIS). Modern optical remote sensing instruments provide high-resolutional imagery, ... -
Dust sputtering within the inner heliosphere: a modelling study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-03)The aim of this study is to investigate how sputtering by impacting solar wind particles influence the lifetime of dust particles in the inner heliosphere near the Sun.<p><p> We consider three typical dust materials: silicate, Fe<sub>0.4</sub>Mg<sub>0.6</sub>O and carbon and describe their sputtering yields based on atomic yields given by the Stopping and Range of Ions in Matter (SRIM) package. ... -
Can Mineral Oil Slicks Be Distinguished From Newly Formed Sea Ice Using Synthetic Aperture Radar?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-18)In this feasibility study discriminating oil slicks and newly formed sea ice using SAR imagery is investigated, using imagery from the L-band high-resolution Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) airborne and the satellite C-band RADARSAT-2 (RS-2) systems. To determine the separability of these two varying but similar appearing low backscatter ocean surfaces, multi-polarization ... -
Auroral classification ergonomics and the implications for machine learning
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-09)The machine-learning research community has focused greatly on bias in algorithms and have identified different manifestations of it. Bias in training samples is recognised as a potential source of prejudice in machine learning. It can be introduced by the human experts who define the training sets. As machine-learning techniques are being applied to auroral classification, it is important to identify ... -
Getting adhesion force maps with an amplitude-modulation AFM in tapping mode
(Research report; Forskningsrapport, 2020-07)Here we demonstrate how to get adhesion force maps with an amplitude-modulation AFM in tapping mode. Our method is tapping mode but it is carried out at ultra-small amplitudes in the presence of surface water layers. The tip is made to vibrated under the water layer in what we call Small Amplitude Small Set-point AM AFM. We show how this is done with an example based on the Cypher scanning probe ... -
CMIP5 model selection for ISMIP6 ice sheet model forcing: Greenland and Antarctica
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-06)The ice sheet model intercomparison project for CMIP6 (ISMIP6) effort brings together the ice sheet and climate modeling communities to gain understanding of the ice sheet contribution to sea level rise. ISMIP6 conducts stand-alone ice sheet experiments that use space- and time-varying forcing derived from atmosphere–ocean coupled global climate models (AOGCMs) to reflect plausible trajectories for ... -
Reconstructing force profiles with an amplitude-modulation AFM in tapping mode
(Research report; Forskningsrapport, 2020-07)Here we demonstrate how to reconstruct force profiles with an amplitude-modulation AFM operated in in standard tapping mode. Our example is based on the Cypher scanning probe microscope from Asylum Research. The method is based on Sader and Katan’s algorithm, but we have implemented an experimental set-up that allows for robust reconstruction. We discuss the details here. -
Automatic validation of Sentinel-1 borne snow avalanche detections
(Master thesis; Mastergradsoppgave, 2020-05-30)Snow avalanches threaten human lives, settlements and roads in snow covered mountainous areas. For avalanche forecasting, knowledge of the spatio-temporal occurrence of avalanche activity is critical. Automatic avalanche detection algorithms have been developed to enable consistent avalanche activity monitoring for large regions. The Satskred avalanche detection algorithm developed by NORCE applies ... -
Explaining decisions of deep neural networks used for fish age prediction
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-19)Age-reading of fish otoliths (ear stones) is important for the sustainable management of fish resources. However, the procedure is challenging and requires experienced readers to carefully examine annual growth zones. In a recent study, convolutional neural networks (CNNs) have been demonstrated to perform reasonably well on automatically predicting fish age from otolith images. In the present study, ... -
Large-Scale Detection and Categorization of Oil Spills from SAR Images with Deep Learning
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-14)We propose a deep-learning framework to detect and categorize oil spills in synthetic aperture radar (SAR) images at a large scale. Through a carefully designed neural network model for image segmentation trained on an extensive dataset, we obtain state-of-the-art performance in oil spill detection, achieving results that are comparable to results produced by human operators. We also introduce a ... -
First observations of the McMurdo-South Pole oblique ionospheric HF channel
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-09)We present the first observations from a new low-cost oblique ionosonde located in Antarctica. The transmitter is located at McMurdo Station, Ross Island, and the receiver at Amundsen–Scott Station, South Pole. The system was demonstrated successfully in March 2019, with the experiment yielding over 30 000 ionospheric echoes over a 2-week period. These data indicate the presence of a stable E layer ...