This thesis is part of a project that aims to develop a sensor for the detection of methane in the air and in water based on a waveguide Mach-Zehnder interferometer. The main application of this sensor is monitoring the environment and the ability to detect a leakage of methane. The development of a sensor includes analysis of operational conditions. In this project one of the greatest concerns is ...

This thesis present a self-consistent derivation of reduced fluid models for geophysical dynamics confined to the midlatitude region. The reduced model will be derived by use of a regular perturbation method, that gives the same result as the classical models, such as the barotropic and baroclinic quasi-gestrophic potential vorticity model. It will be shown that such a rigorous treatment self-consistently ...

The aim of this thesis is to study type-I ion outflows in the high latitude ionosphere. Type-I ion outflows are characterized by strong perpendicular electric fields, enhanced and anisotropic ion temperatures and low electron densities below 300 km, indicating small amounts of hard particle precipitation. We scanned data from the EISCAT Madrigal database over a period of 10 years (January 2000 - ...

In order to keep the scientific significance of the Ny-Ålesund station on Svalbard as the key place for the monitoring of background air it is needed to assess the influence from local human activities on the air quality. Whether research and tourist activity continues to grow or restrictions to be implied the change of impact may affect air chemistry data quality. Therefore the identification of ...

The influence of Arctic summer sea ice area on autumn and winter climate in the extra-tropic Northern hemisphere is investigated. During the last decades, the Arctic has warmed more than twice the global average rate, a phenomenon called the Arctic Amplification (AA). AA involves a remarkable decrease of the Arctic sea ice cover and a decrease of the latitudinal temperature gradient. Both are supposed ...

Modern science is based on observation, and its advances are limited by what is possible to observe. For centuries optical microscopy was limited by the diffraction of light, making structures closer together than half the wavelength of light unresolvable. In recent years, the new field of optical nanoscopy has emerged, enabling diffraction-limited structures to be resolved. As opposed to ...

This work is based on long term monitoring the HF signal data at 9.996 MHz at mid-latitudes from the short radio-path Moscow-Kharkiv and at high-latitudes from the longer radio-path Moscow-Tromso for 2013. The HF signal transmitter is the radio station RWM in Moscow, Russia. The receiver stations are located in Tromso (Norway) and Kharkiv (Ukraine). Using intensity and the Doppler frequency shift ...

The work described in this thesis was carried out to investigate how additional permanent magnets (PM) could affect the confinement and ion beam generation in a plasma which expands from a helicon source. PMs added to a plasma source systems has been shown to provide an increased plasma confinement, but is not widely used. This inexpensive and cheap method of using PMs which does not require any ...

This thesis presents three-dimensional modelling of artificial aurora in the ionospheric F layer, induced by high frequency (HF) O-mode radio waves from the EISCAT heating facility. Understanding how HF radio waves produces enhanced emission in the ionosphere has been one of the one of the major motivations for conducting heating experiments during the last decades. A key element for understanding ...

The main objective of this thesis is to optimize the thickness of sensitive polymer layer highly doped with Cryptophane-A for methane pre-concentration and to make the existing sensor more stable and selective towards methane. In recent years, methane detection has become a hot topic due to the strong impact of methane on the global warming and the climate change. There has also been rising ...