Estimation of the absorption of extraterrestrial radio noise using a narrow beam VHF radar at 53.5 MHz in Andenes, Norway

Abstract: The Earth’s magnetic field works like a shield against the solar wind flux of plasma, but atthe polar regions, where it fails to do so, these charged particles may be guided down tolow altitudes and introduce a lot of impacts on the environment, ranging from the nicecolourful Aurora, to chemical changes in the atmosphere and decrease in the amount ofozone in the middle atmosphere, and from satellite damages to power line cut offs,depending on the type and energy of the particles.Extraterrestrial HF/VHF radio noise from the universe and mainly from our own galaxy iscontinuously coming towards our planet. Absorption of these electromagnetic waves in theEarth’s ionosphere is a well known proxy of the events which can enhance it, mainlyhaving direct or indirect root in the solar activities, like Solar Flares, Coronal MassEjections, and Geomagnetic Storms and the resulted X rays, Solar Proton Events andPrecipitating Energetic charged Particles.Cosmic radio noise power and the corresponding ionospheric absorption is normallymeasured by the riometers (Relative Ionospheric Opacity Meters for ExtraterrestrialElectromagnetic Radiation), and especially in recent years by multiple narrow beamimaging riometers.In this thesis, the data obtained by the vertical beam of a narrow beam MST radar, ALWIN,at Andenes, Norway (69.17°N; 16.01°E) is used as a (narrow beam of a) riometer toestimate the incident cosmic noise power at 53.5 MHz and its absorption, especially duringsolar/geomagnetic activity periods. The results are in good agreement with riometers (IRISand AIRIS in Andenes and Kilpisjarvi Finland, 69.06°N, 20.55°E) common volumemeasurements and with electron density measurements of the Saura MF Radar. Theobtained Quiet Day Curves (QDCs) are in very good agreement with theoretical andobserved QDCs estimated by Friedrich et al. (2001).