University of Oulu

Multi-purpose methods for ionospheric radar measurements

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Author: Virtanen, Ilkka1
Organizations: 1University of Oulu, Faculty of Science, Department of Physical Sciences
Format: ebook
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.6 MB)
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Language: English
Published: Oulu : University of Oulu, 2009
Publish Date: 2009-11-23
Thesis type: Doctoral Dissertation
Defence Note: Academic dissertation to be presented, with the permission of the Faculty of Science of the University of Oulu, for public discussion in the Auditorium L6, Linnanmaa, on 4 December, 2009, at 12 o’clock noon
Tutor: Professor Markku Lehtinen
Professor Tuomo Nygrén
Reviewer: Doctor Jorge Chau
Professor Heikki Haario
Opponent: Doctor Jorge Chau
Kustos: Professor Tuomo Nygrén


From the very beginning of modern ionospheric science, different radar applications have been utilised in ionospheric measurements. The most sophisticated ionospheric radars are the incoherent scatter radars, which detect the extremely weak scattering of radio waves from thermal fluctuations in the ionospheric plasma. Besides the low signal level, the stochastic nature of the scattering process causes further complications to the measurements. The scattering produces a zero-mean random signal, whose autocorrelation function contains the information of the ionospheric plasma parameters. Incoherent scatter radars have been used for about half a century, but the demanding task of developing transmission modulation and data analysis is still in progress.

In this thesis, a statistical inversion based method for removing range ambiguities from the autocorrelation functions, lag profile inversion, is applied to incoherent scatter radar data. The data have been recorded with the EISCAT incoherent scatter radars, located in Northern Fennoscandia. The method is first applied to standard EISCAT experiments, the results giving strong evidence that the method is applicable for the purpose, and it provides results of at least equal quality with the present standard methods. In subsequent studies, new radar modulation methods are developed, which may provide significant improvements to the present incoherent scatter radar experiments. All the methods have been tested with a real radar, and lag profile inversion has been successfully applied to the recorded data. The methods are also put to use in order to measure the predicted effects of artificial heating of the free electrons in the D-region of the ionosphere.

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Series: Report series in physical sciences
ISSN: 1239-4327
ISSN-L: 1239-4327
ISBN: 978-951-42-9284-2
ISBN Print: 978-951-42-9283-5
Issue: 59
Type of Publication: G5 Doctoral dissertation (articles)
Field of Science: 114 Physical sciences
Copyright information: © University of Oulu, 2009. This publication is copyrighted. You may download, display and print it for your own personal use. Commercial use is prohibited.