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FMCW Phased Array Radar for Imaging Snow Avalanches

Ash, M; (2013) FMCW Phased Array Radar for Imaging Snow Avalanches. Doctoral thesis (PhD), UCL (University College London). Green open access

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Abstract

Radar has emerged as a useful tool for measuring avalanches to improve our knowledge of their behaviour. These measurements are used to refine and validate mathematical models of avalanches which are employed in the calculation of avalanche risk zones. However, current radar measurements do not provide a true representation of an entire avalanche flow due to their inadequate range resolution and lack of cross-range resolution. This thesis describes the development of an FMCW phased-array radar for use as a research tool to enable 2-D field measurements of avalanches in unparalleled detail. The design of the radar is presented in detail based on a review of the current avalanche remote sensors and applicable radar literature. The radar operates at 5.3GHz to illuminate dense centimetre-size blocks of snow. It is shown that the developed radar has a range resolution of 1.3m following processing, a 19x gain over other avalanche radar, and is sensitive to snow movements beyond 2.5km, sufficient to measure an entire avalanche flow. Additionally, methods of processing the radar data are developed. These include MTI processing using an IIR filter, avalanche front detection using OS-CFAR, and cohering of the array using low-quality phase synchronising sources within the field-of-view of the radar. The radar is now deployed in a bunker at well-equipped avalanche test site in Switzerland where it automatically records naturally occurring avalanches. This thesis describes two avalanches which were recorded by the radar during the 2010/11 winter. The collected data has been processed using the aforementioned processing techniques. The processing outputs are presented including single channel range-time images, velocity measurements of the avalanche fronts, and detailed 2-D images of the avalanches showing unprecedented detail. It is shown that there is the potential to extract velocity measurements of individual blocks of snow comprising the avalanche.

Type: Thesis (Doctoral)
Qualification: PhD
Title: FMCW Phased Array Radar for Imaging Snow Avalanches
Open access status: An open access version is available from UCL Discovery
Language: English
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
URI: https://discovery.ucl.ac.uk/id/eprint/1383579
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