4 research outputs found

    Remote sensing of avalanches in northern Norway using Synthetic Aperture Radar

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    We present results from using synthetic aperture radar data (SAR) to analyse three avalanches in the county of Troms in northern Norway during the late snow season 2013. During a persistent polar low pressure activity at the end of March and the beginning of April 2013, inducing high precipitation rates in combination with high wind speeds, an extensive avalanche cycle took place in that area. Several avalanches released naturally causing fatalities, road closures and community evacuations. The main goal of our study was to investigate whether high resolution SAR could be used for detecting avalanche debris in the run-out zones. For validation purposes we used, among others, a high resolution camera operated on an Unmanned Airborne Vehicle (UAV) to acquire very accurate ortho-photos of the avalanches. The UAV-maps were of unprecedented resolution (~5 cm). The result of the analysis of the high resolution Radarsat-2 image showed that avalanches could be identified visually due to the high contrast between low radar backscatter from unperturbed snow and high backscatter (caused by increased surface roughness/snow mass) of the avalanche debris in the avalanche run-out zones. In order to assess the accuracy, the avalanche delineations were compared with results from UAV photos and photographs taken during helicopter reconnaissance flights right after the events. In two of three cases, a good correspondence was found between SAR delineated avalanches and outlines derived from optical data

    A review of unmanned vehicles for the detection and monitoring of marine fauna

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    Recent technology developments have turned present-day unmanned systems into realistic alternatives to traditional marine animal survey methods. Benefits include longer survey durations, improved mission safety, mission repeatability, and reduced operational costs. We review the present status of unmanned vehicles suitable for marine animal monitoring conducted in relation to industrial offshore activities, highlighting which systems are suitable for three main monitoring types: population, mitigation, and focal animal monitoring. We describe the technical requirements for each of these monitoring types and discuss the operational aspects. The selection of a specific sensor/platform combination depends critically on the target species and its behaviour. The technical specifications of unmanned platforms and sensors also need to be selected based on the surrounding conditions of a particular offshore project, such as the area of interest, the survey requirements and operational constraints
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