Vegetation Management is a significant preventive maintenance expense in many power transmission and distribution companies. Traditional Vegetation Management operational practices have proven ...ineffective and are rapidly becoming obsolete due to the lack of frequent inspection of vegetation and environmental states. The rise of satellite imagery data and machine learning provides an opportunity to close the loop with continuous data-driven vegetation monitoring. This paper proposes an automated framework for monitoring vegetation along power lines using high-resolution satellite imagery and a semi-supervised machine learning algorithm. The proposed satellite-based vegetation monitoring framework aims to reduce the cost and time of power line monitoring by partially replacing ground patrols and helicopter or drone inspection with satellite data analytics. It is implemented and demonstrated for a power distribution system operator (DSO) in the west of Norway. For further assessment, the satellite-based algorithm outcomes are compared with LiDAR survey data collected by helicopters. The results show the potential of the solution for reducing the monitoring costs for electric utilities.
We investigate the application of ground-based radar
interferometry for measuring flexural–gravity waves in sea ice. We deployed
a GAMMA Portable Radar Interferometer (GPRI) on top of a grounded ...iceberg
surrounded by landfast sea ice near Utqiaġvik, Alaska. The GPRI
collected 238 acquisitions in stare mode during a period of moderate lateral
ice motion during 23–24 April 2021. Individual 30 s interferograms
exhibit ∼ 20–50 s periodic motion indicative of propagating
infragravity waves with ∼ 1 mm amplitudes. Results include
examples of onshore wave propagation at the speed predicted by the water
depth and a possible edge wave along an ice discontinuity. Findings are
supported through comparison with on-ice Ice Wave Rider (IWR) accelerometers
and modeled wave propagation. These results suggest that the GPRI can be a
valuable tool to track wave propagation through sea ice and possibly detect
changes in such properties across variable ice conditions.
The drift of sea ice is an important geophysical process with
widespread implications for the ocean energy budget and ecosystems. Drifting
sea ice can also threaten marine operations and present a ...hazard for ocean
vessels and installations. Here, we evaluate single-pass along-track
synthetic aperture radar (SAR) interferometry (S-ATI) as a tool to assess
ice drift while discussing possible applications and inherent limitations.
Initial validation shows that TanDEM-X phase-derived drift speed corresponds
well with drift products from a ground-based radar at Utqiaġvik, Alaska.
Joint analysis of TanDEM-X and Sentinel-1 data covering the Fram Strait
demonstrates that S-ATI can help quantify the opening/closing rate of leads
with possible applications for navigation. S-ATI enables an instantaneous
assessment of ice drift and dynamic processes that are otherwise difficult
to observe. For instance, by evaluating sea ice drift through the Vilkitsky
Strait, Russia, we identified short-lived transient convergence patterns. We
conclude that S-ATI enables the identification and analysis of potentially
important dynamic processes (e.g., drift, rafting, and ridging). However,
current limitations of S-ATI are significant (e.g., data availability and
they presently only provide the cross-track vector component of the ice drift
field) but may be significantly reduced with future SAR systems.
Arctic landfast sea ice is widely utilized for transportation by local communities and industry, with trafficability largely governed by ice roughness. Here, we introduce an approach to evaluate ice ...roughness that can aid in routing of ice roads and assessment of spatial variability and long-term changes in trafficability. Drawing on synthetic aperture radar (SAR) polarimetry, SAR interferometry (InSAR), and other remote sensing techniques, we integrated approaches into the trafficability assessment that had rarely been applied over sea ice in the past. Analysis of aerial photogrammetry obtained through structure-from-motion helped verify cm-scale accuracy of X-band InSAR-derived ridge height and link L-band polarimetric classification to specific roughness regimes. Jointly, these approaches enable a km-scale evaluation of ridge topography and cm- to m-scale roughness - both critical for the assessment of trafficability. A trafficability index was derived from such SAR data in conjunction with analysis of ice trail routing and ice use near Utqiaġvik, Alaska. The index identifies areas of reduced trafficability, associated with pressure ridges or rubble ice, and served to delineate favorable trail routes for different modes of transportation, with potential uses ranging from ice road routing to emergency evacuation. Community outreach is needed to explore how this approach could assist different ice users in reducing risk, minimizing trail or ice construction efforts, and improving safety.
Seasonal landfast sea ice stretches along most Arctic coastlines and serves as a platform for community travel and subsistence, industry operations, and as a habitat for marine mammals. Landfast ice ...can feature smooth ice and areas of m-scale roughness in the form of pressure ridges. Such ridges can significantly hamper trafficability, but if grounded can also serve to stabilize the shoreward ice. We investigate the use of synthetic aperture radar interferometry (InSAR) to assess the formation and movement of ridges in the landfast sea ice near Utqiaġvik, Alaska. The evaluation is based on the InSAR-derived surface elevation change between two TanDEM-X bistatic image pairs acquired during January 2012. We compare the results with backscatter intensity, coastal radar data, and SAR-derived ice drift and evaluate the utility of this approach and its relevance for evaluation of ridge properties, as well as landfast sea ice evolution, dynamics, and stability.
In light of recent Arctic change, there is a need to better understand sea ice dynamic processes at the floe scale to evaluate sea ice stability, deformation, and fracturing. This work investigates ...the use of the Gamma portable radar interferometer (GPRI) to characterize sea ice displacement and surface topography. We find that the GPRI is best suited to derive lateral surface deformation due to mm-scale horizontal accuracy. We model interferometric phase signatures from sea ice displacement and evaluate possible errors related to noise and antenna motion. We compare the analysis with observations acquired during a drifting ice camp in the Beaufort Sea. We used repeat-scan and stare-mode interferometry to identify two-dimensional shear and to track continuous uni-directional convergence. This paper demonstrates the capacity of the GPRI to derive surface strain on the order of 10−7 and identify different dynamic regions based on sub-mm changes in displacement. The GPRI is thus a promising tool for sea ice applications due to its high accuracy that can potentially resolve pre- and post-fracture deformation relevant to sea ice stability and modeling.
Arctic landfast sea ice has undergone substantial changes in recent
decades, affecting ice stability and including potential impacts on ice
travel by coastal populations and on industry ice roads. We ...present a novel
approach for evaluating landfast sea ice stability on a pan-Arctic scale
using Synthetic Aperture Radar Interferometry (InSAR). Using Sentinel-1
images from spring 2017, we discriminate between bottomfast, stabilized, and
nonstabilized landfast ice over the main marginal seas of the Arctic Ocean
(Beaufort, Chukchi, East Siberian, Laptev, and Kara seas). This approach
draws on the evaluation of relative changes in interferometric fringe
patterns. This first comprehensive assessment of Arctic bottomfast sea ice
extent has revealed that most of the bottomfast sea ice is situated around
river mouths and coastal shallows. The Laptev and East Siberian seas dominate
the aerial extent, covering roughly 4100 and 5100 km2, respectively. These seas also contain the largest
extent of stabilized and nonstabilized landfast ice, but are subject to the
largest uncertainties surrounding the mapping scheme. Even so, we demonstrate
the potential for using InSAR for assessing the stability of landfast ice in
several key regions around the Arctic, providing a new understanding of how
stability may vary between regions. InSAR-derived stability may serve for
strategic planning and tactical decision support for different uses of
coastal ice. In a case study of the Nares Strait, we demonstrate that
interferograms may reveal early-warning signals for the breakup of stationary
sea ice.
Arctic sea ice has undergone rapid changes during the last few decades, with negative implications for over-ice travel and on-ice operations, which benefit from services provided by the sea ice. A ...Parameter-based Trafficability Hierarchy (PATH) is presented here as a framework for developing quantitative assessment strategies that can guide planning and execution of operations on or near sea ice and quantify the impacts of recent changes on ice use. A PATH assessment has been completed for three case studies in Arctic Alaska. These cases, which correspond to a range of different icescapes and ice uses, identify and quantify different parameters linked to trafficability and safe operations. For ice road applications, PATH was used to determine an ice thickness compensation factor, a factor increasing the minimal thickness threshold for operations, to help translate sporadic auger ice thickness measurements along the Kotzebue–Kiana community ice road into an envelope for safe operations. A compensation factor as high as 1.5 was found to be necessary to ensure safety because of the high local thickness variability that is currently a concern for ice road operators. A PATH assessment of ice roughness for ice trail routing at Utqiaġvik draws on satellite remote sensing and is relevant for over-ice travel in general, including escape, evacuation, and rescue. We compared the routing of local snowmobile trails with Synthetic Aperture Radar (SAR) data products to identify specific ranges of ice conditions, roughness, and topography favored for ice trail construction. The same combination of data sources was used to identify potentially beneficial trail routes. Finally, an ice stability and safety assessment was completed for ice road construction and maintenance by industry near the Northstar Island oil production facility. We evaluated small-scale ice displacement data obtained from SAR interferometry to infer internal ice strain and stress and used these data in assessing the potential for fractures to reduce load-bearing capacity.
Au cours des quelques dernières décennies, la glace de l’Arctique a connu des changements rapides. Les déplacements et les activités sur glace pour lesquels la glace de mer revêt de l’importance subissent des conséquences négatives. Une hiérarchie de traficabilité en fonction de paramètres (PATH) est présentée ici comme cadre de référence en vue de l’élaboration de stratégies d’évaluation quantitative pour guider la planification et l’exécution des activités sur glace ou à proximité de la glace ainsi que pour quantifier les incidences des changements récents sur l’utilisation de la glace. Trois études de cas visant l’Extrême-Arctique de l’Alaska ont fait l’objet de la hiérarchie PATH. Ces études de cas correspondent à une gamme d’utilisations et de paysages glaciaires différents. Elles permettent de déterminer et de quantifier divers paramètres liés à la traficabilité et à la sécurité des activités qui y sont exercées. Dans le cas des activités sur routes de glace, PATH a servi à déterminer un facteur de compensation de l’épaisseur de la glace, facteur augmentant le seuil de l’épaisseur minimale nécessaire aux activités, pour aider à traduire les mesures de l’épaisseur de la glace prises sporadiquement au moyen d’une tarière le long de la route de glace communautaire de Kotzebue à Kiana afin de donner lieu à la sécurité des activités qui y sont menées. Un facteur de compensation aussi élevé que 1,5 s’est avéré nécessaire pour assurer la sûreté des activités en raison de la grande variabilité de l’épaisseur de la glace locale, qui est actuellement une source de préoccupation pour les utilisateurs des routes de glace. L’évaluation de la rugosité de la glace au moyen de PATH pour le tracé des routes de glace à Utqiaġvik fait appel à la télédétection satellitaire et est adéquate pour les déplacements sur glace généralement parlant, notamment pour ce qui est de l’échappement, de l’évacuation et du sauvetage. Nous avons comparé le tracé des pistes de motoneige aux données obtenues par radar à synthèse d’ouverture SAR afin de déterminer les gammes précises d’état de la glace, de rugosité de la glace et de topographie qui conviennent le mieux à la construction de routes ou pistes sur glace. La même combinaison de sources de données a servi à déterminer les tracés de routes susceptibles d’être avantageux. Et enfin, l’évaluation des données relatives à la stabilité et à la sûreté de la glace a été faite pour ce qui est de la construction et de l’entretien de routes de glace par l’industrie, près de l’installation de production pétrolière Northstar. Nous avons évalué les données de légers déplacements de la glace obtenues par interférométrie SAR afin de déduire la tension et le stress de l’intérieur de la glace. Ces mêmes données ont également permis d’évaluer les fractures potentielles dans le but de réduire la capacité de charge.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Recent Arctic warming has led to reduced sea-ice thickness and a more dynamic landfast ice cover with potential widespread consequences for ice users. Here, we develop an approach to assess the ...small-scale deformation of landfast ice critical to on-ice operations using synthetic aperture radar interferometry (InSAR). InSAR has previously proven successful in determining long-term qualitative climatology of ice deformation around on-ice operations, but is now used to explore its potential for providing quantitative guidance for ice road planning, construction, and maintenance. A validation effort using X-band SAR and high-precision GPS data over Elson Lagoon, Alaska, confirms the ability of InSAR to accurately estimate 3-dimensional sea ice strain values accumulated between SAR image acquisitions, using an inverse model. The inverse model was further applied to L-band InSAR data over the Northstar Island ice road near Prudhoe Bay, Alaska. Assuming an elasto-brittle rheology, the derived strain values yielded a spatial distribution of internal stress consistent with preexisting ice defects and morphology. In several localized regions of the study area, stress values exceeded expected yield stress. Resulting relative fracture intensity potential was shown to conform with local knowledge based on road inspections by engineers, and may be used to guide ice road planning, construction and maintenance efforts. The results presented here demonstrate that InSAR is an accurate tool for estimating landfast ice deformation and stability in support of ice use. The findings may also provide substantial new insights into the mechanics of landfast ice.
•2D sea ice deformation is reconstructed from InSAR using an inverse model.•From high-resolution ice strain maps we identify regions of high failure potential.•Approach has applications in study of ice dynamics and safety of ice-based operations.
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