Analysis of clustering and selection algorithms for the study of multivariate wave climate

Camus, Paula; Méndez, Fernando J.; Medina, Raúl; Cofiño, Antonio S.

doi:10.1016/j.coastaleng.2011.02.003

Cited by 217 publications

(161 citation statements)

References 14 publications

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“…Camus et al (2011) provides a detailed introduction to the MDA selection routine as well as comparisons to other common clustering and section routines. This MDA has previously been employed to select representative samples from a range of given data (e.g., Goldstein and Coco, 2014).…”

Section: Methodsmentioning

confidence: 99%

“…This MDA has previously been employed to select representative samples from a range of given data (e.g., Goldstein and Coco, 2014). Starting with the plant location having the largest Northing value (initialization requires the user to select a starting point), an iterative process selects the next data point, which is the site with the maximum distance from all previously selected sites (Camus et al, 2011). The MDA routine continues selecting sites until the user-defined number of sites is attained (here we halt the algorithm at 30 sites).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Ground control point requirements for structure-from-motion derived topography in low-slope coastal environments

Goldstein

Oliver

deVries

et al. 2015

Preprint

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Vegetated coastal dunes grow as a result of feedbacks between vegetation and sand transport. Observing the coevolution of vegetation and the sand surface is therefore critical for unraveling the dynamics of coastal dune growth. Capturing synchronous topography and photography at high spatial resolution and high temporal frequency using traditional techniques (airplane-based aerial photography, LiDAR) is expensive and timeconsuming. Structure-from-Motion combined with Multiview-Stereo, a photogrammetry workflow that uses low-cost, consumer-grade equipment, is an economical alternative to traditional collection methods. This workflow still requires the definition of ground control points (GCPs) -locations with known coordinates -to develop accurate digital surface models. In this contribution we address how the number of GCPs used impacts the accuracy of digital surface models. We flew a 9-foot single-line delta kite attached to a consumer-grade camera to photograph the beach and dune of Hog Island, VA, a site that contains 178 high precision GCPs over an area of ~0.025 km 2 (as part of an ongoing field experiment). We then processed the 318 photographs using Agisoft Photoscan and compared the elevation accuracy of digital surface models rendered using SfM, with varying GCPs, to points surveyed by a total station. Our results suggest that there is 'diminishing returns' when greater than 10 GCPs are used. Results from this study can be used to inform future Structure-from-Motion studies using UAVs or kites in flat, lowsloping coastal environments.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Ground control point requirements for structure-from-motion derived topography in low-slope coastal environments

Goldstein

Oliver

deVries

et al. 2015

Preprint

View full text Add to dashboard Cite

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“…The MDA has been proven to identify the most dissimilarity wave conditions in a reanalysis database including the extreme events. The algorithm and details of selection are described in Camus et al (2011b).…”

Section: Selectionmentioning

confidence: 99%

On the feasibility of the use of wind SAR to downscale waves on shallow water

et al. 2016

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Abstract. In recent years, wave reanalyses have become popular as a powerful source of information for wave climate research and engineering applications. These wave reanalyses provide continuous time series of offshore wave parameters; nevertheless, in coastal areas or shallow water, waves are poorly described because spatial resolution is not detailed. By means of wave downscaling, it is possible to increase spatial resolution in high temporal coverage simulations, using forcing from wind and offshore wave databases. Meanwhile, the reanalysis wave databases are enough to describe the wave climate at the limit of simulations; wind reanalyses at an adequate spatial resolution to describe the wind structure near the coast are not frequently available. Remote sensing synthetic aperture radar (SAR) has the ability to detect sea surface signatures and estimate wind fields at high resolution (up to 300 m) and high frequency.In this work a wave downscaling is done on the northern Adriatic Sea, using a hybrid methodology and global wave and wind reanalysis as forcing. The wave fields produced were compared to wave fields produced with SAR winds that represent the two dominant wind regimes in the area: the bora (ENE direction) and sirocco (SE direction). Results show a good correlation between the waves forced with reanalysis wind and SAR wind. In addition, a validation of reanalysis is shown. This research demonstrates how Earth observation products, such as SAR wind fields, can be successfully uptaken into oceanographic modeling, producing similar downscaled wave fields when compared to waves forced with reanalysis wind.

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“…using a previously established methodology (Camus et al, 2011a(Camus et al, , 2011b. The use of the MDA ensures that the multivariate parameter space is captured efficiently.…”

Section: Swan Emulationmentioning

confidence: 99%

Multivariate extreme value modelling of sea conditions around the coast of England

Gouldby

Wyncoll

Panzeri

et al. 2017

Proceedings of the Institution of Civil Engineers - Maritime En

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It is widely recognised that coastal flood events can arise from combinations of extreme waves and sea levels. For flood risk analysis and the design of coastal structures it is therefore necessary to assess the joint probability of the occurrence of these variables. Traditional methods have involved the application of joint probability contours, defined in terms of extremes of sea conditions that can, if applied without correction factors, lead to the underestimation of flood risk and under-design of coastal structures. This paper describes the application of a robust multivariate statistical model to analyse extreme offshore waves, wind and sea levels around the coast of England. The approach described here is risk based in that it seeks to define extremes of response variables directly, rather than the joint extremes of sea conditions. The output of the statistical model comprises a Monte Carlo simulation of extreme events. These distributions of extreme events have been transformed from offshore to nearshore using a statistical emulator of a wave transformation model. The resulting nearshore extreme sea condition distributions have the potential to be applied for a range of purposes. The application is demonstrated using two structures located on the south coast of England. Notation

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Analysis of clustering and selection algorithms for the study of multivariate wave climate

Cited by 217 publications

References 14 publications

Ground control point requirements for structure-from-motion derived topography in low-slope coastal environments

Ground control point requirements for structure-from-motion derived topography in low-slope coastal environments

On the feasibility of the use of wind SAR to downscale waves on shallow water

Multivariate extreme value modelling of sea conditions around the coast of England

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