MetOcean Solutions Ltd.

New Plymouth, New Zealand

MetOcean Solutions Ltd.

New Plymouth, New Zealand
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Schimel A.C.G.,University of Waikato | Healy T.R.,University of Waikato | McComb P.,MetOcean Solutions Ltd | Immenga D.,University of Waikato
Journal of Coastal Research | Year: 2010

A methodology for automatically processing the data files from an EM3000 multibeam echosounder (Kongsberg Maritime, 300kHz) is presented. Written in MatLab, it includes data extraction, bathymetry processing, computation of seafloor local slope, and a simple correction of the backscatter along-track banding effect. The success of the latter is dependent on operational restrictions, which are also detailed. This processing is applied to a dataset acquired in 2007 in the Tamaki Strait, New Zealand. The resulting maps are compared with a habitat classification obtained with the acoustic ground-discrimination software QTC View linked to a 200-kHz single-beam echosounder and to the imagery from a 100-kHz sidescan sonar survey, both performed in 2002. The multibeam backscatter map was found to be very similar to the sidescan imagery, quite correlated to the QTC View map on one site but mainly uncorrelated on another site. Hypotheses to explain these results are formulated and discussed. The maps and the comparison to prior surveys are used to draw conclusions on the quality of the code for further research on multibeam benthic habitat mapping. © Coastal Education & Research Foundation 2010.

Johnson D.,MetOcean Solutions Ltd | Thiebaut S.,MetOcean Solutions Ltd
Coasts and Ports 2013 | Year: 2013

A statistical downscaling technique has been developed to allow computationally efficient local scale ensemble forecasts of wave height and other spectral parameters. The technique transforms global wave model ensemble members to local sites of interest using a statistical model trained on fully dynamically downscaled model spectra. The resulting local ensemble forecasts can then be utilised to make operational decisions based on the probabilistic information provided by the spread of ensemble members. Important spectral information such peak spectral period is retained in the downscaling process, thus allowing derived ensemble products such as long wave surge to also be provided as an ensemble forecast.

Warner W.,MetOcean Solutions Ltd | Johnson D.,MetOcean Solutions Ltd
Coasts and Ports 2013 | Year: 2013

A web application framework has been developed for interactively planning the effect of weather and sea conditions on ship transits, both into and out of ports and for open ocean passages. The system uses a client/server architecture and is intended to operate over the internet. A flexible JavaScript API allows easy and rapid integration into existing web applications or can be used to quickly develop a stand-alone web service. All necessary computations are carried out server-side, thereby reducing the requirements of the client devices to just supporting a web browser. The client side functionality serves two core purposes. The first is to allow for quick and easy point, click and drag editing of a navigation route on a web based mapping service such as Google Maps; an interface also allows for specifying the route plan in terms of speeds, departure times and/or ETAs. The second is to query the server for relevant metocean variables along the defined route for the projected location in time and space and a graphical display immediately presents the along-route forecast. The planner can interactively modify a route or schedule and then immediately access the newly updated forecast. For port transits an under-keel clearance module also returns forecast keel clearance based on nowcast/forecast metocean data and the physical characteristics of the vessel. For ocean transits an optimisation module returns 'minimum cost' routes and schedules based on user specified criteria such as fuel saving, passage time or seakeeping. An overview of the framework is presented including a demonstration of how it could be integrated into an existing web application. The under-keel clearance and optimisation modules are summarized in terms of their underlying principles of operation. A number of examples of how the client side application would be utilized in practise will be demonstrated to highlight its functionality as a management and planning tool.

Boulay S.O.C.,MetOcean Solutions Ltd. | Batt L.,MetraWeather Australia
Australian Coasts and Ports 2015 Conference | Year: 2015

With the increasing number of cargo and cruise ships visiting the ports of Sydney and Botany Bay, the New South Wales Port Authority (NSWPA) recognised a need to increase the capacity for marine weather guidance to ensure safe and efficient operability. The service designed for NSWPA includes high resolution atmospheric and oceanographic forecast solutions, probabilistic model data derivations, real-time weather monitoring and a suite of decision-making tools. All this is delivered from a web platform so the information is readily accessible and fully transparent across their organisation. The focus of the service is to improve the vessel transit safety and cargo transfer efficiency, along with the ability to impose berth risk controls. While the development was customised for the NWSPA, the core infrastructure behind the service leverages more than a decade of R&D into weather intelligence for ports and the marine industry.

Atmospheric models such as the Weather Research and Forecasting model (WRF) can be run at very high resolution to account for complex topography and small scale weather phenomena - often in support of sensitive operations. One problem with running these models at very high resolution is that the resolution of the standard terrain elevation data sets may be coarser than the model resolution. In the case of WRF, the standard data set that comes with the software is from the US Geological Survey which has a finest resolution of around 1 km. Therefore, any WRF configurations with horizontal resolution less than 1 km should consider this issue. This work looks at running WRF using NASA's Shuttle Radar Topography Mission (SRTM) land elevation data set with resolution of 30m. It then considers a case study of running WRF over Admiralty Bay, New Zealand, where on- and off-loads of a semi-submersible oil rig on a heavy lift vessel (HLV) regularly take place. This delicate marine operation is highly sensitive to the wind speed profile, and the complex topography of the Bay make it a challenging place to model as well as provide meaningful operation guidance.

Thiebaut S.,MetOcean Solutions Ltd. | McComb P.,MetOcean Solutions Ltd.
Australian Coasts and Ports 2015 Conference | Year: 2015

Statistical analysis of extreme wave conditions is essential for the effective design of coastal or offshore structures. However, the existing design guidance does not provide a reliable technique to estimate bivariate extreme significant wave heights, Hs, and peak wave periods, Tp, in shallow water sea states. To find the Tp associated with the extreme Hs, wave steepness (Sp) models are commonly used. The main assumption of these models is that the wave steepness is stochastically independent of Hs, which is valid only for relatively deep water waves where linear wave theory is applicable. However, for shallow water waves, the correlation between Sp and Hs should be taken in account. In this paper, the bivariate Hs - Tp return period values are obtained from extrapolation of the marginal distributions of Hs and a de-trended Sp. The method can be applied to any location, and is illustrated here with a 35-year wave hindcast study in the Chatham Islands.

Soutelino R.G.,MetOcean Solutions Ltd. | Beamsley B.,MetOcean Solutions Ltd.
Australian Coasts and Ports 2015 Conference | Year: 2015

The present work evaluates the influence of the Southland Current on the Pegasus Bay (PB) inner and mid shelf circulation using different nesting setups for realistic hydrodynamical hindcasts performed with the Regional Ocean Modelling System (ROMS). The results highlight the importance of the oceanic remote forcing to local flow regime, showing direct and indirect impacts of neglecting such mechanism for PB.

Guedes R.M.C.,University of Waikato | Guedes R.M.C.,MetOcean Solutions Ltd. | Bryan K.R.,University of Waikato | Coco G.,NIWA - National Institute of Water and Atmospheric Research | Coco G.,University of Cantabria
Journal of Geophysical Research: Oceans | Year: 2013

Field observations of swash and ocean waves show that runup saturation at infragravity frequencies (<0.05 Hz) can occur under mild offshore energy conditions if the beach slope is sufficiently gentle. Infragravity saturation was observed for higher-frequency (>0.025-0.035 Hz) infragravity waves, where typically less than 5% of the (linear) energy flux was reflected from the beach and where, similar to the sea swell band, the swash energy was independent of offshore wave energy. The infragravity frequency range of saturation was determined by the tide, with saturation extending to lower frequencies at low tide when the local beach face slope over the concave-shaped profile was gentler. Runup was strongly dominated by infragravity frequencies, which accounted on average for 96% of the runup variance, and its energy levels were entirely consistent with strong infragravity wave dissipation observed in the surfzone, particularly when including the nonlinear contributions to the wave energy fluxes. The infragravity wave dissipation was strongly associated with breaking of sea swell waves, which abruptly decreased nonlinear transfers to infragravity frequencies and made infragravity dissipation prevail over forcing within the breaking region. Our observations show evidence of nonlinear interactions involving infragravity and high-frequency, harmonic waves and suggest that these harmonics could play a role in the wave energy balance near the shoreline on low-sloping, dissipative beaches. ©2013. American Geophysical Union. All Rights Reserved.

Schimel A.C.G.,University of Waikato | Healy T.R.,University of Waikato | Johnson D.,MetOcean Solutions Ltd. | Immenga D.,University of Waikato
ICES Journal of Marine Science | Year: 2010

Map comparison is a relatively uncommon practice in acoustic seabed classification to date, contrary to the field of land remote sensing, where it has been developed extensively over recent decades. The aim here is to illustrate the benefits of map comparison in the underwater realm with a case study of three maps independently describing the seabed habitats of the Te Matuku Marine Reserve (Hauraki Gulf, New Zealand). The maps are obtained from a QTC View classification of a single-beam echosounder (SBES) dataset, manual segmentation of a sidescan sonar (SSS) mosaic, and automatic classification of a backscatter dataset from a multibeam echosounder (MBES). The maps are compared using pixel-to-pixel similarity measures derived from the literature in land remote sensing. All measures agree in presenting the MBES and SSS maps as the most similar, and the SBES and SSS maps as the least similar. The results are discussed with reference to the potential of MBES backscatter as an alternative to SSS mosaic for imagery segmentation and to the potential of joint SBES-SSS survey for improved habitat mapping. Other applications of map-similarity measures in acoustic classification of the seabed are suggested. © 2010 International Council for the Exploration of the Sea.

Milne I.A.,MetOcean Solutions Ltd | Delaux S.,MetOcean Solutions Ltd | McComb P.,MetOcean Solutions Ltd
Ocean Engineering | Year: 2016

This paper presents the validation of tool which combines a model of the steady wind, current and wave loads with numerical estimates of the metocean conditions to predict the heading of a turret-moored vessel such as an FPSO. Estimates of the wave-induced mean drift contribution were obtained using an open-source three-dimensional boundary element code. Empirical data from reduced-scale tests were used to obtain the wind and current loads, which were shown to enable more reliable estimates than would be possible using data for very large crude carriers. The environmental conditions were predicted numerically using multi-resolution nested models which assimilate observed data. Using measurements from an operating FPSO for full-scale validation, the model was shown to be able to predict the heading for a range of environmental conditions including non-collinear seas, swells and winds to an accuracy typically within 5%. Preliminary estimates of the vessel roll amplitudes also agreed favourably with measured values. It is envisaged that the model will be attractive for operators of FPSOs in better facilitating the identification of dangerous conditions. This could ultimately lead to safer and more efficient operations. © 2016 Elsevier Ltd

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