An operational high resolution hydrodynamic forecast model for Port Phillip Bay

MetOcean Solutions has recently operationalised a high resolution hydrodynamic forecast model that allows simultaneous simulation of waves, currents and their interaction for Port Phillip Bay, Australia.

This new capability was developed as part of a larger project funded by the Australian Cooperative Research Centres Projects initiative. The project, a partnership between OMC International, Pivot Maritime International, University of Melbourne and MetOcean Solutions will provide an integrated modelling system for predicting under-keel clearance to support port and shipping services in tidal inlets.

“This project was conceived through an industry-research partnership and has leveraged the technical expertise in all partners,” says MetOcean Solutions’ Development Manager Dr Tom Durrant. “By bringing cross-sector experience, it is possible to develop science value-added solutions designed to increase safety and assist informed decisions at sea.”

In this particular project, the circulation model (SCHISM) is coupled with an upgraded wave physics implemented in the Wind Wave Model (WWM-III). The ‘improved WWM-III’ combined with the state-of-the-art unstructured hydrodynamic model SCHISM develops a forecast model capable of simultaneous simulation of waves, currents and their interaction.

“This is of great importance in this part of the world,” says MetOcean Solutions’ physical oceanographer Phellipe Couto.

“Port Phillip Heads, connecting Port Phillip Bay and Bass Strait is a notorious stretch of water that has claimed many ships and lives. Strong tidal currents interacting with waves combine to create significant challenges to ship navigation. Explicit accounting of this interaction, combined with unstructured model grids allowing the complex features of the main channels to be resolved at much higher resolution than previously, offer significant improvements in our ability to accurately forecast both waves and currents in the heads.

“Working closely with the University of Melbourne has provided a great opportunity to rapidly transition cutting edge science into operational systems.”

The operational high resolution hydrodynamic forecast model developed will provide input into the under keel clearance system operated by OMC international, strengthening the offerings available through the Metocean Solutions and OMC partnership (find more information here).

Operational SCHISM is MetOcean Solutions’ powerful new capability in high resolution coastal hydrodynamics, improving forecast by well representing complex nearshore bathymetries. The forecast model was also operationalised for Tasman and Golden Bay, New Zealand. Click here for more information.

The SCHISM model for Port Phillip Bay is freely available at MetOceanView.

For more information visit www.metoceanview.com or contact us at enquiries@metocean.co.nz

Modelling the effects of dredge spoil disposal

As port weather experts, MetOcean Solutions regularly provides modelling support for port dredging operations. 

“The disposal of dredge spoil requires careful consideration,” explains Oceanographer Simon Weppe. “Over time, disposed sediments will be redistributed by currents and waves. When selecting offshore disposal sites, ports have to consider the hydrodynamic processes of the area and evaluate the longer-term changes to the shape of the seabed (morphological changes). Understanding the general morphological behaviour of the region is essential if we are to reduce the potential for sediment recirculation in the channel and port.

“Through our work with numerous ports, we’ve developed a process for modelling the effects of dredge spoil disposal. The changes to the shape of a disposal mound are governed by long-term hydrodynamic patterns slowly transporting sediments, and by extreme events such as storms, which can drastically change the shape of the seabed over short timescales. We use a coupled wave, current, and morphological model system, Delft3D, to understand the processes governing sediment transport in the area, and to identify key transport pathways. This gives us information to help predict the expected long-term morphological changes, as well as those arising from extreme events.”
 

Morphological changes predicted at the end of an accelerated 1-year simulation. A positive magnitude indicates sedimentation. The black polygons show the proposed disposal grounds and channel.

Morphological changes predicted at the end of an accelerated 1-year simulation. A positive magnitude indicates sedimentation. The black polygons show the proposed disposal grounds and channel.

The Delft3D modelling system is placed within broader regional wave and 3D hydrodynamic models of the area. 

For waves, a 10-year historical data set (hindcast) is prepared using the Simulating WAves Nearshore (SWAN) model, carefully downscaled from a New Zealand-wide model to the high-resolution location domain. 

For currents, the Regional Ocean Modelling System (ROMS) is used to create a 10-year hydrodynamic hindcast using a three-step nesting approach, transferring the energy from a New Zealand-scale domain to a high-resolution local domain. 

The Delft3D model is used to simulate coupled wave, current and sediment transport. The modelling system uses boundary conditions from the regional wave (SWAN) and hydrodynamic (ROMS) models.

“Sediment transport depends on the particle size,” continues Simon. “To accurately predict the dispersal of sediments from the disposal site, we need reliable sediment grain size information. The settlement of larger particles, such as sandy sediments, is governed by gravitational forces, whereas for very fine sediments like silts and clays, inter-particle forces caused by ionic charges become significant. 

“When applying process-based models to predict morphological evolution, the main challenge is that the morphology of coastal systems develops over time scales several orders of magnitude larger than the time scale of the hydrodynamic fluctuations responsible for sediment transport, i.e. hours to days versus years to decades, and more. This means that a model system that can predict the time series of instantaneous hydrodynamics and sediment transport will require an unfeasibly long period to compute a multi-year real-time simulation. 

“To overcome this, we use the Morphological Acceleration Factor (MORFAC) method. MORFAC combines the reduction of the input forcing with the use of morphological factors. This means that we reduce the ambient wave and hydrodynamic forcings to a set of representative conditions that reproduce the same morphological evolution as the real-time forcing would. We do this by combining representative wave events with representative tides and current patterns for the site. 

Morphological Acceleration Factors (MORFACs) are used to represent the long-term effects of tides and waves on the seabed morphology within morphological models. Adapted from Ranasinghe et al. (2011).

Morphological Acceleration Factors (MORFACs) are used to represent the long-term effects of tides and waves on the seabed morphology within morphological models. Adapted from Ranasinghe et al. (2011).

“To account for long-term sediment movement as well as that resulting from storms, we generate two types of results: annual morphological simulations and historical storm simulations. The annual simulations provide information on the net sediment dispersion around the disposal mound each year. The real historical storm simulations model the detailed wave, circulation and sediment transport patterns that develop during energetic events, which normally cause the most significant morphological changes.

“Our modelling provides a best estimate of sediment dispersal from the disposal site over time, taking into consideration both day-to-day currents and waves and storm conditions which move large amounts of sediment in one go. The actual sediment transport may differ slightly depending on the timing of storms, but the overall pattern of sediment movement will remain valid. 

“Regulators use the information to determine the potential effects of the dredge disposal on local hydrodynamic processes, and to ensure there is minimal impact on sites of particular ecological or amenity value. Knowing where sediments will end up helps the mitigation, monitoring and management of dredging operations.”

For more information on dredge disposal modelling, contact us at enquiries@metocean.co.nz.
 

Mean wave, current velocity and sediment transport fields for a disposal site for Lyttelton Port off the Canterbury coast in New Zealand. The black polygons show the proposed disposal grounds and channel.

Mean wave, current velocity and sediment transport fields for a disposal site for Lyttelton Port off the Canterbury coast in New Zealand. The black polygons show the proposed disposal grounds and channel.

Modelling support for port modifications

Over recent years, MetOcean Solutions has modelled the effects of dredging for ports all over New Zealand and Australia. 

Using models we can estimate the percentage of time suspended solid concentration thresholds (here 10 mg/L) are exceeded during dredge spoil disposal operations. Inner and outer dashed circles radius: 500 and 1000 m, respectively. 

Using models we can estimate the percentage of time suspended solid concentration thresholds (here 10 mg/L) are exceeded during dredge spoil disposal operations. Inner and outer dashed circles radius: 500 and 1000 m, respectively. 

“Port modifications and maintenance often involve dredging,” explains Project Director Dr Brett Beamsley. “This can include deepening channels or berth pockets, or maintaining existing depths.” 

“Over the years, we have developed modelling processes to support ports and regulators evaluate the impacts from, and manage, port dredging in the best possible manner.” 

Dredging can have complex effects. It causes sediment release and temporarily increased levels of suspended solids. Dredge spoil disposal changes the shape of the seabed at the disposal site, and deepening channels can alter the waves and tidal flows in nearby areas, potentially affecting structures such as wharves and jetties, as well as processes like shoreline erosion. 

Source of a dredge plume for a Trailing Suction Hopper Dredger. 1. Drag head; 2. Overflow; 3. Prop wash. After Becker et al. (2015).  

Source of a dredge plume for a Trailing Suction Hopper Dredger. 1. Drag head; 2. Overflow; 3. Prop wash. After Becker et al. (2015).
 

The dispersal of sediments occurring during dredge disposal can be modelled.

The dispersal of sediments occurring during dredge disposal can be modelled.

Suspended solids can be harmful to marine life. To minimise adverse effects, managers need to know the extent and duration of suspended sediment plumes, and what levels of suspended solids to expect within the plumes. Because the plumes move with the water, hydrodynamic models can be used to predict their extent and duration.

Managers also need to know the effects of discharging sediment at offshore disposal sites. They need to ensure that dredge spoil is disposed at suitable sites, where potential changes to the seabed shape will not cause adverse effects on flow, tidal flushing and local wave climate, and that disposed sediments will not be carried to nearby areas of environmental or amenity importance.

MetOcean Solutions employs a multi-disciplinary team of scientists with a wide range of expertise in port studies and is therefore well placed to provide scientific advice to ports. Two of the company’s founding directors did PhD research on the wave and sediment dynamics at New Zealand ports.

“We use a variety of techniques to get the modelling spot on,” continues Dr Beamsley. “As a starting point, we collate all information we can find for the site, including any wave or current measurements. Additional field data is often collected to ensure that important flow dynamics are captured.” 

“Once we have enough data, we set up a series of models. First, we develop regional and local-scale wave and hydrodynamic models which capture important processes responsible for sediment entrainment and transport. We nest these into larger-scale wave and hydrodynamic models to ensure atmospheric forcing and river discharges are taken into account where necessary. We calibrate and validate the models against all available measured data.

“Once we’re satisfied our models are performing well, we generate a historical data set for the location, detailing wind, waves and currents for multiple years. This historical data set is used to define the wave and hydrodynamic climate of the site and is used as input into all subsequent studies.

“We simulate dredging plumes using models that track sediment particles as they disperse from the site of dredging. Dredging typically releases sediments near the seabed and just below the water surface. Following an initial near-field phase, dredge plumes move with current flows. Over time, the particulates settle out, with larger grain sizes settling faster and finer sediments being transported further, although flocculation needs to be considered. Through modelling the evolution of the plume over time, our oceanographers simulate the particulates as they settle on the seabed, and trace the levels of suspended solids that remain in the water column. 

Example of plume modelling, showing average near-seabed suspended solid concentrations (SSC) for Lyttelton Harbour, New Zealand.

Example of plume modelling, showing average near-seabed suspended solid concentrations (SSC) for Lyttelton Harbour, New Zealand.

“The dispersal of dredge spoil disposal is investigated using high-resolution morphological models, which account for the surficial sediment grain size within the disposal ground. Using these morphological model we simulate the development of the disposal ground over multiple years to decades, modelling how existing flow patterns will affect the disposal mound and how the mound will affect circulation. As part of this, we determine the likely length of time that discharged sediment resides at the offshore disposal ground and highlight sediment transport pathways, determining where the disposed sediments are likely to ultimately end up.”

After five years the disposed sediments at this site have dispersed. The figure shows the cumulative morphological changes after each year over a 5-year morphological simulation of the disposal of 18 million m3 sediment onto a 12.5 km2 disposal ground. Initial bathymetric contours are shown in black. A positive magnitude (yellow and red colours) indicates sedimentation.

After five years the disposed sediments at this site have dispersed. The figure shows the cumulative morphological changes after each year over a 5-year morphological simulation of the disposal of 18 million m3 sediment onto a 12.5 km2 disposal ground. Initial bathymetric contours are shown in black. A positive magnitude (yellow and red colours) indicates sedimentation.

For a discussion about how MetOcean Solutions can help you predict and manage the effects of your dredging operations, contact us at enquiries@metocean.co.nz.

A real-time data solution supports drilling operations in Wellington Harbour

Griffiths McMillan JV (GMJV) is tasked by Wellington Water and the Greater Wellington Regional Council with drilling for a new water source for Wellington City, with the goal of providing an alternative supply in the event of a severe earthquake. GMJV approached Heron Construction Company to supply the jackup barge and support tug for the project. The target aquifer, however, lies beneath Wellington Harbour - just north of the Miramar Peninsula. A marine drilling rig is required for the operations, which means that operations are very sensitive to the wave conditions.

A marine drilling rig.

A marine drilling rig.

MetOcean Solutions has been supporting Heron Construction in their specialist marine activities with high resolution forecasting for the last decade. Managing director Greg Kroef says, “We rely on the forecast guidance from MetOcean Solutions wherever we are working in Australia and New Zealand. So, when the need arose in Wellington, we approached them for the best possible weather forecasting system for this site.”

The drilling job in the harbour requires very accurate predictions of wave height. However, the oceanographic conditions in Wellington Harbour present significant challenges for forecasting, with ocean swells entering from the south along with local seas generated by the infamous capital city winds.
 
Oceanographer Dr Peter McComb and his science team extensively studied the harbour dynamics for the recent harbour deepening project. “The drilling location is affected by both the southerly ocean swells and the short local wind seas,” explains Peter. “Our forecasting model has to deal with multiple and sometimes simultaneous sources of wave energy, plus discern how those waves refract and transform due to the shape of the seabed and the harbour tidal hydrodynamics.”

The wave buoy, framed by Wellington City

The wave buoy, framed by Wellington City

The operational SWAN wave model for Wellington Harbour has a spatial resolution of 80 m, and is one of nearly 200 forecasting domains that MetOcean Solutions run four times per day for various parts of the planet. This high-resolution model is coupled with the tidal hydrodynamics to capture the effects of the ebb and flood flows through the entrance on the waves, and it has spectral boundaries prescribed by a 3-stage nest into our global WAVE WATCH III wave forecast model. The model system produces the hour-by-hour wave conditions for the coming 7 days.  

Forecast model result from MetOceanView showing the 13 July 2017 southerly storm waves penetrating Wellington Harbour. The X denotes the wave buoy location.

Forecast model result from MetOceanView showing the 13 July 2017 southerly storm waves penetrating Wellington Harbour. The X denotes the wave buoy location.

“However, just having a wave forecast model is sometimes not enough to ensure safe operations - especially in Wellington which is notorious for rapid changes in weather conditions,” continues Dr McComb. “So we decided to deploy one of our directional wave buoys near the drilling site to provide real-time monitoring of the wave conditions along with instant verification of the forecast accuracy.”

The wave buoy sends data ashore every hour so everyone involved can monitor the sea conditions in real time. See for yourself at:  http://wavebuoy.metocean.co.nz/wellington 

“When ingested into the MetOceanView forecasting system, we co-plot the measured and the forecast wave heights. This is the most honest representation of forecast accuracy, and allows users to gain confidence in the timing and the magnitude of the wave predictions. The recent storm from 13 July was a very energetic event, but we captured it perfectly from 3-4 days ahead.”   

The real-time wave buoy data shows the waves resulting from the storm in mid-July.

The real-time wave buoy data shows the waves resulting from the storm in mid-July.

Accurate wave forecast – the significant wave heights measured by the buoy were very close to those forecasted for the storm in mid-July.

Accurate wave forecast – the significant wave heights measured by the buoy were very close to those forecasted for the storm in mid-July.

MetOceanView ingests observations from over 10,000 sites every day, including 252 locations around New Zealand. 

For queries about ingesting site-specific data, contact enquiries@metocean.co.nz.

Geraldton Port - improving long wave predictions with real-time wave buoy data

“MetOcean Solutions has worked exceptionally hard to assist the Port of Geraldton with its surge problem. The product they now deliver is heavily relied on when scheduling shipping. The efficiencies gained in reduced labour costs to port users are significant, but is the contribution to safety that represents the greatest gain. In 2005 there were 242 parted ships lines at Geraldton. Following the developments in forecasting Long Wave effects at Geraldton, last year there were only 30 parted ships lines. This was the lowest number of parted lines since records have been kept. MetOcean Solutions is keeping Geraldton Port efficient, and port workers safe.”
Captain Ross Halsall, Acting Harbour Master, Port of Geraldton.

Observational wave data can help ports manage the onset of long wave events. In recent work for Geraldton Port (Australia), we improved our harbour long wave forecasts by integrating wave buoy data from two upstream locations into the short-range predictions.

Long (or infragravity) waves are created when swell waves interact with the coast and result in water level oscillations with periods much longer than the original swell waves. Long wave periods of 60-120 seconds are typical, and these are very problematic because their wavelength is similar to the size of ships. When such waves enter a harbour the moored vessels are energised, causing dangerous surging which can break lines and put personnel in danger. As a result, ports often have to close when long wave heights exceed a safe threshold.
 
Accurate forecasts of long wave height can help ports increase safety, reduce unwarranted closures and effectively plan for reopening. For the past 11 years, MetOcean Solutions has provided a specialist long wave forecasting service that ports and harbours throughout New Zealand and Australia have come to rely upon.   
 

Numerical simulation showing that the sea-swell climate in the vicinity of the Port of Geraldton is extremely complex, mainly due to the reef near the Port entrance.

Numerical simulation showing that the sea-swell climate in the vicinity of the Port of Geraldton is extremely complex, mainly due to the reef near the Port entrance.

“Our scientific research over many years provides the basis for a robust prediction system,” explains Senior Oceanographer Dr Severin Thiebaut. “We use a semi-empirical technique to establish the relationship between the offshore wave spectra and the long wave height at each berth in a port. It's a method that we have tested at more than 30 locations worldwide”. 
 
The forecast wave spectra is derived from the suite of global and regional numerical models run by MetOcean Solutions. Geraldton Port have been using these predictions to guide the harbour operations since 2007. Predictions have proved very reliable, but sometimes the arrival of a swell front may differ from the forecast by a few hours as the exact timing is difficult to resolve perfectly with a spectral wave model. To supplement the long wave forecasts, we developed a new technique using real-time wave buoy data to improve the short term predictions and better detect occasions with a sharp rise in long wave energy inside the harbour. 
 
‘“The goal is to ensure that our port clients are never surprised by weather events,” says Dr Thiebaut.  

The Department of Transport maintains wave buoys at Rottnest Island and at Jurien Bay, some 370 km and 170 km to the south of Geraldton, respectively. The live data from these buoys, updated at 30 minute intervals, are used to track the progression of swell up the west coast of Australia and provide harbour long wave predictions some 5-6 hours ahead.

Data from wave buoys at Rottnest Island and Jurien Bay help improve long wave predictions for Geraldton Port.

Data from wave buoys at Rottnest Island and Jurien Bay help improve long wave predictions for Geraldton Port.

“Using the live buoy data provides additional confidence to the standard forecasts. In particular, it allows us to accurately capture any rapidly rising long wave events. It also gives the port operators a better idea of when wave heights will decrease to safe working levels. Geraldton Port accesses the forecast information through the web-based MetOceanView platform and through their local environmental monitoring software. On the same plot we show the measured long waves at the berth along with the values that are forecast by our standard system plus those predicted by the buoys.” 
 

Comparison between measured and predicted significant long wave heights (Hslpw) in the Port of Geraldton in 2012 based on Jurien Bay real-time wave buoy data.

Comparison between measured and predicted significant long wave heights (Hslpw) in the Port of Geraldton in 2012 based on Jurien Bay real-time wave buoy data.

Contact us for a discussion of what we can do to help your port. Call +64 6 758 5035, email enquiries@metocean.co.nz or visit www.metoceanview.com.
 

Two million data points a day, and counting

Every day, the MetOceanView service ingests and serves up to our clients more than 2 million unique data points. These are modelled and observed data providing vital marine weather information to users.

The MetOceanView platform displays forecast and historical data for a range of locations. Clients worldwide use the site to access the results from customised wave and hydrodynamic models, helping them make important decisions to maximise safety and improve efficiency.   

“MetOceanView provides a phenomenal amount of information for a wide range of clients,” explains Andre Lobato, who works on data management for MetOceanView. “In order to run such a system, the platform has to process an enormous amount of data.”

Model and observational data are ingested into MetOceanView to provide a complete picture of ocean weather conditions for our clients.

Model and observational data are ingested into MetOceanView to provide a complete picture of ocean weather conditions for our clients.

“Every day, we ingest about 2.25 million discrete data points. More than 2 million of these are unique rows of modelled data from global weather and marine models. In addition to modelled data, we continuously incorporate satellite, lightning, weather station, wave buoy, current meter and tide gauge data as part of the operational infrastructure behind MetOceanView. Some of these data, like METAR stations, NOAA-NDBC buoys, NOAA-MADIS, Himawari 8, GOES and MODIS satellite images are displayed directly on the MetOceanView interface. Others are shown to provide comparisons with our modelled data - e.g. wave buoy data displayed on a graph comparing observed to forecasted wave height.

“Real-time lightning data at times add a huge number of additional observations. Provided through Blitzen (TOA and GPATS), each single lightning strike constitutes a discrete observation. This means that on some days we incorporate millions of lightning data points per day, displaying real-time strikes for Australia, New Zealand and Europe.

Example of one-hour real-time lightning observations for Wednesday 29 March as shown in MetOceanView. Red dots represent clusters of lightning strikes.

Example of one-hour real-time lightning observations for Wednesday 29 March as shown in MetOceanView. Red dots represent clusters of lightning strikes.

We also use observational data to calibrate and validate our meteorological, wave and hydrodynamic forecast models. Observed data can also be used to directly improve our near-real-time forecasts, and can result in significant accuracy gains.

“All this information comes from a variety of sources. Much of the data used in MetOceanView are from our own models and instruments, but some observational data come from external providers. Some of it is private, for example where clients have observations that can help improve the models for their locations.  

“Ingesting such quantities of data requires a range of techniques. Often we have to process the raw information coming in to make it useable for our internal databases. We have designed our systems so that they can handle any data format.

“Ultimately, our clients use MetOceanView as a one-stop-shop for their marine weather information needs. The data we incorporate are valuable to our clients because they help them gain the complete picture of the atmospheric and marine conditions at their site. Good data visualised in an easy-to-understand format allows informed decision-making, which makes for safer operations and increased efficiency, and that is what MetOceanView is all about.”

For more information about MetOceanView, watch our introduction video here, see www.metoceanview.com or email enquiries@metocean.co.nz
 

Kaikoura tsunami waves measured in Wellington Harbour

The location of the wave meters on the eastern side of the entrance to Wellington Harbour.

The location of the wave meters on the eastern side of the entrance to Wellington Harbour.

The MetOcean Solutions science team made some unique wave measurements of the 14 November Kaikoura New Zealand tsunami event.

Oceanographer Florian Monetti has been studying the complex swell wave transformations into Wellington Harbour since 2015 as part of the environmental assessments for the Wellington Harbour Deepening Project. CentrePort, who operates Wellington Harbour, recently commissioned additional wave measurements at the popular surf breaks on the eastern side of the harbour entrance, with the intention to use these data to more precisely validate the numerical wave models of the harbour. MetOcean Solutions supplied three wave meters (RBRsolo) on seabed frames that were placed very close to the surf breaks. These meters record water levels continuously at twice per second, and as luck would have it they were deployed just a few days before the 7.8 magnitude earthquake. 

“The measurements are quite remarkable,” says Florian. “Because the meters were spaced along 3 km of the entrance coastline we can clearly see the progression of the tsunami waves as they enter the harbour.” 

The first noticeable change to the sea surface occurred only 2 minutes after the 12:02 am earthquake, with waves around 0.5 m occurring - likely radiating from the adjacent shoreline.  Then, after 24 minutes a mild disturbance was observed for about 10 minutes, which is probably the waves generated by the quake within the Wellington Harbour. Next, some 48 minutes after the quake, the water level first receded by about 0.8 m and then 12 minutes later it rose by 1.6 m. The tsunami waves moved relatively slowly through the harbour entrance, their speed limited to around 35 km/h by the shallow depth. The time lag between the first wave arriving at the Pipes and then Lion Rock surf breaks was 5 minutes. The two first waves were the largest but another 13 waves between 0.4 m and 1.0 m in size occurred over the following 6 hours. Notably, all these waves had a well-defined periodicity of (i.e. they recurred every) 27 minutes, and this distinctive tsunami signal could still be detected 19 hours after the arrival of the first wave. 

The tsunami waves started soon after the earthquake and continued until 19 hours after the quake. The graphs show the water level as measured (top) and with the tide and normal wave patterns removed (bottom).

The tsunami waves started soon after the earthquake and continued until 19 hours after the quake. The graphs show the water level as measured (top) and with the tide and normal wave patterns removed (bottom).

At Wellington, the size of the largest tsunami wave was quite close to the tidal range (which is 1.4 m), and the largest waves occurred when the tide was still low. This means the sea level changes were similar to what happens most days with the typical rise and fall of the tide. In fact, the highest water level occurred during the 9th tsunami wave, which coincided with the high tide. Some coastal flooding from the tsunami waves would certainly have occurred if the largest waves had arrived during the high tide.      

CentrePort has kindly made the data freely available for international tsunami researchers, and interested people should contact Florian for access (f.monetti@metocean.co.nz).    

High resolution wave forecasts for Chile now available

Good forecasts improve port safety and efficiency.

Good forecasts improve port safety and efficiency.

MetOcean Solutions have set up a high resolution wave forecast model for the coastline of Chile in South America. 
 
"We are delighted to now provide a high quality wave model for Chile," says Senior Oceanographer Dr Rafael Guedes. "We've set up a regional domain covering the central and northern Chilean coast and can now provide nearshore wave forecasts for the area north of 41°S. Accurate wave forecasting is important for ports located along this dynamic, exposed coastline."

The Chile model domain, showing depth (left) and sample wave height (right).

The Chile model domain, showing depth (left) and sample wave height (right).

The work was initiated following a visit by MetOcean Solutions to Chile in October, where the need for high resolution port scale wave forecasts was made apparent.  
 
"We've used the state-of-the-art SWAN (Simulating WAves Nearshore) model," continues Dr Guedes. "Like many New Zealand ports, Chilean ports suffer from wave exposure. Accurate modelling can help ports save money and time, and increase safety. MetOcean Solutions specialise in forecasting wave conditions for weather-exposed ports, and we provide expert forecasts for a number of ports internationally already. We are very happy to potentially extend the service to Chile. Of course, very high accuracy forecasts require accurate bathymetry." 
 
The model domain was set up to cover the coast between 41°S and 17°S at 5 km resolution and was set up using full spectral boundaries from MetOcean Solutions' new, upgraded global WAVEWATCH III wave model. The new model can be accessed via the MetOceanView platform.

Validation of tool for safer and more efficient offshore oil & gas vessel operations

The MetOcean Solutions' tool can predict conditions that are unsafe for FPSOs.

The MetOcean Solutions' tool can predict conditions that are unsafe for FPSOs.

A paper detailing research carried out at MetOcean Solutions has just been published in the Ocean Engineering journal.

The research, done by Ian Milne, Sebastien Delaux and Peter McComb, presents the validation of a tool used to predict the behaviour of the large vessels used for the processing and storage of oil and gas in remote and deepwater offshore locations under different metocean conditions. 

Floating Production, Storage and Offloading (FPSO) and Floating Liquid Natural Gas (FLNG) vessels are used around the world. These huge vessels (lengths of up to 300-400 m) are moored using a turret system, which lets the vessel rotate around the mooring fixed to the seabed. Once tethered, the vessels are typically left for up to 25 years in one location from which they are only moved if the safety of operations is threatened. 

The combined forces of wind, waves and currents determine the alignment of the vessels. Therefore, the ability to forecast headings is important to operators as certain directions could result in roll motion which may compromise safety and hence require operations to be shut down. 

Supported by a research and development grant from Callaghan Innovation, MetOcean Solutions has developed a tool for the prediction of vessel heading. The paper details the validation of the tool using measurements from an operating FPSO.

"The model predicted the vessel heading within an accuracy of 5% for a range of environmental conditions," states Dr Sebastien Delaux. "It is great to have a good validation, and we are looking forward to finalising the tool and making it operational, so that we can help operators identify dangerous conditions. The tool will also be useful in planning stages to assess the operability of an FPSO for a particular site." 


Ian Milne is now with the University of Western Australia.
Data for the validation of the tool was provided by OMV New Zealand.
Click here for details of the Callaghan Innovation Research and Development Grant.  
The full journal article can be found here

MetOcean Solutions enters strategic alliance with OMC International

The Strategic Alliance will help provide maximum benefits to port clients.

The Strategic Alliance will help provide maximum benefits to port clients.

MetOcean Solutions have signed a strategic alliance with Melbourne firm OMC International. The two companies plan to coordinate research and development efforts and offer an expanded level of maritime forecasting and hydrodynamic services to port and harbour clients.

“We are excited to announce the strategic alliance", says Dr Peter McComb, the Managing Director of MetOcean Solutions. "We believe that aligning the ongoing research and development of our two companies will maximise the benefits to our clients.” 

OMC International is the recognised world-leader in real time under keel clearance management technology, offering services for port clients around the world. MetOcean Solutions has worked extensively with OMC International in the past 10 years, providing marine forecasts and modelling services for some of OMC International's client ports. The strategic alliance expands the existing working relationship, and enables the two companies to provide additional services to clients.

“This is a positive step toward creating the next generation of marine services to ports and harbours. We are very pleased about the partnership and are looking forward to working together," states Dr McComb.

Combined, OMC International and MetOcean Solutions employ more than 80 staff, including engineers, naval architects, scientists and software developers.

Founded in 2005, MetOcean Solutions is a science-based consultancy that provides specialist numerical modelling and analytical services in meteorology and oceanography. The company has a solid track record providing high quality environmental data and expert interpretation to meet the rigorous requirements of the offshore and maritime industries as well as regulatory, defence and government agencies.

 
 
 

Long waves in Port Taranaki

Wave model showing swell wave penetration to Port Taranaki. Longwaves are generated by these swell waves. 

Wave model showing swell wave penetration to Port Taranaki. Longwaves are generated by these swell waves. 

When an enormous storm swell was forecast to hit the west coast of the North Island of New Zealand this winter, Remy Zyngfogel, one of our keen oceanographers, decided this was the perfect opportunity to make a unique set of measurements within Port Taranaki.

Long (or infragravity) waves are water level variations with periods of more than 25 seconds. These waves create big problems in many ports around the world because their wavelength is similar to the size of commercial ships. For a moored vessel, the waves directly agitate the ship at the berth, which can cause vigorous motion that can break the mooring lines and present a high danger to personnel.

At Port Taranaki, along with many other ports, MetOcean Solutions provides a hyper-local harbour forecasting service which includes long waves and the vessel surging outcomes. Based on this forecast, Port Taranaki had a 5-day warning of closure due to the storm swell. So, Remy planned an experiment in the empty port. With the help from harbour staff he deployed 7 wave sensors (RBRsolo) on the seabed in a line across the main harbour basin. A remarkable set of data was obtained, as demonstrated by the animation right. Water levels for the different long wave frequencies can be visualised and the complex wave forms and reflection patterns easily identified.

Taranaki Harbourmaster, Neil Armitage, says ‘For the first time we can actually see these waves, how they are behaving, and better understand the effect they have on ships in our harbour.’    

The data will be used to further validate the numerical models of long wave generation and penetration.

Location of the sensors.

Location of the sensors.

Animation showing the long waves measured in Port Taranaki.

Animation showing the long waves measured in Port Taranaki.