University of New South Wales and CSIRO visit MetOcean Solutions

This week, MetOcean Solutions is hosting a workshop for researchers from the University of New South Wales (Australia) Coastal and Regional Oceanography Team and the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO). 

"The workshop will gather experts in physical oceanography from the three organisations as well as students, postdocs and early career scientists," explains Prof Moninya Roughan, the Chief Scientist at MetOcean Solutions. "It will be a great opportunity for us to exchange knowledge and establish collaborations on upcoming initiatives."  

The workshop, which runs from 24-28 April, includes a number of sessions dedicated to scientific writing as well as a series of short research seminars. Themes include meso-scale ocean circulation and oceanic eddies, as well as operational oceanography.

MetOceanView - making the offshore oil & gas industry safer and more efficient

Worldwide, a variety of offshore oil and gas companies use historical data from MetOceanView to understand the environment they work in. Packaged up in the site’s ‘hindcast app’, historical wind, wave and current data is summarised in an easy-to-access format that users can download and integrate into their operational planning.

“The offshore oil and gas industry needs access to reliable site data,” explains Senior Oceanographer Dr Rafael Guedes. “Nowadays, many data sources are available, and the industry needs a robust web platform where they can easily access, browse and download time-series from some of the best hindcast data sources available around the globe. To meet their needs, we set up a hindcast downloading app within our MetOceanView web service.”

Reliable data

The hindcast app provides access to an extensive compilation of data, going as far back as 1958 for some of the datasets.

“We host some of the most reliable global ocean and atmospheric reanalysis data sources in the world,” adds Dr Guedes. “These include NOAA’s CFSR V1 and V2, Hycom from the National Ocean Partnership Program (NOPP) and JRA-55 from the Japanese Meteorological Agency (JMA). In addition, we also provide MetOcean Solutions’ in-house WAVEWATCH III wave hindcast datasets.”

Gaining efficiency

Dealing with huge datasets is not easy, and to set up a useable service, practical obstacles had to be overcome.

“One common problem when accessing historical data is that the volume of data in gridded datasets can be very large,” says Dr Guedes. “For example, a subset of the HYCOM dataset we host comprises about 2.6 trillion individual data points for each variable. Reading long-term time-series from such enormous datasets can be very slow. To make a user-friendly service, we came up with an efficient process to speed up the reading, so that datasets that used to take more than two hours to download could be read in just five minutes.”

One-stop-shop for ocean data

The service works by hosting a range of reference datasets in our servers, giving the client access to unlimited data from all available global datasets as well as MetOcean Solutions’ wave and current model outputs.

“We provide a user-friendly map-based web interface where the user can inspect the different data sources and request time-series for any available grid location,” adds Dr Guedes. “The results are generated without human intervention and delivered within minutes in standard file formats, a link to which is sent directly to the user’s email.”

Data for safer operations

The hindcast app gives access to historical ocean temperature, current, elevation and wave data, as well as atmospheric parameters such as wind, temperature and precipitation.

“Accurate wave, wind and current information is essential for anyone operating offshore,” explains Dr Guedes. “Oil and gas companies use the hindcast data for a range of purposes, including determining the potential operational conditions for offshore locations and ensuring safety at sea.”

The hindcast data subscription service allows customers to browse map views of global datasets with descriptions of the variables that can be downloaded. Grid points show the exact location of each data point. Time-series are provided in either CF-compliant netCDF files or a format specially requested by the client. Wave hindcast data can be downloaded as time-series of spectral parameters or as two-dimensional, frequency-direction wave spectra. This allows a comprehensive description of the modelled wave field over the entire globe. For example, the spectra shed light on the multiple wave systems influencing wave conditions at a certain location and given time.

Making our clients’ life easier

This is the second year of delivering online historical metocean data services to Shell.  “We’ve found the global hindcast portal very valuable,” states Octavio Sequeiros, Shell Metocean Engineer. “Previously, to obtain data for a given location we had to create a specific purchase order for each request. Now, unlimited high quality historical data for any location are just a mouse-click away.

“The fast data download has made our planning easier, more efficient and cost-effective” continues Mr. Sequeiros. “The app is easy to use, and because it provides map layers along with the data grid locations, we can inspect areas and do a few queries before we decide to download time-series. Many summary statistics are shown in tile format, which means we can get a sense of the data before committing to downloads. We mostly use the time-series of wave parameters and wave spectra. On these, we run our own statistics in-house to obtain operational and design criteria for preliminary studies of new potential sites for oil and gas exploration. Our goal is to get workability predictions using accurate modelling.”

High level statistics from each of the datasets hosted by MetOcean Solutions is available via our MetOceanView interface.

Sea surface temperature snapshot from CFS dataset.

Sea surface temperature snapshot from CFS dataset.

Sea ice area snapshot from CFS dataset.

Sea ice area snapshot from CFS dataset.

Eastward wind snapshot from CFS dataset.

Eastward wind snapshot from CFS dataset.

Sea surface wave significant height snapshot from MetOcean Solutions’ dataset.

Sea surface wave significant height snapshot from MetOcean Solutions’ dataset.

Alexis Berthot representing MetOcean Solutions in Australia

We are very pleased to welcome Dr. Alexis Berthot, who will be representing MetOcean Solutions in Australia. Based in Sydney, Alexis's main focus will be looking after the company's Australian clients and providing solutions tailored to the local environment and requirements. 

Alexis’s academic and professional background is in physical oceanography and coastal science. Following an MSc in Marine Environmental Sciences from the University of Marseille, France, he completed a PhD in Physical Oceanography at the University of Western Australia. He has worked in coastal and ocean research and engineering consulting for over 15 years, as a principal numerical modeller, technical lead or project director. 

From his involvement with a wide range of coastal and maritime engineering projects, Alexis has gained extensive experience in hydrodynamic, wave, sediment transport and water quality modelling. 

“I have followed the development of Metocean Solutions since the company started," explains Alexis. "I have been continuously impressed by the high technical quality of the work, the innovative tools developed, and the team's enthusiastic approach when tackling new challenges. I am very excited to join the company and assist in making sure that all Australian companies and government agencies get the opportunity to have Metocean Solutions' great technical expertise and forward thinking solutions at their fingertips.” 

Alexis can be reached at a.berthot@metocean.co.nz or by calling +61 422 369 314.

Sea surges as ex-cyclone Debbie moves through

Heavy rains and surging seas plagued New Zealand as the remnants of cyclone Debbie moved  across the country this week.

“Storm surges occurred in different places across New Zealand as the storm moved through,” explains Senior Oceanographer Dr Rafael Soutelino. “We were lucky that the system moved through fast and did not coincide with large tides, otherwise the coastal flooding could have been a lot worse.”

Storm surges occur when the sea rises as a result of wind and atmospheric pressure changes associated with a storm. The surges build up over time and will worsen when a low pressure system lingers. 

“MetOcean Solutions forecast storm surges nationwide using a complex high definition 3D hydrodynamical model,” continues Rafael. “The model computes the atmospheric effects on coastal water levels. It combines this with baseline water levels generated by open ocean eddies and water column expansions and contractions caused by the spatially-variable vertical density distribution.

“Our modelling shows that as the storm progressed, it caused storm surges in different parts of the country. Although mostly mild, the storm surges were still high enough to cause coastal flooding in sensitive areas. 

The storm progresses: wind and rain (right) and storm surges (left) coincide as ex-cyclone Debbie passes over New Zealand.  

The storm progresses: wind and rain (right) and storm surges (left) coincide as ex-cyclone Debbie passes over New Zealand.
 

Storm surges up to 35 cm high occurred in a number of coastal locations around New Zealand.  

Storm surges up to 35 cm high occurred in a number of coastal locations around New Zealand.
 

“We were very lucky that the storm moved through so fast, and that it coincided with neap tides. Had it happened at spring tides, when the high tide levels are higher, flooding in the area could have been much worse. Our models show that at spring tide, the storm surge would have been high enough to almost match the measured river level after all the rain. In that scenario, the river would not have drained into the ocean as fast, which means the flooding would have been worse and lasted longer.”

Coastal flooding could have been much worse had the storm surge coincided with spring high tide at the Whanganui River mouth.

Coastal flooding could have been much worse had the storm surge coincided with spring high tide at the Whanganui River mouth.

Storm surge forecasts provide valuable information for for low-lying coastal locations, and these solutions are readily available to public authorities. 

“MetOcean Solutions’ New Zealand storm surge model has a resolution of 5 km. It’s the only operational hydrodynamical model for the country and we’ve been running it for more than five years now. During that time we have used it for oil spill and search and rescue modelling, and during the Rena disaster is provided essential guidance for the national response activities. We developed a similar model for the south coast of Australia, which has been operational for more than one year. This model is used by our Alliance partners OMC International in their specialist under keel clearance applications. 

“We run these types of models all over the world,” says Rafael - even in his home country of Brazil where the complex flows along the continental shelf are important to the offshore oil field operations.   

For further information about storm surge warnings and the New Zealand 3D hydrodynamical model, please contact us at enquiries@metocean.co.nz
 

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 wave model data now available

Hindcast wave model data are now available for the Kaikoura region. The data, which includes two high-resolution nested domains around the Kaikoura Peninsula and Clarence (regions where active coastal construction is taking place) were generated by dynamically downscaling waves from MetOcean Solutions’ global wave model using a series of Simulating WAves Nearshore (SWAN) model nests. 

Snapshot of significant wave height (Hs) and peak wave directions for the SWAN domains defined for Kaikoura. Inserts show the Clarence (right) and Kaikoura Peninsula (bottom) nests.   

Snapshot of significant wave height (Hs) and peak wave directions for the SWAN domains defined for Kaikoura. Inserts show the Clarence (right) and Kaikoura Peninsula (bottom) nests. 
 

“We prioritised the model runs to ensure that suitable time-series and boundary data are available for the Kaikoura rebuild effort,” explains Project Manager Dr Brett Beamsley. “The model domains are representative of the pre-earthquake bathymetry, but we don’t expect wave characteristics at depths exceeding ~30m to be significantly different between before the earthquake and now, because depth changes in deeper water are not expected to significantly influence wave propagation.” 

“Much of the rail and SH1 roading network north of of Kaikoura historically went very close to the sea and as a result were often closed due to waves washing over the narrow foreshore. Design tolerances for reconstruction of these networks will require an understanding of the likely impacts of large waves, including storm return periods and maximum expected wave heights. In the absence of measured data, this understanding can only be achieved through long period hindcasts.

“Additionally, these hindcast datasets can be used for boundary conditions for specific high-resolution wave models employed to understand implications of the new harbour (which is expected to be completed by mid year) or breakwaters, including wave energy penetration, overtopping and infragravity waves.”

For further information on the data available, please contact b.beamsley@metocean.co.nz

More heavy weather on the horizon

A low pressure system over the Tasman Sea brought strong winds and heavy downpours to New Zealand's North Island last night, resulting in widespread flooding in east Auckland and the Coromandel. 
 
The New Zealand MetService issued a severe weather warning this morning, predicting continued heavy rainfall and risk of flash flooding for large parts of the northern North Island. 
 
Unfortunately the long range forecast shows more to come. Another intense Tasman Sea low pressure system is currently predicted to develop and bring severe weather to central New Zealand early next week, as the image from MetOceanView shows. 

View to the weather: gale force winds forecast for early next week. Image from MetOceanView.com

View to the weather: gale force winds forecast for early next week. Image from MetOceanView.com

For severe weather warnings, see the New Zealand MetService website http://www.metservice.com/warnings/severe-weather-warnings.

MetOceanView can be found at www.metoceanview.com

An operational oceanographic forecast / hindcast model for Shanghai, China

MetOcean Solutions recently completed the development of operational high-resolution wave and hydrodynamic models for the Yangtze River mouth and coastal areas off Shanghai. 

The work combined cutting-edge science within our agile operating system to set up wave and current models for Hangzhou Bay, a region within the East China Sea which is partially enclosed by the Ryukyu chain of islands. 

“It is a very tricky area to model,” notes Senior Oceanographer Dr Rafael Guedes. “The region is characterised by a wide, shallow and highly irregular shelf with many small islands and underwater reefs. Accurate bathymetry for the area is limited. The site is strongly influenced by the phenomenal seasonal discharge from the Yangtze River, which is one of the largest rivers in the world, and is also subject to strong tidal currents.” 

 Bathymetry of the East China Sea. Red dots show the locations of measured data used to validate the models.

 Bathymetry of the East China Sea. Red dots show the locations of measured data used to validate the models.

 
Progressive downscaling of outputs from MetOcean Solutions’ global wave model WAVEWATCH III using two SWAN nests. 

Progressive downscaling of outputs from MetOcean Solutions’ global wave model WAVEWATCH III using two SWAN nests. 

Snapshot of surface salinity from the ROMS model. Blue denotes low salinities; red high.

Snapshot of surface salinity from the ROMS model. Blue denotes low salinities; red high.

“In order to model the location well, we had to capture the meteorological events occurring within the East China Sea as well as the swell generated beyond the Ryukyu Islands which propagates into the bay. Frequent typhoons ravage the area, and these are always hard to resolve well. All in all, the area displays a challenging combination of highly variable bathymetry, strong temperature and salinity differences and complex mixing processes.”

The SWAN (Simulating WAves Nearshore) model was used to resolve the wave climate and the Regional Ocean Modeling System (ROMS) was applied to simulate the circulation. 

“To model the area we used a technique known as ‘dynamical downscaling’,” explains Rafael. “This process uses information from large scale global models to drive regional models at much higher resolution. The technique allows us to resolve fine-scale features near the coast while still accounting for remote influences to the area from long-generated swell or meso-scale currents.”

Quantile-quantile plot comparing measured and modelled significant wave height (Hs) for wave hindcast using (black) existing CFSR wind fields and (red) adjusted wind fields to correct for observed wind bias.

Quantile-quantile plot comparing measured and modelled significant wave height (Hs) for wave hindcast using (black) existing CFSR wind fields and (red) adjusted wind fields to correct for observed wind bias.

“High-quality input data sources are critical to running wave and hydrodynamic models in such complex settings,” continues Rafael. “We found persistent wind speed bias near the bay in the global reanalysis data source that we used to calibrate the high resolution models. Correcting this bias before running the wave model significantly improved model results just offshore of the bay as shown in the comparison of measured and modelled significant wave height.

The area has heavy shipping traffic, and the operational system outputs, including 7-day forecasts of site-specific waves, winds and currents, are now available to marine users. Please contact us and we will connect you with our partner agency in China.

Live Southern Ocean wave buoy direct data feed

MetOcean Solutions is now hosting the direct data feed from the Southern Ocean wave buoy on our website, at www.metocean.co.nz/wave-buoy.

The direct data feed is live at www.metocean.co.nz/wave-buoy.

The direct data feed is live at www.metocean.co.nz/wave-buoy.

The instrument, which is the southernmost moored open ocean wave buoy in the world, was deployed on February 8, 2017 as part of a collaborative project between the New Zealand Defence Force and MetOcean Solutions. 

"We are pleased to say that everything seems to be working according to plan," says Dr Peter McComb who was present at the deployment. "The buoy is located 11 km south of Campbell Island, a location infamous for its harsh conditions. On average, the island gets less than an hour of sunshine 215 days out of 365, and winds of more than 100 km per hour occur at least 100 days a year. The buoy is moored in a water depth of 150 m and is fully exposed to the predominantly westerly wave systems generated by the relentless procession of mid-latitude storms." 

Southern Ocean important for climate

Senior Oceanographer Dr Tom Durrant is excited to be getting data from the Southern Ocean. "The Southern Ocean is known to play an important role in the Earth's climate system, cycling heat, carbon and nutrients,” he states. “Waves modify the air-sea fluxes and the mixed water masses are then redistributed by the Antarctic Circumpolar Current, creating a complex interacting system. Persistent mid-latitude storms combined with a lack of landmasses create large fetches and strong winds, ideal conditions for generating large waves. 

"The waves generated in this region have far reaching effects, contributing significantly to the wave climate in all the major ocean basins. The New Zealand west coast, for example, is periodically battered by large swell systems generated in Southern Ocean storms. 

The buoy was launched on 8 February 2017.

The buoy was launched on 8 February 2017.

Data will help ocean science

"Despite the importance of the region, there are almost no in situ observations in the Southern Ocean. Currently, there is no published wave spectra data from any location south of 47 S to the ice edge (at ~63 S in summer months). Remote altimeter observations provide a valuable source of significant wave height, and have been used to great effect in the Southern Ocean, but these do not provide spectral information which allows us to explore the details of the extreme sea states. The data from this deployment will fill a valuable gap in our understanding of waves in the region and provide a much needed ground truth for validating the global wave models. In recognition of this value, the data will be made freely available to the scientific community." 
 

Persistent polar activity keeps the cold weather coming

Upper atmosphere temperatures remain influenced by colder polar air masses, shown in blue.  Image based on GFS data.

Upper atmosphere temperatures remain influenced by colder polar air masses, shown in blue.  Image based on GFS data.

If you live on the west coast of New Zealand and feel that the 2016-17 summer has been worse than average you'd be right.

"Since winter 2016, New Zealand has been subjected to persistent polar activity," states Tim Gunn, MetOcean Solutions' weather ambassador. "This results in south-westerly fronts hitting our coastlines, one after the other, bringing with them rain and colder than average temperatures.”

The westerly winds result in upwelling along north-facing coastlines.

The westerly winds result in upwelling along north-facing coastlines.

Polar troughing, which results in westerly wind patterns, is typically replaced by mid latitude synoptic weather systems by mid to late November. These normally bring with them warmer, sunnier and more stable weather. However, this year the change hasn't occurred yet.  

The ocean has been affected too. 

Colder than average temperatures are not stopping enthusiastic bathers in Taranaki.

Colder than average temperatures are not stopping enthusiastic bathers in Taranaki.

"The sea is colder than normal for this time of year in some locations," says Dr Rafael Soutelino, MetOcean Solutions' forecast manager. "On the west coast, the strong pattern of westerly winds which is unusual for this time of year has enhanced upwelling of cooler waters along predominantly north-facing coastlines such as North Taranaki and Bay of Plenty. As a result, those places are experiencing colder than average sea surface temperatures," he explains. 

The world's southernmost open ocean moored wave buoy deployed

The buoy will provide essential data about waves in the rarely studied Southern Ocean. Plot shows wave height in metres; the red dot marks the wave buoy location.

The buoy will provide essential data about waves in the rarely studied Southern Ocean. Plot shows wave height in metres; the red dot marks the wave buoy location.

In collaboration with MetOcean Solutions, the New Zealand Defence Force yesterday launched a moored wave buoy about 11 km south of Campbell Island. The site is the southernmost location that a wave buoy has ever been moored in the world.

Deployed from the HMNZS OTAGO, the buoy is part of a collaborative project between the Defence Technology Agency and MetOcean Solutions. The buoy is planned to remain in location for the next six months, where it will be used to gather precise wave spectral data as well as
wave height and wave direction.

"We are very pleased about our research partnership with the Defence," says oceanographer Dr Peter McComb who led the deployment on OTAGO. "The Southern Ocean is an incredible engine for wave energy generation due to the persistent westerly winds and the expansive ocean fetch. This makes it a difficult region to work in, but we were fortunate with a period of relatively good weather to launch the buoy. The data will be of international significance and the wave research community will benefit from open access to the measurements."

Dr Tom Durrant, the manager of MetOcean Solutions' wave modelling, says that the buoy will provide invaluable data for an area which remains poorly studied. 

"Due to the harsh ocean environment and remote location, the Southern Ocean is the least observed of any ocean body," he explains. "The wave buoy data will aid our understanding of waves in extreme conditions, and provide measurements against which we can validate and improve our global wave models. To help the deployment we provided detailed forecasts, and we are relieved that the conditions were calm enough to launch the buoy."

For more about the deployment, see the DTA website

 

Wave forecast model upgrades

Wave model performance improved by an average of 20% as a result of the new physics (RMSE: root mean square error; the smaller the RMSE the better the model performs. In the bottom figure, red denotes positive percentage improvement). 

Wave model performance improved by an average of 20% as a result of the new physics (RMSE: root mean square error; the smaller the RMSE the better the model performs. In the bottom figure, red denotes positive percentage improvement). 

At MetOcean Solutions, we continuously improve our models to ensure the highest possible performance.

To that end, we recently upgraded the physics in our in-house global and regional wave models.

“Our wave forecasts and services rely on sophisticated open-source atmospheric and wave models,” states Dr Tom Durrant who manages MetOcean Solutions’ wave models. “A global community of scientists are working on these models. As a result, the models are constantly evolving, both in terms of our understanding of the underlying physics and the representation of these physics in the models. At MetOcean Solutions, we strive to maintain our models with the current state-of-the-art science, and the recent upgrade brings us in line with the world’s leading edge practices.”  

“The result is a great improvement in the physical representation of wave generation and dissipation within our global wave models. As the global models provide boundary conditions for all MetOcean Solutions’ coastal models, the changes produce improvements throughout the wave modelling system at all scales,” he adds.

The resulting improvements are shown in the figure above. Using satellite observations to quantify these gains, the figure shows the root-mean-square-error of wave height (i.e. model performance) relative to satellite observations for a) the previous system; b) the upgraded system; with c) indicating the percentage improvement. Clear gains are apparent, with an approximate 20% improvement in model skill demonstrated overall.

 

Oceanology International Conference in San Diego

MetOcean Solutions will be at the Oceanology International Conference North America 14-16 February. The Oceanology International conference, which this year is held at the San Diego Convention Center, is one of the largest maritime conferences in the world.

Please contact Sebastien Boulay at s.boulay@metocean.co.nz if you want to meet at the conference and discuss opportunities.

Moninya Roughan joins MetOcean Solutions as Chief Scientist

Moninya Roughan

Moninya Roughan

We are delighted to welcome Moninya Roughan as Chief Scientist at MetOcean Solutions. Moninya is currently Associate Professor and Group Leader of the Coastal and Regional Oceanography Lab at the University of New South Wales. She will transition to the Chief Scientist role over the next 6 months, and focus on science leadership at MetOcean Solutions. Moninya will retain strong linkages with UNSW  in the School of Mathematics and Statistics.     

As a physical oceanographer specialising in coastal and shelf processes, her research focuses on improving dynamical understanding of coastal ocean circulation. She has substantial experience using a combination of ocean observations and numerical models, and has authored over 50 publications including peer-reviewed journal papers, book chapters, international conference papers, consultancy and technical reports. Moninya gained her PhD in Physical Oceanography from UNSW Australia (2002), and spent 4 years at Scripps Institution of Oceanography as a postdoctoral scholar (2002-2006). Over the past 10 years, she has led the design, deployment and ongoing development of one of the most comprehensive ocean observing systems in the southern hemisphere. Focussed on the East Australian Current, which flows downstream to New Zealand, Moninya and her IMOS team have deployed a network of moorings, HF radar, autonomous ocean gliders and floats along the coast of southeastern Australia to investigate the impact of the current on the continental shelf circulation along Australia’s most populous coastline. At UNSW, Prof Roughan leads a team of PhD students, postdocs and field technicians doing active research. Together they successfully completed over 100 mooring deployments and more than 20 autonomous glider missions. She has conducted fieldwork from Antarctica to Torres Strait, spending more than 100 days at sea on large and small research vessels. 

"The New Zealand ocean science community will benefit greatly from the wealth of knowledge and experience that Moninya brings," says Dr Peter McComb, the Managing Director of MetOcean Solutions. “We look forward to an exciting new chapter for operational oceanography in the South Pacific."

Modelling the impacts of seasonal variability in freshwater input into the Waikouaiti Estuary

Understanding the dynamics of estuaries is important when setting minimum flow levels for the rivers flowing into them.

Model domain showing depth relative to mean sea level in metres.

Model domain showing depth relative to mean sea level in metres.

When Otago Regional Council consulted with local communities about possible minimum flows for the Waikouaiti River, interest groups voiced concern about what potential changes in freshwater inflow would do to the health of the estuary. So Rachel Ozanne, the Council water quality scientist, contracted MetOcean Solutions to investigate the natural variations in freshwater input to help council explore the potential impacts of flow reduction on estuary processes and ecology.

“Regional councils are tasked with setting minimum flow-levels and water allocation limits for rivers,” explains Rachel. “In order to determine whether the proposed minimum flows would cause adverse effects, we need to understand the estuary hydrodynamics.”

The council was particularly interested in assessing the difference that the minimum flow levels would make to the summer flows, when the natural riverine input into the estuary is at its lowest. 

Hydrodynamic model setup

The first step in setting up a hydrodynamic model is to get accurate bathymetry. A survey was carried out by Hunter Hydrographics and the data were combined with council LiDAR and chart data from LINZ. 

A finite-element (triangular mesh) numerical model domain was set up, with 5 m resolution inside the estuary, reducing to 200 m offshore. The SCHISM model was established and validated with measurements of water properties, water levels and currents made during a targeted field campaign undertaken by the Cawthron Institute. 

The effects of different low summer flows on estuary hydrodynamics

“We ran the model for a range of river flow rates representing summer conditions,” explains Dr Brett Beamsley, who was the science leader for the project and is an expert user of the SCHISM code. “The modelling showed that the range of summer flows has negligible effect on the overall hydrodynamics of the estuary. The tidal flows are so strong that they, rather than the river input, dominate the estuary hydrodynamics in the summer.”

Rachel feels that the modelling confirmed council suspicion that the natural variability in the area exceeds potential changes caused by varying the freshwater input.

“In the past, big storms have dramatically changed the estuary. The study showed that the small changes in summer flow investigated (changes in the order of up to 200 l per second) would make little difference to the dynamics of the estuary.” 

Tracing the dilution of pollutants

A eulerian tracer method was used to examine the dilution of fresh water within the estuary, and these simulations clearly showed that the rate of flushing varies for specific areas. 

“Such results are very useful when considering potential pollution events,” adds Rachel. “In the upper reaches of the estuary, it takes more than 10 tidal cycles to flush out the fresh water. This means that if a pollutant enters the estuary through the rivers, it  can take more than a week to dilute to negligible levels.”

Which areas are prone to siltation?

The model was also used to examine sediment transport potential within the estuary.
“When current flows exceed a threshold value, the sediments are mobilised and transported along in suspension,” adds Brett. “The sediments settle out when the current velocity drops. The modelling showed that even the smaller channels within Waikouaiti Estuary have flows that can entrain silts and sands for considerable periods of time on each tide. However some of the adjacent shallow intertidal flats do not, so these areas are susceptible to siltation.

“To help council manage the estuary, we produced a series of maps showing where sediments of different sizes are likely to entrained.” 

Mapping intertidal areas

The number of hours the estuary bed is wetted over the tidal cycle.

The number of hours the estuary bed is wetted over the tidal cycle.

Another aspect that the council was interested in was assessing how large the intertidal area is at different stages of the tide, and at the spring and neap tides. 
“Exposure to air is a critical component determining which species live where in the estuary, and which species prey on them” states Rachel. “Areas that are rarely inundated are susceptible to sedimentation, and maps like these help us understand the ecology and potential future changes that might affect the biological communities.   

Model and data are freely available

“SCHISM is an open-source science model which is freely available,” explains Brett. “This means that all the code is fully transparent, so that other researchers can replicate and modify previous modelling efforts. Council also made available all the measured data, model setup, boundary conditions and configuration files for use by the local community, including university students.”

Making the data and model freely available was important to Otago Regional Council. 
“We expect improvements to the model will be made over time as other users become involved in the model development and more data becomes available for validation,” explains Rachel. “We hope that Otago University will be able to use it for student projects, and are keen to promote it as an active, living model which can be used by community interest groups or organisations. The ultimate goal is for the model to become a useful tool for the community to further understand how the estuarine hydrodynamics affect ecosystem processes.”   

For further information on Otago Regional Council, see their website.
For more information on MetOcean Solutions’ coastal service, click here or view a pdf here.

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.

MetOcean Solutions welcomes Otago University oceanography intern

Dannielle is looking forward to her summer internship.

Dannielle is looking forward to her summer internship.

Dannielle Fougere, a BSc oceanography student from Otago University, recently started an oceanography internship at MetOcean Solutions. 

Otago University Marine Science Department offers a BSc in Oceanography and as part of this provides a summer internship for a top student. This year Dannielle won the prestigious internship and she will be spending 8 weeks over the summer at MetOcean Solution offices in New Plymouth.

Dannielle is excited to be working at MetOcean Solutions for the summer. "It's great to get this opportunity to work among individuals who share a passion for science", she says."I'm looking forward to gaining some experience in my field." 

MetOcean Solutions at Melbourne Wave Workshop

Workshop on waves

Workshop on waves

Dr Tom Durrant attended the Ocean Waves and Wave-Coupled Processes Workshop held at the University of Melbourne 7-9 December 2016. Tom manages MetOcean Solutions' wave modelling and at the workshop he presented the company's wave forecasting.

The workshop launched the Australia-China Centre for Maritime Engineering, of which MetOcean Solutions is an industry partner.

The Centre was established to develop highly sophisticated modelling tools to predict ocean and wave climatology, extremes and trends which will allow offshore industries to prepare and protect their ocean assets as they continue the push further offshore and into more extreme environments.

For more information about the Centre, click here