Southern Ocean Wave Atlas presentation at NZ Antarctic Science Conference

MetOcean Solutions, commissioned by the New Zealand Defence Force, produced a state of the art wave atlas of the Southern Ocean (SO). Next week our key findings will be presented at New Zealand Antarctic Science Conference in Christchurch.

The Southern Ocean Wave Atlas includes a collaborative measurement campaign between MetOcean Solutions and Defence Technology Agency (DTA), and a large modelling effort. A critical analysis of wave model performance against these and other available observations was conducted, as well as the production of a long term hindcast in the SO.

The detailed understanding of the characteristics of wave climate is required to test and inform future designs of vessels that will be tasked with operating in the highly energetic SO. The gathered data help reduce known deficiencies in the model physics for this region and improve model guidance, which are used ultimately to make informed operational decisions.

 
Mean Significant wave height for 1993-2017 presented as layers in files suitable for viewing in Google Earth (www.google.com/earth/)

Mean Significant wave height for 1993-2017 presented as layers in files suitable for viewing in Google Earth (www.google.com/earth/)

 

As part of the measurement campaign, MetOcean Solutions has deployed instruments to collect wave data using moored and drifting buoys. All data is freely available to the scientific community and can be viewed in real time. For further information and data access see www.metocean.co.nz/southern-ocean/.

Running from 17 to 19 June, the NZ Antarctic Science Conference is hosted by Antarctica New Zealand, the government agency charged with carrying out New Zealand's activities in Antarctica, supporting world leading science and environmental protection. This year the conference theme is ‘Our Future in Focus’, showcasing the latest findings from NZ’s Antarctic research programme, discussing research and policy imperatives, and providing an opportunity for researchers, iwi, policy-makers and educators to foster collaborations that will collectively influence our future.

MetOcean Solutions is a division of New Zealand’s National Meteorological Service.

The full abstract is provided below.


Southern Ocean Wave Atlas

Tom Durrant1, Jorge Perez2, Henrique Rapizo2, Rafael Guedes1, Sally Garrett3, Peter McComb1

While the Southern Ocean is the least observed or understood of any major ocean, the combination of persistent westerly winds and the large expanse of sea produces higher wave heights for longer periods than any other body of water. The New Zealand Navy has patrol and search and rescue responsibilities over large areas of this ocean, and are planning the next generation of vessels to safely operate in these waters. However, the spectral wave characteristics have not been adequately characterised for the Southern Ocean, meaning the critical design factors were unavailable.

To meet those needs, a campaign of measurement and modelling was undertaken. Observations included buoy deployments at 52.7S, the southernmost directional wave mooring to date, where phenomenal conditions were observed including the highest measured wave in the Southern Hemisphere (24.8 m). Additionally, five drifting buoys were deployed in a trial of a new technology in energetic open ocean states.

The wave modelling, conducted with WAVEWATCH III, included a comprehensive analysis of available forcings including wind and ice from the CFSR and ERA5 reanalyses. The relative importance of large scale ocean currents was also examined, with currents from CFSR, HYCOM and Glorys considered. ERA5 winds were found to be superior to CFSR, and Glorys provided the best results for currents, significantly reducing the positive wave height bias in the Southern Ocean. This configuration was used to produce a 25 year hindcast, from which an atlas of the relevant physical surface ocean variables was been produced.

The atlas is a freely available gridded dataset of derived statistics that includes monthly and annual directional values for the surface current speed, wavelength, wave period, significant wave height, return period significant wave height, Douglas sea states, and dangerous seas indices.

____________________

  1. Oceanum Ltd, New Plymouth, New Zealand
  2. Meteorological Service New Zealand, Raglan, 3225, New Zealand
  3. New Zealand Defence Force, Devonport, New Zealand

Advances in global wave modelling

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

Our science team has recently made great improvements in global wave hindcasting thanks to using more accurate historical winds and studying the effect of icebergs and ocean currents in ocean waves.

MetOcean’s Southern Ocean Programme in partnership with Defence Technology Agency has been collecting wave data in the Southern Ocean over the last 2 years (find out more at www.metocean.co.nz/southern-ocean). The area presents the highest modelling errors, and the data gathered is helping to reduce that. This is a crucial achievement due to the energetic swells constantly generated in this part of the ocean that have far reaching effects. Consequently, it will result in better wave prediction over coastal areas.

MetOcean Solutions’ physical oceanographer Dr Jorge Perez, responsible for improving wave hindcasting and forecasting capabilities, says the analysis undertaken and the historical reconstruction has made it possible to minimize errors in wave data from deep waters, allowing better boundary conditions for high-resolution grids in coastal regions.

“Lessons learned such as the importance of currents and icebergs will result in advancements to our wave forecasting operational systems and therefore, historical data and wave predictions of the highest quality to end users.”

Clear gains are apparent, with an approximate 30% improvement in model skill demonstrated overall. The resulting improvements for the year of 2015 are shown as an example in the figure below.

 
fig 1-top.png
 
 
Example of bias comparison with model improvements (top) and reference simulation (bottom) for the year 2015.

Example of bias comparison with model improvements (top) and reference simulation (bottom) for the year 2015.

 

MetOcean’s advancements in global wave modelling were presented by Dr Perez at Spanish Conference on Coastal and Port Engineering, XV Jornadas Españolas de Ingeniería de Costas y Puertos, held last week in Málaga, Spain.

The conference is a biennial scientific-technical event, gathering experts and decision makers to facilitate knowledge exchange between all sectors engaged in coastal and port activities. For more information, visit www.costasypuertos2019.com

MetOcean Solutions is a division of New Zealand’s National Meteorological Service.

The full abstract is provided below.


Avances en modelado de oleaje global

Pérez, Jorge* Rapizo, Henrique* Guedes, Rafael* y Durrant, Tom*

*Metocean Solutions, New Zealand Meteorological Service.

1.       Introducción

El modelado de oleaje a escala global ha experimentado un rápido desarrollo en los últimos años dando lugar a reconstrucciones históricas cada vez más precisas (e.g., Durrant et al., 2014; Pérez et al., 2017). No obstante, incluso las bases de datos más recientes presentan errores significativos en ciertas regiones. Esto plantea una doble problemática. Por un lado, la creciente internacionalización de los intereses de empresas e instituciones hace evidente la necesidad de contar con datos de calidad en todo el mundo. Por otro lado, los errores en una ubicación específica a menudo son consecuencia de errores a miles de kilómetros de distancia, en la zona de generación o propagación. Por ejemplo, el Océano Antártico es la región que actualmente presenta mayores errores; en parte porque es un área muy compleja desde el punto de vista del modelado y en parte por la tradicional escasez de medidas instrumentales en el hemisferio sur. No obstante, es crucial reducir dichos errores, ya que constituye la zona de generación de swells muy energéticos que alcanzan las costas de regiones mucho más pobladas.

La forma de más obvia de reducir errores es utilizar forzamientos (i.e., viento, hielo y corrientes) de mayor calidad. En este análisis se han utilizado y comparado las bases de datos más recientes para obtener la combinación de forzamientos que resulta en menores errores en el modelado de oleaje a escala global. Como es habitual en han analizado vientos y cobertura de hielo, en este caso del reanálisis CFSR generado por NCEP-NCAR y del reanálisis ERA5 generado recientemente por el centro europeo para predicciones de medio plazo (ECMWF). Adicionalmente, se han analizado el efecto de la probabilidad de icebergs derivada de imágenes de satélite y de las corrientes oceánicas de tres bases de datos: CFSR, HYCOM y GLORYS. La evaluación de los resultados se ha basado principalmente en mediciones de satélite, pero se ha complementado con boyas y drifters recientemente desplegados en Australia y Nueva Zelanda.

2.       Resultados y conclusiones

La comparación entre experimentos con distintos forzamientos se ha basado en el modelo numérico WaveWatch III en su versión 5.16 utilizando los términos fuente ST4. La configuración de referencia es una malla global de 0.5 grados por 0.5 grados, forzada con vientos y cobertura de hielo de CFSR, sin icebergs ni corrientes. La mejora de mayor magnitud respecto a esta configuración se obtiene al sustituir CFSR por ERA5, lo que reduce notablemente el sesgo y el error cuadrático en la mayor parte del mundo. Estos resultados indican que las mejoras en resolución, asimilación de datos, o modelado de ciclones tropicales respecto al anterior reanálisis del ECMWF han conseguido que actualmente ERA5 sea la opción más adecuada para forzar modelos globales de oleaje. La inclusión de corrientes también produce mejoras a nivel global pero de una magnitud menor. En concreto las tres bases de datos de corrientes ayudan a reducir los sesgos, siendo GLORYS la que produce mejores resultados a pesar de tener menor resolución espacial que HYCOM y menor resolución temporal que CFSR. Es especialmente notable la reducción del sesgo positivo en el Océano Antártico, principalmente por el efecto de la corriente circumpolar antártica, que reduce la transferencia de energía del viento al oleaje. No obstante, incluso con la introducción de corrientes sigue existiendo un sesgo positivo. Este sesgo se reduce aún más con la inclusión de icebergs, que aumentan el bloqueo de energía, pero no llega a desaparecer por completo. La comparación entre el sesgo de la configuración de referencia y el de la configuración óptima para el año 2015 se muestra en la figura 1. La comparación de errores cuadráticos (no mostrado) indica mejoras globales en torno al 30%.

fig 1-top.png
Fig. 1. Sesgo respecto a datos de satélite de la simulación global forzada con vientos de ERA5, icebergs, y corrientes GLORYS (panel superior) y la simulación de referencia, forzada con vientos de CFSR y sin icebergs ni corrientes (panel inferior) para el año 2015.

Fig. 1. Sesgo respecto a datos de satélite de la simulación global forzada con vientos de ERA5, icebergs, y corrientes GLORYS (panel superior) y la simulación de referencia, forzada con vientos de CFSR y sin icebergs ni corrientes (panel inferior) para el año 2015.

Este análisis a escala global y la reconstrucción histórica resultante ha permitido minimizar los errores en los datos de oleaje en aguas profundas y disponer de mejores condiciones de contorno para las mallas de detalle en zonas costeras. Adicionalmente, lecciones aprendidas de este análisis, como la importancia de corrientes y icebergs, van a resultar en mejoras en los sistemas operacionales de predicción de oleaje de Metservice. Esto permite proporcionar a los usuarios datos históricos y predicciones de oleaje de la mayor calidad posible.

Agradecimientos

Se agradece el apoyo a este estudio tanto de la armada de Nueva Zelanda (NZ Navy) como de la oficina de investigación naval (Office of Naval Research, ONR) por medio de la subvención NOOO14-17-S-B001.

Referencias

DURRANT, T., GREENSLADE, D., HEMER, M. y TRENHAM, C. (2014). “A Global Hindcast focussed on the Central and South Pacific”. CAWCR Technical Report , 46.

PEREZ, J., MENENDEZ, M. y LOSADA, I. J. (2017). “GOW2: A global wave hindcast for coastal applications”. Coastal Engineering, 124 , 1-11.

Drifting wave buoys pass the Drake Passage

In February 2018, MetOcean Solutions deployed five solar powered wave buoys (Spotters) in the Southern Ocean in partnership with Spoondrift and the Defence Technology Agency. Now, one year later, these buoys have travelled more than 6500 km and are currently crossing the stormy waters of the Drake Passage, the body of water between South America’s Cape Horn and the South Shetland Islands.

 
DRIFT TRACK AND SIGNIFICANT WAVE HEIGHTS MEASURED OVER THE LAST year.

DRIFT TRACK AND SIGNIFICANT WAVE HEIGHTS MEASURED OVER THE LAST year.

 

The Southern Ocean programme is helping understand waves in the region and their impact on the climate system. The operation was led by MetOcean Solutions’ Technical Support Liaison Dr Aitana Forcén-Vázquez, Principal Investigator for Physical Oceanography aboard the Research Vessel Tangaroa on the science voyage to Antarctica with NIWA and the University of Auckland.

“The buoys were deployed in the Southern Ocean, home to the strongest current on Earth; the Antarctic Circumpolar Current. The Southern Ocean is the circular ocean that flows uninterrupted around Antarctica and occupies almost one quarter of all the world’s oceans. It plays an important role in the climate system, cycling heat, carbon and nutrients. Persistent storms and the lack of landmass in the Southern Ocean result in large fetches and strong winds - ideal conditions for generating large waves,” states Forcén-Vázquez.

MetOcean Solutions’ Science Development Manager Dr Tom Durrant says, “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.”

This is the first time that this kind of wave buoy has been deployed in the Southern Ocean. It is the perfect scenario to test the response of this new technology in an energetic open ocean. If effective however, they could revolutionise the way we monitor remote ocean basins through a constellation of drifting buoys.

 
The wave buoys (Spotters) deployment. Photo: Aitana Forcén-Vázquez.

The wave buoys (Spotters) deployment. Photo: Aitana Forcén-Vázquez.

 

“These buoys (Spotters) are surprisingly easy to deploy, very light and easy to handle, and can be lowered in the water by hand using a line. As a result, you can deploy them in almost any kind of conditions, which greatly facilitates Southern Ocean operations,” complements Forcén-Vázquez.

Spoondrift developed the Spotter buoy as a citizen sensor to drive distributed ocean sensing and democratized data access. Tim Janssen, CEO of Spoondrift, explains “The Spotter buoy is designed to be easy to use, low-cost and solar-powered. From the Spotter Dashboard the user can access data and change settings on the device. The current generation Spotters have a battery protection feature that triggers a hibernation mode during extreme temperatures and extended periods of darkness in the Southern Ocean winter. Spoondrift continuously innovates its technology to simplify deployments and provide high-latitude options to ensure continuous data acquisition in extreme conditions”.

In addition to the five drifting buoys, MetOcean has the world’s southernmost open ocean moored buoy which last year recorded the highest wave in the Southern Hemisphere.

In recognition of the importance of this programme of work, this data is freely available to the scientific community.

MetOcean Solutions is a science-based consultancy wholly owned by MetService. MetOcean specialise in providing numerical modelling and analytical services in meteorology and oceanography.

A record wave height measured in the Southern Ocean

Last night, the MetOcean Solutions wave buoy moored in the Southern Ocean recorded a massive 23.8 m wave.

so-wave.png

“This is a very exciting event and to our knowledge it is largest wave ever recorded in the Southern Hemisphere,” says Senior Oceanographer Dr Tom Durrant. “Our own previous record was one year ago when we measured a 19.4 m wave, and before that in 2012  an Australian buoy recorded a maximum individual wave (Hmax) of 22.03 m. So, this is a very important storm to capture, and it will add greatly to our understanding of the wave physics under extreme conditions in the Southern Ocean.”

“However, it is likely that the peak heights during this storm were actually much higher, with individual waves greater than 25 m being possible as the wave forecast for the storm show larger wave conditions just north of the buoy location. Also, to conserve battery during the one year deployment, the solar-powered buoy samples the waves for just 20 minutes every 3 hours then sends the data via a satellite link. During that 20 minute recording period, the height, period and direction of every wave is measured and statistics are calculated. It's very probable that larger waves occurred while the buoy was not recording.  

“The Southern Ocean is a unique ocean basin and is the least studied despite occupying 22% of the global ocean area. The persistent and energetic wind conditions here create enormous fetch for wave growth, making the Southern Ocean the engine room for generating swell waves that then propagate throughout the planet - indeed surfers in California can expect energy from this storm to arrive at their shores in about a weeks time! Yesterdays storm is the perfect example of waves generated by the easterly passage of a deep low pressure system with associated wind speeds exceeding 65 knots. Such storms are frequent and can occur at any time of the year, which differs from the high latitude northern hemisphere storms that only occur in winter. What is interesting about yesterday's event is the storm speed appears to match the wave speed, allowing wave heights to grow dramatically as the system tracks eastward.”

Simulation of the storm: wind and mean sea level pressure (left) and significant wave height (right) passing over south New Zealand.

Simulation of the storm: wind and mean sea level pressure (left) and significant wave height (right) passing over south New Zealand.

“This is exactly the sort of data we were hoping to capture at the outset of the program,” says MetOcean Solutions General Manager Dr Peter McComb, who led the deployment of the buoy in March onboard the HMNZS WELLINGTON. “ We know that the speed of these storms plays an important role in the resultant wave climate and that has great relevance under both the existing and climate change scenarios.”

The ‘significant wave height’ is the WMO standard value to characterise a sea state - approximately the average of the highest third of the measured waves. During this storm, the significant wave height reached 14.9 m. This is also a record for the Southern Ocean, but falls short of the 19 m world record buoy measurement that was recorded in the North Atlantic during 2013.

The Campbell Island Wave Rider Buoy was moored on 2 March 2018 at Campbell Island, New Zealand’s southernmost estate and an ideal spot to sample the complex directional wave spectra from the Southern Ocean.

The Southern Ocean wave studies are a collaborative project with New Zealand Defence Force, Defence Technology Agency and  Spoondrift. As part of that program, MetOcean Solutions has deployed seven instruments to collect wave data, using one moored and six drifting buoys. All data is freely available to the scientific community and can be viewed in real time. For further information and data access see www.metocean.co.nz/southern-ocean/ or contact us at enquiries@metocean.co.nz.

MetOcean Solutions is a wholly owned subsidiary of state-owned enterprise, Meteorological Service of New Zealand (MetService). MetService is New Zealand’s national weather authority, providing comprehensive weather information services, to help protect the safety and well-being of New Zealanders and the economy.

Southern Ocean Wave Buoy – Update

In 2017, MetOcean Solutions partnered with New Zealand Defence Force and Defence Technology Agency to deploy a scientific wave buoy in the Southern Ocean. Moored 11 km south of the remote Campbell Island, the buoy collected 170 days of great data - including the May 2017 storm with a whopping 19.4 m wave! By July however, the perpetually rough seas caused fatigue in the mooring line and the buoy started on a new and rather intrepid journey toward Chile.

The buoy was launched on 2 March 2018.

The buoy was launched on 2 March 2018.

“It is still sending us valuable data while drifting,” says oceanographer Dr Tom Durrant. “We are now seeing high quality wave measurements coming in from some of the remotest locations on Earth; it is extremely valuable data for our research.”

Meanwhile, the mission to collect wave data for NZ Navy’s SubAntarctic applications continues, and this year’s initiative has seen another wave buoy positioned at Campbell Island. This is New Zealand’s southernmost estate and an ideal spot to sample the complex directional wave spectra from the Southern Ocean. On 2 March 2018, MetOcean Solutions manager and senior oceanographer Dr Peter McComb led the buoy deployment from the Offshore Patrol Vessel HMNZS WELLINGTON, with support from Sally Garrett and William Coldicutt from the Defence Technology Agency.

Offshore Patrol Vessel HMNZS WELLINGTON.

Offshore Patrol Vessel HMNZS WELLINGTON.

“The crew of HMNZS WELLINGTON undertook the task with utmost professionalism and detailed planning to ensure a safe and successful execution,” says Peter. “In 2.5 m seas and light winds, the new wave buoy and its mooring were carefully placed at the same site as last year.”

This year however, the mooring design has been modified to better suit the harsh conditions and reduce the risk of mooring failure before the servicing mission next summer.

“We have to find the right balance for robustness in the mooring system while maintaining scientific integrity of the data. It is certainly a challenge working in these southern latitudes,” admits Peter. “But every month of data adds significantly to our knowledge of this ocean basin, so it’s a very worthy challenge”.

All data from the wave buoy programme is openly available for research, and interested members of the public can check the Southern Ocean wave conditions in real-time at http://www.metocean.co.nz/southern-ocean.

Aitana Forcén-Vázquez heading to Antarctica

Aitana with the wave drifter buoys on board Tangaroa.

Aitana with the wave drifter buoys on board Tangaroa.

On February 9, Dr Aitana Forcén-Vázquez headed to Antarctica aboard the research vessel Tangaroa on a six week science voyage with colleagues from NIWA and the University of Auckland.

Aitana’s role as Principal Investigator for Physical Oceanography is to support instrument deployment and data collection, including the deployment of 9 drifting wave buoys for MetOcean Solutions and the New Zealand Defence Technology Agency.

“I am delighted to be part of this important voyage,” says Aitana. “I have been to Antarctic waters once  before, but this time we are going much closer to the continent, which will make for a very interesting trip.”

Tangaroa leaving Wellington on 9 February 2018.

Tangaroa leaving Wellington on 9 February 2018.

The research project, entitled ‘Taking the pulse of the Ross Sea outflow’ focuses on collecting data to further the understanding of water movement between the shallow shelf and the deeper ocean. How the Ross Sea outflow changes over time is important for our understanding of future Southern Ocean and South Pacific climate.

During the voyage, Aitana will contribute to the mission blog, which can be found at www.oceanphysicsauckland.co.nz

Drifting wave buoy caught in Southern Ocean eddy

The drifting Southern Ocean Wave Buoy is going round in circles deep in the Southern Ocean, temporarily slowing down its steady passage east across the southern margin of the Pacific. 

The buoy is caught in an eddy, a circular movement of water created when a bend in a surface ocean current pinches off to make a loop, which separates from the main current. 

The buoy, which has been drifting with the ocean currents since it left its moored location on 28 July, was deployed south of Campbell Island in February 2017. Part of a collaborative research project involving the Defence Technology Agency and MetOcean Solutions, the buoy has been transmitting wave spectra data via a satellite link, providing vital information which will help the New Zealand Defence Force to design patrol ships suited to the rough seas of the Southern Ocean. 

In the two and a half months since its escape, the buoy has drifted some 450 nautical miles east-northeast. In late September, the buoy passed within 20 nautical miles of the remote uninhabited Antipodes Island group.

Senior Oceanographer Dr Peter McComb is happy that data is still being transmitted. "The buoy is solar powered, and we were expecting the batteries to run out during the subantarctic winter. However, it is still happily sending wave spectra data from its path drifting slowly eastwards along the southern margin of the Pacific Ocean. So far, it has encountered moderately rough seas, with significant wave heights of up to 9 m and maximum wave heights of 15 m. 

"The prevailing winds and ocean currents in this region are towards the east, however, the buoy track meanders significantly as the drift is influenced by ocean eddies within the Antarctic Circumpolar Current. The average drift speed is about 1 km per hour, but the net eastward drift is about half that. The buoy has been trapped in an eddy for the last three weeks, resulting in almost no net drift. The eddy is unlikely to last long, and the buoy will soon be released and continue drifting east. From now on, there are very few islands in the way - if it continues due east at the current speed, it will get to the west coast of South America in about a year and a half. However, a strong southerly blow in the next few weeks could push it north toward the Chatham Islands, and if that happens we might launch a recovery mission.”  

In May 2017 the buoy made headlines when it measured a monster 19.4 m wave from the moored location near Campbell Island. 
 

Map wave buoy.PNG

Southern Ocean wave buoy heading for Chile!

On Friday 28 July, New Zealand’s Southern Ocean Wave Buoy started drifting eastward with the ocean currents.  
 
"We're not exactly sure what happened," advises oceanographer Dr Peter McComb. "However it’s likely the compliant bungy section of the mooring failed under the extreme wave conditions down there. Since February 2017, the maximum wave heights have exceeded 10 m for 26% of the time, and there are very few places on our planet that energetic. At the start of the project there were many uncertainties. Would there be enough solar power to keep it alive during the deep south winter? Would the mooring survive the constant stresses and ride out the ferocious storms? Ultimately, we are very pleased to have succeeded in our goal of making almost 6 months of very detailed spectral measurements at this location in the sub-Antarctic.”

The HMNZS OTAGO deployed the buoy in February 2017 for a collaborative research project between the Defence Technology Agency and MetOcean Solutions. From the chilly waters just south of Campbell Island, the buoy has been sending back vital wave spectral data via a satellite link. These data will now be used by the New Zealand Defence Force to design the next class of patrol ships suited to the harsh Southern Ocean climate. MetOcean Solutions have a research project to develop a global wave model with improved performance in the Southern Hemisphere, and will use the data to verify the next generation of model physics. The wave data will also be made freely available to the international research community. The Southern Ocean is known to play an important role in the climate system - cycling heat, carbon, and nutrients. Waves modulate the air-sea fluxes and the swells generated in this region have far-reaching effects, contributing significantly to the wave climate in all the major ocean basins. 

Drift track and significant wave heights measured over the last 14 days.

Drift track and significant wave heights measured over the last 14 days.

Another positive outcome is the realisation that our research project is not over yet - the buoy continues to measure wave spectra and send its data via the satellite link as long as there is sufficient solar power.  

“Now we have a new and unique opportunity to make ongoing Southern Ocean wave measurements at the very extremity of the planets’ largest ocean – the Pacific. It’s highly valuable data for oceanographers," says Peter. “Conceivably, it might take over a year to reach Chile, which would make a fantastic and very significant dataset. Let’s hope there is enough sunlight to keep powering the system during this journey.”   

MetOcean Solutions plans to deploy another wave buoy at the Campbell Island site in February 2018, with the goal of establishing a long term sub-Antarctic wave monitoring station.

“The international ocean research community recognises the value of detailed wave spectra collected at this remote location,” notes Peter, “and Campbell Island is the perfect site to make baseline measurements for climate change studies as well improving our fundamental understanding of wave physics at a planetary scale. New Zealand can make a very practical contribution to global oceanography by making high quality, real-time measurements from this site. As a nation, we are very fortunate to have some Deep South real estate with a great harbour. It’s got a lot of potential for meaningful, long term research.” 

The buoy was deployed in February 2017.

The buoy was deployed in February 2017.

Monster wave measured by Southern Ocean Wave Buoy

Earlier today, MetOcean Solutions' wave buoy in the Southern Ocean recorded a whopping 19.4 m wave.

Senior Oceanographer Dr Tom Durrant is thrilled. "This is one of the largest waves recorded in the Southern Hemisphere," he explains. "This is the world's southern-most wave buoy moored in the open ocean, and we are excited to put it to the test in large seas."

Persistent westerly winds and unlimited fetch combine to make Southern Ocean waves among the biggest in the world. Sub-Antarctic waters are difficult to work in, and reliable wave data for the area is scarce. The buoy was deployed in a collaboration between the New Zealand Defence Force and MetOcean Solutions aiming to get valuable observations from this remote part of the ocean. Such observations will enable better forecasting and design of vessels built to withstand Southern Ocean conditions. Moored in a water depth of 150 m, the buoy is located within the New Zealand Exclusive Economic Zone, 11 km south of Campbell Island. 

"The buoy is performing extremely well so far," adds Tom. "Not only is it surviving these large waves, but it is making detailed recordings of extreme sea states in the Southern Ocean, a region rarely observed by in-situ instruments. During the depths of winter, Southern Ocean waves are enormous, with significant wave heights averaging over 5 m, and regularly exceeding 10 m. Individual waves can double that size. Accurate measurements of these conditions will help us understand waves and air-sea interactions in these extreme conditions. This, in turn, will lead to improvements in the models used to simulate the waves, providing better forecasts, both for the Southern Ocean and for the wider region. Waves generated in the Southern Ocean have far-reaching effects, contributing significantly to the wave climate in all the major ocean basins."

The Southern Ocean Wave Buoy data are freely available from MetOcean Solutions. View the data here or contact us by emailing enquiries@metocean.co.nz.

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." 
 

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