Marine Mammals Exploring the Oceans Pole to Pole

When diving animals help us to observe the oceans

Over 800,000 vertical profiles of Temperature and Salinity have been collected since 2004 in the World Ocean by attaching tags on marine mammals, such as Southern elephant seals.

In this website, you will find information about the marine mammal tagging programs, and an access point to the publicly available databases.

Please let us know if you are using our data. You can contact us by mail to if you have any question.

The MEOP data portal

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Content of the website

The MEOP-CTD_2024-03-08 database now available

Sunday, 10 March 2024

The new version of the MEOP-CTD database is now available. The MEOP-CTD database version 2024-03-08 is a major update on the previous version, with more than 150,000 new profiles. The number of CTD profiles is now exceeding 800,000.
As in the previous version, the post-processing includes all the features presented in Siegelman et al., 2019, with in particular the removal of density inversion and a correction for the thermal cell effects. Check out the page on Data processing for more information. 

The code used to process the data is available on a public GitHub repository.
In parallel, the AniBOS network, an emerging GOOS network endorsed as an Ocean Decade Action, is pursuing its work toward a better integration of animal-borne sensors into the Global Ocean Observing System.
To follow us, subscribe to the AniBOS twitter account.

The MEOP-CTD_2021-11-26 database now available

Thursday, 25 November 2021

After a long (long) wait, the new version of the MEOP-CTD database has finally arrived. The MEOP-CTD database version 2021-11-26 is a major update on the previous version:
The post-processing now includes all the features presented in the publication by Siegelman et al., 2019, with in particular  the removal of density inversion and a correction for the thermal cell effects. Check out the page on Data processing for more information. 
Also, there is of course more recent data in the new release, and the number of CTD profiles is now exceeding 600,000. 
Finally, an enormous work has been done to transition the processing from Matlab to python. The code is available on a public GitHub repository. This should help scaling up the data flow in the future, and we expect this means that the MEOP database is about to expand dramatically in the next few months. Stay tuned to hear more about it when it happens.
In parallel, we are working hard on the new AniBOS network, which rep

Observing near-surface meltwater exiting from beneath Pine Island Glacier, Antarctica

Tuesday, 29 June 2021

Yixi Zheng is a PhD student working on physical oceanography at the Centre for Ocean and Atmospheric Sciences, University of East Anglia, UK. She is interested in the interactions between sea ice, ice shelves and ocean in Antarctic continental shelf seas, and how they affect ice-shelf melting and our future climate through upper-ocean processes. In a recent Nature communication paper, she used MEOP data, combined with ship-based observations to reveal the wintertime meltwater distribution in front of Pine Island Glacier for the very first time. They show that the wintertime meltwater surfaces and provides near-surface heat that helps to maintain polynyas close to ice shelves.

Pine Island Glacier is melting rapidly and exporting glacial meltwater into the ocean. The glacial meltwater is thought to play a role in hydrography and sea ice distribution but it is poorly observed and its pathways poorly known due to the sparse observations, especially in winter. In this study we turn...

There is much more supercooled ocean water on planet Earth than previously noticed

Tuesday, 15 December 2020

Dr. Alexander Haumann is an Associate Research Scholar at the program in Atmospheric and Oceanic Sciences at Princeton University, USA. He is interested in the interaction between the ocean, ice, and atmosphere in the Southern Ocean and how these processes affect our climate through their influence on the exchange of heat and carbon between the deep ocean and the atmosphere. In a new study, he analyzed MEOP, Argo and ship-based observations to provide first estimates of the horizontal and vertical extent of supercooled waters in the Southern Ocean and analyzed their underlying processes.

Supercooled ocean water refers to seawater that has a temperature lower than the reference freezing point. In our analysis, we combine all available data collected by instrumented marine mammals, data from profiling floats, and ship-board observations in the Southern Ocean to study this process. While supercooling has been previously found in certain coastal locations due to melting of Antarctic...

Submesoscale flows described during the Southern Ocean winter for the first time

Wednesday, 3 June 2020

Dr Louise Biddle is a researcher at the University of Gothenburg, Sweden. She is interested in the interactions between ice and ocean around Antarctica, with research focusing on both glacial meltwater and sea ice-ocean dynamics to understand how these processes affect the upper ocean. Using the MEOP database, she and co-author Dr Sebastiaan Swart described the variability in submesoscale processes under sea ice during the Southern Ocean winter for the first time, highlighting a significant submesoscale flux during the winter months of August and September (Biddle and Swart, 2020).
Submesoscale processes occur on small (1-10 km) and short (< day) scales, but can have a significant impact on vertical oceanic fluxes. Due to their submesoscale resolution, until recently they have been hard to observe – particularly so in the Southern Ocean. The oceanic uptake of heat and carbon in this region is of global significance and understanding any processes that can contribute to their v

Pathways of warm water across the Antarctic slope

Friday, 21 February 2020

This is a sample blog postDr. Annie Foppert is Postdoctoral Fellow in the Centre for Southern Hemisphere Oceans Research at CSIRO Oceans and Atmosphere in Hobart, Tasmania. She is interested in the dynamics, circulation, and water-mass transformation of the Southern Ocean. Using the MEOP-CTD database, she and co-authors quantified eddy-driven transport of Circumpolar Deep Water across the East Antarctic slope and identified hotspots of this onshore transport.

The transport of relatively warm and salty water (known as Circumpolar Deep Water, CDW) from the open ocean to the Antarctic continental shelf has global significance. The amount of warm water that reaches the ice shelves regulates how quickly the ice melts which affects sea levels rise. At the same time, the amount of salt on the continental shelf regulates how much heat and carbon are stored in the deep ocean through dense water formation. Yet, the ways in which this circumpolar deep water makes it across the slope and onto...

MEOP-SMS: a new database for submesoscale-resolving CTD data

Thursday, 16 May 2019

It is with great excitement that we are finally able to present you a brand new MEOP product, the MEOP-SMS database.
The MEOP-SMS database is a collection of CTD data gathered with CTD-SRDLs attached to elephant seals. The CTD-SRDLs were set in continuous recording mode, and could be recovered in the field, enabling retrieval of the entire CTD archive at the sampling frequency (0.5 Hz) for periods of several months. Instruments were deployed at the Kerguelen Islands and at Peninsula Valdes (Argentina) as part of the SO-MEMO program led by Christophe Guinet (CEBC/CNRS, France).
A set of 28 CTD-SRDL datasets is now available in the MEOP-SMS database, with a typical number of 50-100 profiles/day in the highly energetic oceanic regions around the Kerguelen Plateau and across the Argentine shelf break. With such a high sampling frequency, it becomes possible to observe directly the ocean submesoscale variabilibity for extended periods of time. 
A description of the dataset and the...

Elephant seals enjoy fine-scale fronts

Wednesday, 15 May 2019

Lia Siegelman is a graduate student at the University of Western Brittany, France, and currently a visiting student at Caltech/Jet Propulsion Laboratory in the US, studying fine ocean fronts (<50 km), known as submesoscale fronts. Here, she describes recent research that seeks to understand the distribution of these fronts in the under-sampled area of the Southern Ocean as well as their influence for higher trophic levels. 

Advances in theory and modeling of the last two decades suggest that submesoscale fronts are a conspicuous feature of the ocean. In particular, they are thought to play a key role in the transport of heat, carbon and nutrients between the atmosphere and the ocean. Yet, little is known about them in the real ocean as their short lifetime (< week) and small size (<50 km) make them hard to observe directly.
In a recently published study (Siegelman et al. 2019a), we used newly available CTD data collected by a single female southern elephant seal (Miroung

Ringed seals like meltwater plumes

Wednesday, 20 February 2019

Alistair Everett is a Research Scientist at the Norwegian Polar Institute interested in ice-ocean interactions at marine-terminating glaciers. Here he describes recent research as part of the TIGRIF project, which seeks to understand the influence of tidewater glaciers on fjord dynamics and marine ecosystems, with particular focus on how these fjords may change in future when the glaciers retreat onto land.

In a recently published study (Everett et al. 2018), we investigated the water properties close to a glacier terminus in Kongsfjorden, northwestern Svalbard using a unique dataset collected by ringed seals (Pusa hispida) instrumented with GPS-CTD-SRDLs in 2012. The dataset had already been used to look at seal behaviour and their response to variations in sea ice (Hamilton et al., 2016). But in this new study the focus was instead on glaciology and the meltwater plume that could be observed very close to the glacier terminus; a place where it remains otherwise very challenging...

Amundsen Sea data and Northern Seas data released in the public domain

Tuesday, 10 April 2018

A new release of the MEOP-CTD database is available publicly (version MEOP-CTD_2018-04-10) that now includes :
the deployment ct104 (M. Fedak, SMRU), obtained as part of the iSTAR A Programme (PI: K. Heywood, UEA)
A large number of deployments on hooded seals and harbour seals carried outover the previous decade by researchers at the Norwegian Polar Institute (PI: Kit Kovacs and Christian Lydersen).
Note also that the list of publication has been updated with more than 10 publications in 2017 and already 5 publications in 2018.

New release of the MEOP-CTD database

Saturday, 11 November 2017

A new release of the MEOP-CTD database is now available. In this new release, about 80 CTD-SRDL tags have been added.
The data processing has been improved, with in particular two additional steps ensuring a better accuracy of salinity data:
A thermal cell effect correction has been applied on the entire database. Details of the method can be found in the following submitted manuscript:Mensah, V., Roquet, F., Picard, B., Pauthenet, E., Guinet, C., 2017.  A correction methodology for the thermal mass induced-errors of CTD tags mounted on marine mammals. In review in the Journal of Atmospheric and Oceanic Technologies. [PDF]
A density inversion removal algorithm is also applied, which seeks the minimum adjustment on the salinity profile to achieve neutral stability. The method is described in: Barker, P. M. and McDougall, T. J., 2017. Stabilizing Hydrographic Profiles with Minimal Change to the Water Masses. Journal of Atmospheric and Oceanic Technology, 34:1935-1945. doi: 10.11...

The MEOP review is out in Oceanography

Thursday, 7 September 2017

I am pleased to announce the publication of "Marine Mammals Exploring the Oceans Pole to Pole: A Review of the MEOP Consortium" by Anne Treasure et al. Marine Mammals Exploring the Oceans Pole to Pole: A Review o...
Another short note gives an overview of the current state of ocean observations using tagged animals: Ocean Observations Using Tagged Animals by Roquet et al.
These papers are part of the Special Issue on Autonomous and Lagrangian Platforms and Sensors (ALPS) in Oceanography, following the meeting ALPS ( that took place in San Diego last February and was aimed at developing a broad vision for ALPS technology, capabilities, infrastructure, and user base in the next decade, and in the coming decades.
Note that this special issue also include the following papers on new exciting technologies of great potential for bio-logging:
      Do Southern Elephant Seals Behave Like Weather Buoys? by Cazau et al.

Antarctic predators unravel the mysteries of the Weddell Sea

Thursday, 25 May 2017

Sara Labrousse is Doctor in Marine and Antarctic Science interested in the foraging ecology of southern elephant seals (Mirounga leonina) in relation to physiography, hydrological factors, and sea ice condition. She tells us here about her recent experience in the Weddell Sea, where she deployed CTD-SRDL tags on Weddell seals as part of an oceanographic cruise led by Jean-Baptiste Sallée (CNRS researcher at LOCEAN in Paris) on board the R/V James Clark Ross.  [French link:]  

In January-March 2017, I was involved in an oceanographic cruise led by Jean-Baptiste Sallée (CNRS researcher at LOCEAN in Paris) in the Weddell Sea aboard the British Antarctic Survey vessel, the James Clark Ross. 
The Weddell Sea is a unique region responsible for 50 - 70% of the formation of deep water in Antarctica, motor of the global thermohaline circulation regulating the Earth's climate. The Weddell Sea also harbors rich

The MEOP-CTD database in ODV has been updated

Thursday, 27 October 2016

The updated version of the MEOP-CTD database is now available in Ocean Data View as a ready-to-use data collection, thanks to Reiner Schlitzer (AWI, Germany):
Use ODV to explore MEOP-CTD data, easily plotting the data profiles, property sections and making beautiful horizontal maps with the DIVA gridding software.

Antarctic bottom water formation in Prydz Bay

Tuesday, 23 August 2016

Research published today in Nature Communications (Williams et al. 2016), and supported through the Australian Antarctic Program, has demonstrated that fresh water from Antarctic’s melting ice shelves slows the processes responsible for the formation of deep-water ocean currents that regulate global temperatures. 
A fourth production region for the globally important Antarctic bottom water has been attributed to dense shelf water formation in the Cape Darnley Polynya, adjoining Prydz Bay in East Antarctica. Here we show new observations from CTD-instrumented elephant seals in 2011–2013 that provide the first complete assessment of dense shelf water formation in Prydz Bay. After a complex evolution involving opposing contributions from three polynyas (positive) and two ice shelves (negative), dense shelf water (salinity 34.65–34.7) is exported through Prydz Channel. This provides a distinct, relatively fresh contribution to Cape Darnley bottom water. Elsewhere, de

Release of MEOP-CTD_2016-07-12

Monday, 11 July 2016

Already one year that the MEOP portal has been launched!
A very successful year for our growing community… in one year, 23 new publications using MEOP data have been added, increasing the number of MEOP-related peer-reviewed publications to 94. Simultaneously, the MEOP-CTD database has been included in major oceanographic data centres, including the NODC, Coriolis, and the BODC. More than 100 individual users have requested the database using the MEOP web interface.
It is now time to release a major update of the MEOP-CTD database. In this new version, namely the MEOP-CTD_2016-07-12, more animal-borne instrument data are included. The number of profile publicly distributed has increased from slightly less than 300,000 to almost 400,000 profiles. Also, 125,000 other profiles are included into the database, although they remain private, i.e. accessible only upon request. In total, the database has now reached the 500,000 profiles milestone.
Two datasets have been added in partic...

Unraveling the circulation and melwater distribution in the Bellingshausen Sea

Tuesday, 5 July 2016

Xiyue (Sally) Zhang is a PhD student in Environmental Science and Engineering at the California Institute of Technology. She here reporting on some exciting science recently published in the Geophysical Research Letters.
Xiyue Zhang in a mountain trek

The polar regions have long been fascinating to me, not only for their exoticness, but also their importance to the global climate. My thesis focuses on polar cloud dynamics, and I also worked closely with oceanographers at Caltech to enhance our understanding of ocean/ice shelf interactions in Antarctica.
We started by exploring data from 13 seals that were tagged in 2010. A couple of seals traveled all the way from the tip of the Antarctic Peninsula to t
he western Bellingshausen Sea shelf break. What really inspired us to focus on the Bellingshausen Sea is the observational study that showed high ice shelf basal melt rates in the region. Therefore, we decided to use all available data in the MEOP consortium in the Bellingshausen...

Fieldwork at Davis Station, Antarctica

Sunday, 19 June 2016

This is a sample blog postThis year the Integrated Marine Observing system (IMOS) Animal Tracking facility again sent a team of three researchers to Davis Station in Antarctica for the southern summer to partner with some unlikely research collaborators - southern elephant seals. Sophisticated Conductivity-Temperature-Depth (CTD) relay loggers were attached to the seals to collect ocean profiles from south of 60 degrees South.

Doctors Clive McMahon, Esther Tarszisz and Louise McMahon, all from the Sydney Institute of Marine Science, teamed up to build on ten years of ocean sampling by the Australian and French Antarctic Programs and IMOS between Iles Kerguelen and Prydz Bay. The CTD profiles that are currently being beamed back to us via the ARGOS satellite system build on the time-series of high-resolution oceanographic data that looks at annual variation in ocean structure and the formation of the globally important Antarctic Bottom Water.

This year the...

Where do olive ridley sea turtles go after nesting on the French Guiana beaches?

Wednesday, 16 March 2016

To describe the migration and diving behavior of the population of olive ridley sea turtles nesting in French Guiana, 18 females were satellite tracked using CTD-SRDL tags between 2013 and 2015. Results from this exciting study have just been published in Chambault et al. 2016, and are summarized below. 

Philippine Chambault, PhD student in ecology at IPHC (Strasbourg, France),taking measurements of a leatherback turtle

The olive ridley Lepidochelys olivacea is the smallest of the seven sea turtles species in the world (on average 36 kg for 70 cm), classified as vulnerable by the International Union for Conservation of Nature and known to have a carnivorous diet, feeding either on crustaceans, cephalopods, jellyfish or even small fishes. Such preys can be found in highly dynamic ecosystems, such as the western part of the Equatorial Atlantic, on the Guiana basin. This productive area is under the influence of the Amazon River plume and is also shaped by strong oceani

A trip to the Kerguelen Islands

Monday, 15 February 2016

Between December 18 2015 and January 18 2016, Fabien Roquet from the Stockholm University stayed on the Kerguelen Islands to put instruments on elephant seals. He is giving a short description of his amazing trip here.
For more than a decade now, I have been working with seal-derived oceanographic data, first as a data engineer, then as a PhD student and now as a researcher. Most of the time, this involves to stay seated in front of my computer screen. So much that it is sometimes easy to forget where these amazing data actually come from.
When Christophe Guinet proposed me to join the small team that would go to the Kerguelen Island this year to work on elephant seals, I joyfully accepted. Such opportunities are rare and priceless, plus it had been exactly ten years since I had visited the Kerguelen Islands and the best way to celebrate this anniversary was clearly to go there again.
On December 8, I embarked on board the R/V Marion Dufresne, the French ship that supplies the...

The MEOP-CTD database in ODV

Sunday, 11 October 2015

Thanks to the amazing work of Reiner Schlitzer from AWI (Germany), the MEOP-CTD database is now directly available on the Ocean Data View (ODV) webpage as an easy-to-use Data Entry. Check out the webpage:
Among the many things you can easily do with ODV, you can produce the following animations of seal data positions (color coding corresponds to measured surface temperature).

The MEOP-CTD database has been updated

Tuesday, 30 June 2015

The MEOP-CTD database has just been updated. It now contains more data, including the German and South African deployments. More than 330,000 profiles are now available.
In addition, a new data format is now available: the STD_ODV format is exactly like the ODV Spreadsheet format, except that CTD data are interpolated on standard depth levels !!
Please don’t hesitate to send us feedbacks on your use of the MEOP-CTD database !!
Fabien and the MEOP consortium

The MEOP portal is open

Monday, 1 June 2015

Welcome to the new shiny MEOP portal, home to the marine mammal oceanographers. This website is a natural place to present the MEOP consortium and its work. It is also the portal to the MEOP-CTD database. You can now find scientific and technical information on the database. News will be posted here regularly, about database updates, new deployments, new scientific studies or simply to share nice pictures. If you want to share your impressions or your work with us, please send us an email to