MAP-IO: a marine and atmospheric observatory aboard the Marion Dufresne

© Léa Gest

From 11 January to 8 March, the SWINGS oceanographic expedition surveyed the southwest Indian Ocean with a team of 48 scientists aboard the Marion Dufresne II to explore the Southern Ocean’s role in regulating Earth’s climate. Teams at Data Terra’s ODATIS and AERIS data hubs were also involved in some of the campaign’s studies and in the fledgling MAP-IO observatory.

Exploring the Southern Ocean with SWINGS

The SWINGS oceanographic expedition’s goal was to gain new insights into how atmospheric CO2 is sequestered in the oceans, particularly where the chemical elements vital to storing it come from and how the oceans transport and transform them.

The Southern Ocean encircling the Antarctic is a remote, inaccessible region that plays an important and complex role in capturing and storing atmospheric CO2. Many factors are at play, from biological activity to ocean circulation. To study these processes, we need to quantify geochemical elements—silicon, nitrates and iron, as well as radium and rare-earth elements, for example—present in minute concentrations in sea water.

SWINGS is a French contribution to the international GEOTRACES programme that has been compiling data on geochemical trace elements since 2010 with a view to building a chemical atlas of the oceans. The French assembly centre for GEOTRACES is the LEFE-CYBER geochemical database at the ODATIS data hub’s CDS-IS-IMEV in-situ data centre.

The MAP-IO project team was among the other teams working alongside the SWINGS project scientists.

Studying global changes with MAP-IO

MAP-IO (for Marion Dufresne Atmospheric Programme – Indian Ocean) is an observatory in development that aims to study ocean-atmosphere processes over the long term to gain a deeper understanding of their impacts on climate and numerical weather predictions. This programme has fitted out the Marion Dufresne II with 19 semi-autonomous measuring systems dedicated to observing the atmosphere and marine biology. MAP-IO subsequently aims to ensure retention of observations within the data hubs in line with quality standards defined by research infrastructures.

The Marion Dufresne II ferries personnel, food, equipment and fuel to France’s sub-Antarctic islands roughly 120 days a year, sailing to remote territories like the Kerguelen Islands, the Crozet archipelago, Amsterdam Island and occasionally the Scattered Islands in the Indian Ocean. It is therefore both a transport ship and a scientific research vessel with 650 m2 of laboratory space. MAP-IO takes advantage of these rotations between the French Southern and Antarctic Lands (TAAF) and survey campaigns planned by the French Oceanographic Fleet (FOF) to explore scarcely documented scientific fields of investigation over long periods in a still largely unexplored region of the globe. The repetitive routes of TAAF sailings will enable the study of seasonal and climatic trends.

These interannual observations fulfil six multidisciplinary objectives:

  • Document oceanic sea surface state and biological composition (phytoplankton)
  • Monitor global atmospheric variations, particularly in the sparsely documented Indian Ocean and Southern Ocean
  • Study air mass transports and redistribution of aerosols and chemical compounds in the troposphere and stratosphere
  • Document gas and marine aerosol emissions for atmospheric numerical prediction or climate models
  • Ensure open data retention
  • Strengthen regional climate change observation networks deployed for the ReNovRisk Cyclones and Climate Change (INTERREG-V), IOGA4MET (TAAF, Scattered Islands call for projects) and UV-Indian (INTERREG-V) programmes

MAP-IO is a consortium of eight research laboratories and 21 scientists coordinated by the LACy atmosphere and cyclones laboratory and the University of La Réunion. It is funded by the European Regional Development Fund (ERDF), a CPER regional development plan, the FOF and CNRS’s INSU national universe science institute.

The current programme is planned to run for four years. It began in September 2020 and entered its operational phase with the launch of the SWINGS mission on 11 January 2021. It will take another two to three years to develop and secure the observatory in the long term. It has to follow a dedicated quality protocol and get all of its instruments accredited. At the end of this period, if MAP-IO is accredited by CNRS/INSU, it will become the only permanent mobile observatory of its kind in the world.

Example data collected by MAP-IO during SWINGS:

Comparison of ozone column measured by the onboard Mini-SAOZ spectrometer (MS_MD) and TROPOMI satellite instrument. Mini-SAOZ observations from a mobile platform like the Marion Dufresne enable scientists to match ground stations on Kerguelen and Réunion with similar NDACC-accredited instruments and to validate different satellite measurements in the Indian Ocean. The first results show good agreement between MS_MD and TROPOMI observations, with a bias of less than 1% and a correlation coefficient of 0.93 during the SWINGS campaign. © Andrea Pazmino (LATMOS)

AERIS and ODATIS working towards data retention

With regard to data dissemination, MAP-IO plans to feed the major observation networks attached to the ACTRIS, ICOS and OHIS research infrastructures via INSU’s national observation departments (CLAP, PHOTON, NDACC, RAMCES, COOL/OISO) and the AERIS and ODATIS data hubs. All data will be deposited for open access and stored on OSU’s GeoSUR platform in La Réunion.

Data Terra’s AERIS and ODATIS hubs are supporting these new observations and will be stakeholders in the project, notably for retention of atmosphere (AERIS) and oceanography (ODATIS) data.

The data distribution model is in construction and not yet standardized. Data will be progressively referenced in the data hubs’ catalogues.

ODATIS’s flow cytometry scientific expertise consortium (CES) is also involved through a flow cytometer aboard the Marion Dufresne II. Flow cytometry provides a way of classifying micro-organisms and phytoplankton into functional groups, each defined by cells with similar optical properties, to determine their abundances. The goal of this CES is to federate a scientific community to retain, share and disseminate all these environmental flow cytometry data in line with FAIR principles.

Cytosense measures a sample of sea water pumped continuously from the surface. This instrument analyses cells of phytoplankton of all sizes one by one. Collected images aid taxonomic recognition of micro-phytoplankton and large nano-phytoplankton. Cytograms (bottom left and right) enable cell abundances to be quantified from the smallest to the largest (Synechococcus, pico-eukaryotes, nano-eukaryotes and micro-phytoplankton are illustrated here). These two cytograms collected during SWINGS missions show the optical diversity of groups encountered (red fluorescence (proxy for chlorophyll a) versus forward scatter (proxy for size). © Melilotus Thyssen (MIO)

Learn more

➡️ MAP-IO programme website

➡️ GEOTRACES website: SWINGS campaign log

➡️ LACy website: Measurements on the Marion Dufresne – MAP-IO