Publisher: Direction – Updated on 14/12/2020

Scientific objectives

The DYNOTROP team is built around a common object of study: the tropical oceans.

The team is interested in the dynamics of ocean currents at regional and basin scales, and in scale interactions. It is interested in the processes operating in the ocean surface layer, including fine-scale processes, and studies how the properties of this surface layer affect ocean-atmosphere interactions. Finally, it focuses on oceanic and atmospheric teleconnections to/from the subtropics, in relation to the dominant modes of variability in the tropics. The study of these modes of variability on interannual and decadal scales (ENSO (El Nino Southern Oscillation), IOD (Indian Ocean Dipole), PDO (Pacific decadal Oscillation), Atlantic zonal and meridional modes) is an important contextual element.

The research of the team is organized around 4 main axes:

• Tropical ocean dynamics: circulation and scale interactions (from finescales to basin scales). What are the mechanisms that govern the dynamics and variability of currents in the tropical band at different spatial (regional to basin) and temporal (sub-inertial to decadal) scales?
• The ocean surface layer and the ocean-atmosphere coupling. What are the processes that govern the variability of ocean surface layer properties (in terms of current shear, temperature, salinity, heat content, stratification, chlorophyll,…)? What are the impacts on ocean-atmosphere exchanges and on extreme events?
• Tropical-subtropical interactions. What are the mechanisms and impacts of oceanic and atmospheric teleconnections between the tropics and subtropics?
• Use and impact of observations in operational systems. Which sustained observing systems in the tropical Pacific and Atlantic oceans will be needed in the coming years to meet the needs of both research and operational forecasting systems?

Strategy and tools

To answer these questions, the DYNOTROP team relies on a wide range of tools, including numerical modeling, collection of in situ observations, and analysis of in situ and space-based observations. It is responsible for two National Observation Services – the Global Ocean Surface Salinity Network (SNO SSS) and the Tropical Atlantic Moorings Network (SNO PIRATA) – and has organized several cruises in the Tropical Atlantic (annual PIRATA cruises) and in the Southwest Tropical Pacific (MoorSPICE, CASSIOPEE).
The team is also involved in international observations projects (TPOS2020, TAOS). It is a user and producer of in situ data (organization of oceanographic cruises, deployment of gliders, moorings, Argo floats, drifters).

Team members also use satellite data (Jason altimetry satellites, AltiKa, Sentinel-3, MODIS water color satellites, etc…) and are involved in the definition and use of satellite missions, such as SMOS, SWOT and STREAM.

In terms of modeling, the researchers use and implement numerical simulations with community ocean models (NEMO, CROCO, SCHISM), atmospheric models (simple “in-house” model DREAM), coupled AO (WRF, SIMBAD), and coupled physical-biogeochemical (PISCES, BIO-EBUS). The team implements regional simulations for its needs, and develops numerical modeling tools for hydrodynamic connections between river mouths and the tropical ocean.

Projects

These issues are relevant to all three tropical basins.

In the tropical Atlantic, the study regions are the Amazon river plume, and the western boundary current system off Brazil; the cold  tongue of the equatorial upwelling and the Gulf of Guinea, key regions for the African climate; the Benguela upwelling, and the “Benguela Nino” phenomenon; the Caribbean Sea and the Gulf of Mexico, where complex mesoscale and submesoscale structures interact.

In the Tropical Pacific, the study regions are the Southwest Pacific and the western boundary current system of the Solomon Sea; the frontal region north of the equatorial cold tongue; and the Northeast Tropical Pacific, a tropical cyclone generation zone.

In the Indian Ocean, the study region is the Bay of Bengal.

This research relies heavily on southern partnerships strengthened in particular during long-term assignments of team members. These partnerships exist with Benin, South Africa, Mexico, Brazil, as well as New Caledonia, and the University of the South Pacific in Fiji.

News

Non classé

December 2022. D-1 before the launch of SWOT !

SWOT, the NASA/CNES high-resolution oceanographic and hydrological satellite mission, will make the first global survey of the Earth’s surface waters and of our changing oceans and coastal waters, over 90% of the Earth’s […]

Current thesis

Nonlinearities in the atmospheric response to El Niño: Idealisedstatistical and dynamical modelling

Name: Margot BENICHE Start date: 2020/11/01 Thesis supervisor: Nicholas HALL Co-supervision 1: Jérôme VIALARD Keywords: Southern Oscillation – El Niño, Numerical models, Ocean-atmosphere interactions, Non-linear dynamics, Atmospheric convection, Sea surface […]

Current thesis

Air-Sea Interactions at Submesoscale, characterization and impact on Western Boundary Current Dynamics

Name: Marcela CONTRERAS CONTRERAS Start date:  2020/10/01 Thesis supervisor: Lionel RENAULT Co-supervision 1:  Patrick MARCHESIELLO Keywords: Air-Sea Interactions, Western Edge, Coupled Numerical Ocean-Atmosphere Simulations, Sub-mesoscale Ocean Processes

Current thesis

SWOT observability of internal tides and eddies interactions around New Caledonia

Name: Arne BENDINGER Start date: 2020/09/30 Thesis supervisor: Lionel GOURDEAU Co-supervision 1: Sophie CRAVATTE Keywords: Mesoscale, Internal waves, Modelling, Sea level, Tropical Pacific, SWOT

Composition

Permanent staff

All team members

A

ALORY Gael

Enseignant-Chercheur / Research Professor
Ph. Adj. CNAP

D

Durand Fabien

Chargé de Recherche IRD
CR IRD

G

GL

Gourdeau Lionel

J

Jouanno Julien

Chercheur
Directeur de Recherche IRD

K

KE

Kestenare Elodie

Ingénieur de Recherche
IRHC IRD

Khan Jamal

PostDoc

T

Téchiné Philippe

Ingénieur de Recherche
IRHC CNRS