Researcher in Ocean Acoustics, Specialist in

The Physical Resources and Deep-Sea Ecosystem Department of Ifremer deals with questions related to deep ocean/lithosphere and ocean/climate interactions. It carries technological developments necessary for ocean observation and contributes to research into renewable marine energies. Its strengths in geosciences are grouped within UMR 6538 Geo-Ocean, a new joint research unit, to which the CNRS also contributes (with a main attachment to INSU), the University of Brest (UBO) and with a secondary supervisory body: the University of South Brittany (UBS).

Geo-Ocean's scientific and technical skills are broken down into research topics with a strong emphasis in national and international collaboration, particularly in Europe and with industry. The Research Unit is involved in research projects in support of French public policies. The major scientific and societal challenges being addressed by Geo-Ocean are:

- To observe, understand and model our coastal systems in order to better manage and protect them in the face of climate change and cumulative anthropogenic impacts
- To push the boundaries of observation and understanding of active processes (tectonic, volcanic, sedimentary, and chemical) in the marine environment
- To define and understand the heterogeneities, dynamics, and interactions within the Earth and their impact on the geodynamics and vertical motions of the ocean domains
- To identify the relationships between living organisms and their geological environment at all temporal and spatial scales
- To guide society's access to marine resources in a sustainable and responsible manner

Within this Unit, the Biogeochemical Cycles and Resources (CYBER) team is interested in the exchange of matter and energy between the oceanic lithosphere and the hydrosphere. Research activities on these different envelopes and their interfaces are carried out via geological, geochemical, and numerical approaches in order to understand the fluxes and transfer mechanisms from the deep subseafloor to up to the open ocean, and the formation of potential deep-sea resources (e.g. mineral resources, natural hydrogen). The team is also interested in the study of biogeochemical cycles of the deep ocean and the ancient Earth (e.g. metal cycles, CO2, methane). The team integrates a transversal technical component in the fields of in situ and ex situ physicochemical measurements, and the development of new biogeochemical tracers (proxies) in the water column, fluids, sediments and rocks.

**General tasks**

As part of our research activities on fluid emission processes at the seafloor, including the source, transport and transformation of particulate and dissolved chemical species, the laboratory plans to strengthen its expertise by addressing the phenomena linked to the hydrodynamics of plumes. In order to further improve the understanding of plumes detected by acoustic methods, the laboratory is recruiting a researcher in physical modeling specializing in fluid emissions (including gases) from the seabed and/or turbide plumes.

Placed under the responsibility of the head of the CYBER team, you will develop and use physical and acoustic models to characterize the morphology and flow of plumes according to their origin (hydrothermal, magmatic and volcanic), their nature (thermal, chemical and particle) and their behavior in the water column. You design and contribute to data acquisition and in situ experimentation plans for the validation of the models developed. In this position, you will contribute to improving the interpretation of the acoustics response associated with plumes for a better understanding of the sources and behavior of fluids in the water column. Collaborations are expected with other laboratory researchers who study the chemical and physicochemical nature of plumes and the geology of fluid emission sites.

Consequently, you will develop thermo-hydrodynamic models from acoustics, oceanographic and geochemical data to better assess the impact of plumes at the local scale, and predict their temporal and spatial behavior. You will bring strong skills to the team for ocean exploration and the quantification of matter and heat flows associated with fluid emission sites on the seabed.

**Main activities**

You carry out research activities on the physics of fluid emissions in the ocean, based on strong expertise in acoustics and plume hydrodynamics.

You are at the center of instrumental and methodological developments using acoustics for the detection and characterization of plumes in the context of marine geosciences.

You develop hydrodynamic models integrating the physics of bubble-seawater and seawater-liquid interactions of different densities.

You actively participate in the exploration strategy for active hydrothermal and volcanic systems.

You collaborate with acoustic engineers, computer scientists and researchers in national and international research and expertise projects.

You supervise students from ma