WP3 - Ocean, marine biogeochemistry and cryosphere processes

This work package (WP) aims to improve the representation of “blue” (ocean physics and dynamics), “green“ (marine biogeochemistry) and “white” (interaction with ice sheets) ocean processes in the next generation of Earth System Models. It is crucial to correctly represent these processes in numerical models to better explain and understand future Earth system changes and, in particular, the processes involved in the response of the ocean and the cryosphere to increasing atmospheric CO2 and climate warming.

Our overall objective is to enhance the numerical ocean of the next generation of Earth System Models across three different axes: 1) “blue” physicists will develop new parameterizations that better represent ocean eddies and convection; 2) “green” biogeochemists will improve the representation of ocean carbon and nitrogen cycling and associated marine emissions of trace gases and aerosol percursors to better integrate marine biogeochemistry within Earth System Models; and 3) “white” scientists will improve the representation of ocean-ice sheet interactions in standalone ocean or ice-sheet models.

Institutions involved: MF-CNRM and UREAD will develop two mesoscale eddy parameterizations (geometric and backscatter); MOI, MF-CNRM and MPI-M will develop an eddy and convective mixing scheme; CNRS-IPSL, MPI-M and ULB will improve the representation of the nitrogen cycle in ocean biogeochemistry and its link to N2O and NH3 emissions; CNRS-IGE will implement parameterizations of ice-shelf basal melt for small ice shelves (Antarctica) and iceberg calving; UREAD will develop a method to represent melt on vertical ice faces for Greenland; MF-CNRM will improve the representation of icebergs; and SMHI will coordinate the work on the evaluation of new ocean and cryosphere process parameterizations in collaboration with Cross-Cutting Activity 1 (XCA1).

WP3 Leaders

Sarah Berthet

Sarah Berthet

Oceanographer, Meteo FRance - CNRM (France)
Water cycle and ocean-atmosphere interactions have been in the center of my research activity since my PhD. Starting from small scale processes at play in cloud microphysics and aerosol nucleation, my knowledge of the Earth System has been gradually widened toward larger and longer scales: first by the study of mesoscale convective systems over the northeastern Pacific Ocean (e.g. how their structure and lifetime are driven by their thermodynamical and dynamical environments), and more generally by the study of ocean-atmosphere interactions in the tropical climate. Finally, I dived into the ocean to understand how perturbations of the water cycle and interactions at the ocean-atmosphere interface may also affect marine biogeochemistry and oceanic greenhouse gases emissions.

In ESM2025, my role in WP3 is to coordinate scientists working on the “blue” (physical) and “green” (biogeochemical) ocean components.

Nicolas Jourdain

Nicolas Jourdain

CNRS research scientist, IGE - Grenoble (France)
I am currently studying the interactions between the Antarctic and Greenland ice sheets and the climate system at IGE, Grenoble, France. My main aim is to reduce uncertainty on sea level projections. Previously, I worked on tropical cyclones, the Indo-Pacific climate, and ocean-atmosphere interactions, at IRD, Nouméa, New Caledonia, and at CCRC-UNSW, Sydney, Australia. A large part of my work is based on numerical models designed to simulate some physical constituents of the climate system.

In ESM2025, I coordinate the work in WP3 aiming to improve the representation of ice-sheet processes in ESM2025. The aim is to focus on the processes that will be crucial for the inclusion of ice sheet models in WP8-9, e.g., melting beneath ice shelves or on the vertical face of glaciers termini, iceberg calving.

WP3 Milestones & Deliverables

MS3.1 – 30 November 2021

Definition of key diagnostics to evaluate planned ESM improvements at the process level (CT1/WP2/land) and with respect to coupled interactions and coupled performance (CT2). Identification of key observational data sets and initial scoping of diagnostics intended for ESMValTool

MS3.2 – 30 November 2022

Preliminary versions of new/improved ocean and ocean – ice sheet parameterisation schemes passed to CT2 for coupling and initial testing

MS3.3 – 31 May 2024

Ocean-only (CMIP6 OMIP, ISMIP6) simulations for evaluation of new parameterisations developed in WP3 and made available to XCA1

MS3.4 – 31 August 2024

Updated versions of new/improved ocean and ocean – ice sheet parameterisation schemes passed to CT2 for final coupling, tuning and use in XCA2 coupled simulations

D3.1 – 30 November 2023

Report on the improved representation of ocean—ice-sheet interactions in climate models

D3.2 – 29 February 2024

Report on the implementation and evaluation of the improved ocean physics (eddies and mixing) and its impacts on marine uptake of heat and carbon and marine biogeochemistry

D3.3 – 31 May 2024

Report on the improved C and N cycling in marine biogeochemical models and its implication for emissions of N2O, NH3 and POA/DMS