Interdisciplinary and multi-tracer scientific exploitation of the GEOTRACES GEOVIDE cruise results, through modelling and observations – GEOMOBS

The scientific analysis of trace elements and isotopes (TEIs) data in the ocean, obtained through GEOTRACES cruises, is often conducted using simplified tools such as box models, one-dimensional models, or optimal multiparametric analyses. These approaches generally do not allow for the full integration of diverse observations—namely, physical processes (currents, transport, mixing), biogeochemistry, and the combined constraints of different isotopic tracers. The GEOMOBS project aims to achieve this truly multidisciplinary (physics, biogeochemistry, TEIs) and truly multi-tracer scientific analysis of the GEOVIDE (GA01) cruise by combining modeling efforts with the production of new tracer data. The coupled physical-biogeochemical model NEMO/PISCES will be coupled to TEI modules to simultaneously simulate the distributions of iron isotopes, 231Pa, 230Th, 228Ra, and rare earth elements. The project will include a global 1° configuration and a higher-resolution North Atlantic 1/4° configuration. For the latter, efforts will be mutualized with ongoing work at LOPS and LSCE. New iron isotope and 228Ra concentration data will be generated from suspended particle samples collected during the cruise but not yet analyzed, complementing the existing dissolved-phase data. These new datasets will provide essential constraints for representing and parameterizing TEI cycles in numerical models. The selected tracers were chosen for their complementary roles in constraining biogeochemical cycles, particularly regarding the nature and fluxes of sedimentary sources and particle-dissolved exchanges in the water column. In turn, simulations will facilitate the interpretation of in situ data by integrating all available physical and biogeochemical information. To optimize the mutual benefits of modeling and observational data, specific statistical, visualization, and machine learning tools will be implemented, notably via JupyterLab.

One of the limitations of the GEOTRACES program is that each cruise provides only a snapshot in time, while the program itself spans 20 years. The GEOVIDE cruise took place along the OVIDE section, which has documented the temporal variability of the region’s physical and biogeochemical properties (excluding TEIs) every two years from 2002 to 2021, with varying intensities of the Atlantic Meridional Overturning Circulation (MOC). By developing two coupled physical-biogeochemical configurations representing the minimum and maximum MOC states over the 2002–2021 period, we aim to assess the representativeness of the 2014 GEOVIDE TEI observations within this two-decade context.

GEOMOBS is primarily driven by its scientific objectives. However, by leveraging previously collected but unexploited samples and pooling efforts in numerical modeling, it also aligns with a low-carbon strategy.
This project aspires to generate significant academic and societal impacts. It will adhere to the FAIR principles (Findable, Accessible, Interoperable, Reusable) to maximize data accessibility and reusability within the scientific community.