Preprints
https://doi.org/10.5194/egusphere-2025-5907
https://doi.org/10.5194/egusphere-2025-5907
27 Dec 2025
 | 27 Dec 2025
Status: this preprint is open for discussion and under review for Nonlinear Processes in Geophysics (NPG).

The advantages of data assimilation in parametric space rather than classic grid space

Solène Dealbera, Stéphane Raynaud, Carlos Granero Belinchon, Brahim Boussidi, Clément Le Goff, and Pierre Tandeo

Abstract. Data assimilation (DA), by merging observation and background information, is an important tool in the field of geosciences. However, in the presence of geophysical structures such as cyclones or ocean eddies, classic DA schemes in gridded space fail to properly estimate the structure properties, for example, their position and intensity. In this work, we propose a new DA scheme, in a reduced parametric space, which assimilates only the relevant parameters to describe the structures, with an application to a one-dimensional ocean eddy. Comparison of DA performed in the classic gridded field and in the parametric space is made through a series of experiments with perturbed eddy parameters. Results show that DA in the parametric space can account for the nonlinearity of the eddy parameters and preserve eddy properties. This is not the case for classic DA in the gridded space. Moreover, DA in the parametric space considerably reduces the computational cost.

Competing interests: At least one of the (co-)authors is a member of the editorial board of Nonlinear Processes in Geophysics.

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Solène Dealbera, Stéphane Raynaud, Carlos Granero Belinchon, Brahim Boussidi, Clément Le Goff, and Pierre Tandeo

Status: open (until 21 Feb 2026)

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Solène Dealbera, Stéphane Raynaud, Carlos Granero Belinchon, Brahim Boussidi, Clément Le Goff, and Pierre Tandeo
Solène Dealbera, Stéphane Raynaud, Carlos Granero Belinchon, Brahim Boussidi, Clément Le Goff, and Pierre Tandeo
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Latest update: 27 Dec 2025
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Short summary
The goal of data assimilation in geoscience is to merge information from models and observations. In the presence of structures such as ocean eddies, classic assimilation schemes fail to merge those two sources, resulting in position and shape errors. Here, we propose a new scheme which assimilates only the parameters describing a simplified eddy structure. Comparison with classic schemes shows that our approach preserves the eddy parameters and reduces the computational cost.
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