A Strictly Geostrophic Product of Sea‐Surface Velocities From the SWOT Fast‐Sampling Phase
Abstract
While geostrophy remains the simplest and most practical balance to extract velocity information from sea‐surface height anomaly (SSHa), confusions remain within the oceanographic community to what extent this balance can be applied to altimetric observations with the launch of the Surface Water and Ocean Topography (SWOT) satellite. Given the limited temporal resolution of SWOT, many studies have resorted to claiming that the spatially filtered SSHa fields correspond to the geostrophic component. This introduces the ambiguity of which spatial scale to choose. Here, we build upon the recent developments in internal tide (IT) corrections (Yadidya, Arbic, et al., 2025, https://doi.org/10.1029/2025ea004511 ) and apply a dynamic mode decomposition (DMD)‐based method introduced by Lapo, Ichinaga, and Kutz (2025, https://doi.org/10.1073/pnas.2415786122 ) to robustly extract the geostrophic component associated with sub‐inertial frequencies from the SWOT one‐day‐repeat orbit; we distribute the global data set as a public good. We provide the joint probability density function (PDF) of vorticity and strain, and spectra of SSHa at a few cross‐over regions.
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BibTeX
@article{uchida2026strictly,
title = {{A Strictly Geostrophic Product of Sea‐Surface Velocities From the SWOT Fast‐Sampling Phase}},
author = {Takaya Uchida and Badarvada Yadidya and Vadim Bertrand and Brian Arbic and Jay Shriver and Julien Le Sommer},
journal = {Geophysical Research Letters},
year = {2026},
month = jul,
doi = {10.1029/2026gl121978},
eprint = {2601.18182},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05790125v1},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - A Strictly Geostrophic Product of Sea‐Surface Velocities From the SWOT Fast‐Sampling Phase
AU - Takaya Uchida
AU - Badarvada Yadidya
AU - Vadim Bertrand
AU - Brian Arbic
AU - Jay Shriver
AU - Julien Le Sommer
PY - 2026
DA - 2026/07/22
JO - Geophysical Research Letters
DO - 10.1029/2026gl121978
UR - https://hal.science/hal-05790125v1
AB - While geostrophy remains the simplest and most practical balance to extract velocity information from sea‐surface height anomaly (SSHa), confusions remain within the oceanographic community to what extent this balance can be applied to altimetric observations with the launch of the Surface Water and Ocean Topography (SWOT) satellite. Given the limited temporal resolution of SWOT, many studies have resorted to claiming that the spatially filtered SSHa fields correspond to the geostrophic component. This introduces the ambiguity of which spatial scale to choose. Here, we build upon the recent developments in internal tide (IT) corrections (Yadidya, Arbic, et al., 2025, https://doi.org/10.1029/2025ea004511 ) and apply a dynamic mode decomposition (DMD)‐based method introduced by Lapo, Ichinaga, and Kutz (2025, https://doi.org/10.1073/pnas.2415786122 ) to robustly extract the geostrophic component associated with sub‐inertial frequencies from the SWOT one‐day‐repeat orbit; we distribute the global data set as a public good. We provide the joint probability density function (PDF) of vorticity and strain, and spectra of SSHa at a few cross‐over regions.
SN - 0094-8276
SN - 1944-8007
ER -