Preprints
https://doi.org/10.5194/egusphere-2026-5130
https://doi.org/10.5194/egusphere-2026-5130
14 Sep 2026
 | 14 Sep 2026
Status: this preprint is open for discussion and under review for Nonlinear Processes in Geophysics (NPG).

The drag-law for turbulent air-sea interaction is locally linear

Achim Wirth

Abstract. The momentum transfer between the atmosphere and the ocean is typically parameterized using a quadratic drag law. However, analytical calculations reveal that such a drag law leads to a vorticity blow-up. Results from dedicated numerical simulations demonstrate that, at horizontal scales several times the boundary layer thickness, the drag parameterization is locally linear.

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Achim Wirth

Status: open (until 09 Nov 2026)

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Achim Wirth
Achim Wirth
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Short summary

The atmosphere-ocean exchange of momentum, heat, water, and chemicals drives climate dynamics. While momentum transfer is often modeled with a quadratic drag law, this can cause vorticity blow-up. Simulations show that at scales much larger than the boundary layer, drag behaves linearly. A new momentum parameterization is proposed.

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