2025/12/21 by Lauren McClure, Suzana Silva, McClure, Lauren +7
Physics and Astronomy · #Astro and Planetary Science #FOS: Physical sciences #Ionosphere and magnetosphere dynamics #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR)
paper · doi:10.48550/arxiv.2512.18876
openalex publication_date 2025/12/21 · openalex created_date 2025/12/24 · openalex updated_date 2026/07/28
Small-scale vortices in the solar photosphere play a central role in transporting mass, energy, and momentum into the upper solar atmosphere, yet reliably detecting these structures remains rather challenging. We address this problem by introducing a simple preprocessing step that normalises the velocity field by its magnitude. Our method preserves flow topology while suppressing shear-induced artefacts that lead to spurious detections in non-uniform, high-rotation environments. For validation, we apply this approach to high-resolution Bifrost simulations and evaluate vortex detection using four commonly employed methods: IVD, the λ2-criterion, the Q-criterion, and the Γ method. We assess which structures exhibit physically consistent rotation by using the d-criterion to automatically detect rotational plasma-flow features, which we use as an approximate ground truth. We find that, in the unnormalised field, a substantial fraction of detections made by the first three methods are false positive detections. Normalisation removes most of these. The Γ method detects true vortices but misses a large number of vortical flows. The normalisation step yields better-defined and more realistic vortex boundaries. As the Γ method underpins most observational analyses, current studies likely capture only a subset of vortical flows. By comparison, the other three methods detect four to five times more vortices after normalisation, suggesting that the true photospheric vortex coverage may be underestimated by a similar factor. Overall, this physically motivated preprocessing step enhances the accuracy and physical realism of vortex detection and offers a practical enhancement for analysing vortical flows in turbulent flows.