Assessing the Accuracy of Local Correlation Tracking (LCT) for Photospheric Vortex Detection with Radiative–MHD Simulations
Analysing high-resolution photospheric observations requires robust techniques to recover plasma flow features across different spatial and temporal scales. Local correlation tracking (LCT) is widely used to infer horizontal velocities from intensity evolution, but most validations focus on the velocity field in a global or statistical sense. There is limited work quantifying how errors in LCT-derived flows propagate into biases in vortex identification and in derived vortex properties. This study concentrates on validating the combined LCT+Γ method for recovering photospheric vortices in a realistic
radiative-MHD simulation. We apply LCT to R2D2 intensity maps using spatial windows of FWHM = 2.5–4.0 Mm and temporal averaging windows of 10–60 min. Vortices are identified with the same Γ-method in both the LCT-derived and “true” simulation velocity fields to enable direct comparison. LCT systematically underestimates vortex counts, and completeness decreases strongly with increasing temporal averaging. LCT also yields lower vorticity amplitudes within detected vortices, consistent with suppression of small-scale rotational signals. For vortices recovered in both fields, radius distributions agree closely, but lifetime statistics are biased toward longer persistence in the LCT detections.
These findings provide quantitative constraints on how accurately LCT recovers coherent photospheric vortices and their temporal evolution at mesogranular scale.