Dynamics of small-scale convective motions

TL;DR

This study investigates the evolution and dynamics of small-scale solar granules using high-resolution simulations and observations, revealing distinct behaviors influenced by vortex motions and differences from regular-sized granules.

Contribution

Developed a novel temporal tracking algorithm for solar granulation, enabling detailed analysis of small granule dynamics in simulations and observations.

Findings

Small granules have different size, intensity, and depth evolution compared to regular granules.

Vortex motions are strongly associated with small granules and influence their dynamics.

Most simulated granules do not fragment, unlike those observed in high-resolution data.

Abstract

Previous studies have discovered a population of small granules with diameters less than 800 km showing differing physical properties. High resolution simulations and observations of the solar granulation, in combination with automated segmentation and tracking algorithms, allow us to study the evolution of the structural and physical properties of these granules and surrounding vortex motions with high temporal and spatial accuracy. We focus on the dynamics of granules (lifetime, fragmentation, size, position, intensity, vertical velocity) over time and the influence of strong vortex motions. Of special interest are the dynamics of small granules compared to regular-sized granules. We developed a temporal tracking algorithm based on our developed segmentation algorithm for solar granulation. This was applied to radiation hydrodynamics simulations and high resolution observations of the quiet Sun by SUNRISE/IMaX. The dynamics of small granules differ in regard to their diameter, intensity and depth evolution compared to regular granules. The tracked granules in the simulation and observations reveal similar dynamics (lifetime, evolution of size, vertical velocity and intensity). The fragmentation analysis shows that the majority of granules in simulations do not fragment, while the opposite was found in observations. Strong vortex motions were detected at the location of small granules. Regions of strong vertical vorticity show high intensities and downflow velocities, and live up to several minutes. The analysis of granules separated according to their diameter in different groups reveals strongly differing behaviors. The largest discrepancies can be found within the groups of small, medium-sized and large granules and have to be analyzed independently. The predominant location of vortex motions on and close to small granules indicates a strong influence on the dynamics of granules.