Magnetic pattern at supergranulation scale: the Void Size Distribution

TL;DR

This study analyzes the magnetic void pattern at supergranulation scales on the Sun using magnetogram data, revealing a quasi-exponential distribution with a notable deviation around 35 Mm, supporting multi-scale flow hypotheses.

Contribution

It introduces a fast circle packing algorithm to quantify magnetic voids and characterizes their size distribution, highlighting multi-scale surface flows.

Findings

Void size distribution follows a quasi-exponential decay between 10-60 Mm.

Departure from exponential decay observed around 35 Mm.

Supports the presence of multi-scale convective flows on the solar surface.

Abstract

The large-scale magnetic pattern of the quiet sun is dominated by the magnetic network. This network, created by photospheric magnetic fields swept into convective downflows, delineates the boundaries of large scale cells of overturning plasma and exhibits voids in magnetic organization. Such voids include internetwork fields, a mixed-polarity sparse field that populate the inner part of network cells. To single out voids and to quantify their intrinsic pattern a fast circle packing based algorithm is applied to 511 SOHO/MDI high resolution magnetograms acquired during the outstanding solar activity minimum between 23 and 24 cycles. The computed Void Distribution Function shows a quasi-exponential decay behavior in the range 10-60 Mm. The lack of distinct flow scales in such a range corroborates the hypothesis of multi-scale motion flows at the solar surface. In addition to the quasi-exponential decay we have found that the voids reveal departure from a simple exponential decay around 35 Mm.