Supergranular turbulence in the quiet Sun: Lagrangian coherent structures

DOI: 
10.1093/mnras/stz1909
Publication date: 
01/07/2019
Main author: 
Chian, Abraham C. -L.
IAA authors: 
Bellot Rubio, Luis R.
Authors: 
Chian, Abraham C. -L.;Silva, Suzana S. A.;Rempel, Erico L.;Gošić, Milan;Bellot Rubio, Luis R.;Kusano, Kanya;Miranda, Rodrigo A.;Requerey, Iker S.
Journal: 
Monthly Notices of the Royal Astronomical Society
Refereed: 
Yes
Publication type: 
Article
Pages: 
3076-3088
Abstract: 
The quiet Sun exhibits a wealth of magnetic activities that are fundamental for our understanding of solar magnetism. The magnetic fields in the quiet Sun are observed to evolve coherently, interacting with each other to form prominent structures as they are advected by photospheric flows. The aim of this paper is to study supergranular turbulence by detecting Lagrangian coherent structures (LCS) based on the horizontal velocity fields derived from Hinode intensity images at disk centre of the quiet Sun on 2010 November 2. LCS act as transport barriers and are responsible for attracting/repelling the fluid elements and swirling motions in a finite time. Repelling/attracting LCS are found by computing the forward/backward finite-time Lyapunov exponent (FTLE), and vortices are found by the Lagrangian-averaged vorticity deviation method. We show that the Lagrangian centres and boundaries of supergranular cells are given by the local maximum of the forward and backward FTLE, respectively. The attracting LCS expose the location of the sinks of photospheric flows at supergranular junctions, whereas the repelling LCS interconnect the Lagrangian centres of neighboring supergranular cells. Lagrangian transport barriers are found within a supergranular cell and from one cell to other cells, which play a key role in the dynamics of internetwork and network magnetic elements. Such barriers favor the formation of vortices in supergranular junctions. In particular, we show that the magnetic field distribution in the quiet Sun is determined by the combined action of attracting/repelling LCS and vortices.
Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080960223&doi=10.1093%2fmnras%2fstz1909&partnerID=40&md5=ece2813d577a959b356377241afaea11
ADS Bibcode: 
2019MNRAS.488.3076C
Keywords: 
Sun: granulation;Sun: magnetic fields;turbulence;chaos;Astrophysics - Solar and Stellar Astrophysics