Power spectra of velocities and magnetic fields on the solar surface and their dependence on the unsigned magnetic flux density

Abstract

We have performed power spectral analysis of surface temperatures, velocities, and magnetic fields, using spectro-polarimetric data taken with the Hinode Solar Optical Telescope. When we make power spectra in a field-of-view covering the super-granular scale, kinetic and thermal power spectra have a prominent peak at the granular scale while the magnetic power spectra have a broadly distributed power over various spatial scales with weak peaks at both the granular and supergranular scales. To study the power spectra separately in internetwork and network regions, power spectra are derived in small sub-regions extracted from the field-of-view. We examine slopes of the power spectra using power-law indices, and compare them with the unsigned magnetic flux density averaged in the sub-regions. The thermal and kinetic spectra are steeper than the magnetic ones at the sub-granular scale in the internetwork regions, and the power-law indices differ by about 2. The power-law indices of the magnetic power spectra are close to or smaller than -1 at that scale, which suggests the total magnetic energy mainly comes from either the granular scale magnetic structures or both the granular scale and smaller ones contributing evenly. The slopes of the thermal and kinetic power spectra become less steep with increasing unsigned flux density in the network regions. The power-law indices of all the thermal, kinetic, and magnetic power spectra become similar when the unsigned flux density is larger than 200 Mx cm^-2.

9 pages, 6 figures, accepted for publication in ApJ

References in corpus (7)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• A solar surface dynamo
• The intensity contrast of solar granulation: comparing Hinode SP results with MHD simulations
• Turbulent small-scale dynamo action in solar surface simulations
• Comparison of transient horizontal magnetic fields in a plage region and in the quiet Sun
• Point spread functions for the Solar Optical Telescope onboard Hinode
• Scaling laws for magnetic fields on the quiet Sun

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• Mesogranulation and small-scale dynamo action in the quiet Sun
• Multi-Scale Deep Learning for Estimating Horizontal Velocity Fields on the Solar Surface
• Analysis of quiet-sun turbulence on the basis of SDO/HMI and Goode Solar Telescope data
• The power spectrum of solar convection flows from high-resolution observations and 3D simulations
• Power spectrum of turbulent convection in the solar photosphere
• Magnetic flux structuring of the quiet Sun internetwork. Center-to-limb analysis of solar-cycle variations
• High-resolution Observations of Halpha Spectra with a Subtractive Double Pass
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