Characteristic length of energy-containing structures at the base of a coronal hole

V. I. Abramenko, G. P. Zank, A. Dosch, Vasyl Yurchyshyn, P. R. Goode, Kwangsu Ahn, Wenda Cao

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

An essential parameter for models of coronal heating and fast solar wind acceleration that rely on the dissipation of MHD turbulence is the characteristic energy-containing length λτ of the squared velocity and magnetic field fluctuations (u 2 and b 2) transverse to the mean magnetic field inside a coronal hole (CH) at the base of the corona. The characteristic length scale directly defines the heating rate. We use a time series analysis of solar granulation and magnetic field measurements inside two CHs obtained with the New Solar Telescope at Big Bear Solar Observatory. A data set for transverse magnetic fields obtained with the Solar Optical Telescope/Spectro-Polarimeter on board the Hinode spacecraft was utilized to analyze the squared transverse magnetic field fluctuations . Local correlation tracking was applied to derive the squared transverse velocity fluctuations u 2. We find that for u 2 structures, the Batchelor integral scale λ varies in a range of 1800-2100 km, whereas the correlation length ς and the e-folding length L vary between 660 and 1460 km. Structures for yield λ ≈ 1600 km, ς ≈ 640 km, and L ≈ 620 km. An averaged (over λ, ς, and L) value of the characteristic length of u 2 fluctuations is 1260 ± 500 km, and that of is 950 ± 560 km. The characteristic length scale in the photosphere is approximately 1.5-50 times smaller than that adopted in previous models (3-30 × 103 km). Our results provide a critical input parameter for current models of coronal heating and should yield an improved understanding of fast solar wind acceleration.

Original languageEnglish (US)
Article number167
JournalAstrophysical Journal
Volume773
Issue number2
DOIs
StatePublished - Aug 20 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Sun: corona
  • Sun: photosphere
  • Sun: surface magnetism
  • turbulence

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