{
  "id": "1307.4421",
  "version": "v1",
  "published": "2013-07-16T20:41:37.000Z",
  "updated": "2013-07-16T20:41:37.000Z",
  "title": "Characteristic Length of Energy-Containing Structures at the Base of a Coronal Hole",
  "authors": [
    "V. I. Abramenko",
    "G. P. Zank",
    "A. Dosch",
    "V. B. Yurchyshyn",
    "P. R. Goode",
    "K. Ahn",
    "W. Cao"
  ],
  "comment": "21 pages, 9 figures",
  "doi": "10.1088/0004-637X/772/1/1",
  "categories": [
    "astro-ph.SR"
  ],
  "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 $\\lambda_{\\bot}$ 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 defines directly 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 (NST) at Big Bear Solar Observatory. A data set for transverse magnetic fields obtained with the Solar Optical Telescope/Spectro-Polarimeter (SOT/SP) aboard {\\it Hinode} spacecraft was utilized to analyze the squared transverse magnetic field fluctuations $b_t^2$. Local correlation tracking (LCT) was applied to derive the squared transverse velocity fluctuations $u^2$. We find that for $u^2$-structures, Batchelor integral scale $\\lambda$ varies in a range of 1800 - 2100 km, whereas the correlation length $\\varsigma$ and the $e$-folding length $L$ vary between 660 and 1460 km. Structures for $b_t^2$ yield $\\lambda \\approx 1600$ km, $\\varsigma \\approx 640$ km, and $L \\approx 620$ km. An averaged (over $\\lambda, \\varsigma$, and $L$) value of the characteristic length of $u^2$-fluctuations is 1260$\\pm$500 km, and that of $b_t^2$ is 950$\\pm$560 km. The characteristic length scale in the photosphere is approximately 1.5-50 times smaller than that adopted in previous models (3-30$\\times10^3$ 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.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2013-07-16T20:41:37.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "coronal hole",
      "fast solar wind acceleration",
      "transverse magnetic field fluctuations",
      "energy-containing structures",
      "length scale defines"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "journal": "The Astrophysical Journal",
      "year": 2013,
      "month": "Aug",
      "volume": 773,
      "number": 2,
      "pages": 167
    },
    "note": {
      "typesetting": "TeX",
      "pages": 21,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1243074,
      "adsabs": "2013ApJ...773..167A"
    }
  }
}