{
  "id": "1606.01092",
  "version": "v1",
  "published": "2016-06-03T14:05:31.000Z",
  "updated": "2016-06-03T14:05:31.000Z",
  "title": "Correlation Between Sunspot Number and ca II K Emission Index",
  "authors": [
    "Luca Bertello",
    "Alexei A. Pevtsov",
    "Andrey Tlatov",
    "Jagdev Singh"
  ],
  "comment": "16 pages, 8 figures, accepted for publication in Solar Physics",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "Long-term synoptic observations in the resonance line of Ca II K constitute a fundamental database for a variety of retrospective analyses of the state of the solar magnetism. Synoptic Ca II K observations began in late 1904 at the Kodaikanal Observatory, in India. In early 1970s, the National Solar Observatory (NSO) at Sacramento Peak (USA) started a new program of daily Sun-as-a-star observations in the Ca II K line. Today the NSO is continuing these observations through its Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility. These different data sets can be combined into a single disk-integrated Ca II K index time series that describes the average properties of the chromospheric emission over several solar cycles. We present such a Ca II K composite and discuss its correlation with the new entirely revised sunspot number data series. For this preliminary investigation, the scaling factor between pairs of time series was determined assuming a simple linear model for the relationship between the monthly mean values during the duration of overlapping observations.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-06-03T14:05:31.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "emission index",
      "correlation",
      "revised sunspot number data series",
      "synoptic optical long-term investigations",
      "long-term synoptic observations"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 16,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}