Details

Autor(en) / Beteiligte

• Rotter, T.
• Veronig, A. M.
• Temmer, M.
• Vršnak, B.

Titel

Relation Between Coronal Hole Areas on the Sun and the Solar Wind Parameters at 1 AU

Ist Teil von

• Solar physics, 2012-12, Vol.281 (2), p.793-813

Ort / Verlag

Dordrecht: Springer Netherlands

Erscheinungsjahr

2012

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• We analyze the relationship between the coronal hole (CH) characteristics on the Sun (area, position, and intensity levels) and the corresponding solar wind parameters (solar wind speed v , proton temperature T , proton density n , and magnetic field strength B ) measured in situ at 1 AU with a 6-h time resolution. We developed a histogram-based intensity thresholding method to obtain fractional CH areas from SOHO/EIT 195 Å images. The algorithm was applied to 6-h cadence EIT 195 Å images for the year 2005, which were characterized by a low solar activity. In calculating well-defined peaks of the solar wind parameters corresponding to the peaks in CH area, we found that the solar wind speed v shows a high correlation with correlation coefficient cc=0.78, medium correlation for T and B with cc=0.41 and cc=0.41. No significant correlation was found with the proton density n . Applying an intensity-weighted CH area did not improve the relations, since the size and the mean intensity of the CH areas are not independent parameters but strongly correlated (cc=− 0.72). Comparison of the fractional CH areas derived from GOES/SXI and SOHO/EIT and the related solar wind predictions shows no systematic differences (cc=0.79).