242 citations · 1.7k across the 39 of their papers we have counts for
6 papers · 1 filter
Structure and evolution of the photospheric magnetic field in 2010 - 2017: comparison of SOLIS/VSM vector field and potential field
Ilpo I. Virtanen, Alexei A. Pevtsov, Kalevi Mursula
The line-of-sight (LOS) component of the large-scale photospheric magnetic field has been observed since the 1950s, but the daily full-disk observations of the full vector magnetic…
Explicit IMF -effect maximizes at subauroral latitudes (Dedicated to the memory of Eigil Friis-Christensen)
Lauri Holappa, Nat Gopalswamy, Kalevi Mursula
The most important parameter in the coupling between solar wind and geomagnetic activity is the -component of the interplanetary magnetic field (IMF). However, recent studies…
Automated identification of coronal holes from synoptic EUV maps
Amr Hamada, Timo Asikainen, Ilpo Virtanen +1
Coronal holes (CH) are regions of open magnetic field lines in the solar corona and the source of fast solar wind. Understanding the evolution of coronal holes is critical for sola…
Principal component analysis of geomagnetic activity: New information on solar wind
Kalevi Mursula, Lauri Holappa
We use the principal component analysis (PCA) to study geomagnetic activity at annual resolution using a network of 26 magnetic stations in 1966-2015, and an extended network of 40…
Centennial evolution of monthly solar wind speeds: Fastest monthly solar wind speeds from long-duration coronal holes
Renata Lukianova, Lauri Holappa, Kalevi Mursula
High speed solar wind streams (HSSs) are very efficient drivers of geomagnetic activity at high latitudes. In this paper we use a recently developed parameter of geomagnetic…
Seasonal solar wind speeds for the last 100 years: Unique coronal hole structures during the peak and demise of the Grand Modern Maximum
Kalevi Mursula, Lauri Holappa, Renata Lukianova
Solar coronal holes are sources of high-speed solar wind streams, which cause persistent geomagnetic activity especially at high latitudes. Here we estimate seasonal solar wind spe…