36 citations · 170 across the 8 of their papers we have counts for
8 papers
Magnetic storms during the space age: Occurrence and relation to varying solar activity
Kalevi Mursula, Timo Qvick, Lauri Holappa +1
We study the occurrence of magnetic storms in space age (1957-2021) using Dst and Dxt indices. We find 2526/2743 magnetic storms in the Dxt/Dst index, out of which 45% are weak, 40…
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…
Explicit IMF -dependence in high-latitude geomagnetic activity
Lauri Holappa, Kalevi Mursula
The interaction of the solar wind with the Earth's magnetic field produces geomagnetic activity, which is critically dependent on the orientation of the interplanetary magnetic fie…
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…
Occurrence of high-speed solar wind streams over the Grand Modern Maximum
Kalevi Mursula, Renata Lukianova, Lauri Holappa
In the declining phase of the solar cycle, when the new-polarity fields of the solar poles are strengthened by the transport of same-signed magnetic flux from lower latitudes, the…
A new method to estimate annual solar wind parameters and contributions of different solar wind structures to geomagnetic activity
Lauri Holappa, Kalevi Mursula, Timo Asikainen
In this paper, we study two sets of local geomagnetic indices from 26 stations using the principal component (PC) and the independent component (IC) analysis methods. We demonstrat…