Zobrazeno 1 - 10
of 184
pro vyhledávání: '"Holappa, Lauri"'
Publikováno v:
J. Geophys. Res.: Space, 127, e2022JA030830
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% moderate, 12% intense and 3% major storms. Occurrence of storms in s
Externí odkaz:
http://arxiv.org/abs/2212.00510
The most important parameter in the coupling between solar wind and geomagnetic activity is the $B_z$-component of the interplanetary magnetic field (IMF). However, recent studies have shown that IMF $B_y$ is an additional, independent driver of geom
Externí odkaz:
http://arxiv.org/abs/1904.04568
Autor:
Holappa, Lauri, Mursula, Kalevi
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 field (IMF). Most solar wind coupling functions quantify this dependence
Externí odkaz:
http://arxiv.org/abs/1805.10699
Autor:
Mursula, Kalevi, Holappa, Lauri
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 stations in 1980-2015. The first principal component (PC1) describes
Externí odkaz:
http://arxiv.org/abs/1709.06885
High speed solar wind streams (HSSs) are very efficient drivers of geomagnetic activity at high latitudes. In this paper we use a recently developed $\Delta{H}$ parameter of geomagnetic activity, calculated from the night-side hourly magnetic field m
Externí odkaz:
http://arxiv.org/abs/1702.03924
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 speeds at 1 AU for the last 100 years using high-latitude geomagnetic mea
Externí odkaz:
http://arxiv.org/abs/1612.04941
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 polar coronal holes expand and form non-axisymmetric extensions toward
Externí odkaz:
http://arxiv.org/abs/1501.05010
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 demonstrate that the annually averaged indices can be accurately represented as
Externí odkaz:
http://arxiv.org/abs/1501.03716
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