Solar activity dependence of geomagnetic field line resonance frequencies at low latitudes

2007 ◽  
Vol 112 (A2) ◽  
pp. n/a-n/a ◽  
Author(s):  
M. Vellante ◽  
M. Förster ◽  
U. Villante ◽  
T. L. Zhang ◽  
W. Magnes
Keyword(s):  
Solar Activity ◽  
Field Line ◽  
Geomagnetic Field ◽  
Geomagnetic Field Line ◽  
Field Line Resonance ◽  
Resonance Frequencies ◽  
Low Latitudes ◽  
Line Resonance ◽  
Activity Dependence

scholarly journals Pc5 field line resonance frequencies and structure observed by SuperDARN and CANOPUS

1998 ◽  
Vol 103 (A6) ◽  
pp. 11771-11785 ◽  
Author(s):  
C. W. S. Ziesolleck ◽  
F. R. Fenrich ◽  
J. C. Samson ◽  
D. R. McDiarmid
Keyword(s):  
Field Line ◽  
Field Line Resonance ◽  
Resonance Frequencies ◽  
Line Resonance

scholarly journals Upstream waves and field line resonances: simultaneous presence and alternation in Pc3 pulsation events

1998 ◽  
Vol 16 (1) ◽  
pp. 34-48 ◽  
Author(s):  
J. Verõ ◽  
H. Lühr ◽  
M. Vellante ◽  
I. Best ◽  
J. Střeštik ◽  
...  
Keyword(s):  
Field Line ◽  
Geomagnetic Field ◽  
Interplanetary Medium ◽  
Mhd Waves ◽  
Field Line Resonance ◽  
Field Line Resonances ◽  
Line Resonance ◽  
Mhd Waves And Instabilities ◽  
Field Lines ◽  
Upstream Waves

Abstract. Based on a detailed study of Pc3 events at an array between L = 1.5 and 3 in Central Europe, the authors found quick changes between upstream waves (UW, i.e. pulsation directly driven by UW) and field line resonance (FLR, i.e. azimuthal oscillations of geomagnetic field lines). The alternation of the two types is especially characteristic (and the UW part stronger) if the interplanetary magnetic field (IMF) is highly variable. Events due to field line resonance may have a structure consisting of multiple lines with frequencies differing by about 10%, corresponding to neighbouring shells of field lines separated by about 100 km at the surface. This coincides with previous findings (about 10% at a meridional distance of 80 km). The frequency of the UW type is well correlated with the frequency of waves in the interplanetary medium. Additionally, there are signals of unidentified origin which also seem to be influenced by IMF.>Key words. Magnetosphere Physics · MHD waves and instabilities · Plasmasphere · Solar wind/magnetosphere interactions

scholarly journals On the Geomagnetic Field Line Resonance Eigenfrequency Variations during Seismic Event

2021 ◽  
Vol 13 (14) ◽  
pp. 2839
Author(s):  
Mirko Piersanti ◽  
William Jerome Burger ◽  
Vincenzo Carbone ◽  
Roberto Battiston ◽  
Roberto Iuppa ◽  
...  
Keyword(s):  
Field Line ◽  
Density Variation ◽  
Coupling Mechanism ◽  
Geomagnetic Field Line ◽  
Field Line Resonance ◽  
Acoustic Gravity Waves ◽  
Line Resonance ◽  
Field Lines ◽  
Remote Sensing Methods ◽  
The Magnetic Field

In this paper, we report high statistical evidence for a seismo–ionosphere effects occurring in conjunction with an earthquake. This finding supports a lithosphere-magnetosphere coupling mechanism producing a plasma density variation along the magnetic field lines, mechanically produced by atmospheric acoustic gravity waves (AGWs) impinging the ionosphere. We have analysed a large sample of earthquakes (EQ) using ground magnetometers data: in 28 of 42 analysed case events, we detect a temporary stepwise decrease (Δf) of the magnetospheric field line resonance (FLR) eigenfrequency (f*). Δf decreases of ∼5–25 mHz during ∼20–35 min following the time of the EQ. We present an analytical model for f*, able to reproduce the behaviour observed during the EQ. Our work is in agreement with recent results confirming co-seismic direct coupling between lithosphere, ionosphere and magnetosphere opening the way to new remote sensing methods, from space/ground, of the earth seismic activity.

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