Publication Date:
2017-04-04
Description:
We conduct a statistical analysis of the coherence and phase difference of low frequency geomagnetic fluctuations
between two Antarctic stations, Mario Zucchelli Station (geographic coordinates: 74.7 S, 164.1 E; corrected
geomagnetic coordinates: 80.0 S, 307.7 E) and Scott Base (geographic coordinates: 77.8 S 166.8 E; corrected geomagnetic
coordinates: 80.0 S 326.5 E), both located in the polar cap. Due to the relative position of the stations, whose displacement is essentially along a geomagnetic parallel, the
phase difference analysis allows to determine the direction of azimuthal propagation of geomagnetic fluctuations. The
results show that coherent fluctuations are essentially detectable around local geomagnetic midnight and, in a minor
extent, around noon; moreover, the phase difference reverses in the night time hours, indicating a propagation direction
away from midnight, and also around local geomagnetic noon, indicating a propagation direction away from the subsolar
point. The nigh time phase reversal is more clear for southward interplanetary magnetic field conditions, suggesting
a relation with substorm activity.
The introduction, in this analysis, of the Interplanetary Magnetic Field conditions, gave interesting results, indicating
a relation with substorm activity during nighttime hours. We also conducted a study of three individual pulsation
events in order to find a correspondence with the statistical behaviour. In particular, a peculiar event, characterized
by quiet magnetospheric and northward interplanetary magnetic field conditions, shows a clear example of waves propagating
away from the local geomagnetic noon; two more events, occurring during southward interplanetary magnetic field conditions, in one case even during a moderate storm,
show waves propagating away from the local geomagnetic midnight.
Description:
Published
Description:
2405–2412
Description:
3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
Description:
JCR Journal
Description:
reserved
Keywords:
Magnetospheric physics (MHD wave and instabilities
;
Polar cap phenomena;
;
Solar wind-magnetosphere interactions
;
01. Atmosphere::01.03. Magnetosphere::01.03.03. Magnetospheric physics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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