A Comparative Analysis of Ground, Magnetospheric and Interplanetary Observations of Long Period Magnetic Oscillations
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Continuous measurements of the geomagnetic field variations at ground stations are important to investigate several aspects of magnetospheric dynamics related to variations in the solar wind conditions which, ultimately, originate from the Sun. We present a comparative analysis of geomagnetic field measurements at several ground stations with simultaneous magnetospheric and interplanetary observations in order to understand the origin and characteristics of the observed fluctuations. The results suggest that long period geomagnetic field fluctuations can be directly driven by solar wind density fluctuations at the same frequencies via the modulation of the magnetopause current. We also discuss the possible occurrence of additional contributions related with cavity/waveguide resonances of the entire magnetosphere as well as those of resonance processes of the geomagnetic field lines.
KeywordsSolar wind Magnetosphere MHD waves
This research activity is supported by MIUR and Consorzio Area di Ricerca in Astrogeofisica. The authors thank the Institutes that operate the observatories which provided data for this study: the INTERMAGNET network (THY, HRB, BEL, HLP) and the IMAGE magnetometer array (UPS, HAN, OUJ, PEL, MUO, MAS, and SOR).