Geomagnetic and solar wind fluctuations at discrete frequencies: A case study

[1] A worldwide analysis of geomagnetic field measurements, during a period of wave activity following an intense magnetospheric perturbation, revealed signals at discrete frequencies (f ≈ 1.0, ≈1.9, ≈2.2–2.4, ≈2.6, ≈3.4–3.6, and ≈4.7 mHz) which are similar to the frequencies identified from auroral to low latitudes in previous investigations. All the power enhancements found correspondence in enhancements, approximately at the same frequencies, in the solar wind dynamic pressure, and/or speed and interplanetary magnetic field components. The modes dominant in the wide afternoon sector (f ≈ 1.9, ≈2.6, and ≈3.4–3.6 mHz) were almost ubiquitously detected, and rough estimates of the propagation parameters appear consistent with those expected for standing cavity modes. The modes emerging in the morning sector (f ≈ 1.0 and ≈2.2–2.4 mHz) appear related to the fluctuations of the magnetopause current, driven by those of the solar wind pressure.