Magnetic pulsations

Magnetic pulsations are extremely low frequency disturbances in the Earth's magnetosphere driven by its interactions with the solar wind.^[1] These variations in the planet's magnetic field can oscillate for multiple hours when a solar wind driving force strikes a resonance.^[2] This is a form of Kelvin–Helmholtz instability.^[1] The intensity, frequency, and orientation of these variations is measured by Intermagnet.^[2]

In 1964, the International Association of Geomagnetism and Aeronomy (IAGA) proposed a classification of magnetic pulsations into continuous pulsations (Pc) and irregular pulsations (Pi).^[1][3]