It is shown that, according to observations, during the last geomagnetic field inversion, there was a decrease in the amplitude of four axisymmetric harmonics in the expansion of the magnetic field in spherical functions. Only the dipole component changed sign at the moment of reversal. For all four modes, quasi-variations with characteristic times of 10–50 thousand years were observed over an interval of 200 thousand years. During the reversal, there was an increase in magnetic field variations with characteristic times of 100–1000 years, caused by the destabilization of hydrodynamic flows in the core.
M.Yu. Reshetnyak (2025) studied this question.