Observations of solar wind pressure initiated fast mode waves at geostationary orbit and in the polar cap

Abstract

This study involves a multi-satellite investigation of magnetic field perturbations in the magnetosphere due to solar wind dynamic pressure variations. The case study uses data acquired on 3 August 1986 from IMP-8, GOES-5, GOES-6, VIKING, and ground magnetograms. As expected, dramatic solar wind dynamic pressure variations, recorded at IMP-8, produced compressions and rarefactions of the magnetosphere as seen in GOES-5 and GOES-6 magnetic field observations at geostationary orbit. These same compressions and rarefactions were also recorded by the VIKING magnetic field experiment over the polar cap at mid-altitudes. The magnetic field perturbations are interpreted in terms of fast mode waves which were generated near the magnetopause and propagate anti-sunward into the inner magnetosphere. In addition, we compare the amplitude of the magnetic field perturbations recorded at geostationary orbit and VIKING. The wave amplitudes recorded by GOES and VIKING were nearly identical, suggesting a low damping rate of the waves in the magnetosphere.