Observations of ionospheric gravity and diamagnetic current systems inferred from CHAMP and Swarm measurements

Abstract:

Large scale currents in the ionosphere are driven by a variety of sources, including neutral winds, gravity, and plasma pressure gradients. While the
stronger day-time wind-driven currents have been extensively studied, gravity and diamagnetic currents in the ionosphere have received
little attention, but can have substantial effects even during the night. With the availability of a new generation of magnetic field models based
on high-accuracy satellite magnetic measurements, it becomes increasingly important to account for these smaller current systems. In this study,
we use over a decade of high-quality geomagnetic field measurements from the CHAMP and Swarm missions to study the seasonal and longitudinal
structure of these currents. These results allow us to visualize the global structure of these currents and quantify their magnetic
perturbations both on the ground and at satellite altitude.