Missions and efforts using magnetic field observations to advance our knowledge of the coupled magnetosphere-ionosphere-thermosphere (MIT) system

Magnetic field observations have a long history of advancing our understanding of ionospheric current flow, even before we launched space missions. Earlier magnetic field missions were single satellites that provided new insights into ionospheric current flow. Swarm is the first constellation focused on measuring magnetic fields from LEO. In this talk, we will focus on the value of knowing the magnetic field variation and discuss challenges, advances, and future opportunities.

One scientist's signal is another scientist's noise, and therefore working with magnetic perturbation leads to the collaboration of scientists from solid Earth to the magnetosphere. Opportunities can be challenges since magnetic observations include the signal from many sources which can be from far away or close by, making the interpretation of magnetic signals often difficult. In ionosphere-thermosphere numerical modeling, magnetic perturbations are not a standard diagnostic even though a wealth of data exists. While ionospheric data is used for data assimilation, magnetic data so far is not. A huge advantage of the Swarm satellite configuration is that it can unambiguously identify ionospheric current flow when the satellites are close. A similar concept is used by NASA Electrojet Zeeman Imaging Explorer (EZIE), a CubeSat mission scheduled for launch in spring 2025. In addition, EZIE is unique as it will measure the magnetic field around 80 km remotely via Zeeman splitting, to shed light on the substorm current flow and the equatorial electrojet.

In this presentation, we will describe the value of studying the ionospheric current to gain insights into the ionosphere-thermosphere system. We will show examples from high to low latitudes illustrating how magnetic perturbation especially in constellations and combined ground and space based data can advance our understanding of the MIT system. We conclude with thoughts about future observations.