Karl Magnus Laundal (DTU Space, Dänemark) Global inductive magnetosphere-ionosphere-thermosphere coupling
Karl Magnus Laundal (DTU Space, Dänemark) wird auf unserem IAP-Kolloquium einen Vortrag zum Thema "Global inductive magnetosphere-ionosphere-thermosphere coupling" halten.
Zusammenfassung:
The ionosphere forms the inner boundary of near-Earth space, where collisionless space plasma transitions into a partially ionized gas that interacts with the neutral atmosphere through collisions. Conventional models of magnetosphere-ionosphere (MI) coupling use an electric circuit framework, where an electric potential is calculated from the current continuity equation on a thin spherical shell that represents the ionosphere. This approach neglects induction, the dynamic evolution of magnetic field disturbances, and therefore omits a fundamental element of the global MI coupling process.
I will present a new, global model of the ionosphere that incorporates induction and treats the magnetic field as the primary dynamical variable (https://doi.org/10.5194/angeo-43-803-2025). By including induction, the model provides a fundamentally different description of how high- and low-latitude regions are coupled than conventional magnetostatic approaches. It self-consistently describes the generation and temporal evolution of Sq currents, their modification by high-latitude current systems, and the emergence of penetration electric fields.
The model accommodates arbitrary global patterns of ionospheric conductance, neutral winds, and main magnetic field geometry. Simulations reveal a rich induction dynamics on timescales ranging from seconds to several minutes. These timescales depend on the magnitude and spatial structure of the conductance, neutral winds, imposed magnetic perturbations (field-aligned currents), and the background magnetic field. I will discuss the conceptual distinctions between this framework and conventional MI coupling models, how these ideas can be tested observationally, and how they can be incorporated into ionospheric data assimilation schemes.
