Ionospheric Closure of Field-Aligned Currents: Mechanisms and Impacts in Geospace and Beyond

Ionospheric closure of field-aligned currents (FACs) is central to understanding how energy and momentum are exchanged between the magnetosphere and the ionosphere thermosphere (I-T) region. Although classic models depict FACs and auroras under simplified, steady-state, and one-dimensional conditions, real systems display far more complex three dimensional and time-dependent behavior. Ground- and space-based studies reveal significant variability in how currents close through the I-T, influenced by altitude distribution, neutral winds, and diverse geomagnetic conditions. Yet, crucial questions remain about the mechanisms governing current closure, the interplay between Pedersen, Hall, and field aligned ionospheric currents, alongside with the coupled responses within the broader geospace environment. The lessons learned from the Earth system extend to other planetary and astrophysical systems, underscoring the universal relevance of FAC closure processes. This Research Topic will advance our understanding of the multidimensional and dynamic aspects of ionospheric closure of FACs. Primary objectives include identifying how different closure pathways operate under various conditions, clarifying the roles of associated currents and atmospheric coupling, and improving models that predict energy transfer and space weather impacts. By combining empirical observations, simulations, and theoretical approaches, this Research Topic seeks to bridge gaps in current knowledge and inform both practical applications and fundamental research across geospace and planetary environments. The scope includes studies focused on FAC closure mechanisms within Earth’s I-T system and in other planetary contexts. We invite contributions addressing core theoretical principles, advanced modelling, and observational insights, provided they relate to the three dimensional FAC closure. We welcome articles addressing, but not limited to: • Three-dimensional FAC closure at auroral arcs and more complex aurora • Differences in FAC closure by Pedersen and Hall currents under quasi quiet versus disturbed conditions • Polarization and Cowling mechanism at high and low latitudes • Multiscale analysis of FACs and associated closure pathways • Relationship between plasma convection topology and FAC closure • Joule heating and energy deposition across spatial scales • Coupling with the neutral atmosphere, dynamo, and wind-driven effects • Comparative studies of FAC closure in planetary and astrophysical environments • Space weather implications of FAC closure and Joule heating.We welcome original research, reviews, perspectives, methods, and data reports. Topic editors: Octav Marghitu, Jesper W Gjerloev, Tomas Karlsson, Kristina A Lynch Source: https://www.frontiersin.org/research-topics/78996/ionospheric-closure-of-field-aligned-currents-mechanisms-and-impacts-in-geospace-and-beyond