One of the critical grand challenges of Solar and Space Physics today is understanding and predicting stormtime geospace spanning altitudes from a few tens to millions of kilometers.
The term "geomagnetic storms", coined by Alexander von Humboldt, originates from 19th century observations of sunspots (most notably by Richard Carrington) coinciding with strong perturbations of the geomagnetic field and displays of aurorae. Geomagnetic storms are a consequence of complex plasma disturbances that start at the surface of the sun and then propagate through, and interact with, the interplanetary space environment, before impacting Earth. Storms occur in near-Earth space in response to this increased energy input from the solar wind, especially when coupled with certain interplanetary magnetic field orientations. Storms can have different solar and interplanetary drivers but intense and extreme events often involve series of coronal mass ejections (CMEs) or composites of structures including CMEs and corotating interaction regions.
Stormtime geospace is a system of systems representing interconnected physical domains of the near-Earth environment: the magnetosphere, including all of its regions; the ionosphere; the upper atmosphere in which the ionosphere is embedded; and the lower atmosphere. These domains are populated by neutral gases and plasmas that are immersed in electromagnetic fields and evolve on different temporal and spatial scales. During geospace storms, all of these domains become active and engage in complex, cross-scale interactions that profoundly alter the entire system.
To highlight their pervasive effects throughout geospace, we refer to geomagnetic storms as geospace storms.
The space science community has made significant progress in developing theoretical and numerical models of geospace.
Even so, the complexity of the coupled geospace system has defied attempts to describe stormtime geospace with the completeness and fidelity required for comprehensive understanding and reliable space weather forecasting and mitigation.
The scientific challenges are both physical and computational. On one hand, because of the collective cross-scale interactions that define stormtime geospace, such understanding can only be derived by treating geospace as a whole. On the other hand, there is strong evidence of the critical role of smaller, mesoscale processes in driving and mediating stormtime geospace dynamics across regions and spatiotemporal scales.
This entails the conception, implementation, and use of highly accurate numerical algorithms running on powerful supercomputers.