There exists a large number of fundamental magnetospheric dynamics questions that are currently unanswerable with the existing suite of observational and numerical tools. A major obstacle is the difficulty of probing observationally and adequately simulating the mesoscale regime that lies between the kinetic and global scales. Mesoscales in Earth’s magnetosphere are ~1-2 RE, which makes observations difficult without large constellations of in situ spacecraft. Numerically, global MHD simulations are just now getting to the scale necessary to resolve these scales and are finding mesoscale dynamics that are unconfirmed by our limited observations.

The purpose of this Working Group is to summarize the state-of-the-art of mesoscale dynamics in Earth’s magnetosphere, with a primary focus on the nightside, and clearly identify future science, mission, and toolset needs. The outcome will be published as volume 18 in the ISSI Scientific Reports Series. This volume will clearly identify the science questions that need answered, in prepara- tion for large constellations of magnetospheric spacecraft that are appearing soon on the horizon.