Whitepaper #347 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: basic research. Additional topics: planetary ionospheres / upper atmospheres; space-based missions/projects; system science.
The ITM regime is a critical region in the geospace system, where the dominant physical processes transition from neutral dynamics to plasma dynamics. This region is sensitive to forcing from both above (Solar radiation, solar wind, and magnetosphere) and below (lower atmosphere). NASA must understand how the ITM system varies at mesoscales, all over the globe, on timescales of minutes to days.