This collaborative research effort will study magnetosphere-ionosphere-thermosphere coupling through a coordinated campaign of observations and modeling using the Poker Flat Incoherent-Scatter Radar (PFISR), the Resolute Bay Incoherent-Scatter Radar (RISR), a variety of optical instruments, the Super Dual Auroral Radar Network (SuperDARN), the Homer Very High Frequency (VHF) radar, and the Global Ionospheric-Thermospheric Model (GITM). The ionosphere, thermosphere, and magnetosphere comprise a tightly coupled system at high latitudes. The ionosphere is the mediating element in this view, facilitating the transfer of free energy generated by solar wind-magnetosphere coupling into heat and bulk motion of the neutral atmosphere. This mediation occurs through electric fields, particle precipitation, diffusion, and field-aligned currents, agents that act collectively to structure the plasma density and composition within the system. Although elements of this system have been studied in considerable detail, their nonlinear interactions, and the global implications of these regional processes, remains poorly understood and inadequately observed. The electronic steering capability of PFISR offers a unique diagnostic to fill this gap. Using a dense grid of beams, a three-dimensional, time dependent view of the ion-neutral interactions can be developed. These results, in coordination with observations by common volume optical, and VHF and HF radar observations, allow access to system dynamics and system responses which were previously unobservable. The experimental campaign, involving twenty researchers from nine institutions, will be carried out over two winter seasons. The results will be used to address fundamental questions of the physics of the upper atmosphere and its coupling to the magnetosphere and the lower atmosphere, which have remained obscured for lack of key data. As a result, although it is understood that small-scale processes play critically important roles in this coupling, they have been difficult to include in quantitative models. The new information will be implemented in the GITM model validating the new understanding of the coupled magnetosphere, ionosphere and thermosphere, and thereby providing enhanced simulation capabilities.