Whitepaper #445 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: space weather applications; basic research. Additional topics: space weather research/applications/operations pipeline; planetary ionospheres / upper atmospheres; system […]
This paper reviews the current state of first-principles (i.e. physics-based) ionosphere-thermosphere-mesosphere (ITM) models that use numerical solutions to systems of underlying differential or algebraic equations. We identify compelling future directions and urgent needs, and make near-term recommendations for investments in several different aspects of physics-based modeling and simulation.