The Wizard of O(z)—Thermosphere physics revisited

This seminar is based on an Encyclopedia article that Jia Yue and Wenbin Wang recently wrote. The thermosphere is where many LEO objects including satellites, International Space Station and space debris are flying inside. Thermosphere density is by far the largest uncertainty forecasting satellite drag and orbit propagation. In this talk, I will review the recent progress of thermosphere physics driving the variability of thermosphere density, composition, temperature, and wind. In particular, mass density in the upper thermosphere is mainly controlled by the abundance of atomic oxygen as a function of geometric height (O(z)). Many processes can cause variations in O(z), including solar EUV heating, vertical and meridional advection, eddy and molecular diffusion, NO and CO2 cooling, etc. During geomagnetic active times, Joule heating, enhanced NO cooling, altered circulations, strong EUV heating and other processes lead to drastic changes of neutral density. At the end, I would review the fundamental thermosphere physics under the lens of future missions, GDC and DYNAMIC.