Impact of the altitudinal Joule heating distribution on the thermosphere

The thermospheric response at satellite altitudes along low Earth orbit is subject to the energy deposition locally, i.e., at high altitudes, and the vertical wave propagation from the energy injection at lower altitudes. In this study, a general circulation model has been run to investigate the source of nonhydrostatic effects and the sensitivity of the vertical wind and neutral density at satellite orbits to the energy deposited at low and high altitudes. Through comparing the simulations with and without the Joule heating enhancement above 150 km altitude, the impact of the heating at low and high altitudes on the high-altitude thermosphere has been separated. The numerical simulations show that most of the nonhydrostatic effects at high altitudes (300 km) arise from sources below 150 km and propagate vertically through the acoustic wave. The heating above 150 km is responsible for a large increase of the average vertical velocity (40 m/s) and neutral density (50%) at 300 km and higher altitudes.