The Effect of Energy Input on the Earth's Upper Atmosphere.

Thermosphere;Ionosphere;Modeling;Energy Inputs;Upper Atmosphere;Atmospheric;Oceanic and Space Sciences;Science;Atmospheric, Oceanic and Space Sciences

Zhu, JieZou, Shasha ;

University of Michigan

关键词: Thermosphere;    Ionosphere;    Modeling;    Energy Inputs;    Upper Atmosphere;    Atmospheric;    Oceanic and Space Sciences;    Science;    Atmospheric, Oceanic and Space Sciences;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/120748/zhjie_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The Earth;;s upper atmosphere is affected by a variety of energy inputs, mainly incident solar irradiance, dissipation of internal gravity waves, solar wind electric fields and energetic particle precipitation. This dissertation consists of four studies focusing on the response of the coupled thermosphere ionosphere system to several energy inputs by using the Global Ionosphere Thermosphere Model (GITM). Two studies focus on how a sudden increase in solar EUV emissions affects the ionospheric density and thermospheric dynamics during a solar flare. Both the flare incident energy and the background conditions, i.e., the geomagnetic fields and seasons, control the ionospheric response. Solar flares with different incident energies into the same background hemisphere caused ionospheric disturbances of similar profiles but different magnitudes, while the same flare spectra caused perturbations of similar magnitude but different profiles in different backgrounds. In addition, large scale gravity waves are shown to travel from the dayside to the nightside when a flare occurs. Acoustic waves are modulated by neutral-ion momentum coupling because ion drag can be comparable to the gradient in pressure in the acoustic temporal scale.Ionospheric temperatures are strongly coupled with the neutral atmosphere and control many chemical and physical processes. An improved ionospheric energy model was developed in GITM and is described here. The model allows self-consistent energy coupling between electrons, ions and neutrals. The model was applied to explore the ionospheric response to an idealized substorm. The ion temperature was controlled mainly by the solar wind electric field, while the electron temperature was controlled by particle precipitation. In addition, the performance of a commonly used neutral-ion collisional heating approximation was investigated. The global averaged neutral temperature could be underestimated by approximately 10% due to the neglect of the indirect heating from electrons through ions. The use of a photoelectron heating efficiency for neutrals by global IT models that use Joule heating for energy coupling between the thermosphere and ionosphere, was essentially a compensation for the neglect of this heating.