Wave-Mean Flow Interaction in the Storm-Time Thermosphere Using a Two-DimensionalModel

摘要

A two-deminsional pole-to-pole numerical model with back ground solstitial windshas been used to study the global dynamical response of the thermosphere to high-latitude energy inputs associated with a model geomagnetic storm. This model storm, consisting of a series of substorms, has four distinct pulses of heat input over a 12-hr period. The storm generated six groups of wave disturbances in the form of internal gravity waves. Characteristics of these disturbances such as their vertical structure, phase propagation speeds, and influences of dispersion and dissipation are illustrated. The disturbances in the velocity field and in the temperature field are shown, along with their mutual phase relationship with regard to the meridional and vertical transport of heat and momentum. In addition to the generation of disturbances, the thermospheric response to the sustained part of the heat input is found to consist of the establishment of a global meridional circulation which is initiated in about 3 to 4 hours after storm commencement and never quite reaches steady-state in the simulation. The time development of this circulation and its associated temperature field are described. Keywords: Thesis. (rh)