Global modeling of storm-time thermospheric dynamics and electrodynamics

摘要: Understanding the neutral dynamic and electrodynamic response of upper atmosphere to geomagnetic storms, quantifying balance between prompt penetration disturbance dynamo effects, are two significant challenges facing us today. This paper reviews our understanding dynamical storms from a modeling perspective. After injection momentum energy at high latitude during storm, winds begin respond almost immediately. The high-latitude wind system evolves quickly by action ion drag kinetic energy; however, Joule dissipation provides bulk source change dynamics electrodynamics globally. Impulsive latitudes drives large-scale gravity waves that propagate transmit pressure gradients initiating in global circulation. Numerical simulations coupled thermosphere, ionosphere, plasmasphere, indicate although dynamic, with apparent "sloshing" hemispheres, net effect is for an increased equatorward wind. changes storm provide conduit many physical processes ensue atmosphere. For instance, meridional mid push plasma parallel magnetic field regions different composition. circulation carries molecular rich air lower thermosphere upward equatorward, changing ratio atomic species, loss rates ionosphere. also dynamo, which through transport modifies strength location equatorial ionization anomaly peaks. On scale, winds, generation zonal via Coriolis produce current opposing normal quiet-time Sq system. At equator, storm-time electric fields reduce or reverse downward drift on dayside nightside, respectively. In numerical simulations, dayside, appears fairly uniform, whereas night stronger local time dependence midnight dawn. possibility rapid within 2 h onset, before arrival waves. All these wind-driven can result dramatic ionospheric storms. combine interact magnetospheric equator.