Forecasting the Ionosphere Driven by Solar, Geomagnetic, and Lower Atmosphere Disturbances

Abstract:

Ionospheric forecasting has traditionally focused upon, and been limited by, our ability to forecast magnetospheric drivers one to two days in advance of a geomagnetic storm. The advances in this area are significant as physics-based solar wind propagation models have been transitioned to operations, and provide the time of arrival of a solar disturbance. Although predicting the magnetic field orientation and strength is still a challenge, once the solar wind drivers are forecast, the accuracy of the ionospheric predictions are dependent on the ability of thermosphere-ionosphere models to correctly capture the physical processes in the upper atmosphere response to magnetospheric energy and momentum dissipation. Many of the storm-time thermosphere responses impacting the ionosphere can be modeled reasonably well, such as changes in winds, gravity waves, temperature, density, and composition. However, some of the electric field effects driving storm enhanced plasma density and the disturbance dynamo are still a challenge. Under quieter geomagnetic conditions, forecasting solar extreme ultraviolet radiation becomes more important, as does the impact of forcing from the lower atmosphere. These two new research thrusts are also showing promise to provide the drivers of ionospheric prediction several days in advance. There is also a possibility that whole atmosphere models could provide the background conditions for forecasting ionospheric irregularities.