HAO Colloquium - Astrid Maute, HAO

Modelling Ionospheric Electrodynamics

Ionospheric electrodynamics plays a central role in the coupling of the thermosphere and ionosphere. Thermospheric winds push the weakly ionized plasma of the ionosphere through the geomagnetic field, generating ionospheric current. Electric fields are set up in such a way to make the ionospheric current divergence free. In addition to the described wind dynamo, smaller ionospheric current sources due to gravity and plasma pressure gradient forces exist at Low Earth Orbit (LEO) heights, and can dominate over the wind driven current especially at night. At high latitudes, the solar wind and magnetosphere interact with the ionosphere and energy is transferred into the ionosphere via auroral precipitation and Joule heating. Especially during geomagnetic activity, the huge amount of energy dissipated in the ionosphere leads to large changes in the ionosphere and thermosphere globally. In addition, energy is transferred from the lower atmosphere to the ionosphere-thermosphere via upward propagating waves and tides. Strong meteorological disturbances in the lower atmosphere couple vertically to the upper atmosphere and lead to large changes in the thermosphere ionosphere system.

In this presentation, we will highlight examples of ionospheric electrodynamics modeling, which have helped explain ionospheric effects associated with coupling to the lower and to the magnetosphere. The upcoming Ionosphere Connection Explorer (ICON) mission will examine the vertical coupling mechanisms by combining observations and modeling. The ICON related modeling has already been employed to study the effect of lower atmospheric waves on the thermosphere and ionosphere. The electrodynamo and its electric fields are organized with respect to the geomagnetic main field. Therefore, variations of the geomagnetic main field on decadal scale are important to consider since they can modify the storm strength and its impact on the thermosphere-ionosphere, and on geomagnetic indices. We have developed a new 3D electrodynamo model which is able to determine the 3D ionospheric current flow and the associated magnetic perturbations at LEO heights. Examples will be shown to illustrate how the new 3D electrodynamo model is employed beyond the space science community to address scientific questions. We will discuss plans for future developments of ionospheric electrodynamics.

Date and time: 
Wednesday, December 19, 2018 - 2:00pm to 3:00pm