When and why are the auroras in the two hemispheres asymmetrical?

• Why is geospace asymmetric?

• What are the important temporal and spatial scales of geospace dynamics?

 

Geospace, the region of space where Earth’s magnetic field dominates, is very often considered to be symmetric between the northern and southern hemispheres. But in reality, the system is highly asymmetric. One goal for the research at BCSS is to understand Geospace as a coupled bipolar system in its entirety.

Asymmetries are observed in the ionosphere in the aurora, flows and currents. Asymmetries are also observed in the magnetosphere, such as large-scale warping of the magnetotail and asymmetric distributions of energy and pressure. Known causes of asymmetries include the orientation of the interplanetary magnetic field with respect to the Earth’s dipole tilt angle, solar irradiation, differences in Earth’s magnetic field, and disparities in wind forcing from the neutral atmosphere. Without including these asymmetries, our understanding of the Sun-Earth system will not be complete and models will not be able to accurately predict the location and timing of Geospace phenomena. As exploration of other planetary systems relies heavily on our understanding of the Sun-Earth system, this knowledge is important for understanding other planet systems as well.

The magnetosphere and ionosphere near the Earth constitute a strongly coupled system, where the dynamics involves a wide range of spatial and temporal scales. A second goal is therefore to determine the timescales for changes in the magnetosphere-ionosphere system and to understand the role that small-scale structures in the ionosphere play for the overall dynamics. Auroral arcs, flow channels, and polar patches are examples of puzzling ionospheric features under investigation.

To carry out these investigations we utilize a large variety of observations in Geospace: AMPERE, SWARM, CHAMP, DMSP, SuperDARN, SuperMAG, EISCAT, GNSS receivers, solar wind data, and other supplementary ground-based instruments in the polar ionosphere.