CAWSES Theme 3: Atmospheric Coupling Processes
Aim: Investigating the equatorial ionization anomaly and low latitude ionospheric instabilities.
Characteristic electron density structures and plasma processes regularly develop due to strong vertical coupling in the equatorial and low-latitude upper atmosphere. The continuous CHAMP data set of in situ electron density readings builds an excellent opportunity, e.g., to investigate the Equatorial Ionisation Anomaly at 400 km. Together with ground-based instruments we infered typical response times of the upper F region plasma structure to E-layer dynamo actions.
Equatorial plasma instabilities, also known as 'bubbles', dramatically disturb the low-latitude ionosphere during the hours after sunset and they are responsible for the most severe radio wave scintillations globally. The precise magnetometer on board CHAMP showed for the first time in a multi-year series that bubbles have magnetic signatures, and we derived their global climatological features. CHAMP also provides observations of bubble magnetic signatures perpendicular to the main field direction. These deflections imply the existence of field-aligned currents. Such observations will be used for characterising the electrodynamic state of the instability event. (Claudia Stolle)