Space Physics (Department of Earth Physics)

Responsible: Balázs HEILIG, Ph.D.

ULF wave research

Ultra low frequency (ULF: 1 mHz – few Hz) waves are the wave phenomena of planetary magnetospheres and the interplanetary space. Thy can be observed regularly in the terrestrial magnetosphere. Their ground correspondents are also called geomagnetic pulsations. Some of these are generated outside the magnetosphere. An important example is the upstream waves. These waves are driven by a wave particle interaction between the super-magnetosonic solar wind particles and the Earth’s magnetosphere. Since their upstream origin, these waves can be used to investigate the interplanetary medium (the solar wind).
The wavelength of ULF waves match closely the characteristic sizes of the magnetosphere, hence various resonance phenomena develop. The most well-known of these is the field line resonance, i.e. the eigen-resonance of the geomagnetic field lines. Due to the dependence of the resonant frequency on the field line length and geometry, as well as on the plasma mass density along the field lines, FLRs are used to monitor the plasmaspheric mass density.
We have been involved in various European magnetic LEO (low-Earth orbit) satellite projects, such as the German CHAMP mission and the ongoing SWARM mission, a 3-satellite mission of the European Space Agency. Our results on ULF waves observed at LEO have been internationally recognized. We have also worked with data of other space missions (ESA’s 4 Cluster satellites, NASA’s THEMIS, ACE, Wind solar wind monitors, etc.)

Plasmasphere dynamics

MFGI has been coordinating the MM100 magnetometer network since 2001. In 2012 MM100 was merged with SEGMA (South-European GeoMagnetic Array) to establish EMMA (European quasi-Meridional Magnetometer Array) unifying efforts made in Finland, Estonia, Lithuania, Poland, Slovakia, Hungary, Croatia, Italy. EMMA was formed in the frame of the EU FP7 project PLASMON with the aim to provide continuous real time data for the monitoring of plasmaspheric mass density.
We developed a new method making use of the LEO observations of the magnetic signatures of small scale field aligned currents to locate the plasmapause, the outer boundary of the plasmasphere. This boundary region is very important for the investigation of various magnetospheric phenomena. Our technique yields continuous observation of the plasmapause with unprecedented time resolution. Using SWARM observations we are close to the state where we are able to provide plasmapause positions in near real time (providing the SWARM data are available).