Speaker
Dr
Iannis Dandouras
(IRAP, CNRS / University of Toulouse)
Description
The Earth’s plasmasphere dominates the mass content of the inner magnetosphere and therefore plays an essential role in governing the radiation belt dynamics. The configuration of the plasmasphere is highly sensitive to geomagnetic disturbances. During extended periods of relatively quiet geomagnetic conditions the outer plasmasphere can become diffuse, with a gradual fall-off of plasma density. During increasing magnetospheric activity, however, the plasmasphere is eroded and plasmaspheric ions can be peeled off and escape toward the outer magnetosphere. Plumes, forming at the plasmapause and released outwards, constitute a well-established mode for plasmaspheric material release to the Earth’s magnetosphere. They are associated to active periods and the related electric field change. In 1992, Lemaire and Shunk proposed the existence of an additional mode for plasmaspheric material release to the Earth’s magnetosphere: a plasmaspheric wind, steadily transporting cold plasmaspheric plasma outwards across the geomagnetic field lines, even during prolonged periods of quiet geomagnetic conditions. This has been proposed on a theoretical basis. Direct detection of this wind has, however, eluded observation in the past. Analysis of ion measurements, acquired in the outer plasmasphere by the CIS experiment onboard the four Cluster spacecraft, provide now an experimental confirmation of the plasmaspheric wind. This wind has been systematically detected in the outer plasmasphere during quiet and moderately active conditions, and calculations show that it could provide a substantial contribution to the magnetospheric plasma populations outside the Earth’s plasmasphere. Similar winds should also exist on other planets, or astrophysical objects, quickly rotating and having an atmosphere and a magnetic field.
Primary author
Dr
Iannis Dandouras
(IRAP, CNRS / University of Toulouse)
