Speaker
Dr
Timo Pitkänen
(Department of Physics, Umeå University)
Description
Ionospheric electron density depletions are often observed at the boundaries of
auroral precipitation. Previous investigations suggest that these depletions, known
also as auroral density cavities, are associated with a downward field-aligned current
(FAC) region within the localized auroral current system. While precipitating electrons
carry an upward FAC, the density depletions have been explained to be created by
upgoing ionospheric electrons carrying the downward FAC. Enhanced perpendicular
ionospheric electric fields are suggested to the FAC closure and they have been
observed to be associated with the depletions. In this investigation, we use field-
aligned measurements from the EISCAT UHF incoherent scatter radar from the years
2001-2011 to statistically study ionospheric density depletion events associated with
auroral precipitation. We investigate the occurrence of the density depletions and
study their dependence on geomagnetic activity as well as their general statistical
properties.
Primary author
Dr
Timo Pitkänen
(Department of Physics, Umeå University)
Co-authors
Dr
Anita Aikio
(Ionospheric Physics and Geospace Environment, University of Oulu, Finland)
Dr
Hans Nilsson
(Swedish Institute of Space Physics)
Dr
Liisa Juusola
(Finnish Meteorological Institute, Helsinki, Finland)
Dr
Maria Hamrin
(Department of Physics, Umeå University)
Dr
Tomas Karlsson
(KTH)
