Disturbances over polar cusps: Interball-1 and Polar joint statistics
Abstract
We study the statistical properties of nonlinear magnetic and plasma fluctuations over polar cusps and compare them with that of dayside magnetopause and near tail. Interball-1 and Polar data are normalized by the solar wind (SW) dynamic pressure and parameterized by the Bx, By and Bz in SW and by the magnetic dipole tilt. The latter controls the magnetopause (MP) shape over cusp and the geometry of highly disturbed regions: (a) for the positive tilts (the dipole inclined towards the Sun) the disturbed magnetosheath (MSH) plasma locates over indented MP, (b) for the negative tilts the turbulence is seen from both sides of the smooth MP, having less pronounced higher-frequency component. In some Interball-1 cases and regularly in Polar data quite strong disturbances are seen deep in the cusp for any tilt angles during highly dynamic SW behavior. POLAR usually tracks the bottom of the disturbed region where the fluctuation energy is diminished and magnetic perturbations have compressible character. We use energetic particle data for positioning of the fluctuations relative to MP. In such a way we confirm, that the ‘plasma balls’ large-scale heated MSH plasma sites, registered mostly at the negative tilts are encountered generally inside MP. Correlation between the waves and accelerated particles in the cusp throat is studied. On the basis of the statistics we discuss also the orbit for the ROY mission (grant INTAS-2000-465).
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA......903P