 |
| Titel |
Distribution of the electron pitch-angle diffusion rates in the radiation belts |
| VerfasserIn |
A. Artemyev, O. Agapitov, H. Breuillard, V. Krasnoselskikh, G. Rolland |
| Konferenz |
EGU General Assembly 2012
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250063101
|
|
|
|
|
|
| Zusammenfassung |
| We performed a statistical study for VLF emissions using a whistler frequency
range for ten years (2001-2010) of Cluster measurements. We utilized data from
the STAFF-SA experiment, which spans the frequency range from 8.8 Hz to 3.56
kHz and present distributions of wave magnetic and electric field amplitude and
wave-normals as a function of MLat, MLT, L-shell and geomagnetic activity in a form of
probability levels, which were directly applied for electrons diffusion coefficients
calculation in the outer radiation belt. The propagation direction of chorus waves
rapidly deflects from the magnetic field with the increase of latitude and for a given
frequency tends to the resonance cone at 15-25 degrees. The width of the distribution
increases also. Results were proved using numerical ray tracing simulation. The
increase of the mean value and the variance of the wave vector distribution with
latitude results in important growth of the pitch-angle diffusion rates due to significant
increase of the contribution of higher order cyclotron resonances at larger latitudes,
which is most efficient for electrons with small equatorial pitch-angles. The statistics
of the wave magnetic field amplitude also shows strong dependence on magnetic
latitude. The probability density function of the magnetic field preturbation has the
form, which significally deviates from Gaussian, and can not be represented by its
averaged value. We processed the set of the amplitude levels of the probability
cumulative function to compose the probability density functions for the diffusion
coefficients for day and night sectors and for different geomagnetic activity regimes. |
|
|
|
|
|
|