The properties of chorus waves effective for wave-particle interactions in the outer radiation belts
Résumé
Chorus waves are among the most important natural electromagnetic emissions in the magnetosphere as regards to their potential effects on electron dynamics. They can efficiently accelerate or precipitate electrons trapped in the outer radiation belt, producing either fast increases of relativistic particle fluxes or auroras at high latitudes. Accurately modeling their effects, however, requires detailed models of their wave power and wave normal angle distribution as a function of geomagnetic activity in a particularly wide spatial domain, rarely available based solely on the statistics obtained from only one satellite mission. We combine VLF measurements from the recent multi-spacecraft missions Cluster, THEMIS and Van Allen Probes and reveled the whistler waves parameters and derived the consensuses for effectiveness of wave-particle interactions during the geomagnetic storms. Taking into account the new findings of significant part of oblique wave normal contribution and higher wave amplitudes in the night sector, latitudinal amplitude distribution, dependence of whistler frequency on latitude it is shown that the wave pitch-angle and especially energy diffusion rates are strongly increased near the equator, whereas pitch-angle diffusion near the loss cone is also enhanced. The proposed chorus model is important for accurately modeling global acceleration and loss of electrons over the long run in the outer radiation belt, allowing a comprehensive description of electron flux variations over a very wide energy range.