The Global Distribution Characteristics Of Auroral Kilometric Radiations In The Radiation Belt

Auroral kilometric radiation(AKR)is one of the strongest terrestrial radio emissions at frequencies 30?800 kHz with its power being as high as 107?109 W.It has been firstly observed and reported by Benediktov et al in the Soviet Union in 1965.Because its wavelength is in the range of kilometer,it is called kilometric radiation.The enhancements of AKR generally associated with the global auroral sighting and especially the occurrence of discrete auroral arcs,provides information on magnetosphere-ionosphere-atmosphere coupling.AKR generally occurs in high latitudes,and its explosion accelerates energetic electrons into relativistic electrons.If it appears near the equator,it will have a significant impact on the dynamics of the radiation belt and cause serious damage to the geosynchronous satellite.Therefore,it is important to investigate their spatial distribution via comprehensive observations and statistics.We examine the global distribution of auroral kilometric radiation in the radiation belts based on a 51-month database of Van Allen Probes.The absolute linear correlation coefficients between the number of events and the monthly averaged geomagnetic activity indices Dst and AE are nearly 0.4,suggesting that the occurrence of AKR is closely associated with the compression of plasmapause and suprathermal electron flux enhancements.Detailed statistics indicates that the AKR extends to lower L-shell and covers wider MLT during active times.The incidence rate in the nightside is significantly higher than that in the dayside,and the high frequency occurrence area is in the partial annular area of 5?L?6.5,20?MLT?24,00?MLT?04.The current result is expected to be applied to the quantification of relativistic electron dynamics in the radiation belt.