Another envelope soliton event below the H+gyrofrequency and localized density depletion was discovered in low auroral region(~1760 km)by Freja satellite.This envelope soliton has a characteristic frequency at~190 Hz,...Another envelope soliton event below the H+gyrofrequency and localized density depletion was discovered in low auroral region(~1760 km)by Freja satellite.This envelope soliton has a characteristic frequency at~190 Hz,which is also closed to the resonance frequency of hydrogen ion-oxygen ion hybrid wave.This event is correlated in time with the observations of the sharp increase of the ratio of oxygen ion density to hydrogen and with the electrons energization along the magnetic field.A theoretical model on the ion-ion hybrid wave excited by energetic electron beam has also been presented.It is found that the ion-ion hybrid wave is mainly excited by the Cherenkov instability in auroral region.展开更多
In this paper we present a method of calculation of the flux density of radio source for high spatial resolution solar radio observations,i.e.,according to the observed solar antenna temperature,we make a correction f...In this paper we present a method of calculation of the flux density of radio source for high spatial resolution solar radio observations,i.e.,according to the observed solar antenna temperature,we make a correction for the K factor of antenna power pattern,then we can obtain values of solar radio flux.According to models of different brightness temperature distributions of the quiet sun and radio sources,we deduced the expression of the K factor of antenna power pattern,and calculated the fluxes of the quiet sun and slowly varying component emission of radio sources at 22 GHz.展开更多
In the observations of Freja satellite in the energization region of the low aurora(1700 km),a new nonlinear plasma oscillation with a turbulent spectrum at the fractional harmonics of the local proton gyrofrequencies...In the observations of Freja satellite in the energization region of the low aurora(1700 km),a new nonlinear plasma oscillation with a turbulent spectrum at the fractional harmonics of the local proton gyrofrequencies is reported and analyzed with the wavelet transformation in the time-frequency spectrum.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.19803050.
文摘Another envelope soliton event below the H+gyrofrequency and localized density depletion was discovered in low auroral region(~1760 km)by Freja satellite.This envelope soliton has a characteristic frequency at~190 Hz,which is also closed to the resonance frequency of hydrogen ion-oxygen ion hybrid wave.This event is correlated in time with the observations of the sharp increase of the ratio of oxygen ion density to hydrogen and with the electrons energization along the magnetic field.A theoretical model on the ion-ion hybrid wave excited by energetic electron beam has also been presented.It is found that the ion-ion hybrid wave is mainly excited by the Cherenkov instability in auroral region.
基金Supported by the National Natural Science Foundation of China under Grant No.19833050the Joint Radio Astronomy Research Laboratory of the Chinese Academy of Sciences.
文摘In this paper we present a method of calculation of the flux density of radio source for high spatial resolution solar radio observations,i.e.,according to the observed solar antenna temperature,we make a correction for the K factor of antenna power pattern,then we can obtain values of solar radio flux.According to models of different brightness temperature distributions of the quiet sun and radio sources,we deduced the expression of the K factor of antenna power pattern,and calculated the fluxes of the quiet sun and slowly varying component emission of radio sources at 22 GHz.
基金Supported by the National Natural Science Foundation of China under Grant Nos.19673019 and 69575010.
文摘In the observations of Freja satellite in the energization region of the low aurora(1700 km),a new nonlinear plasma oscillation with a turbulent spectrum at the fractional harmonics of the local proton gyrofrequencies is reported and analyzed with the wavelet transformation in the time-frequency spectrum.
