The Coupling Between The Inner Magnetosphere And Low Ionosphere

In the basically collision-less inner magnetosphere, there are a variety of plasma waves, such as hiss, chorus, EMIC wave, ECH wave. Among them, hiss and chorus can scatter the energetic electrons into the loss cone, the energetic electrons precipitate into the low ionosphere. Part of the neutral components in low ionosphere can be ionized due to collision with the precipitating energetic electrons, Therefore the electron density in the low ionosphere can increase. The chorus/hiss-energetic electrons interaction is one of the main mechanisms of the wave-particle interaction in the inner magnetosphere. In order to better understand the important role of chorus/hiss-energetic electrons interaction in the loss of electrons in the inner magnetosphere and the property of low ionosphere, the works below have been done.(1) Study about the impact of the precipitating energetic electrons on the ionosphere during substorm. Using the observations of the NOAA 16, LANL-01A, IMAGE satellites, ground-based riometers at high geomagnetic latitudes, and VLF radio wave receivers at middle geomagnetic latitudes, we present perturbation of low ionosphere associated precipitating energetic electrons due to tail current scattering (TCS) mechanism and wave-particle interaction during one substorm on November 8, 2004. Associated with a substorm dispersion injection observed by the LANL-01A satellite, the riometers observed obvious enhancements of ionospheric absorption within the electron isotropic zone which is attributed to TCS mechanism. With observations of the NOAA 16 satellite, we find a sharp enhancement of the precipitating electron flux within the anisotropic zone with an obvious separation of energetic electron precipitation at high latitudes. This energetic electron precipitation within the anisotropic zone leads to variations of VLF radio wave amplitudes. Since the projection of electron precipitation region within the anisotropic zone is at the inner edge of the plasmapause observed by the IMAGE EUV. The precipitation of energetic electrons should be attributed to ELF hiss-ring current electron interaction. The result of research reveals the impact of energetic electron precipitation due to two mechanisms on the characters of low ionosphere.(2) Studies about the interaction between plasmaspheric hiss and energetic electron and its impact on the ionospheric cosmic radio noise absorption. The Van-Allen probes, low-altitude NOAA satellite, MetOp satellite and riometer are used to analyze variations of precipitating energetic electron fluxes and cosmic radio noise absorption (CNA) driven by plasmaspheric hiss with respect to geomagnetic activities. The hiss-driven energetic electron precipitations (at L-4.7-5.3, MLT-8-9) are observed during geomagnetic quiet condition and substorms, respectively. We find that the CNA detected by riometers increased very little in the hiss-driven event during quiet condition on September 06,2012. The hiss-driven enhancement of riometer was still little during the first substorm on September 30,2012. However, the absorption detected by the riometer largely increased while the energies of the injected electrons became higher during the second substorm on September 30,2012. The enhancement of CNA (ACNA) observed by the riometer and calculated with precipitating energetic electrons are in agreement during the second substorm, implying that the precipitating energetic electrons increase CNA to an obviously detectable level of the riometer during the second substorm on September 30,2012. Through the combination of the observations and theory calculations, we find that higher-energy electron (>55 keV) precipitation contribute more to the ?CNA than the lower-energy electron precipitation. In this paper, the higher-energy electron precipitation is related to lower-frequency hiss. As a result, the lower frequency hiss can cause the obvious ACNA more easily.(3) Study about the global distribution of energetic electron precipitation (EEP) events driven by lower band chorus waves with observations of Polar Orbit Environment satellites (POES). By using global total electron content (TEC) map to identify the mid-latitude trough minimum as the footprint of plasmapause, we distinguish EEP events driven by chorus waves outside the plasmapause or those driven by hiss waves inside the plasmapause. Based on the simultaneous observations of EEP in the el 0°(>30 keV) and e20°(>100 keV) channels from POES satellites, a total of 5544 chorus-driven EEP events are seek out. The chorus-driven EEP events mainly distribute in the midnight-noon sector which is similar to the distribution of lower band chorus waves. As the geomagnetic activity become more disturbed, the occurrence rate is higher which is contributed to excitation of chorus waves associated with substorm electron injection, the peak of occurrence rate also moves to lower L-shell. Under the action of active geomagnetic activity, the events in the nightside are confined to lower L-shells due to smaller electron gyro-frequencies relative to those in the dayside. The occurrence rate of the EEP events in the dayside with high L-shells suggest that the strong solar wind dynamic pressure can also contribute to the excitation of events in the dayside with high L?shells. As a result, the occurrence rate of chorus-driven EEP events is close relation with the geomagnetic activity and solar wind dynamic pressure. The statistics of chorus-driven EEP events are helpful to analysis the distribution of lower band chorus waves and their contributions to the loss of energetic electrons in the inner magnetosphere.The results in this study are important to reveal the energetic electron loss in the inner magnetosphere and the change of ionospheric D layer due to wave-particle interaction.