Ionosphere is the most challenging part of Space Weather with its spatio-temporal variability and dispersive nature. Ionospheric models are very important in reducing positioning error in GNSS system.International Reference Ionosphere(IRI) is an empirical, deterministic and climatic model of ionosphere up to 2000 km in height. Recently, IRI Extended to Plasmasphere(IRI-Plas) model has been developed to extend the interest region of IRI to the GPS orbital height of 20,000 km. Both IRI and IRI-Plas provide ionospheric parameters such as electron density, electron and ion temperatures according to their height profiles. In order to update the model to current ionospheric conditions, IRI-Plas can input F2 layer critical frequency(foF2), maximum ionization height(hmF2), and also Total Electron Content(TEC).Online IRI-Plas is developed for the ionospheric community to run multiple tasks at various locations,dates and times with optional foF2, hmF2 and TEC inputs in a user-friendly manner. In this paper, we are going to present the capabilities of the Online IRI-Plas service and provide some comparisons between IRI-Plas outputs and ionosonde measurements. The comparison between online IRI-Plas foF2 outputs and ionosonde foF2 measurements indicates that the model with TEC input can significantly improve the representation of the current ionospheric state, which is very successful especially in the geomagnetically disturbed days.
Modulated high frequency （HF） heating of the ionosphere provides a feasible means of artificially generating ex- tremely low frequency （ELF）/very low frequency （VLF） whistler waves, which can leak into the inner magnetosphere and contribute to resonant interactions with high energy electrons. Combining the ray tracing method and test particle simulations, we evaluate the effects of energetic electron resonant scattering driven by the discrete, multi-frequency arti- ficially generated ELF/VLF waves. The simulation results indicate a stochastic behavior of electrons and a linear profile of pitch angle and kinetic energy variations averaged over all test electrons. These features are similar to those associated with single-frequency waves. The computed local diffusion coefficients show that, although the momentum diffusion of relativistic electrons due to artificial ELF/VLF whistlers with a nominal amplitude of ~ 1 pT is minor, the pitch angle scattering can be notably efficient at low pitch angles near the loss cone, which supports the feasibility of artificial triggering of multi-frequency ELF/VLF whistler waves for the removal of high energy electrons from the magnetosphere. We also investigate the dependences of diffusion coefficients on the frequency interval （△f） of the discrete, multi-frequency waves. We find that there is a threshold value of Af for which the net diffusion coefficient of multi-frequency whistlers is inversely proportional to △f （proportional to the frequency components Nw） when △f is below the threshold value but it remains unchanged with increasing Af when △f is larger than the threshold value. This is explained as being due to the fact that the resonant scattering effect of broadband waves is the sum of the effects of each frequency in the ＇effective frequency band＇. Our results suggest that the modulation frequency of HF heating of the ionosphere can be appropriately selected with reasonable frequency intervals so that better performance of controlled preci
The plasma transport between the plasmasphere and the ionosphere in response to the interplanetary conditions is still not fully understood until now.Simultaneous observations of the plasmasphere and ionosphere from the newly developed Chinese Meridian Project provide a new opportunity for understanding the characteristic of the plasma transport and the coupling mechanism between these two regions.We investigate the response of the plasmasphere(L≈2)and ionosphere to the solar wind dynamic pressure pulse during geomagnetically quiet period of 21–27 March 2011.The response of the plasmasphere shows a significant depletion.The plasmaspheric density nearly decreases by half in response to the solar wind dynamic pressure pulse,and subsequently recovers to the original level in 1–2 d.Meanwhile,the maximum electron density of the ionospheric F2 layer(NmF2)and the total electron content(TEC)increase by 13%and 21%,respectively,and then gradually recover,which is opposite to the behavior during magnetic storms.Preliminary analysis shows that the plasmaspheric depletion may be mainly caused by the southward interplanetary magnetic field and changing dawn-dusk electric field.The plasmaspheric density variations seem to be controlled by both the IMF and ionospheric conditions.
