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As an important part of the inner magnetosphere, the Earth's plasmasphere plays a vital role in linking the occurrence and development of space weather processes. The Earth's plasmasphere is a torus-shaped cold (< 10 eV) and dense (10~104 cm−3) plasma region of ionospheric origin co-rotating with the planet. The plasmasphere contains several populations of particles such as electrons, H+, He+, and O+ ions. The outer boundary of the plasmasphere is defined by a sharp gradient of density called the plasmapause, in which the density decreases by 1~ 2 orders of magnitude within 0.5 RE (the Earth radius). Additionally, large scale plasmaspheric features have been observed, including shoulders, plumes, notches, bulges, and refiling. The Earth's plasmasphere is dynamic, and the abundance of particles in it changes substantially with interplanetary and geomagnetic activity. The large-scale structure evolution of the plasmasphere during geomagnetic storms controls the generation and propagation of waves in the plasmasphere, thus affecting the wave-particles interaction, resulting in a change in the spatial distribution of electrons and ions in the plasmasphere, and then affecting other magnetospheric and ionospheric processes. During periods of geomagnetic storms, the plasmaspheric material eroded is transported sunward and observed near the dayside magnetopause regularly. This local plasmaspheric density enhancement greatly impacts global large-scale convection. Therefore, the plasmaspheric density is undoubtedly an important parameter in space weather. The structural dynamic change of the Earth's plasmasphere is an indicator of the disturbance state of the space weather environment. Its structural form and dynamic process are controlled by the geomagnetic activity, and the short-term changes in the geomagnetic field originate from the sun-terrestrial disturbance caused by solar activity. The high-speed plasma ejected from the solar corona impacts the Earth and induces large-scale convective motion in the magnetosphere. Part of the energy enters the magnetosphere, causing disturbances in its inner regions, including the plasmasphere. Further research on the Earth’s plasmasphere is of great significance to reveal the mass transport and energy transfer in the solar wind-magnetosphere-ionosphere coupling process, and space weather forecast. Here, we introduce the research progress in the response of the plasmasphere to geomagnetic activities, the waves in the plasmasphere, variation of the electron content in the topside ionosphere and plasmasphere, and plasmasphere models. Finally, we also list some important issues for future studies.

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This paper presents the project Comprehensive spAce wEather Studies for the ASPIS prototype Realization (CAESAR), which aims to tackle the relevant aspects of Space Weather (SWE) science and develop a prototype of the scientific data centre for Space Weather of the Italian Space Agency (ASI) called ASPIS (ASI SPace Weather InfraStructure). To this end, CAESAR involves the majority of the SWE Italian community, bringing together 10 Italian institutions as partners, and a total of 92 researchers. The CAESAR approach encompasses the whole chain of phenomena from the Sun to Earth up to planetary environments in a multidisciplinary, comprehensive, and unprecedented way. Detailed and integrated studies are being performed on a number of well-observed "target SWE events", which exhibit noticeable SWE characteristics from several SWE perspectives. CAESAR investigations synergistically exploit a great variety of different products (datasets, codes, models), both long-standing and novel, that will be made available in the ASPIS prototype: this will consist of a relational database (DB), an interface, and a wiki-like documentation structure. The DB will be accessed through both a Web graphical interface and the ASPIS.py module, i.e., a library of functions in Python, which will be available for download and installation. The ASPIS prototype will unify multiple SWE resources through a flexible and adaptable architecture, and will integrate currently available international SWE assets to foster scientific studies and advance forecasting capabilities. [ABSTRACT FROM AUTHOR]

The dynamic global core plasma model (DGCPM) is used in this paper to calculate the He+ density distribution of the Earth’s plasmasphere and to investigate the configurations and 30.4 nm radiation properties of the plasmasphere. Validation comparisons between the simulation results and IMAGE mission observations show: That the equatorial structure of the plasmapause is mainly located near 5.5 R E and the typical scale of plasmasphere shrinking or expansion within 10 min is approximately 0.1 R E; that the plasmaspheric shoulders are formed and rotate noon-ward from the dawn sector under the conditions of strong southward turning of the interplanetary magnetic field (IMF); that the plasmaspheric plumes will rotate dawn-ward from the night sector and become narrow for the southward turning of the IMF. The simulated images from the lunar orbit show that the plasmasphere locating within the geocentric distance of 5.5 R E corresponds to field of view (FOV) of 10.7°×10.7° for the moon-based EUV imager, and that the 30.4 nm radiation intensity of the plasmasphere is 0.1–11.4 R. The plasmaspheric shoulders and plumes locating toward the moon-side are for the first time simulated with typical scale level of 0.1 R E from the side view of the moon. These simulated results provide an important theoretical basis for the lunar-based EUV camera design. [ABSTRACT FROM AUTHOR]