In this paper, the new statistical and empirical models of thermal electron temperature profiles are developed based on the measurements of Thermal Electron Detector onboard AKEBONO launched 1989 from the Gagoshima space center, Japan. These models cover the missed spatial regions from 3000 km to 7000 km, which are near the inner, core plasmasphere co-rotating with the Earth, focused on the temperature profiles of the thermal electrons. And the dynamics and morphology of plasmasphere during the uncovered temporal period of 22nd solar maximum are investigated with the developed models hiring the newly archived data as inputs. The empirical model is built to investigate the temperature variation of electrons along the geomagnetic field line and the statistical model is set up to study the temperature profiles according to each L-shell value.
The models are based on the data sorted into and averaged over the altitude, the invariant latitude or L-shell values, the magnetic local time, the season, the geomagnetic activity, and the geomagnetic latitude. The altitude ranges from 3000 km to 7000 km with 150-km bin and the invariant latitude interval includes two categories, the one between 40 and 50 degree, and the other between 50 and 60 degree. The L-shell value is selected to cover the inner plasmasphere between 1.2 and 4.0. The diurnal variation of the models is based on the magnetic local time and the seasonal variation is investigated according to the Equinox period, the Summer period, and the Winter period in the Northern hemisphere. The geomagnetic activity effects is shown based on the $K_p$ index.
The analyses based on the models show the photoelectron control over the thermal structure of the inner plasmasphere, and the magnetic local time, the invariant latitude and the altitude can be the major parameters for the temperature variation. Also the study concludes that season and geomagnetic latitude can not be neglected in contrast to the previous studies. The models of this study has been compared with the theoretical model and another measurements of satellite (S3-3).
The models developed can contribute to the extension of the International Reference Ionosphere that is the empirical model for the Earth's ionosphere and used for practical purposes like the new instrument and spacecraft design. Also some model studies, such as wave propagation ray tracing, depend on analytical description of plasmaspheric properties. In addition, the development of theoretical or physical models of plasmaspheric properties continues to depend on the availability of corresponding empirical models.