Development of Ionospheric-Plasmaspheric Data Assimilation Model(1/2)

The data assimilation model global ionospheric specification (GIS) reconstruct ionospheric three-dimensional electron density structure by using Gaussian-Markov Kalman filter to assimilate ground-based GNSS and FORMOSAT-3/COSMIC (FORMOSAT-7/COSMIC-2) radio occultation slant total electron content (TEC) observations. Since the altitude coverage of model is from 100 to 1,000 km, it is necessary to reduce plasmaspheric weighting from ground-based GNSS observation data before assimilation. The global plasmaspheric map is established by using FORMOSAT-3/COSMIC podTec data to eliminate the weighting of the plasmasphere. However, global plasmaspheric structure needs to accumulate about 3 month data to get better coverage, and it could result in incorrect plasmaspheric weighting. The research plans to extend the altitude boundary of assimilation model from the ionosphere to the plasmasphere (from 1,000 to 21,000 km). The new ionospheric-plasmaspheric data assimilation model could improve ionospheric electron density structure, and also reconstruct the plasmasphere. The observing system simulation experiment (OSSE) is applied to confirm the accuracy of the reconstructed electron density structure in the ionosphere and plasmasphere. Moreover, the nadir down ionospheric TEC observed by Jason-2 or Jason-3 satellite will be assimilated into model and OSSE will verify the feasibility and impact to the assimilation model. In addition, the ionosphere influenced by solar eclipse on August 21, 2017 is reconstructed to study the correlation between the obscuration caused by moon shadow and the variation of three-dimensional ionospheric structure. Furthermore, the reconstruction of ionospheric as well as plasmaspheric electrion density is also implemented during geomagnetic storms. The reconstructed electron density can use to study the geomagnetic storm influence to the ionosphere and plasmasphere.