This project will use a novel ionospheric modeling technique, the Spherical Elementary Currents System (SECS), to determine the spatiotemporal behavior of the true ionospheric currents. The new method will not require information about ionospheric conductances and will enable a direct solution for full ionospheric electrodynamics if the electric field is known. The field-aligned currents will be determined from the magnetometer data obtained from the Iridium satellites. The global, high latitude electric fields in the ionosphere will be determined from the Super Dual Auroral Radar Network (SuperDARN) data. These data, when combined with ground-based observations of the magnetic perturbations generated by ionospheric currents, allows one to solve for the true ionospheric currents. This opens an entirely new and potentially transformative window to the quasi-instantaneous global ionospheric electrodynamics and general geospace circulation. Parts of magnetospheric currents are closed through the ionosphere and as a result, ionospheric electrodynamics has a significant control over large-scale geospace electrodynamics, general plasma circulation and magnetospheric energy transfer.
The results from this research can be used as a metric for the validation of geospace general circulation models (GGCMs). It would also be possible to use the knowledge of the true ionospheric currents to then determine the ionospheric conductances for the events being studied.
Project Outcomes In this award new techniques were developed to utilize ground-based and space-based data for extracting information about upper atmospheric (~100 km height) electric current systems. We used SuperMAG ground magnetometer stations (Fig. 1) and Iridium-based upper atmospheric field-aligned current (FAC) observations (Fig. 2). The observations were applied with Spherical Elementary Current System (SECS) method that allows combining these two different data sets to generate, for the first time, directly observed true upper atmospheric electric current system distributions (Fig. 3). We combined also third global data set into the analysis: SuperDARN upper atmospheric electric field observations. With SuperDARN observations we were able to derive directly also upper atmospheric conductances thus providing us the full electrostatic characterization of the upper atmospheric conditions. The new type of electrostatic characterization based on three different types of global space science data sets will allow us to better understand and predict the behavior of the upper atmosphere during quiet and storm times. This has great importance for our capacity to mitigate the potentially harmful effects of solar activity on our society. The data sets and tools developed in the project have been made publicly available and are being used by colleagues around the world. The project was a close collaboration between JHU Applied Physics Laboratory, The Catholic University of America and NASA Goddard Space Flight Center. Figure 1: SuperMAG ground magnetometer stations used in the study. Figure 2: Iridium spacecraft distribution used in the study. Figure 3: Snapshot of first-ever directly derived true ionospheric currents (top left) and the corresponding ionospheric electric field (top right) and conductances (two bottom panels).
