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Developing an empirical bow shock model using deep learning codes
When I worked at the Finnish Meteorological Institute from 2010 to 2011 I developed an algorithm to determine the bow shock time and location from Cluster measurements. The task is to test the prediction abilities of the code and improve its capability using deep learning methods. The tested and improved code is applied for the measurements of the Cluster, Time History of Events, and Macroscale Interactions during Substorms (THEMIS) and other spacecraft to determine the time and location of the bow shock transitions. The candidate will create a new empirical bow shock model depending on the data of Advanced Composition Explorer (ACE) and Deep Space Climate Observatory (DSCOVR) solar wind monitoring spacecraft; furthermore the Kp and Dst geomagnetic indexes.
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Testing shock jump predictions: THEMIS Observations
After the solar wind crossed the bow shock and entered the magnetosheath the temperature, the magnetic field magnitude, and the density of the solar wind increased; furthermore the solar wind velocity dropped and its course changed. The theory of magnetohydrodynamics (MHD) had predictions for the ratio of these parameters on each side of the boundary layer. The three THEMIS spacecraft were in the same orbit therefore their particular configuration, magnetic field, and ion plasma measurements let us test the MHD bow shock jump predictions. Twenty events are selected and analyzed in this study. The ratio of the down- and upstream magnetic field magnitude and solar wind speed are calculated and compared to the theory. We expect deviances from the MHD theory at the quasi-parallel bow shock region and when transient dayside magnetospheric events are observed near the bow shock crossing.
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Mother's Day Solar Storm Event
On May 10/11, 2024, night, a set of strong coronal mass ejections (CMEs) hit the terrestrial magnetosphere to push it back and compress, triggering magnetic storms, and high aurora activity visible even from Hungary. This research aims to study this event in two ways: (1) finding and determining the CME shocks in the observations of various heliospheric spacecraft, calculating the shock normals in various fronts and determining the shape of the shocks, and finally comparing them to heliospheric magnetohydrodynamic (MHD) simulations. (2) Perform an MHD simulation from the L1 Lagrangian point to the terrestrial magnetotail using the Grand Unified Magnetosphere-Ionosphere Coupling Simulation (GUMICS-4) code and compare the simulation results to observations.
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Comparing 1-year GUMICS-4 simulations of the Terrestrial Magnetosphere with Cluster Measurements
We compare the predictions of the GUMICS-4 global magnetohydrodynamic model for the interaction of the solar wind with the Earth's magnetosphere with Cluster SC3 measurements for over one year, from January 29, 2002, to February 2, 2003. In particular, we compare model predictions with the north/south component of the magnetic field (Bz) seen by the magnetometer, the component of the velocity along the Sun-Earth line (Vx), and the plasma density as determined from a top hat plasma spectrometer and the spacecraft's potential from the electric field instrument. We select intervals in the solar wind, the magnetosheath, and the magnetosphere where these instruments provided good quality data and the model correctly predicted the region in which the spacecraft is located. We determine the location of the bow shock, the magnetopause and, the neutral sheet from the spacecraft measurements and compare these locations to those predicted by the simulation. The GUMICS-4 model agrees well with the measurements in the solar wind however its accuracy is worse in the magnetosheath. The simulation results are not realistic in the magnetosphere. The bow shock location is predicted well, however, the magnetopause location is less accurate. The neutral sheet positions are located quite accurately thanks to the special solar wind conditions when the By component of the interplanetary magnetic field is small.