Supervision of Scientific Student (TDK) thesis

Name:	Mr. Bertalan MAJOR, MSc in Aerospace Engineering, Budapest University of Technology and Economics, Budapest, Hungary
Title:	Testing shock jump predictions: THEMIS Observations
Topic:	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.
Keywords:	Terrestrial bow shock shock, Solar wind: space plasma

Supervision of MSc thesis

Name:	Mr. Munkhjargal LKHAGVADORJ, MSc in Physics, Eötvös Loránd University, Budapest, Hungary
Title:	Propagation of interplanetary shocks in the heliosphere
Topic:	NASA and the European Space Agency dispatched a fleet to study the heliosphere and the planets of the Solar System. A few probes were measured inside the orbit of the Earth, some missions collected data outside of the orbit of the our planet. In the meantime, another group of space probes recorded the variations ofthe solar wind at the L1 Lagrange point. The purpose of this thesis is the observation of interplanetary shocks by at least two different spacecraft. Furthermore, to determine the changes and developements of the shock parameters during propagation. Finally, the collected conjigated observations should be compared with exixting models and simulations.
Graduation:	2023

Supervision of Scientific Student (TDK) thesis

Name:	Mr. Munkhjargal LKHAGVADORJ, MSc in Physics, Eötvös Loránd University, Budapest, Hungary
Title:	Temporal Development of Interplanetary Shocks in the Heliosphere
Topic:	Interplanetary shocks are one of the crucial dynamic processes in the Heliosphere. They accelerate particles into high energy, generate plasma waves and could potentially trigger geomagnetic storms in the terrestrial magnetosphere disturbing significantly our technological infrastructures. In this study, two IP shock events are selected to investigate the temporal variations of the shock parameters using magnetometer and ion plasma measurements of the STEREO A and B, the Wind, and the ACE spacecraft. The shock normal vectors are determined using the minimum variance analysis (MVA) and the magnetic coplanarity methods. During the May 07 event, the shock parameters and the shock normal direction are consistent. During the April 23 event, the shock parameters do not change significantly, however, the shape of the IP shock appears to be twisted along the transverse direction to the Sun-Earth line. Stereo B does not observe the IP shock signatures during this event.
Keywords:	Interplanetary shock, Solar wind: space plasma, Heliosphere
Conference:	Outstanding Thesis, Particle Physics Section, Physics Conference of Faculty of Science, Budapest, December 17, 2022.
Conference:	Special Prize, Plasma Physics Subsection, Earth Sciences, Physics and Mathematics Section, Veszprém, April 11-13, 2023. Closing ceremony

PhD and MSc thesis topics

1. 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.

2. 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.

3. 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.

Last modified by Gabor FACSKO on November 8, 2023