Correlation properties of magnetosheath fluctuations

Student: Olga Gutynska
Školitel: Prof. RNDr. Jana Šafránková, DrSc.
Stav práce: obhájená


Geomagnetic storms and sudden changes of magnetospheric properties due to significant changes in solar wind conditions affect a wide variety of systems on the Earth and in orbit. For example, large geomagnetic storms can interrupt radio communications; increase pipeline and power grid currents and change high altitude atmospheric drag affecting low-altitude satellite orbits. Interplanetary pressure events, like interplanetary (IP) shocks compressing the magnetosphere, lead to sudden impulses that can have a high enough rate of ground magnetic field change producing an adverse amount of current in technological system. In developing an understanding how to accurately forecast the state of the Earth's magnetosphere, solar wind and interplanetary magnetic field (IMF) measurements serve as the primary input parameters. Therefore, by using multiple solar wind inputs in self-consistent MHD fashion, we can predict the solar wind/IMF properties more accurately and thus more sofisticated and precise magnetospheric models can be developed, at least for the cases when the uncertainties in solar wind/IMF properties are the limiting factor in the prediction chain. However, this topic involves many different phenomena - a propagation and gradual evolution of different solar eruptive phenomena from inside 1 AU into the magnetosphere, related dynamics of magnetospheric boundaries (bow shock and magnetopause), their modification in the foreshock and magnetosheath, the penetration of charged particles through both boundaries, their accumulation in the magnetospheric tail, acceleration processes which create the hot magnetospheric population from the cold solar wind plasma, the starting mechanisms of geomagnetic storms, etc.

The precise aims of the thesis are following:
(1) to prepare a survey of observations of interplanetary shocks and other significant solar wind instabilities and their classifications
(2) to study their interaction with the bow shock, propagation through the magnetosheath, and their modification at the magnetopause
(3) to correlate parameters of different shock types (discontinuity normal orientations, discontinuity shapes and geometries) with their geo-effective features.

The solution of these tasks is based on multipoint spacecraft measurements and/or numerical simulations (using global 3-D and local magnetohydrodynamic models), all experimental data already exist.

The study is supported by the grant project and there is a possibility to visit one of our cooperating institutions abroad.

Předpokládané znalosti:
Znalosti studenta magisterského studia na MFF UK.