Role of Magnetosheath Parameters on Magnetopause Processes

Student: Oksana Tkachenko
Školitel: Prof. RNDr. Jana Šafránková, DrSc.
Stav práce: obhájená


Magnetopause reconnection is one of the most important source of the plasma of a solar origin in the Earth's magnetosphere. During intervals of a southward oriented interplanetary magnetic field (IMF), reconnection occurs at the low-latitude subsolar magnetopause, whereas it moves to the cusp vicinity for northward and other IMF orientations. Since IMF lines are draped around the magnetopause and blown tailward with the magnetosheath flow, a permanent reconnection takes place at the cusp-magnetosheath boundary. Reconnection produces accelerated plasma populations that excite different kinds of plasma waves. As a result, the region adjacent to the magnetopause is highly turbulent and occupied by the heated magnetosheath-like plasma with a low drift velocity. This region is called turbulent boundary layer, stagnation region or exterior cusp in different papers and it seems to be a proper source of the cusp precipitation. As we noted, a position of the reconnection site moves in accordance with an actual IMF orientation. A change of the plasma flow direction suggests the presence of the vortex-like structure in the exterior cusp.

Despite an importance of high-latitude reconnection for magnetospheric physics, there are only a few papers dealing with this phenomenon. Due to well chosen orbits, the INTERBALL-1 and MAGION-4 spacecraft crossed the high-latitude magnetopause near the cusp about 40-times during each year and thus they collected a unique set of observations under various upstream plasma and IMF conditions.

The aims of the thesis are following:
(1) to prepare a survey of Interball-1 passes through the high-latitude magnetopause
(2) to complement the above observations with corresponding solar wind and IMF measurements
(3) to check all available magnetospheric measurements (DMSP, POLAR, GEOTAIL)
(4) to map all observations onto the auroral oval
(5) to analyze the whole set of observations in order to determine the influence of the IMF direction and magnitude on the structure of the high-latitude cusp region
(6) to discuss the contribution of magnetosheath plasma and magnetic field parameters and fluxes of energetic particles on the formation process.

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.