Student: Xirogiannopoulou Niki
Školitel: Mgr. Oleksandr Gončarov, Ph.D.
Konzultant: Prof. RNDr. Zdeněk Němeček, DrSc.
Stav práce: zadaná
Anotace:
Our society heavily depends on present technologies including global power grids, long pipelines and space based communications that are very sensitive to effects connected with solar activity that bear a common name space weather [1]. Probably the most dangerous events are explosive cases in the solar corona (Coronal Mass Ejections, CMEs) that spew out huge amount of ionized matter into the interplanetary space. When such dense cloud hits the Earth, it deforms the geomagnetic field and induces large currents in power grids that can cause so called blackouts. However, similarly dangerous events can evolve even in a quiet solar wind due to the interaction of the high-speed streams with upstream slow-speed streams that leads to the formation of the region known as the Corotating Interaction Regions, CIRs. The third class of the variations of the geomagnetic field is spontaneous or driven reconfigurations of the field known as geomagnetic storms and substorms. The chain of processes connecting events on the Sun with their response in the Earth environment is long and complicated and thus it is a subject of intensive research for more than four decades [2].
Our department deals with different aspects of the space weather from very beginning of space era, participated in numerous space missions (at present in the project Taranis – the French satellite for investigations of the processes in the ionosphere) and collaborates with leading institutions involved in space physics over the world. At present, the topic called Role of foreshock variations on the processes in the magnetosheath and at the magnetopause is solved in our group. We suppose investigations of non-MHD foreshock processes modifying parameters of the solar wind and its significant discontinuities prior to they hit the bow shock as well as investigations of new discontinuities created in the foreshock region. As known, kinetic interactions create foreshock bubbles or cavitons propagating further downstream and local bow shock deformations produce magnetoheath jets [3,4] or plasmoids [5]. Moreover, the reduced total pressure upstream the bow shock due to some foreshock transients results in strong (thermal and magnetic) pressure gradients in the magnetosheath [6]. These gradients directly accelerated the magnetosheath plasma causing fast sunward flows followed by outward magnetopause motion. Thus, magnetosheath variations influence a formation of magnetopause boundary layers and affect the rate of solar wind entry into the magnetosphere. It includes a change of the interplanetary magnetic field orientation (including small cone angles [7]) on the magnetopause processes (magnetic reconnection, LLBL formation and variations [8]).