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Space Science Center and Department of Physics, University of New Hampshire, Durham, NH
Sjedinjene američke države
Institute of Geophysics and Planetary Physics, University of California, CA
Sjedinjene američke države
Short description of project
Much effort - in theoretical modelling, data interpretation, and global MHD simulations - is increasingly being devoted to the understanding of interplanetary coronal mass ejections (CMEs) and magnetic clouds (MCs). These explosive expulsions of mass and energy from the Sun, besides being among the most spectacular manifestations of solar activity, are largely responsible for the strongest disturbances in the Earth's geophysical environment, since their strong, southward magnetic fields of long duration can apply strong forcing to the magnetosphere. As human society increasingly relies on technologies which are situated outside or at the edge of the Earth's atmosphere and ionosphere, forecasting such events (so called "Space Weather") has become an urgent need for an increasing amount of institutions, companies and people.
Short description of the task performed by Croatian partner
The new NASA STEREO mission (launched in October 2006) offers for the first time a stereoscopic view of the entire evolution of CMEs propagating from the Sun to the Earth. This raises the interesting possibility of following these large disturbances from their origin on the Sun down to their consequences as they arrive at the Earth. MCs show a special in situ behaviour, namely a strong magnetic field vector rotating smoothly through a large angle in a low beta plasma, from which they can be quite easily detected by near-Earth satellites and thus, makes them ideal objects to study geomagnetic storms and solar-terrestrial relations in general. In an attempt to advance our understanding of the structure and inner-heliospheric evolution of these transients further, we propose using a sophisticated 2.5 D numerical technique to reconstruct the magnetic and plasma structure in a cross-section of these ejecta intercepted by spacecraft, and applying it to a representative and large sample of ejecta. The method, based on solving the Grad-Shafranov (GS) equation, makes no preconceptions on the geometry and, in particular, does not assume an underlying cylindrically symmetric magnetic flux tube. If it would be possible to identify the parameters on the Sun that indicate the special properties to generate a geoeffective MC, then one could predict the interplanetary consequences of solar eruptions. In order to gain better knowledge on the pre-eruptive structures of CMEs/MCs we will analyse their morphology and underlying magnetic field configuration, and will trace them during their eruption phase and subsequent propagation through the interplanetary space. We will analyse different data sets (photospheric, chromospheric, coronal) using ground-based and space-borne instruments (STEREO, Hinode, SoHO, TRACE) in order to evaluate "key" parameters (orientation, magnetic flux, magnetic twist) which will be compared to in situ MC observations using the new multi-spacecraft GS-reconstruction method. The time of the minimum and rising phase of solar cycle 24 during which the project is planned (late 2007 until late 2010) is a time range which is ideal a) due to the operation of the new STEREO spacecraft which will be fundamental for the heliospheric research for the next years and b) since it will be possible to relate isolated MC signatures back to their solar counterparts.
Ovo web sjedište koristi tehnologiju "kolačića" (eng. cookie) da bi se korisnicima prikazao dinamičan i personaliziran sadržaj, te su oni nužni za ispravan rad. Ako nastavite pregledavati ove stranice, kolačići će biti korišteni u suradnji s vašim preglednikom Weba.
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