Browsing by Subject "GLOBAL MHD SIMULATION"

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  • Palmroth, Minna; Grandin, Maxime; Sarris, Theodoros E.; Doornbos, Eelco; Tourgaidis, Stelios; Aikio, Anita; Buchert, Stephan; Clilverd, Mark A.; Dandouras, Iannis; Heelis, Roderick; Hoffmann, Alex; Ivchenko, Nickolay; Kervalishvili, Guram; Knudsen, David J.; Kotova, Anna; Liu, Han-Li; Malaspina, David M.; March, Gunther; Marchaudon, Aurélie; Marghitu, Octav; Matsuo, Tomoko; Miloch, Wojciech J.; Moretto-Jørgensen, Therese; Mpaloukidis, Dimitris; Olsen, Nils; Papadakis, Konstantinos; Pfaff, Robert; Pirnaris, Panagiotis; Siemes, Christian; Stolle, Claudia; Suni, Jonas; van den Ijssel, Jose; Verronen, Pekka T; Visser, Pieter; Yamauchi, Masatoshi (2021)
    The lower-thermosphere-ionosphere (LTI) system consists of the upper atmosphere and the lower part of the ionosphere and as such comprises a complex system coupled to both the atmosphere below and space above. The atmospheric part of the LTI is dominated by laws of continuum fluid dynamics and chemistry, while the ionosphere is a plasma system controlled by electromagnetic forces driven by the magnetosphere, the solar wind, as well as the wind dynamo. The LTI is hence a domain controlled by many different physical processes. However, systematic in situ measurements within this region are severely lacking, although the LTI is located only 80 to 200 km above the surface of our planet. This paper reviews the current state of the art in measuring the LTI, either in situ or by several different remote-sensing methods. We begin by outlining the open questions within the LTI requiring high-quality in situ measurements, before reviewing directly observable parameters and their most important derivatives. The motivation for this review has arisen from the recent retention of the Daedalus mission as one among three competing mission candidates within the European Space Agency (ESA) Earth Explorer 10 Programme. However, this paper intends to cover the LTI parameters such that it can be used as a background scientific reference for any mission targeting in situ observations of the LTI.
  • Eastwood, J. P.; Nakamura, R.; Turc, L.; Mejnertsen, L.; Hesse, M. (2017)
    The magnetosphere is the lens through which solar space weather phenomena are focused and directed towards the Earth. In particular, the non-linear interaction of the solar wind with the Earth's magnetic field leads to the formation of highly inhomogenous electrical currents in the ionosphere which can ultimately result in damage to and problems with the operation of power distribution networks. Since electric power is the fundamental cornerstone of modern life, the interruption of power is the primary pathway by which space weather has impact on human activity and technology. Consequently, in the context of space weather, it is the ability to predict geomagnetic activity that is of key importance. This is usually stated in terms of geomagnetic storms, but we argue that in fact it is the substorm phenomenon which contains the crucial physics, and therefore prediction of substorm occurrence, severity and duration, either within the context of a longer-lasting geomagnetic storm, but potentially also as an isolated event, is of critical importance. Here we review the physics of the magnetosphere in the frame of space weather forecasting, focusing on recent results, current understanding, and an assessment of probable future developments.