Μάθημα : Ενημέρωση φοιτητών κατεύθυνσης Αστροφυσικής

Speaker: Prof.  Vassilis Angelopoulos (UCLA, USA)  

Title:  "Exploring magnetospheric dynamics using combined low- and high-altitude observations"  

Abstract: Conjunctions between polar-orbiting low altitude and equatorial high-altitude missions allows disentangling space and time variations and mapping magnetospheric phenomena to the ionosphere and aurora. The recent availability of high-resolution energy and pitch angle spectra from the ELFIN mission in conjunction with low altitude, and high-altitude missions, reveals new methods for exploring magnetospheric processes and provides new perspectives on the dynamics of substorms, charge particle precipitation and the aurora. It has been realized that one of the most intense particle precipitation occurs at latitudes with equatorial magnetic footpoints at the transition region from tail-like to dipole like field lines. Poleward (tailward) of that magnetic latitude (equatorial distance) lie auroral zone (plasma sheet) field lines. The energy spectrum and flux variations of the precipitating-to-trapped flux ratio of energetic particles (>50keV, unaffected by potential drops) can be used to infer the dynamics of the equatorial plasma sheet. Such information from low altitude can explore the magnetospheric drivers and field-aligned current sources of the precipitation and of various auroral forms, when imaging is available. The global magnetic flux redistribution in the plasma sheet during substorms and the emergence of reconnection outflow activity are both visible in low altitude spectra. The contribution of waves excited by injections (EMIC, whistler mode chorus, ECH waves and TDS) and of field-line scattering are also evident. The combined observations from a range of altitudes demonstrate the key role of mesoscale DFBs in controlling the dynamics of the inner magnetosphere. Arguably, the value of small satellite missions (such as CubeSats) is not only scientific. They afford quick-turnaround, low-cost experimentation for maturation of advanced technologies, and are invaluable for workforce training and incubation of startups.

Connection information:   https://uoa.webex.com/uoa/j.php?MTID=m041800c21ee43d5156ab30a32e529314 

Friday, March 20, 2026 4:00 PM | 1 hour 30 minutes | (UTC+02:00) Athens, Bucharest

Meeting number: 2784 343 6615

Password: RPxw3mPBZ56