Storm-time Estimates of Radial Diffusion from Ground- and Space-based Measurements

Georgiou, Marina

Storm-time Estimates of Radial Diffusion from Ground- and Space-based Measurements

Monday, 5 March 2018: 14:45

Longshot and Bogey (Hotel Quinta da Marinha)

Marina Georgiou¹, Jonathan Rae², Jasmine Kaur Sandhu³, Ioannis A. Daglis⁴, Colin Forsyth⁵, Eftyhia Zesta⁶, David G Sibeck⁶, Ian Mann⁷ and Georgios Balasis⁸, (1)University College London, Mullard Space Science Laboratory, Department of Space and Climate Physics, London, United Kingdom, (2)University College London, Mullard Space Science Laboratory, London, United Kingdom, (3)Mullard Space Science Laboratory, Dorking, RH5, United Kingdom, (4)National and Kapodistrian University of Athens, Athens, Greece, (5)Mullard Space Science Lab., Dorking, United Kingdom, (6)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (7)University of Alberta, Edmonton, AB, Canada, (8)ISAARS, National Observatory of Athens, Athens, Greece

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Abstract:

Ultra-low-frequency (ULF) waves and energetic electrons have long been associated with outer radiation belt dynamics via diffusive transport and energization due to the potential of these magnetospheric waves to resonantly interact with energetic electrons at Pc5 frequencies of a few millihertz. One limitation of previous efforts in the past to definitively determine the role of such resonant wave-particle interactions driving radial diffusion had been the limited coverage of Pc5 wave activity over magnetic local time and magnetic L-shell. We examine ULF wave-driven radial diffusion of outer belt electrons using ground- and space-based measurements in order to determine both the spatial and temporal profile of Pc5 wave activity during entire geomagnetic storms. We find significant differences in the MLT distribution of electromagnetic power spectral densities during storms that need to be taken into account in radiation belt modelling. In addition, the earthward penetration of Pc5 wave power shows a strong dependence upon the size and duration of each magnetic storm. Power spectral densities derived from ground station and spacecraft magnetic and electric field measurements are then used in order to derive the magnetic and electric field component of radial diffusion coefficients. The new multi-platform coefficients are compared to previous published results to discuss the implications of uncertainties in their calculations for trapped particle studies. We demonstrate that a combination of ground and space-based measurements and the continuity of data in both space and time is required to fully evaluate diffusion coefficient calculations during any given storm.