Investigating energetic electron precipitation through combi

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TitleInvestigating energetic electron precipitation through combining ground-based and balloon observationsAbstractA detailed comparison is undertaken of the energetic electron spectra and fluxes of two precipitation events that were observed in 18/19 January 2013. A novel but powerful technique of combining simultaneous ground-based subionospheric radio wave data and riometer absorption measurements with X-ray fluxes from a Balloon Array for Relativistic Radiation-belt Electron Losses (BARREL) balloon is used for the first time as an example of the analysis procedure. The two precipitation events are observed by all three instruments, and the relative timing is used to provide information/insight into the spatial extent and evolution of the precipitation regions. The two regions were found to be moving westward with drift periods of 5--11 h and with longitudinal dimensions of 20 deg and 70 deg (1.5--3.5 h of magnetic local time). The electron precipitation spectra during the events can be best represented by a peaked energy spectrum, with the peak in flux occurring at 1--1.2 MeV. This suggests that the radiation belt loss mechanism occurring is an energy-selective process, rather than one that precipitates the ambient trapped population. The motion, size, and energy spectra of the patches are consistent with electromagnetic ion cyclotron-induced electron precipitation driven by injected 10--100 keV protons. Radio wave modeling calculations applying the balloon-based fluxes were used for the first time and successfully reproduced the ground-based subionospheric radio wave and riometer observations, thus finding strong agreement between the observations and the BARREL measurements. Copyright 2017 Crown copyright. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.AcknowledgementsData for this paper are available at the British Antarctic Survey Polar Data Centre (http://psddb.nerc-bas.ac.uk/data/access/). M.A.C. and N.C. would like to acknowledge the important contributions from Nick Alford and Tom Stroud, particularly for their skill and assistance in building and deploying the autonomous AARDDVARK systems. The authors would like to thank the Natural Environmental Research Council/British Antarctic Survey and the South African National Antarctic Program for their support and collaboration during the BARREL balloon campaigns. The research leading to these results has received funding from the Natural Environmental Research Council under the Antarctic Funding Initiative (AFI/11/22). C.J.R. was supported by the New Zealand Marsden Fund. M.M. was supported (through Dartmouth College) on the NASA grant NNX08AM58G. This work was supported in part by the CSSWE funding grant NSF AGSW 0940277 as well as the JHU/APL contract 922613 (RBSP-EFW). The Dartmouth College portion of this work was supported by NASA grant NNX08AM58G. This research was supported by the International Space Science Institute's International Teams program project no. 329.Other fieldsOther fieldsFunding DetailsNASA, National Aeronautics and Space Administration

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1st AuthorClilverd, M. AuthorClilverd, M.Rodger, C.McCarthy, M.Millan, R.Blum, L.Cobbett, N.Brundell, J.Danskin, D.Halford, A.Year2017JournalJournal of Geophysical Research: Space PhysicsVolume122Number1Pages534-546DOI10.1002/2016JA022812URLhttps://www.scopus.com/inward/recor.....8385216495b54f0fab3eb4864Author KeywordsAARDDVARKBARRELelectron precipitationEMIC waves

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TypeArticleCitationClilverd, M., Rodger, C., McCarthy, M., Millan, R., Blum, L., Cobbett, N., Brundell, J., Danskin, D. and Halford, A. (2017). Investigating energetic electron precipitation through combining ground-based and balloon observations. Journal of Geophysical Research: Space Physics, 122(1): 534-546Antarctica NZ supported?YesNZARI?No