Nature's Grand Experiment: Linkage between magnetospheric co

Details of Research

TitleNature's Grand Experiment: Linkage between magnetospheric convection and the radiation beltsAbstractThe solar minimum of 2007-2010 was unusually deep and long lived. In the later stages of this period the electron fluxes in the radiation belts dropped to extremely low levels. The flux of relativistic electrons (>1 MeV) was significantly diminished and at times was below instrument thresholds both for spacecraft located in geostationary orbits and also those in low-Earth orbit. This period has been described as a natural GÌrand Experiment Ìallowing us to test our understanding of basic radiation belt physics and in particular the acceleration mechanisms which lead to enhancements in outer belt relativistic electron fluxes. Here we test the hypothesis that processes which initiate repetitive substorm onsets drive magnetospheric convection, which in turn triggers enhancement in whistler mode chorus that accelerates radiation belt electrons to relativistic energies. Conversely, individual substorms would not be associated with radiation belt acceleration. Contrasting observations from multiple satellites of energetic and relativistic electrons with substorm event lists, as well as chorus measurements, show that the data are consistent with the hypothesis. We show that repetitive substorms are associated with enhancements in the flux of energetic and relativistic electrons and enhanced whistler mode wave intensities. The enhancement in chorus wave power starts slightly before the repetitive substorm epoch onset. During the 2009/2010 period the only relativistic electron flux enhancements that occurred were preceded by repeated substorm onsets, consistent with enhanced magnetospheric convection as a trigger. Copyright2015. American Geophysical Union. All Rights Reserved.AcknowledgementsThe authors would like to thank the researchers and engineers of NOAA's Space Environment Center for the provision of the data and the operation of the SEM-2 instrument carried on board these spacecraft and the many individuals involved in the operation of SAMPEX over 20 years. K.C.-M. was supported by the University of Otago via Summer Studentship and a PhD scholarship. For the SuperMAG substorm lists we gratefully acknowledge the following: Intermagnet; USGS, Jeffrey J. Love; CARISMA, PI Ian Mann; CANMOS; the S-RAMP database, PI K. Yumoto, and K. Shiokawa; the SPIDR database; AARI, PI Oleg Troshichev; the MACCS program, PI M. Engebretson, Geomagnetism Unit of the Geological Survey of Canada; GIMA; MEASURE, UCLA IGPP, and Florida Institute of Technology; SAMBA, PI Eftyhia Zesta; 210 Chain, PI K. Yumoto; SAMNET, PI Farideh Honary; the institutes who maintain the IMAGE magnetometer array, PI Eija Tanskanen; PENGUIN; AUTUMN, PI Martin Conners; DTU Space, PI JÃ¼rgen Matzka; South Pole and McMurdo Magnetometer, PIs Louis J. Lanzarotti and Alan T. Weatherwax; ICESTAR; RAPIDMAG; PENGUIn; British Antarctic Survey; McMac, PI Peter Chi; BGS, PI Susan Macmillan; Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN); GFZ, PI JÃ¼rgen Matzka; MFGI, PI B. Heilig; IGFPAS, PI J. Reda; University of LÃquila, PI M. Vellante; and SuperMAG, PI Jesper W. Gjerloev. For the GOES and POES data we acknowledge the Space Weather Prediction Center, Boulder, CO, National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce. Data availability is described at the following websites: http://www.srl.caltech.edu/sampex/DataCenter/index.html (SAMPEX), http://satdat.ngdc.noaa.gov/sem/poes/data/ (POES SEM-2), http://Demeter.cnrs-orleans.fr/ (Demeter) and http://supermag.jhuapl.edu/substorm/ (SuperMAG), wdc.kugi.kyoto-u.ac.jp (AE and Kp), ftp://spdf.gsfc.nasa.gov/pub/data/omni/high_res_omni/monthly_1min/ (solar wind speed), ftp://spdf.gsfc.nasa.gov/pub/data/omni/high_res_omni/ (GOES protons), and http://satdat.ngdc.noaa.gov/sem/goes/data/new_avg/YYYY/MM/goesXX/csv/ (GOES electrons).

Details

1st AuthorRodger, C.AuthorRodger, C.Cresswell-Moorcock, K.Clilverd, M.Year2016JournalJournal of Geophysical Research A: Space PhysicsVolume121Number1Pages171-189DOI10.1002/2015JA021537URLhttps://www.scopus.com/inward/recor.....09fd76fa0fbdd9fd9d819b828Keywordsrank3Author Keywordsmagnetospheric convectionmagnetospheric substormsradiation belt electronssolar wind speedwhistler mode chorusProgrammeK060 - AARDDVARK - Long Range Environmental Monitoring by Radio

Other

TypeArticleCitationRodger, C., Cresswell-Moorcock, K. and Clilverd, M. (2016). Nature's Grand Experiment: Linkage between magnetospheric convection and the radiation belts. Journal of Geophysical Research A: Space Physics, 121(1): 171-189