Ground‐based estimates of outer radiation belt energetic electron precipitation fluxes into the atmosphere

• Published in: Journal of Geophysical Research: Space Physics
• Main Authors: Clilverd, Mark A., Rodger, Craig J., Gamble, Rory J., Ulich, Thomas, Raita, Tero, Seppälä, Annika, Green, Janet, Thomson, Neil R., Sauvaud, Jean‐andré, Parrot, Michel
• Other Authors: British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Department of Physics Dunedin, University of Otago Dunedin, Nouvelle-Zélande, Sodankylä Geophysical Observatory, University of Oulu, Earth Observation Research Division Helsinki, Finnish Meteorological Institute (FMI), NOAA Space Weather Prediction Center (SWPC), National Oceanic and Atmospheric Administration (NOAA), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales Paris (CNES), LAPBIAT2 program (contract RITA‐CT‐2006‐025969), European Project: 237461,EC:FP7:PEOPLE,FP7-PEOPLE-IEF-2008,EPPIC(2009)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: [SDU]Sciences of the Universe [physics]; Sodankylä
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-01180570; https://hal-insu.archives-ouvertes.fr/insu-01180570/document; https://hal-insu.archives-ouvertes.fr/insu-01180570/file/jgra20735.pdf; https://doi.org/10.1029/2010JA015638

International audience [1] AARDDVARK data from a radio wave receiver in Sodankylä, Finland have been used to monitor transmissions across the auroral oval and just into the polar cap from the very low frequency communications transmitter, call sign NAA (24.0 kHz, 44°N, 67°W, L = 2.9), in Maine, USA, since 2004. The transmissions are influenced by outer radiation belt (L = 3–7) energetic electron precipitation. In this study, we have been able to show that the observed transmission amplitude variations can be used to determine routinely the flux of energetic electrons entering the upper atmosphere along the total path and between 30 and 90 km. Our analysis of the NAA observations shows that electron precipitation fluxes can vary by 3 orders of magnitude during geomagnetic storms. Typically when averaging over L = 3–7 we find that the >100 keV POES " trapped " fluxes peak at about 10 6 el. cm −2 s −1 sr −1 during geomagnetic storms, with the DEMETER >100 keV drift loss cone showing peak fluxes of 10 5 el. cm −2 s −1 sr −1 , and both the POES >100 keV " loss " fluxes and the NAA ground‐based >100 keV precipitation fluxes showing peaks of ∼10 4 el. cm −2 s −1 sr −1. During a geomagnetic storm in July 2005, there were systematic MLT variations in the fluxes observed: electron precipitation flux in the midnight sector (22–06 MLT) exceeded the fluxes from the morning side (0330–1130 MLT) and also from the afternoon sector (1130–1930 MLT). The analysis of NAA amplitude variability has the potential of providing a detailed, near real‐time, picture of energetic electron precipitation fluxes from the outer radiation belts.