https://hal-insu.archives-ouvertes.fr/insu-01255148Mourenas, DDMourenasCEA-DAM - Centre d'Études de Limeil-Valenton - DAM - Direction des Applications Militaires - CEA - Commissariat à l'énergie atomique et aux énergies alternativesArtemyev, A.V.A.V.ArtemyevLPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace - OSUC - Observatoire des Sciences de l'Univers en région Centre - INSU - CNRS - Institut national des sciences de l'Univers - Observatoire de Paris - PSL - Université Paris sciences et lettres - UO - Université d'Orléans - CNRS - Centre National de la Recherche Scientifique - CNES - Centre National d’Études Spatiales [Paris]Agapitov, O. V.O. V.AgapitovSSL - Space Sciences Laboratory [Berkeley] - UC Berkeley - University of California [Berkeley] - UC - University of CaliforniaNational Taras Shevchenko University of KievApproximate analytical formulation of radial diffusion and whistler-induced losses from a preexisting flux peak in the plasmasphereHAL CCSD2015[SDU] Sciences of the Universe [physics]POTHIER, Nathalie2016-01-13 11:26:392023-03-24 14:53:012016-01-13 17:11:28enJournal articleshttps://hal-insu.archives-ouvertes.fr/insu-01255148/document10.1002/2015JA021623application/x-download1Modeling the spatiotemporal evolution of relativistic electron fluxes trapped in the Earth's radiation belts in the presence of radial diffusion coupled with wave-induced losses should address one important question: how deep can relativistic electrons penetrate into the inner magnetosphere? However, a full modeling requires extensive numerical simulations solving the comprehensive quasi-linear equations describing pitch angle and radial diffusion of the electron distribution, making it rather difficult to perform parametric studies of the flux behavior. Here we consider the particular situation where a localized flux peak (or storage ring) has been produced at low L < 4 during a period of strong disturbances, through a combination of chorus-induced energy diffusion (or direct injection) at low L together with enhanced wave-induced losses and outward radial transport at higher L. Assuming that radial diffusion can be further described as the spatial broadening within the plasmasphere of this preexisting flux peak, simple approximate analytical solutions for the distribution of trapped relativistic electrons are derived. Such a simplified formalism provides a convenient means for easily determining whether radial diffusion actually prevails over atmospheric losses at any particular time for given electron energy E and location L. It is further used to infer favorable conditions for relativistic electron access to the inner belt, providing an explanation for the relative scarcity of such a feat under most circumstances. Comparisons with electron flux measurements on board the Van Allen Probes show a reasonable agreement between a few weeks and 4 months after the formation of a flux peak.