Rajkumar Hajra
University of Orléans
France
Title: High-Intensity Long-Duration continuous AE activity (HILDCAA) events and “Killer Electrons†in Earth’s outer radiation belt
Biography
Biography: Rajkumar Hajra
Abstract
High-intensity long-duration continuous AE activity (HILDCAA) events have been shown to be associated mostly with high-speed solar wind streams (HSSs) [Hajra et al., JGR, 118, 5626, 2013]. These geoeffective events, by definition [Tsurutani and Gonzalez, PSS, 35, 405, 1987], have peak AE intensities > 1,000 nT and continue for more than 2 days when AE values do not drop below 200 nT for more than 2 h at a time. The events are caused by the southward component of interplanetary Alfvén waves embedded within the HSSs. Recent studies show that HILDCAA events are associated with generation of relativistic (MeV) electron acceleration in the Earth’s outer radiation belt [e.g., Hajra et al., GRL, 41, 1876, 2014]. The relativistic electrons are known as “killer electrons” for their hazardous effects to orbiting spacecraft. In the present talk, we will present a detailed study on the geomagnetic characteristics and interplanetary causes of the HILDCAA events as well as the solar cycle and seasonal dependences of the events. It will be shown that the ground-based AE observations during HILDCAAs may potentially be used to predict by > 1 day advance the acceleration of radiation belt relativistic electrons at geosynchronous orbit. Relativistic electron acceleration and decay timescales will be provided for wave-particle investigators to attempt to match their models to empirically derived values.