Experimental Determination of the Conditions Associated With "Zebra Stripe" Pattern Generation in the Earth's Inner Radiation Belt and Slot Region. Issue 7 (14th July 2020)

• Record Type: Journal Article
• Authors: Lejosne, Solène; Mozer, Forrest S.
• Is Part Of: Journal of geophysical research. Volume 125:Issue 7(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-07-14
• Subjects: zebra stripes -- superposed epoch analysis -- prompt penetration electric fields -- inner radiation belt -- substorm; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2020JA027889
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: The "zebra stripes" are peaks and valleys commonly present in the spectrograms of energetic particles trapped in the Earth's inner belt and slot region. Several theories have been proposed over the years to explain their generation, structure, and evolution. Yet, the plausibility of various theories has not been tested due to a historical lack of ground truth, including in situ electric field measurements. In this work, we leverage the new visibility offered by the database of Van Allen Probes electric drift measurements to reveal the conditions associated with the generation of zebra stripe patterns. Energetic electron fluxes by the Radiation Belt Storm Probes Ion Composition Experiment between 1 January 2013 and 31 December 2015 are systematically analyzed to determine 370 start times associated with the generation of zebra stripes. Statistical analyses of these events reveal that the zebra stripes are usually created during substorm onset, a time at which prompt penetration electric fields are present in the plasmasphere. All the pieces of experimental evidence collected are consistent with a scenario in which the prompt penetration electric field associated with substorm onset leads to a sudden perturbation of the trapped particle drift motion. Subsequent drift echoes constitute the zebra stripes. This study exemplifies how the analysis of trapped particle dynamics in the inner belt and slot region provides complementary information on the dynamics of plasmaspheric electric fields. It is the first time that the signature of prompt penetration electric fields is detected in near‐equatorial electric field measurements below L = 3. Key Points: An algorithm is designed to analyze the zebra stripes present in the spectrograms of energetic electrons trapped below L = 3 A superposed epoch analysis of 370 events is performed to determine the experimental conditions associated with zebra stripe generation Experimental evidence suggests that prompt penetration electric fields associated with substorm onsets routinely generate zebra stripes