Hourly Periodic Variations of Ultralow‐Frequency (ULF) Waves in Jupiter's Magnetosheath. Issue 2 (20th February 2023)

• Record Type: Journal Article
• Authors: Gu, W. D.; Yao, Z. H.; Pan, D. X.; Xu, Y.; Zhang, B.; Delamere, P. A.; Fu, S. Y.; Xie, L.; Ye, S. Y.; Chen, Y. N.; Dunn, W. R.; Wei, Y.
• Is Part Of: Journal of geophysical research. Volume 128:Issue 2(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-02-20
• Subjects: Jupiter -- ULF waves -- magnetosheath -- periodicity; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1029/2022JE007625
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: Periodic variations are widely identified in the Jovian system, varying from 10 s of seconds to several days or even longer. These processes are strongly influenced by solar wind conditions, planetary rotation and Io's volcanic activity. Ultralow‐frequency (ULF) waves at 10 s of minutes, which are the typical time scale of field‐line resonance, are considered as a crucial process in driving the Jovian energy circulation. The longer time‐scale periodicities are likely associated with global mass circulation. In this study, we focus on multihour variations of the ULF wave energy, which are difficult to identify within the magnetosphere due to the rapid planetary rotation modulation. Using the magnetic field observations from Juno and Galileo in Jupiter's magnetosheath, we found multiple significant multihour periodicities, widely distributed from 2 to 10 hr, peaked at different values from case to case. The most common periodicities were between 3 and 5 hr, existing in both the dawn and dusk sides. These common periodicities are likely associated with the energy transport from the inside to the magnetosheath. Plain Language Summary: Periodicities, as detected in aurora, particles, waves, etc., widely exist in the Jovian system. The periodic variations are key signatures to assess theoretical hypotheses, and the coherence between the periodicities in different types of observations can be a crucial constraint to reveal physical causality. Jupiter's magnetic axis is about 10 degrees offset from the rotation axis, resulting in a periodic vibration of the magnetosphere. A spacecraft traveling in Jupiter's magnetospheric space would persistently detect rapid variations of the magnetic field every several hours, and the variation feature depends on the relative location to the magnetic equator and the dynamic magnetospheric processes. Therefore, the investigation of hourly variation of the Jovian magnetosphere is highly challenging due to the strong mixture of spatial and temporal effects. To overcome this difficulty, we analyze magnetic field and plasma wave data in Jupiter's magnetosheath, where the planetary rotation induced spatial variations no longer exist. Many multihour periodicities are identified, which are believed to be consequences of compressions from the rotating magnetospheric plasma to the magnetopause. Key Points: We systematically investigate the hourly periodic variations in Jupiter's magnetosheath by analyzing magnetic field data Periodicities from 2 to 10 hr are widely identified, where results of periodic analysis change from time to time Similar hourly periodicities were identified in both dawn and dusk sides