The dune aurora,at a scale of~30 kilometers,was reported recently using ground camera.The small-scale dune aurora occurs on the duskside and exhibits a monochromatic oscillation in the auroral emission,implying fundam...The dune aurora,at a scale of~30 kilometers,was reported recently using ground camera.The small-scale dune aurora occurs on the duskside and exhibits a monochromatic oscillation in the auroral emission,implying fundamental energy conversions.However,whether the dune auroras correspond to atmospheric waves or are associated with magnetospheric dynamics should be determined.This paper reports a dune aurora that occurred during a storm;further,we demonstrate that it was the substructure of the sawtooth aurora that was generated by plasmapause surface waves.Conjugate observations in the magnetospheric source region suggest that the exohiss waves,which are periodically modulated by the plasmapause surface wave-excited ultralow frequency wave,might be responsible for the generation of the dune aurora.Most reported dune aurora events have occurred simultaneously with sawtooth auroras,suggesting that both are plasmapause-driven cross-scale auroral structures.展开更多
A mirror mode wave is a fundamental magnetic structure in the planetary space environment that is persistently compressed by solar wind,especially in the magnetosheath.Mirror modes have been widely identified in the m...A mirror mode wave is a fundamental magnetic structure in the planetary space environment that is persistently compressed by solar wind,especially in the magnetosheath.Mirror modes have been widely identified in the magnetosheaths of the Earth and other planets in the solar system,yet the understanding of mirror mode waves on extraterrestrial planets is not as comprehensive as that on the Earth.Using magnetic field data collected by the Cassini spacecraft,we found peak and dip types according to the magnetic morphology(i.e.,structures with higher or lower magnetic strengths than the background field).Moreover,mirror mode waves and electromagnetic ion cyclotron waves were found one after the other,implying that the two wave modes may evolve into one another in the Kronian magnetosheath.The results indicate that many fundamental plasma processes associated with the mirror mode structure exist in the Kronian magnetosheath.The energy conversion in Saturn’s magnetosheath may provide key insights that will aid in understanding giant planetary magnetospheric processes.展开更多
upiter's space environment is highly dynamic,shaped by interactions between the solar wind,Jupiter’s strong magnetic field,and its moons[1].As one of Galilean moons,the volcanic moon Io introduces fresh plasmas t...upiter's space environment is highly dynamic,shaped by interactions between the solar wind,Jupiter’s strong magnetic field,and its moons[1].As one of Galilean moons,the volcanic moon Io introduces fresh plasmas to Jupiter’s space environment,providing a major plasma source in Jupiter’s magnetosphere[2].This process of mass loading is primarily supplied by Io’s dense atmosphere through the sublimation of surface frost[3].Due to interchange instability,cold and dense plasmas sourced from Io are transported outward,while hot and tenuous plasmas move inward[4].The process of plasma interchange instability can be captured observationally in terms of both charged particles and plasma waves[5].展开更多
基金supported by the National Natural Science Foundation of China(42222408,41931073)supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y2021027)supported by the Key Research Program of the Institute of Geology&Geophysics,Chinese Academy of Sciences(grant IGGCAS-201904).
文摘The dune aurora,at a scale of~30 kilometers,was reported recently using ground camera.The small-scale dune aurora occurs on the duskside and exhibits a monochromatic oscillation in the auroral emission,implying fundamental energy conversions.However,whether the dune auroras correspond to atmospheric waves or are associated with magnetospheric dynamics should be determined.This paper reports a dune aurora that occurred during a storm;further,we demonstrate that it was the substructure of the sawtooth aurora that was generated by plasmapause surface waves.Conjugate observations in the magnetospheric source region suggest that the exohiss waves,which are periodically modulated by the plasmapause surface wave-excited ultralow frequency wave,might be responsible for the generation of the dune aurora.Most reported dune aurora events have occurred simultaneously with sawtooth auroras,suggesting that both are plasmapause-driven cross-scale auroral structures.
基金Z.Y.acknowledges the National Natural Science Foundation of China(Grant No.42074211)the Key Research Program of the Institute of Geology&Geophysics,Chinese Academy of Sciences(Grant No.IGGCAS-201904).
文摘A mirror mode wave is a fundamental magnetic structure in the planetary space environment that is persistently compressed by solar wind,especially in the magnetosheath.Mirror modes have been widely identified in the magnetosheaths of the Earth and other planets in the solar system,yet the understanding of mirror mode waves on extraterrestrial planets is not as comprehensive as that on the Earth.Using magnetic field data collected by the Cassini spacecraft,we found peak and dip types according to the magnetic morphology(i.e.,structures with higher or lower magnetic strengths than the background field).Moreover,mirror mode waves and electromagnetic ion cyclotron waves were found one after the other,implying that the two wave modes may evolve into one another in the Kronian magnetosheath.The results indicate that many fundamental plasma processes associated with the mirror mode structure exist in the Kronian magnetosheath.The energy conversion in Saturn’s magnetosheath may provide key insights that will aid in understanding giant planetary magnetospheric processes.
基金supported by the National Natural Science Foundation of China(42025404,42188101,and 423B2409)the National Key R&D Program of China(2022YFF0503700)the B-type Strategic Priority Program of the Chinese Academy of Sciences(XDB41000000).
文摘upiter's space environment is highly dynamic,shaped by interactions between the solar wind,Jupiter’s strong magnetic field,and its moons[1].As one of Galilean moons,the volcanic moon Io introduces fresh plasmas to Jupiter’s space environment,providing a major plasma source in Jupiter’s magnetosphere[2].This process of mass loading is primarily supplied by Io’s dense atmosphere through the sublimation of surface frost[3].Due to interchange instability,cold and dense plasmas sourced from Io are transported outward,while hot and tenuous plasmas move inward[4].The process of plasma interchange instability can be captured observationally in terms of both charged particles and plasma waves[5].
