EMIC Waves Observed Throughout the Inner Magnetosphere Driven by Abrupt Enhancement of the Solar Wind Pressure. Issue 9 (28th April 2022)

• Record Type: Journal Article
• Authors: Xue, Zuxiang; Yuan, Zhigang; Yu, Xiongdong; Deng, Dan; Huang, Zheng; Raita, T.
• Is Part Of: Geophysical research letters. Volume 49:Issue 9(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-28
• Subjects: electromagnetic ion cyclotron wave -- solar wind pressure -- temperature anisotropy -- multipoint observations -- inner magnetosphere; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2022GL098954
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Electromagnetic ion cyclotron (EMIC) waves were simultaneously observed in the day‐ and night‐side region driven by a sudden enhancement of the solar wind pressure on 12 July 2013, which was registered by both ground stations and space satellites. The amplitude enhancements of EMIC waves are well correlated to the intensification of the ambient magnetic field caused by the enhanced solar wind pressure pulse. Due to the northward interplanetary magnetic field, the magnetic field intensification is found to appear globally in the inner magnetosphere, which is predicted by field model outputs and evidenced by satellite observations. As a result, the observed nightside protons become more anisotropic, which further promotes proton instabilities and amplifies pre‐existing EMIC waves. Our findings provide direct observational evidence that enhanced solar wind pressure pulse can directly drive the ring current ion dynamics and EMIC wave evolutions throughout the inner magnetosphere. Plain Language Summary: There are fruitful observations of compression‐related electromagnetic ion cyclotron waves (EMIC), most of which are located at subsolar regions. Some studies also indicate that solar wind pressure enhancements can excite EMIC waves in the nightside. However, simultaneous and direct space observations of EMIC waves driven by the enhanced solar wind pressure both at noon and night sector are lacking. In this letter, we provide a typical event where suddenly enhanced solar wind pressure can lead to magnetic field intensification and EMIC wave generation/amplification throughout the inner magnetosphere. The calculated linear growth rates based on the observed plasma parameters show that the nightside anisotropic protons should be responsible for the EMIC wave amplification. Our findings show that ion dynamics and EMIC wave evolutions can be modified by the solar wind pressure intensification throughout the inner magnetosphere. Key Points: Electromagnetic ion cyclotron waves are simultaneously observed in day‐ and night‐side inner magnetosphere driven by enhanced solar wind pressure with northward interplanetary magnetic field The generation/amplification of EMIC waves is well correlated with the enhanced background magnetic field Intensified magnetic field is found to further promote proton anisotropic instabilities and amplify pre‐existing EMIC waves at nightside