Global ULF Waves Generated by a Hot Flow Anomaly

Monday, 10 July 2017: 14:05
Furong Room (Cynn Hotel)
Liangliang Zhao, Peking University, Beijing, China, Hui Zhang, University of Alaska Fairbanks, Physics Department & Geophysical Institute, Fairbanks, AK, United States and Qiugang Zong, Peking University, School of Earth and Space Sciences, Beijing, China
Abstract:
Hot flow anomalies (HFAs), which are frequently observed near Earth's bow shock, are phenomena resulting from the interaction between interplanetary discontinuities and Earth's bow shock. Such transient phenomena upstream the bow shock can generate ULF waves in the Earth's magnetosphere. A large HFA was observed by Cluster on April 27, 2008. Nearly monochromatic Pc 3 ULF waves generated by the HFA were observed by multiple spacecrafts and ground stations. The ULF waves show characteristics of standing Alfvén waves. The wave power of the poloidal mode of the generated ULF waves is stronger than that of the toroidal mode. The Pc 3 ULF waves generated by the HFA were observed at dawn, noon, dusk sectors and night side, indicating that the Pc 3 ULF wave response of the magnetosphere to the HFA is global. Our results show that the impact of HFAs to the magnetosphere is much stronger than what we thought before.
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