THEMIS satellite observations of hot flow anomalies at Earth's bow shock

摘要: Abstract. Hot flow anomalies (HFAs) at Earth's bow shock were identified in Time History of Events and Macroscale Interactions During Substorms (THEMIS) satellite data from 2007 to 2009. The events classified as young or mature also regular spontaneous hot (SHFAs). dataset has 17 SHFAs, 49 15 HFAs, 55 HFAs. They span a wide range magnetic local times (MLTs) approximately 7 16.5 MLT. largest ratio solar wind HFA core density occurred near dusk larger distances the shock. In this study, HFAs SHFAs observed up 6.3 RE 6.1 RE (Earth radii), respectively, upstream model HFA–SHFA occurrence decreases with distance highest event ion temperatures not seen flanks. temperature increase electron is around 12 MLT slightly duskward. For (Tihfa∕Tisw)/(Tehfa∕Tesw) generally increased Both are more prevalent when there an radial interplanetary field. occur most preferentially for speeds 550 600 km s−1. correlation coefficient between thermal energy values decrease kinetic 0.62. do show major differences study.