Spontaneous hot flow anomalies at quasi‐parallel shocks: 1. Observations

摘要: [1] We present Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations a “Spontaneous Hot Flow Anomaly” (SHFA) upstream from the prenoon bow shock at 0431 UT on 12 August 2007. Although SHFA exhibited greatly heated deflected solar wind plasmas used to identify hot flow anomalies (HFAs), it did not result standard mechanism invoked for formation HFAs, namely interaction an interplanetary magnetic field (IMF) discontinuity with shock. We employ THEMIS A, B, C, D describe evolution event proto-SHFA exhibiting regions depressed strength density but little evidence plasma heating or deflection, well-developed further downstream. These show that can be generated without presence IMF are therefore new category HFAs.