Hot Flow Anomalies at Earth's Bow Shock and Their Ground Signatures

Hot flow anomalies (HFAs) at Earth's bow shock were identified in THEMIS C satellite data for August 2007 to December 2009. The 142 events were classified as "young" or "mature" and then "spontaneous" or "regular". Spontaneous HFAs are also called SHFAs. HFAs occur over a wide range of magnetic local times (MLT). In this study, HFA parameters were analyzed relative to their locations with respect to a model bow shock and the MLT. HFAs and SHFAs occurred more often for more radial interplanetary magnetic field orientations. In this study, SHFAs and HFAs do not show major differences in their plasma parameters and occurrence locations. Initial results indicate that there are signatures at geosynchronous orbit and on the ground corresponding to HFAs.