Magnetosheath response to the interplanetary magnetic field tangential discontinuity

We present a multipoint observational study of the magnetosheath response to the interplanetary magnetic field tangential discontinuities which form hot flow anomaly-like (HFAs) structures. We identify these structures in the vicinity of the bow shock as well as deeper in the magnetosheath. Two or more points of simultaneous observations allow us to describe the gradual evolution and propagation of these HFAs through the magnetosheath. From tens of events recorded by INTERBALL-1, we present two cases. In the first, GEOTAIL identified HFAs in the solar wind near the bow shock, and INTERBALL-1 and MAGION-4 observed related events in the magnetosheath. During the second interval, all three spacecraft observed the HFA features in the magnetosheath. Our analysis of reported events suggests the negligible evolution of these structures in the magnetosheath. A survey of the INTERBALL-1 data has shown that magnetosheath HFAs are observed predominantly during periods of fast solar wind.