Three-dimensional plasma structures with anomalous flow directions near the Earth's bow shock

摘要: We have examined AMPTE IRM data obtained in the solar wind near Earth's bow shock and found 16 well-defined cases where a region of hot subsonic plasma is embedded wind. Such structures had been observed first with instruments on ISEE 1 2 later UKS distinguished from crossings. Our observations confirm some earlier findings, notably event profile, showing hot, low-density core flanked by narrow regions high density strong magnetic field. also find low (∼200 km/s) flow velocities, strongly deflected wind, we substantially strengthen local time dependence which invariably directed dawnward for prenoon events duskward postnoon events. results differ reported two respects. First, flows observe tend to larger angles relative they often even sunward component. Second, selected cannot be described as diamagnetic cavities. On contrary, fields are usually significantly enhanced. This apparent discrepancy may simply result different selection criteria. A quantitative analysis flanking shows consist fast, nearly perpendicular, supercritical shocks outside tangential discontinuities inside. systematic difference between orientations leading trailing edge boundary normals. While former largely transverse flow, latter more aligned Another new finding concerns presence enhanced fluxes >70-keV electrons appear magnetospheric origin. The majority associated directional interplanetary not but occur magnetosheath, at times replacing regular shock. Among mechanisms discussed causes these formation jets magnetopause reconnection, or amplification stresses rotational medium; sudden localized enhancements reflection; interaction having specific internal structure.