Variable field-to-normal angles in the shock foreshock boundary observed by ISEE 1 and 2

摘要: Saturated ULF waves in the foreshock, with amplitudes comparable to magnitude of average field, are convected by solar wind quasi-parallel shock where field-normal angle is less than, or about, 45°. Several examples from ISEE 1 and 2 magnetometer data show that defined local, instantaneous angles very different periodically average. Local geometric conditions at nominally varied nearly parallel perpendicular, periods typical upstream waves. Clear magnetic transitions occurred under temporarily quasi-perpendicular geometry.