Bow shock observations by Prognoz–Prognoz 11 data: analysis and model comparison Original Research Article

Observations of the terrestrial bow shock by the Prognoz’ orbiters are collected since 1972 (Prognoz) till 2000 (Prognoz 11 = Interball 1 with Magion 4 subsatellite). Data from the different spacecraft are organized into a uniform database for detailed analysis of the terrestrial bow shock position and shape and their variations. A previously developed analytical bow shock model is used to study the motions of this boundary in response to variations of the solar wind pressure, sonic and Alfvenic Mach numbers, and the angle between the plasma flow and magnetic field directions ϑbv. It is shown experimentally that the bow shock is located closer to the obstacle for small ϑbv and farther for ϑbv ≈ 90° for fixed values of ρV2, Ma, Ms. The asymmetry of the terrestrial bow shock in the terminator plane is confirmed, which was found earlier in the Wind bow shock observations for non field-aligned flow with anisotropic Friedrichs diagrams.