Magnetic Cavities in the Solar Wind, Their Influence on the Bow Shock Position and Geomagnetic Activity

Abstract

Based on a detailed study of the sporadic solar wind (SW) recorded at 1a.u. December 15-16, 2013, as well as 13 selected sporadic SW streams for the period 1996-2012, within the structure ICME, a region referred to as a "magnetic cavity" ("magnetic cavity") is distinguishеd. It is characterized and determined by a high degree of anticorrelation between the plasma density N and the IMF modulus B. At its front boundary, N sharply drops and B increases, and at the rear boundary, on the contrary, N sharply increases and B falls. Inside the cavity, the duration of which can be in the interval ≈ 1-30 hours N and B change little. According to measurements on the TNE and TNV satellites located in the daytime and nighttime magnetospheres, respectively, it is shown that the effect of the cavity on the bow shock wave (NESH) leads to a sharp drop in the geomagnetic field modulus along the duration corresponding to the duration of the magnetic cavity and to a sharp shift of the GOAW towards the Sun.