Influence of the solar-wind magnetic field on the magnetosheath turbulence behind the bow shock

Abstract

The experiment Sura–-WIND (1996–1997) on radio-raying of geodisturbed solar-wind region is interpreted in terms of modern knowledge of an interaction between the magnetized solar wind and the Earth's magnetosphere. Characteristics of the scattered signal at 9 MHz, determined by a plasma turbulence level with scales about 100 km, are statistically related to in situ measurements of solar wind parameters such as plasma density and the orientation and magnitude of the interplanetary magnetic field (IMF) onboard WIND spacecraft. The dependence of the scintillation index of the detected scattered signal, characterising the average turbulence level of the Earth's magnetosheath behind the bow shock, on the IMF orientation and magnitude is revealed. To verify the relation obtained, modern nonlinear correlation techniques based on the theory of artificial neural networks (ANN) are applied. The results obtained using a three-layer ANN with error backpropagation confirm an essential IMF influence on the plasma turbulence in the magnetosheath.