The effect of upstream turbulence and its anisotropy on the efficiency of solar wind – magnetosphere coupling
Abstract. The importance of space weather and its forecasting is growing as interest in studying geoeffective processes in the Sun – solar wind – magnetosphere – ionosphere coupled system is increasing. This paper introduces the proper selection criteria for solar wind magnetic turbulence events during duskward electric field and southward Bz driven geomagnetic storms. Two measures for the strength of solar wind fluctuations were investigated: the standard deviations of magnetic field components and a proxy for the so-called Shebalin anisotropy angles. These measures were compared to the strength of geomagnetic storms obtained from a SYM-H index time series. We found a weak correlation between standard deviation of interplanetary magnetic field GSM component Bz and SYM-H index, and a strong correlation between Shebalin anisotropy angle and the SYM-H index, which can be the result of an increase of probability of magnetic reconnection in fluctuating magnetic fields.