Relationship between the Parameters of Various Solar Wind Types and Geomagnetic Activity Indices

This paper analyzes the correlation between planetary indices of geomagnetic activity Dst, ap, and AE and the values of coupling functions, calculated from data on plasma and magnetic field parameters during four types of solar wind (SW) streams: the regions of interaction of streams with different velocities (co-rotating interaction region—CIR), interplanetary manifestations of coronal mass ejections ICMEs (MC and Ejecta), and the Sheath compression regions in front of MC and Ejecta. To select SW types, we used data from ftp://ftp.iki.rssi.ru/pub/omni/ for 1995–2016, in which 744 CIR, 118 MC, 501 Sheath, and 843 Ejectaevents were identified. The coupling functions were calculated based on the OMNI data base. The analysis has shown low values of correlation coefficients ( R < 0.5) between the coupling functions and Dst index for all SW types. For the ap and AE indices, a rather strong correlation with coupling functions (0.6 < R < 0.82) was obtained for all SW types. The geoeffectiveness of coupling functions, estimated from the values of linear regression coefficients, has the highest values for the ap index for the Sheath and MC SW types. For the auroral AE index, the highest values of coupling function efficiencies were obtained for the CIR and Ejecta SW types.