ИСТИНА

High-speed solar wind streams (HSSWSs) and magnetic sectors observed during March-December 2007 simultaneously onboard twin STEREO, SOHO and ACE spacecraft are used for better understanding of three-dimensional and time-dependent properties of heliospheric plasma and magnetic field parameters at the Earth’s orbit around the minimum of solar activity cycle. Available space born telescopic and coronographic observations helped to find the origins of the HSSWSs and sectors on the Sun and investigate their dynamics. Sources of HSSWSs with velocities of about 600-700 km/s were identified inside coronal holes with variable angular spans, geometry and time history. Their life times and characteristic time variations were measured and found to be from several hours (CMEs) up to many months (big coronal holes). The corresponding radial extent of resulting HSSWS was very short, less than 1 AU, or very long, seemingly penetrating up to boundaries of the heliosphere with the interstellar medium and beyond. All intermediate length and time scales are also present and coupled by non-linear interactions. We analyze an interesting situation when the active region (AR) was situated inside the big coronal hole (CH) and resided here for several months. In this clear case, the whole complex (CH+AR) evolution determined the observed properties of HSSWSs and the magnetic sector structure. Temporal, longitudinal and latitudinal variations of bulk plasma and magnetic field parameters were analyzed and partially separated in the coronal source regions and in the resulting HSSWSs. Persistent heliolatitudinal gradient in the solar wind speed existed in November 2007, when it was about 20 km/s per 1 angular degree in average. Rapid changes of the sources and corresponding HSSWSs were documented on time scale of a day and less in several instances together with slower changes from one rotation of the Sun to another. Objective classification is suggested based on the dimensionless scaling using Strouhal numbers instead of subjective delimitations between ‘corotating’, ’quasi-steady’ and ‘transient’ events in the solar wind. This allows an accurate and more quantitative description and definition of permanent, temporary and transient situations. This study was supported by the RFBR grants 07-02-00147, 06-05-64500, INTAS 03-51-6202 and MSU Interdisciplinary Scientific Project. It is also fulfilled as a part of the Programs of the Russian Academy of Sciences: “Origin and evolution of stars and galaxies” (P-04), “Solar activity and physical processes in