Non-dipolar solar wind structure observed in the cycle 23/24 minimum

Abstract

Interplanetary scintillation (IPS) observations made in the Cycle 23/24 minimum using the Solar-Terrestrial Environment Laboratory (STEL) multi-station system indicated that during intervals the solar wind had a significantly non-dipolar structure that consisted of fast wind components at the poles and the equator and slower wind components in between. The solar wind structure revealed from the IPS observations was consistent with a marked increase in the occurrence of fast winds observed in situ near the earth. The poleward boundary of the slow wind region observed during this minimum was ±30 north and south. In addition, our IPS observations revealed that the organization of the 3-dimensional solar wind was highly variable during 2007-2008. These features greatly differ from those observed during the previous minima. This fact may be attributed to the weak magnetic field intensity at the poles during the Cycle 23/ 24 minimum. Copyright 2009 by the American Geophysical Union.