Investigation of Solar/Heliospheric Anomalies Associated with the Solar Minimum of 2007 - 2008

Abstract

The unusually long-extended solar minimum between cycles 23 and 24 (from 2007 to 2008) yielded a number of anomalies with regard to solar/heliospheric phenomena wherein the solar wind magnetic field is 36% weaker than that for the previous solar cycle minimum (from 1996 to 1997) at 1 AU, the solar wind dynamic pressure is the lowest observed since the beginning of the space age, the unusually high tilted angle of the solar dipole, and the absence of a classical quiescent equatorial streamer belt. To understand the cause of the anomalies, we perform numerical simulation of a realistic inner heliosphere using a global three-dimensional, time-dependent, numerical model with observed solar inputs. It is suggested that these solar extremes are associated with (1) an inflated heliospheric current/plasma sheet (HCS/HPS) and (2) a decrease in the integrated fluxes of mass and magnetic field ejected from the Sun, which was manipulated by some unknown internal solar dynamics.

Keywords

• Interplanetary magnetic field
• Solar cycle
• Heliospheric current sheet
• Solar anomaly