On the General Correlation between 3D Solar Wind Speed and Density Model and Solar Proxies

Abstract

The solar wind (SW) is a supersonic outflow of plasma from the solar corona, with the latitudinal speed and density profiles varying with the solar activity. The SW protons charge exchange with the inflowing interstellar neutral atoms and create energetic neutral atoms (ENAs), which bring information on the physical state of the plasma within the boundary region of the heliosphere. The speed of the ENAs depends on their energies, and consequently observations at different energies provide information on different epochs backward in time. Therefore, understanding the history of the evolution of the SW is important to understand this information. In this paper, we extend the work by Porowski et al., who provided the WawHelioIon 3DSW model of the time evolution of latitudinal profiles of the SW speed and density based on results of analysis of interplanetary scintillations (IPSs). Based on results of principal component analysis, we search for correlation between selected solar proxies and the structure of the SW obtained from IPSs and show that it is possible to reproduce the evolution of the SW structure during the past three solar cycles based on the proxies. With this, we extend the history of the evolution of the SW structure back to 1976, i.e., to the epoch when observations of the key proxies—the inclination of the SW current sheet and the solar polar magnetic fields—became available. We point out the potential of the use of the proxies for forecasting the structure of the SW into the future.

Keywords

• Fast solar wind
• Slow solar wind
• Solar physics
• Solar wind
• Solar activity
• Stellar activity