Solar cycle changes of large-scale solar wind structure

TL;DR

This study analyzes the evolution of solar wind density turbulence over solar cycles 22 to 24, revealing a significant decrease in turbulence levels during the current minimum, indicating a global change in solar wind sources.

Contribution

It provides new insights into the long-term variation of solar wind turbulence and its correlation with solar cycle phases from 1985 to 2009.

Findings

Turbulence peaks around solar maximum and drops to ~70% at minimum.

Turbulence has decreased to ~30% since 2005 during the current minimum.

Solar wind mass and energy supply have reduced significantly in recent years.

Abstract

In this paper, I present the results on large-scale evolution of density turbulence of solar wind in the inner heliosphere during 1985 - 2009. At a given distance from the Sun, the density turbulence is maximum around the maximum phase of the solar cycle and it reduces to ~70%, near the minimum phase. However, in the current minimum of solar activity, the level of turbulence has gradually decreased, starting from the year 2005, to the present level of ~30%. These results suggest that the source of solar wind changes globally, with the important implication that the supply of mass and energy from the Sun to the interplanetary space has significantly reduced in the present low level of activity.