Figure 5: Variation of solar wind and geomagnetic properties over the past four decades.
From: The solar magnetic activity band interaction and instabilities that shape quasi-periodic variability
The data presented are from the NASA/GSFC Space Physics Data Facility OMNI database (http://omniweb.gsfc.nasa.gov/). (a) Variation in 50-day running averages of the fast (red) and slow (blue) solar wind helium abundance (AHe; ref. 17)—a proxy of plasma heating at the base of the solar wind16. (b) Variation in the 50-day running averages of the solar wind speed (Vsw; black) and geomagnetic storm Ap index (green). Note the steady drop in AHe over the time frame and the strongly correlated quasi-periodicities in all four quantities where the surges in Vsw, AHe and Ap are of the order 100 km s−1, 15 and 50%, respectively. The error bars in the plot reflect the variance of the signal over the 50-day running window.
