The solar wind variations are caused by solar flare(sunspots) activity creating a 'faster' wind that flows around the planet faster than non-flare activity.
The resultant reduction in 'wind' creates a shallow field resulting in a higher friction interface. Possibly causing higher atmospheric temperatures.
Put simply. Drop a round rock in a fast moving steam. The water moves around the rock at an accelerated rate and has little time to impart all of its energy as the barrier built up around the rock pushes the faster moving water around it.
Now slow the steam of water down, and the effect on the rock is much greater in magnitude as the barrier build up is reduced.
good example... so how is this new? We have been reading about this for years.