Leif Svalgaard writes in with a collection of points on the 10.7 cm solar radio flux. Being busy tonight, I’m happy to oblige posting them. – Anthony
People often call out that F10.7 flux has now reached a new low, and that a Grand minimum is imminent.
The blue curve is the current F10.7 flux [adjusted to 1 AU, of course] and the red curve is F10.7 back at the 1954 minimum. The D spike (in 1954) was due to an old cycle  region.
There is always the problem of how to align two such curves.. These two were aligned by eye to convey the general nature of the flux over a minimum. The peaks labeled B and C and the low part A were arbitrarily aligned, because peaks often influence the flux for several weeks so would form natural points of correspondence. The detailed similarity is, of course, of no significance. Note, however that because of the 27-day recurrence one some peaks are aligned others will be too. again, this has no further [deeper] significance. The next solar cycle is predicted to be quite low and the cycle following the 1954 minimum was one of the largest recorded. We will, of course, with excitement watch how the blue curve will fare over the next year or so, to see how the ‘ramp up’ will compare to the steep ramp up in 1955-1956.
Of course, as there was more activity before and after the minimum and even during [as cycles overlap]. For the very year of the minimum apart from the spike at D there is very little difference. The important issue [for me] is the absolute level, because that is a measure of the density and temperature of the lower corona, generated by the ‘network’ or background magnetic field, which seems very constant from minimum to minimum, and certainly does not portend an imminent Grand Minimum, which is not to say that such could not come, just that a low F10.7 is not an indicator for it.