Why there is no evidence for a new Maunder Minimum

Doug Biesecker

Appearance of Jet Streamsaka Torsional Oscillations

Solar Min

Start of Poleward Branch

Solar Min

Weak and patchy

Comments on ‘jet stream’• Press release says expected to form by 2008. – Formation of pole-ward jet last cycle started ~8 months

after solar minimum.– Poleward jet was weak and patchy at start of last cycle for

anywhere from 18-30 months– The recent solar minimum wasn’t until December, 2008,

so assuming the same delay as last cycle, we wouldn’t expect it before mid-2009.• Don’t I see a hint of something at almost the exact same delay?• This cycle is weaker than the last, so why not expect a weaker

signal than last time?• We only have a 1-cycle history. What makes us think that one

cycle is normal? There is no way of knowing what the natural variability is.

The slowing ‘rush to the poles’Cycle 21(10.3 yrs)

Cycle 22(10.0 yrs)

Cycle 23(12.2 yrs)

Comments on ‘rush to the poles’

• Press release says Cycle 24 started out late and has a slow rush to the poles– Yes, cycle 24 started ‘late.’ Cycle 23 was 12 years

long, 2 years longer than the previous two cycles. However, I see the iron emission appearing right as expected, 12 years after the last one

– Why is the cycle 24 rush to the poles drawn to include a segment of the equatorward branch. • There is no physical reason to connect both• This results in a misleading slope

Weakening Magnetic Fields in Sunspots

What was in the press releaseThe raw data presented at Space Weather Workshop 2010

Solar Max Solar Min

Comments on weakening magnetic field in sunspots

• Press release says that >13 years of data show 50 Gauss per year drop in magnetic field– The figure used in the press release, available at

http://www.boulder.swri.edu/~deforest/SPD-sunspot-release/ is somewhat misleading (I know, it does have error bars), but the reality is the data before and at solar max is incredibly sparse.

– There is no obvious reason that a straight line is the appropriate fit to these data. A curve that follows the solar cycle may in fact provide a better reduced chi square.• That is, an increase in the magnetic field strength before solar

maximum and also an increase after solar minimum looks completely consistent with the data