Solar activity and climate

Posted: December 5, 2020 by oldbrew in Cycles, data, solar system dynamics
Tags: , , ,

Sunspots [image credit: NASA]

Wikipedia’s Solar activity and climate web page says:
Solar activity has been on a declining trend since the 1960s, as indicated by solar cycles 19-24, in which the maximum number of sunspots were 201, 111, 165, 159, 121 and 82, respectively.

We’re probably not surprised that they prefer a metric which appears to support their often-expressed view in various climate-related pages that modern global warming can’t be natural.

But is the sunspot maximum the most relevant metric to judge the level of solar activity by? Another Wikipedia page is its List of Solar Cycles.

It has various stats on the known cycles, one of which is ‘Average spots per day’. There’s no data shown before SC 10, but that’s good enough as it started in 1855, roughly when modern warming is thought to have originated.

Based on the Gnevyshev-Ohl rule, which Wikipedia says ‘is an empirical rule according to which the sum of Wolf’s sunspot numbers over an odd cycle exceeds that of the preceding even cycle’, we’ll obtain the ‘average spots per day’ figures of solar cycles 10+11, 12+13, 14+15 etc. and check the results, giving a ranking ().

10+11 = 181/2 (4)
12+13 = 122/2 (7)
14+15 = 127/2 (6)
16+17 = 164/2 (5)
18+19 = 238/2 (1)
20+21 = 197/2 (2)
22+23 = 188/2 (3)
[24+25 = 49 + ?(unknown as cycle 25 only recently started)]

According to this list, the three most active pairs of sunspot cycles since 1855 were between 1944 and 2008 (solar cycles 18-23). So is it true to say ‘solar activity has been on a declining trend since the 1960s’, or is it perhaps an attempt to downplay the role of the sun in climate?

It’s not a coincidence that recent cycles, prior to the last one (SC 24), have mostly been of shorter duration than the ~11 year average. The data point to greater sunspot intensity in such cycles, as a rule of thumb.
– – –
Re the Gnevyshev-Ohl rule, Wikipedia points out: ‘The rule breaks down under certain conditions.’ The only example in our list is for cycles 22 and 23, the previous breach being for cycles 8 and 9 (see List of Solar Cycles).

UPDATE Dec. 2020: The average sunspot number in the 100 years from 1913-2012 (SC 15 – SC 23) was nearly 96, but for SC 24 it was down to 49 i.e. barely half the 100-year average.

  1. Chaswarnertoo says:

    It’s that big yellow thing in the sky! Who’d a thunk it?

  2. oldbrew says:

    DECEMBER 4, 2020
    Solar telescope releases first image of a sunspot

    “The sunspot image achieves a spatial resolution about 2.5 times higher than ever previously achieved, showing magnetic structures as small as 20 kilometers on the surface of the sun”.

    The image reveals striking details of the sunspot’s structure as seen at the Sun’s surface. The streaky appearance of hot and cool gas spidering out from the darker center is the result of sculpting by a convergence of intense magnetic fields and hot gasses boiling up from below.

  3. oldbrew says:

    Average duration of the Hale cycle (a pair of solar cycles):
    SC 08-15 inclusive = 22.6 years (per pair)
    SC 16-23 inclusive = 21.125 years (per pair)

    The difference there is nearly 1.5 years. Expected long-term average: around 22.1 years.

  4. Paul Vaughan says:

    OB: 1 measurement per cycle is too crude. Use a wavelet with multidecadal extent and Schwabe grain on monthly data to take about 11*12 measurements per cycle. Letting the “experts” mislead will only take us to 1984. People are such idiots about this. It’s so far beyond ridiculous it’s criminal.

  5. Phoenix44 says:

    The rule breaks down? Hmm.

    I must say I find much of this solar cycle stuff unconvincing. We know so little about what’s going on it feels like any attempt to impose order rather than explain.

  6. oldbrew says:

    Solar Cycle (2020)
    Lidia van Driel-Gesztelyi and Mathew J. Owens

    Figure 11. TSI variations over the period 1978–2013 from the PMOD composite (Fröhlich & Lean, 1976; see also (Dudok de Wit, Kopp, Fröhlich, & Schöll, 2017). White and red lines show 27-day and 1-year average values, respectively. The solar cycle is indicated by the black-shaded area, which shows sunspot number, arbitrarily scaled.
    – – –
    Pity it stops at 2013, or 2015. Difference between max and min of the graph is 2 Wm² (1367-1365). The 2013-2014 peak is obviously lower than the earlier ones, although the red and white lines stop short of it.

  7. Paul Vaughan says:

    Phase-biased estimates of SCL and graphs of TSI beginning in 1979 together signal only 1984 doubling luck D-own. Effectively you can count on 1 hand (perhaps 1 finger) how many people on Earth understand what is really going on. But a lot more people will be able to see this (maybe 20%) : Democracy is being used as a tool to destroy western freedom.

  8. […] a recent post we looked at the average daily sunspot numbers, finding that far from the claimed decades-long […]

  9. […] a recent post we looked at the average daily sunspot numbers, finding that far from the claimed decades-long […]

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