Tropical timings – a 983-year or ‘Eddy’ cycle

Jupiter and Saturn

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Using data from our tropical timings posts we offer a formula for this proposed cycle. Here’s a reference to it by Nicola Scafetta from the PRP paper: The complex planetary synchronization structure of the solar system – ‘the quasi-millennial oscillation (∼ 983 yr) found in both climate and solar records (Bond et al., 2001).’

See also Figure 7[B] below where ‘Harmonic P=983 yr’.

In a more recent paper: Reconstruction of the Interannual to Millennial Scale Patterns of the Global Surface Temperature (2021), Scafetta says [bold added]:

Note that the millennial temperature oscillation, which was theoretically estimated to be 983 years (Scafetta [72]), is skewed having theoretical maxima in 1077 and 2060 (which were determined from astronomical considerations), and a minimum in 1680 during the Maunder solar grand minimum. This is why Equation (7) could represent the millennial oscillation using two truncated harmonics: note that 1206/2 + 760/2 = 983. The skewness is likely induced by additional multi-secular oscillations that are ignored here [2]. The reported equation is valid only within the interval 1077–2060 because it describes only one temperature millennial cycle.”

From ‘1206/2 + 760/2 = 983’ we get:
1206 + 760 = 1966 = 983*2.
The 1966 year figure will be analysed in this post shortly.

In another PRP paper (note the title): Responses of the basic cycles of 178.7 and 2402 yr in solar–terrestrial phenomena during the Holocene (2014) by I. Charvátová and P. Hejda, the authors say:

This paper will deal with the solar inertial motion (SIM). The SIM is not negligible, it is a very noticeable phenomenon.’…’The periods found in the SIM (in all its motion characteristics such as the velocity, the acceleration, the radii of curvature, etc.) are higher harmonics of the basic period of 178.7 yr (Bucha et al., 1985; Jakubcová and Pick, 1987). The basic period of 178.7 yr was found by Jose (1965) and further described by Fairbridge and Shirley (1987).’

The Jose cycle consists of 9 Jupiter-Saturn (J-S) conjunctions, or equivalently 15 solar barycentric orbits (SBO) – see here. The other period (‘long SIM’) we define here as 121 J-S = 2403.1464 tropical years, the nearest whole number of J-S to the PRP paper’s 2402-yr period.

We then see that 121 Jose cycles = 9 long SIM cycles, because 121*9 J-S = 2403.1464 TY *9, the whole period being 21628.317 TY.

Since 21628.317 TY / 22 = 983.1053 TY, we can state:
9 long SIM cycles = 22 of ‘983 year’ or ‘Eddy’ theoretical cycles.

Let’s return now to our calculation derived from the Scafetta paper:
1206 + 760 = 1966 = 983*2
This pairing is 11*9 (= 99) J-S = 11 Jose cycles. The ratio of the 11 Jose cycle period to the long SIM cycle is then 11:9 (because 11*11 = 121).

The solar barycentric orbits view.
The proposed (mean) 983~year period is 5.5 Jose cycles or 82.5 SBO. The full or double cycle may be split (skewed) in a different way, as described earlier in this post (see quote from the Scafetta (2021) paper, above). It’s 1966~ years in 11 Jose cycles which means 11*15 = 165 SBO, so a whole number of those orbits.

So we’ve derived an Eddy cycle period of 983~years from the two periods of solar inertial motion discussed in the Charvatova/Hejda PRP paper. It’s the half period of 11 Jose cycles, or 11*178.74642/2.
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Top image: Jupiter and Saturn

Footnote: Nicola Scafetta has a new book –
The Frontier of Climate Science: Solar Variability, Natural Cycles and Model Uncertainty

NS: ‘In this article, I share some of the motivations behind the book and highlight a few of its central themes.’

Rethinking climate change

Source: https://tallbloke.wordpress.com/2026/03/12/tropical-timings-a-983-year-or-eddy-cycle/