The Dansgaard-Oeschger 1470 year climate cycle is anomalistic

This is easily shown from the 74 Jupiter-Saturn conjunctions in the period:
1 J-S = 19.865036 sidereal years = 19.865036*365.25636 days = 7255.8307
(7255.8307*74) / 365.259636 (anomalistic year) = 1469.99945 (1470)

So Earth reaches its perihelion with the Sun exactly 1470 times per 74 J-S.

Both numbers are even, so why is the Dansgaard-Oeschger event not at half the period?
The short answer is: Neptune.

In 1470 years there are 41 Saturn-Neptune conjunctions, not an even number.

The triple conjunctions of J,S and N (see example in graphic below) coincide with Earth’s perihelion at 1470 years — according to the numbers that is, but of course average values can have +/- variations.

From a 2015 paper on the 1470-year cycle:
An astronomical correspondence to the 1470 year cycle of abrupt climate change
A. M. Kelsey, F. W. Menk, and P. T. Moss
Received: 09 Sep 2015

Abstract. The existence of a ~ 1470 year cycle of abrupt climate change is well-established, manifesting in Bond ice-rafting debris (IRD) events, Dansgaard–Oeschger atmospheric temperature cycle, and cyclical climatic conditions precursory to increased El Niño/Southern Oscillation (ENSO) variability and intensity. This cycle is central to questions on Holocene climate stability and hence anthropogenic impacts on climate (deMenocal et al., 2000). To date no causal mechanism has been identified, although solar forcing has been previously suggested. Here we show that interacting combination of astronomical variables related to Earth’s orbit may be causally related to this cycle and several associated key isotopic spectral signals. The ~ 1470 year climate cycle may thus be regarded as a high frequency extension of the Milankovitch precessional cycle, incorporating orbital, solar and lunar forcing through interaction with the tropical and anomalistic years and Earth’s rotation.

https://www.clim-past-discuss.net/cp-2015-146/

– – –
Quote: ‘To date no causal mechanism has been identified’.

The planetary conjunctions, and the Jupiter-Saturn synchronisation with Earth’s anomalistic year, can offer such a mechanism for the detected ‘abrupt climate change’.

Note: re. ‘interaction with the tropical and anomalistic years’ – we might return to that in a later post.

Example of 1470 year conjunction cycle, via Arnholm’s solar simulator: click to enlarge. The Sun is where the lines meet – note similarity of positions.
[Red crosshairs meet at the solar system barycentre]