What follows here is a demonstration of how earth orbit shapes Arctic ice and in a later post I intend to show how this may well relate to palaeoclimatology shown in ice cores.
You will have seen the plots of Arctic sea ice. I am going to use one dataset here, which one is unimportant, others give the same answer.
I won’t say much here now, busy.
This seems to confirm a huge date mistmatch between the two sets of ice core data.
This is a deliberately large plot. Contact me if you need data or help.
Simplest way to provide data is an export to XLS format of work, warts and all.
Contains usable resampled data and originals
Added later, easiest way to provide data is export to XLS, is scruffy workfile
See part 1 if you haven’t.
Seemed a good test to see if I could reproduce the temperature vs. CO2 lead lag result but using signal processing, data resampling. Turns out the CO2 data is even worse than the isotope ratio temperature data, fewer data points and sampled at different dates.
Easy. I applied identical processing to both datasets and then figured out how to time shift one of them. To my surprise there is a very high correlation, r2=0.82, at least given the preprocessing used. The quick and dirty way to do the time shift was apply an offset at the decimate stage, simply picks off data at a different point. (this is valid)
If I have done this right it is about 1,500 years for best fit of rise and fall. I then aligned the datasets and plotted (Y axis reacaled and offset CO2 by hand so the data roughly matches on one scale) for an eyeball.
There is obviously a lot going on but there it is visibly on one plot.
A net dig shows a work by Jo Nova (know the name, no idea who she is)
That says 800 years and seems to cite others.
As a result of helping someone out with lunar effects in Earth length of day I wondered if a slightly more comprehensive version would work.
The result is an interactive spreadsheet which might be useful.
I would not usually produce such a monster, this is an xls >30Mbyte but it does include reconstruction of the lunar LoD signal, subtraction from the raw LoD and decimation for plotting. It is live, you can turn on or off individual terms/factors and see the effect.
This needs a great deal of explanation, codas, and so on.
For now here is the file lod-work
Do not try this unless you have a fairly large computer. Checked it works with gnumeric, openoffice/libreoffice. Excel should not have a problem but recursion is used.