Solanki 2004 is a widely cited reconstruction of solar activity based on INTCAL98 (1998) 14C as a proxy. Nature abstract
I have used INTCAL09 (2009) as a basis and a trivially simple method to reconstruct the Solanki et al result, with differences and excluding the older portion of their result. (14C record deteriorates to coarse sampling about 9500BP).
All following plots are time left to right and adjusted to AD calendar.
Method and data used
Intcal09 is a 14C reference work presented as two 14C reference curves, one for atmospheric (vegetation) and the other for marine sediment.
An intractable problem with extracting a radiation proxy signal is large long term change which has no definitely known causal. This is usually compensated out using signal processing filtering or shape subtraction or statistical pseudo filtering.
On noticing the marine 14C response is muted I guessed there is natural gaussian filtering of the atmospheric original as material passes down to marine sediment and might be exploitable.
Assuming the authors of reference data have been fastidious on accuracy, somewhat likely, perhaps an old trick will work.
Difference the two datasets point by point. This does require rescaling of one or the other (because of attenuation by the marine process), which was done by trial and error using std deviation minimisation of the output as a guide. (goes though a minima)
Scale value 1.039
The above gave an interesting result which was then refined by lead/lag of one data against the other, atmospheric leading by about 20 years; from plot about 18 years would be closest but the result is not especially sensitive to change so it has been left simple.
For plotting the reconstruction was Y-axis normalised to the Solanki data and the X-axis left as-is, allowing the plot software to use different time steps: Solanki is sampled at 10 years and Intcal09 at 5 years.
Overall thumbnail of two input data and effect.
- r2 = 0.63 no lag (using every other sample for reconstruct data)
- r2 = 0.74 10 year lag
Visually the two data are self evidently the same, differing in detail.
Warning, huge linked image follows, web browser might need to scroll.
There is an obvious timing difference but there is likely to be argument over which is correct. A fundamental question is the delay between the ionising radiation creating 14C and incorporation into the proxy. Certainly there will be a time lag but I assume this is little more than a year for atmospheric.
There is very little time overlap between human direct solar records and proxy data. AA index, a magnetic measure is most often shown starting 1868 and sunspot number with varying degrees of reliability back no further than 1600. The Solanki record ceases 55BP which is 1950-55=1895AD
An initial look at the problem of tuning the 14C data to solar etc. data indicates there is no obvious solution and great ambiguity, hence I have left the result as-is. Discussion and correction is welcome.
I decided to check IntCal98, the data source for Solanki 2004 because I wondered why such short recent data was used. My guess was correct Solanki has withheld data, hiding the most recent data.
A bright red tail is then added to the plot and seems to be instrumental or observation data. Why is a mystery since it does not seem to add anything useful.
Here is the tail end of the Solanki data, 55BP is the last data.
95 48.7 8.5
85 55 12.7
75 40 13.3
65 27 9.4
55 28.7 9.9
Abstract INTCAL98 stating “24,000-0 cal BP (Before Present, 0 cal BP = AD 1950)” here
As usual, ask if you want data.
In response to Tallbloke (July 22, 2011 at 8:09 am) querying the reason for a discrepancy around year 1850 I add a comparative plot of data since 1400AD of IntCal98 and IntCal09.
Atmospheric is essentially identical. Marine combined with the differencing method is the cause of the difference.