The evident relationship between solar and ice?

A (dutch) tweet from Martien de Laat this morning triggered my attention:

Of een elfstedentocht wordt verreden ligt aan de zonnecyclus Jaartallen onder foto: tochten! http://plixi.com/p/67879978 Opmerkelijk! #yam

It states that there is a relationship between the Elfstedentocht and solar cycles.
The Elfstedentocht ("Eleven Cities Tour"), a 200 kilometres skating competition, is held irregularly in the province of Friesland, Netherlands.
The solar cycle is the main source of the on average 11 year periodic solar variation which drives variations in space weather and weather on the ground

The accompanying picture only showed the last 45 years and seemed to conveniently leave out the last 5, so I decided to do some research of my own - that's when it usually gets best :P

The Elfstedentocht is an event that requires a long period of frost all across the North East of the Netherlands. As such, it's rarely held as the requirement now is that the ice should be 15 centimetres (6 inches) thick all across the entire track. With us Dutchies shivering at the idea of frost during the daytime, you'll get what that takes, I think: a severe winter once every so-so years

Here are the years the Elfstedentocht was held:
1909, 1912, 1917, 1929, 1933, 1940, 1941, 1942, 1947, 1954, 1956, 1963, 1985, 1986, 1997

Basically, less sunspots mean less warmth on Earth. I can't make heads or tails of the explanations given really, but at least all agree on a correspondence with "the little Ice-age" and a lack of sunspots

From NASA, here are the solar cycles for the last 260 years (181 kb JPEG image) which I edited myself into one picture covering 1900-2010:

I merged the two last pictures, and added an extra x-bar so the 5-year ranges are also shown - and that's all I did. What you see is the number of sun spots: the higher the graph, the more there are

Now, let's plot the Elfstedentocht years:

• 1909 - certainly not a winner, but close-ish - 80%
• 1912 - dead on target - 100%
• 1917 - dead off target, if there is such a thing; that is at the very height of sunspots - 0%
• 1929 - same as 1909 - 80%
• 1933 - dead on target - 100%
• 1940 - a little bit more off target even than 1909 and 1929 - 60%
• 1941 - another 1909 - 80%
• 1942 - even better - 90%
• 1947 - off - 60%
• 1954 - spot-on - 100%
• 1956 - almost - 90%
• 1963 - close - 90%
• 1985 - close again - 90%
• 1986 - dead on target - 100%
• 1997 - dead on target - 100%

Now, let's get an average score there. No deviation or difficult mathematical stuff, just sum and avg. The score? An average of 81% - that's not bad at all. In fact, that's pretty great

Right, to spoil the fun, let's pick one, and only one, year for every "sun spot low" out of the average 11-year cycle and deduct points for the Elfstedentocht not happening then

• 1912 - safe
• 1923 - 100% off
• 1934 - benefit of the doubt here, 1933 was a hit
• 1944 - well it was a War and all, let's just forget about it
• 1954 - very, very safe
• 1965 - mulling, in doubt - but let's subtract 100% anyway
• 1976 - 100% off for sure
• 1987 - again, benefit of the doubt
• 1997 - home free again
• 2008 - 100% off for sure, was even a mild Winter if memory serves me right

Have I been lenient there? I'm sure I have. Now, for the score: that's 400% off - that must hurt. Going back to the initial score, that's not 1220% now but a mere 820%. Divided by the 15 Elfstedentochten, that makes for...

an average 55% for solar cycles and Elfstedentochten coinciding
Disappointing? I think so - how about you?