"Martin Rowley" schreef in bericht
...

... can't read the Dutch I'm afraid, at least to pick out the answer to
my question: is this sunshine record with respect to the *same*
recording instrument?


That's a rightly marginal note, Martin. The KNMI (Dutch Met-Office) used the
Campbell-Stokes untill 1992; from that year on the institute works with the
pyranometer. And still has the Campbell-Stokes for backing-up and comparing
the data.
I have tried to find something about the formula which is used to calculate
sun-hours out of radiation; the estimation-errors etc. Unfortunately,
despite the perfect information of the KNMI-site, I haven't found an answer
yet. But will keep on searching ;-).


Wijke