A post about “Engineering the Software for Understanding Climate Change” by Steve M. Easterbrook and Timbo “Not the Dark Lord” Johns (thanks Eli). For the sake of a pic to make things more interesting, here is one:
It is their fig 2, except I’ve annotated it a bit. Can you tell where? Yes that’s right, I added the red bits. I’ve circled vn4.5, as that was the version I mostly used (a big step up from vn4.0, which was horrible. Anecdote:it was portablised Cray Fortran, which had automatic arrays, but real fortran didn’t. So there was an auto-generated C wrapper around each subroutine passed such things, which did the malloc required. Ugh). vn4.5 was, sort of, HadCM3, though the versionning didn’t really work like that. Although that pic dates vn4.5 to 1999 that is misleading: it was widely used both within and without the Met Office until, well, outside it was still being used when I left in 2007, partly because HadGEM (which as I recall was vn6.0/1, though I could be wrong) was much harder to use. Also the “new dynamics” of vn5.0, although in theory deeply desirable, took a long time to bed in.
Note: you should also read Amateurish Supercomputing Codes? and the interesting comments therein.
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