Part of that process is quality-checking the data to make sure it doesn't have anything weird going on in it that needs to be fixed. Like this:
This is an air temperature field. The swirly colorful stuff is all values in the 200-300 ish range. The stripe of obviously wrong? The red is 1e+38, and the blue is -1e+38. Yeah, I'm gonna have to throw that bit out.
And then you occasionally find things like this:
This is three separate vertical layers of v-wind. I have no idea how we managed to get a big geometric blob of glitch values like that. My best guess is that it was stored on tape, that the layout on tape matches the layout in memory, and we're seeing some kind of physical flaw in the storage medium. (But the important thing is, it's probably not a problem with the model -- the model would have crashed and died if it managed to produce values like this -- so all I have to do to fix it is delete the bad values.)