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General guidelines for nudging to reanalysis data

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Hello, are there general guidelines on when grid nudging to reanalysis data may be needed? For example, if I'm running a year-long simulation, I'll probably want nudging on at least the d01 domain provided it has sufficiently coarse resolution. But I I ran a 2-day simulation, I probably wouldn't need nudging.

But what about the middle ground? At what length of simulation period is reanalysis nudging recommended to avoid possible model 'drift''?

Anything beyond about 3 days is recommended, but it depends on what tolerance you have for phase errors. Without nudging there would be timing errors, especially in large continental sized domains.
You may have already seen this presentation, or it may not contain anything relevant to you, but in case you're interested, take a look for additional nudging information: