Email 5307, April 2008, UEA's Ian "Harry" Harris: "We do have 'station files' - these give the number of stations theoretically contributing to each cell. Where it's a zero, and it's also a land cell, you'll get (full) relaxation to the climatology"

Email 5307

[Gerard van der Schrier] Would you happen to have information at which gridpoints the CRU TS 3.0 data are relaxed to climatology?

[Ian "Harry" Harris] Ahhh. Great question! We do have 'station files' - these give the number of stations theoretically contributing to each cell. Where it's a zero, and it's also a land cell, you'll get (full) relaxation to the climatology. However, that won't show you 'strong relaxation', I'm not sure if your current approach isn't the most pragmatic!
...
[Gerard van der Schrier] I'm working on the PDSI now, and the self-calibrating aspect of the algorithm does not really like climatology. When a gridbox is strongly relaxed towards climatology, only a very minor deviation from climatology makes the algorithm think that a major dourght or pluvial is happening!