Email 1023, April 2008, UEA's Tim Osborn has a good question about exactly how CRU data is fudged: "Is this algorithm written down anywhere?"

Email 1023

date: Tue Apr 1 15:25:08 2008 from: Tim Osborn subject: "missing" values in CRU TS to: "Ian Harris"
...I'm currently struggling with how to distinguish between actual values in CRU TS 3.0 and values that have reverted towards climatology due to the absence of nearby observations. I found the cru_ts...tmp.stn.nc (and also the ...tmp.cstn.nc) files on /cru/cruts, which are proving useful. Similar .stn. files for DTR and PRE (and for VAP when available) will be useful... can you let me know where they are (and set read permission if necessary). However it would also be good to know the exact algorithm used to grid the anomalies, and how this reversion towards climatology is done (e.g. when do values revert partly towards climatology and when do they revert fully?). Is this algorithm written down anywhere?