You are still missing the point.
Even the enhanced blending is wrong. RomanM and I discussed this at length on CA some time ago. A physics driven model like ERA40 will have a much reduced error over a simple or even a complex blending algorithm. Both the complex blending of CRU and the physics based blending of ERA40 ARE MODELS… That is the point.
There is no RAW DATA.
There are no observations at the cell level.
There are modelled results from the GCMS
There are TWO MODELS of gridded temps
A) the cru MODEL which models a 5 degree grid by averaging
averages, to quote william briggs, are NOT OBSERVATIONS
B) the ERA40 MODEL which models gridded temps using
1. point observations
2. physics
So, your notion that comparing GCM grids with Cru grids is somehow comparing model results with observations is confused at the depths of its soul. Its confused because the CRU priduct is not observations it is a MODEL of observations. all averages, all means, all anomalies are data MODELS. they are not observations.