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The data on the CDS disks, contains analysed parameters, if available, otherwise it contains forecast parameters. Therefore, on the CDS disks, the "2 metre temperature" is an analysed parameter, whereas the "Maximum temperature at 2 metres since previous post-processing" and "Minimum temperature at 2 metres since previous post-processing" are forecast parameters.
The forecast model in the version version (CY41R2) of the ECMWF Integrated Forecasting System (IFS) used in ERA5, CY41R2, has a cold bias in most regions over the globe, w.hich is at least partially corrected by the analysis system. This forecast cold bias means that the analysed "2 metre temperature" can be larger than the "Maximum temperature at 2 metres since previous post-processing".
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