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The forecast model in the version (CY41R2) of the ECMWF Integrated Forecasting System (IFS) used in ERA5, has a cold bias in most regions the lower regions of the troposphere over most parts over the globe, w.hich which 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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