Pan-European homogenization of daily multi-decadal temperature series from station-based observations

Summary:

The temperature measured at a meteorological station will change when the station is re-located. Re-locations are necessary sometimes when e.g. houses need to be on or close to the measurement site. These changes affect the reliability of the climatological series, and as nearly all long temperature series suffer from such inhomogeneities, a way needs to be found to adjust for these non-climatological temperature changes. The homogenization described here is based on a statistical technique called QuantileMatching, which calculates different adjustments for each part of the temperature distribution. This method perfoms good, especially for extreme temperature values. This process has been applied to a European dataset (ECA&D) and a more reliable assessment of trends in extreme hot (or cold) events over Europe is now possible. The relevant increase of warm events in the Mediterranean summers and the reduction of cold events for the Eastern-European winters are two examples of the findings. This method has been validated against well-known homogenization procedures. finally this dataset has been used to verify the latest climate simulations for Europe that are at the basis of the upcoming IPCC reports.