Precipitation-temperature relationships over Europe in CORDEX regional climate models

We studied spatial and temporal patterns of precipitation-temperature (P-T) relationships through correlations between monthly standardized precipitation index (SPI) and monthly temperature anomalies in individual climatic seasons over Europe. In the observed data (represented by E-OBS), positive correlations (wet-warm/dry-cold relationships) prevail during winter over most of Europe, while negative values (dry-warm/wet-cold) are dominant in summer. In the next step, an ensemble of seven regional climate models (RCMs) from the CORDEX project driven by the ERA-Interim reanalysis were examined as to their reproduction of the regional patterns of the P-T correlations. In winter, the RCMs yielded overly strong positive P-T correlations over northern Europe, while the correlations were too weak in the south compared to observed data. During summer, the biases were generally larger; the RCMs were able to capture the overall negative P-T correlations but these tended to be too weak over northern Europe. This deficiency was found to be linked to simulated differences in shortwave radiation (a proxy for cloud cover) between dry and wet months. In western, central, and southeastern Europe, by contrast, most RCMs yielded too strong negative correlations in summer, and overly large decreases of relative humidity during dry months probably contributed to these errors. The results pointed up issues that should be addressed as the reported RCMs' deficiencies may lower credibility of projected compound dry-hot events in climate change scenarios.

Automated summary

The study identified positive P-T correlations in winter and negative correlations in summer over Europe, with RCMs showing deficiencies in accurately reproducing these patterns, particularly in northern Europe and during summer months. Simulation differences in shortwave radiation and relative humidity were identified as contributing factors to these errors. This highlights the importance of addressing these deficiencies to enhance the credibility of projected climate change scenarios.