Evaluation of extreme temperature events in the Iberian Peninsula based on Copernicus CERRA reanalysis

Climate change has intensified extreme temperature events (ETEs), jeopardizing water resources, agriculture, and human health. Monitoring surface air temperature with comprehensive datasets is crucial, given the spatial and temporal limitations of in situ data. This study evaluates the recent Copernicus European Regional Reanalysis (CERRA) product to investigate unusually high (heatwaves) or low (cold spells) temperatures over the Iberian Peninsula (IP) during two extended seasons. The assessment was performed with daily maximum and minimum air temperatures from 12 stations in mainland Portugal for 2000−2020, and from a high-resolution gridded dataset covering continental Spain and the Balearic Islands for 1985−2020. Several metrics describing the number, frequency, duration, amplitude, and magnitude of hot and cold extreme events were assessed. CERRA exhibits good performance, with a cold bias for maximum and a warm bias for minimum air temperature. It tends to underestimate the frequency, duration, and intensity of heatwaves, Nevertheless, both the observations and CERRA identify the southwestern and interior regions of the IP as the most impacted whereas northern and coastal areas experience fewer and weaker heatwaves. Regarding cold spells, CERRA reproduces the general spatial gradient and the effects of orography, though it slightly underestimates their intensity and duration. The study of ETEs is highly relevant to the IP economy, especially agriculture, health, energy, and tourism, making their understanding crucial for mitigation and adaptation. The ability of CERRA to capture key ETEs features makes it a valuable dataset for evaluating health or agricultural models for the IP.