Extreme temperature events on the Iberian Peninsula: Statistical trajectory analysis and synoptic patterns

• Published in: International Journal of Climatology
• Main Authors: Mohammed, Ali J., Alarcón, Marta, Pino, David
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2018
• Subjects: North Atlantic
• Online Access: http://dx.doi.org/10.1002/joc.5733; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjoc.5733; https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/joc.5733

The occurrence of heat waves and cold spells has been receiving special attention in recent years due to their impact on human health, ecosystems and other aspects, such as the economy. The present work uses a Lagrangian approach to analyse the physical processes leading to temperature extremes in the Iberian Peninsula (IP) for the 20‐year period 1994–2013. Principal component analysis has also been carried out to identify the associated synoptic scale configurations. Spatial pattern analysis shows that the highest temperatures during hot events are reached in the SW region and the lowest ones in the NE, while a latitudinal gradient of 26 K was obtained for the cold events, with the lowest values in the NE regions and the Pyrenees. Most of the extremes persisted between 1 and 3 days for both hot and cold events. Rather than meridional advection, the primary cause behind the occurrence of hot extremes seems to be progressive diabatic warming, which becomes accentuated in its final stage and is caused, on the one hand, by air masses with long residence times over the IP and, on the other hand, by recirculation processes during summer days of weak baric gradient. The air masses producing the extreme cold events have faster trajectories and mainly originate in north and northeast Europe, due to a relative low in the central Mediterranean and a blocking high in the North Atlantic and/or in northeast Europe.