NAO influence on extreme winter temperatures in Madrid (Spain)

• Main Authors: Prieto, L., Garcia, R., Dìaz, J., Hernandez, E., del Teso, T.
• Other Authors: Depto. Fisica de la Tierra II, Centro Universitario de Salud Publica
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2002
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; North Atlantic; North Atlantic oscillation
• Online Access: https://hal.science/hal-00317468; https://hal.science/hal-00317468/document; https://hal.science/hal-00317468/file/angeo-20-2077-2002.pdf

International audience Extremely cold days (ECDs), with minimum temperatures lower than -4.6°C, have been analysed for Madrid. This threshold corresponds to the 5th percentile of the period 1963?1999. Adopting a case analysis approach, five synoptic patterns have been identified that produce these extremely low temperatures. Three of them are associated with cold air flows over the Iberian Peninsula, and the other two with a lack of significant circulation over the region. A nonlinear association with the North Atlantic Oscillation (NAO) has been identified using log-linear models. The NAO positive phase leads to an increase in the winter frequency of those synoptic patterns associated with stagnant air flow over Iberia, while those characterised by cold, northern flows do not appear to be similarly influenced.