RT Journal Article T1 NAO influence on extreme winter temperatures in Madrid (Spain) A1 Prieto, L. A1 García Herrera, Ricardo Francisco A1 Díaz, J. A1 Hernández Martín, Emiliano A1 Teso, T. del AB 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 non-linear 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. PB European Geophysical Society SN 0992-7689 YR 2002 FD 2002-12 LK https://hdl.handle.net/20.500.14352/59840 UL https://hdl.handle.net/20.500.14352/59840 LA eng NO © European Geosciences Union 2002. The authors thank D. A. Wheeler for his extremely helpful review which improved substantially the manuscript and two anonymous reviewers for their comments. The INM for providing the data. DS Docta Complutense RD 8 abr 2025