Articles | Volume 11, issue 9
Nat. Hazards Earth Syst. Sci., 11, 2407–2417, 2011

Special issue: The record of marine storminess along European coastlines

Nat. Hazards Earth Syst. Sci., 11, 2407–2417, 2011

Research article 02 Sep 2011

Research article | 02 Sep 2011

Historical variation and trends in storminess along the Portuguese South Coast

L. P. Almeida1, Ó. Ferreira1, M. I. Vousdoukas1,4, and G. Dodet2,3 L. P. Almeida et al.
  • 1CIMA-Universidade do Algarve, Campus Gambelas, Faro, Portugal
  • 2Faculdade de Ciências da Universidade Nova de Lisboa, Lisboa, Portugal
  • 3Laboratório National de Engenharia Civil, Lisboa, Portugal
  • 4Forschungszentrum Küste, Hannover, Germany

Abstract. This work investigates historical variation and trends in storm climate for the South Portugal region, using data from wave buoy measurements and from modelling, for the period 1952 to 2009. Several storm parameters (annual number of storms; annual number of days with storms; annual maximum and mean individual storm duration and annual 99.8th percentile of significant wave height) were used to analyse: (1) historical storminess trends; (2) storm parameter variability and relationships; and (3) historical storminess and its relationship to the North Atlantic Oscillation (NAO). No statistically significant linear increase or decrease was found in any of the storm parameters over the period of interest. The main pattern of storm characteristics and extreme wave heights is an oscillatory variability with intensity peaks every 7–8 yr, and the magnitude of recent variations is comparable with that of variations observed in the earlier parts of the record. In addition, the results reveal that the NAO index is able to explain only a small percentage of the variation in storm wave height, suggesting that more local factors may be of importance in controlling storminess in this region.