IntroductionFigure 1. NAO from NOAA (http://www.climatewatch.noaa.gov/wp-content/uploads/2011/03/ao-nao2_pos_vs_neg.jpg).
Introduction Possible reasons Increase in winds Increase in storminess Storminess variations in decadal scales
Wave Models Usefulness Interpret data Study impacts of climate change Investigate physical explanations Extrapolate the model
Wave ModelsFigure 2. Mean atmospheric conditions for January 1993. Coloured shading/contours is wind speedin m/s, arrows indicate direction of flow.
Wave Models Data ECMWF ERA-40 re-analysis model, January 1993 NCEP/NCAR re-analysis model Validation TOPEX/Poseidon Buoys
Wave Models Variables Strength of the westerlies Frequency of storms Intensity of storms Strom tracks Storm translation speeds
Wave ModelsFigure 3. Idealized storm with maximum wind speed 10m/s.
Wave ModelsTable 1. Features of the Storm Varied in the Experimentsa. Feature Low Medium HighFrequency (month -1) 3 6 9Intensity (m s-1) 10 15 20Relative Strength 0.5 1 1.5Direction ENE NE NNESpeed (km h-1) 25 50 100aValues in bold are the "standard" case.
Results Storm frequency Storm intensity Relative strength of westerlies Storm track Storm translation speedFigure 4. Effects of the variables on wave height.Red crosses = monthly maximum, blue squares = monthly mean.
Discussion Is it possible to predict storms using this model? Can the model be used in other regions? Is NAO and storm frequency related to global warming?