A new statistical approach to extreme wind speeds in France

To analyze all wind data available in the French meteorological stations, to elaborate a new extreme wind speeds map, an homogenization tool is developed that allow the detection and the correction of breaks due to sensor change and modification of measurement environment. Breaks are detected on annual mean wind speed series. Daily maximal wind speed values for about 150 wind speed stations have been selected using this method. The meteorological station environment influence is corrected with the help of the Danish software WAsP that takes into account the relief, the roughness of the land within a radius of 5 km as well as the near wakes in a radius of 500 m. The relief is described by the numeric model of terrain of Institut Geographique National (IGN) on a 50 m grid step and the roughness of the land, by an interpretation of the database CORINE land cover by the Geographic Information System software MapInfo, coupled with a description of environment of each station by Météo-France. The time series of the maximal daily mean wind speed built from the maximal daily peak velocity are analyzed by the method of independent storms, first proposed by Cook [1982. Towards better estimation of extreme winds. J. Wind Eng. Ind. Aerodyn. 9, 295–323] already applied for UK by Miller et al. [2001. Towards a revised base wind speed map for the United Kingdom. Wind Struct. 4(3), 197–212]. The normalized mean wind speed of 50 years return period irrespective of wind direction is obtained for each meteorological station, by fitting the cumulative distribution by a Pareto law.