Wind power densities in watts per square metre (W/m²) at 100m height. These datasets cover the land area and coastal waters of Ireland (ex. Northern Ireland), and emanate from a 2003 wind mapping project. The 2003 project reported that some experts regarded mean wind power density as a more accurate indicator of the wind resource. Wind power density (ρw), which depends on the air density (ρ) and the cube of the mean wind speed (V), is calculated by formula: ρw = 0.5ρV³. Zipped collections of shapefiles are available in two spatial reference or coordinate systems: 1) Irish Transverse Mercator (ITM, EPSG:2157) 2) WGS 84 Web Mercator (EPSG:3857) The Sustainable Energy Authority of Ireland (SEAI) offers the same data in its Wind Atlas, a digital map of Ireland's wind energy resource (http://gis.seai.ie/wind). SEAI's 2003 datasets of wind characteristics assist wind energy planners, developers and policy makers. __Background on 2003 wind maps__ The 2003 wind-mapping project was completed by ESB International and TrueWind Solutions for SEAI (then SEI). It predicted wind characteristics, at heights of 50m, 75m and 100m, spanning onshore and offshore. (Larger heights of 125m and 150m were later covered in SEAI’s 2013 wind-mapping project.) The resulting GIS maps cover onshore in 200m grids, and offshore in 400m grids. Generally, wind maps extend to 15km offshore, or occasionally 20km. About the 2003 methodology, it iterated a MesoMap system and a faster WindMap model through reducing grid sizes. MesoMap is built on MASS (Mesoscale Atmospheric Simulation System), a numerical weather model that embodied the fundamental physics of the atmosphere. Iterations through the nested grids accounted for local land elevation, land cover and roughness. Final iterations accounted for increased wind shear and reduced near-surface wind speed at less windy sites. The 2003 Wind-mapping Project Report is available [here](https://seaiopendata.blob.core.windows.net/wind/Report_2003_Wind_Atlas.pdf).

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  Webpage of SEAI Wind Atlas
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  Wind power density 2003 50m in WGS 84 (EPSG:3857)
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  Wind power density 2003 100m in ITM
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