The landscape influence on the wind energy distribution in height on the Latvian coast of the Baltic Sea

The paper presents results of the assessment made for the wind speed and energy distribution with height in Latvia and the Latvian coast of the Baltic Sea. The data are presented for observations made in 2007 - 2012 obtained from a meteorological mast equipped with LOGGER 9200 Symphonie measuring system in combination with ZephIR lidar for the heights from 40 to 160 m together with the meteorological data provided by "Latvian Environment, Geology and Meteorology Centre". The wind speed distribution with height is analyzed, and the coefficients of approximating functions calculated. Extrapolation results are shown for the distribution curves of averaged wind speed and energy density values at heights up to 200 m. The analysis includes comparison of vertical wind shear for three different terrain types (forest, complex urban area and coastal area). The impact of landscape variation on the wind speed approximating function is discussed. In some cases, under the influence of terrestrial roughness, the approximated wind speed distribution with height loses its exponential behaviour.