A Simple Method for Spatial Interpolation of the Wind in Complex Terrain

The topographical elevation difference is proposed as a new variable for spatial interpolation of the sparse surface wind measurements to a finer mesh in a complex terrain area. The most used method for the initialization of diagnostic wind field models is based on the inverse-distance-squared weighted averaging interpolation technique regardless of the topographical elevation. Analysis of experimental data obtained from six meteorological towers deployed at several heights on the slopes along a valley in the South of Spain has shown a good correlation between wind speed and elevation above valley bottom. The efficiency of the inverse absolute elevation difference and the inverse distance squared as averaging weights for interpolation of the wind vector at several locations is checked; this is done for two meteorological synoptic weather types: strong synoptic winds, and thermal low over the Iberian Peninsula. For the latter weather type, the formation of nocturnal thermal inversion and the drainage flows are taken into account. Wind fields in the valley resulting from the two interpolation methods are compared. The elevation difference between meteorological station and grid point seems to be an important variable to be included in the wind field initialization process, that is, interpolation of the wind vector to a grid, when complex terrain areas are considered.