Gives the elevation in meters above sea level. If source is set to a specific model, the model topography with the according resolution is returned. If no model or mix is selected, the topography from NASA SRTM/ASTER with a horizontal resolution of approximately 90 meters is returned.
Roughness length of the ground, depending of the land usage. Roughness length is a parameter of some vertical wind profile equations that model the horizontal mean wind speed near the ground; in the log wind profile, it is equivalent to the height at which the wind speed theoretically becomes zero.