The measurement wind height is the height above the ground at which wind observations were recorded. Typically wind observations are taken at a height of 2 m in clearings. However, the VIC model assumes wind observations are made above the vegetation cover in each grid cell and that wind speeds through and below the canopy can be found using exponential and logorithmic wind profiles. For short vegetation types (grasses, shrubs, etc.), the wind measurment height should be ~2 m above the top of the vegetation. For tall vegetation types (trees), especially those defined with an overstory, the wind measurement height should be set much higher than the vegetation. This is physically justified because a forest canopy impacts atmospheric stability to a much higher elevation, than shorter vegetation. If the model is required to run with an overstory defined, and the wind height set to just above the vegetation (for example the tree height + 2m) large negative evaporations and sublimations may be found during the winter months, as the snow interception algorithm is forced to use unrealistically strong wind speeds.
When defining a vegetation type with overstory, it is strongly reccommended that wind_h be defined at least 10 m higher than the height of the vegetation.