Micrometeorology of shelter belts and forest edges

Abstract

The micrometeorological effects of shelter belts are briefly summarized, paying particular attention to the similarity framework that is used to bring order to the empirical data. Stretching downwind from the top of a shelter belt is a turbulent wake. This spreads and reaches the ground at about eight heights out, more or less depending on the properties of the incident wind profile. Closer to the fence is a quiet zone where the wind is less turbulent. Turbulent transport of scalars is suppressed in the quiet zone and enhanced in the wake zone. Much less information is available on shelter in the lee of forest edges. It appears that a similar pattern of quiet zone and wake zone is found there, but the pattern is much shortened. However, windspeed continues to increase over a longer distance as a deeper layer of air adjusts progressively to the roughness change. Shelter belts whose width is comparable to their height are transitional cases, but too little information is available to chart the transition.