Measurements of Wind Speed, Direction, and Vertical Profiles in an Evergreen Forest in Central Cambodia.

The wind characteristics of speed, direction, and vertical profile were studied to determine the effects of undulations in the local topography and canopy surface on flux observations made from a tower in an evergreen forest in Kompong Thom Province, Cambodia. Three seasonal patterns of wind speeds and directions were identified. The first occurred in December and January and was characterized by northerly monsoons that persisted all day, as well as a diurnal variation in wind speed, with a maximum and minimum around noon and near sunset, respectively. A second pattern, in February, was characterized by southerly to westerly prevailing monsoon winds, along with an easterly mountain wind observed in the early morning. Wind speed was low throughout the day. The third pattern was similar to the second but included brief, strong winds associated with squalls. Thus, regional effects on circulation were limited, and monsoon winds were found to dominate the meteorological system above the evergreen forest of central Cambodia. In the forest, the estimated roughness length and zero plane displacement height averaged 18.3 m and 7.5 m, respectively, and the average canopy height was 27.2 m. The dependence of roughness length and zero plane displacement height on the wind direction was within the standard deviation. Thus, the undulating canopy surface had little effect on the tower flux observations. [ABSTRACT FROM AUTHOR]