Surface wind structure in forest clearings during a chinook

During a chinook wind period, 5-8 April 1979, horizontal wind speed and its vertical component at 2 m height were measured in 12 circular 1 to 6 tree height diameter clearings in 20 m tall lodgepole pine forest in Alberta. These values are compared with horizontal wind speed in the centre of a 400 X 400 m clearcut and at 10 m above the tree canopy. Wind speed in all of the small circular clearings averaged about 1/20 of that above the canopy; that in the square clearcut was approximately equal. Vertical motion in 4 and 6 tree height clearings was 4 X that in the smaller ones.