An Investigation of Turbulence Within the Forest

View More View Less
  • 1 Meteorological Service of Canada, Toronto
© Get Permissions
Restricted access

Abstract

A Gill propeller vertical anemometer and wet- and dry-bulb thermocouples were used to measure the turbulence within a forest canopy. Preliminary trials were run in a 65-ft pine forest and five trials of 10 min duration were run in a 15-ft lodgepole pine forest. The results indicate that the intensity of turbulence in a forest is as high as or higher than is usually measured over open ground. The cospectra of w and T indicated that the shape of the cospectra in the forest may be different from that over open ground. The turbulent heat fluxes were calculated by the eddy correlation method and their sum did not even approximately balance the net radiation. Part of the imbalance may have been due to instrument response. However, it is felt that the problems of an inhomogeneous environment necessitate a method of obtaining spatial as well as time averages of the turbulent heat fluxes and the net radiation.

Abstract

A Gill propeller vertical anemometer and wet- and dry-bulb thermocouples were used to measure the turbulence within a forest canopy. Preliminary trials were run in a 65-ft pine forest and five trials of 10 min duration were run in a 15-ft lodgepole pine forest. The results indicate that the intensity of turbulence in a forest is as high as or higher than is usually measured over open ground. The cospectra of w and T indicated that the shape of the cospectra in the forest may be different from that over open ground. The turbulent heat fluxes were calculated by the eddy correlation method and their sum did not even approximately balance the net radiation. Part of the imbalance may have been due to instrument response. However, it is felt that the problems of an inhomogeneous environment necessitate a method of obtaining spatial as well as time averages of the turbulent heat fluxes and the net radiation.

Save