Micrometeorological study of an urban valley

Winds, temperatures, and carbon monoxide concentrations were measured in a cross section of the North Saskatchewan River Valley in central Edmonton on a clear October evening with cross-valley winds. The evolution of a complex asymmetrical valley inversion with vertical temperature gradients up to 12 degrees C (100 m) super(-) super(1) on the north-facing slope and 6 degrees C (100 m) super(-) super(1) on the south-facing slope is described. The inversion was accompanied by downslope winds of about 0.4 m sec super(-) super(1) and a reversal from upvalley to downvalley winds. Carbon monoxide concentrations on the south-facing slope exhibit a well-defined evening maximum and an immediate response to the reversal from upslope to downslope winds.