Interactions of Nocturnal Slope Flows with Ambient Winds

A quasi-one-dimensional numerical mode1 containing a prognostic turbulent kinetic energy parameterization and simplified approximations to horizontal gradients is used to study interactions of thermally induced nocturnal slope flows with following and opposing ambient winds. It is found that a following ambient wind causes the peak perturbation wind to be weaker and to be realized at a greater height, while an opposing ambient wind leads to a stronger perturbation wind at a lower height. The reason for this response lies in the interactions of the shears of the thermal and ambient components through the mechanical production of turbulent kinetic energy.