Boundary Layer Wind Maxima and Their Significance for the Growth of Nocturnal Inversions

A sharp maximum is frequently observed at night in the wind speed profile below 3000 ft. The wind speed maximum is usually at the top of the nocturnal inversion, is supergeostrophic, and is often associated with extremely large values of wind shear at low levels. It is shown that the characteristic velocity profile tends to promote an orderly growth of the nocturnal inversion. The supergeostrophic wind speeds suggest that an inertia oscillation is induced when the constraint imposed by the daytime mixing is released by the initiation of an inversion at about the time of sunset.