University of British Columbia
Vancouver, British Columbia, Canada
One of the necessary considerations of laboratory modeling is the scaling-up to the ``real'' world. Many rotating flow experiments have, in particular, large aspect ratio distortions. In many situations this is justified but for non-hydrostatic flows it is questionable. At the front of a gravity current the flow turns down in a localized, non-hydrostatic region. Here we will contrast laboratory observations of gravity currents with recently published observations of the Columbia River Plume. in the laboratory, the speed, width, depth and velocity structure of a surface gravity current in a rotating frame was measured using video techniques. In addition to the well documented dependence on the wave speed, the speed of the head of the gravity current showed a higher order correction proportional to the hydrostatic number (the ratio of the Coriolis parameter to the Brunt-Vaisala frequency). The speed decreases as the rotation rate increases. Incorporating the effect of the hydrostatic number, comparable to the aspect ratio of the system, should allow more accurate interpolation from laboratory experiments to the field.