AbstractHorizontal velocity measurements on the lower part of Engabreen, Norway, were made from repeat aerial photography. IMCORR software, which has been widely used to measure velocities from satellite images, was used to make the measurements. This is the first known successful use of IMCORR on aerial photographs. Supplementary horizontal velocity measurements were made from repeat measurements of stakes, giving velocities over different periods and also in areas that are too slow-moving to register a measurable velocity after only a few days.
The paper deals with the velocity fields in the neighbourhood of the breakers and the correlation between the wave asymmetry and the velocity asymmetry. The velocity measurements were made on two beach slopes 1 9 and 1.18. Earlier work (3) showed that the two slopes produced different breaker types; the slope of 1:9 produced plunging breakers and the slope of 1 18 spilling breakers. The velocities (velocity - tune history) of the water particles were measured at a height of 5mm above the bed using the hydrogen bubble method combined with cine photography. Two types of horizontal velocity asymmetry were defined and investigated, namely (1) horizontal velocity (Magnitude) asymmetry and (2) horizontal velocity (time) asymmetry. It was found that there are both qualitative and quantitative correlation between the asymmetry of the wave, and the asymmetry of the resulting velocity field. As a result of the correlation two alternative expressions are given for the horizontal velocity (magnitude) asymmetry.
Continuous Data Assimilation for a 2D Bénard Convection System Through Horizontal Velocity Measurements Alone