With an aperture angle of 2 Deg. and a nominal depth of 50 m, the sonar beam covers a footprint on the underside of the ice of radius 1.75 m. The speed and direction is measured for the ice and in five levels beneath the ice. The DCM 12 also measures the wave height. When the wind is weak, the ice drifts with the current, at about the same speed. Under strong wind forcing, the ice moves much faster than the water beneath and the current measurements cannot be used to estimate the ice speed.
Long waves can travel far into the ice field and have strong influence on braking up the ice field.
The Norwegian Polar Institute will continue the monitoring of the ice flux through the Fram Strait for the coming years using four ULSDs. Right click on the drawing or image to zoom in and out and also grab and move it.