Abstract
The writers carried out some measurements of the relative motions of sea-ice to the surface sea-water due to wind in 10 miles off the coast by two methods: the one is a method by the current measuring drift-buoy and the other is that by the inclination of lead-line. And they ascertained that the velocity of the relative motion changed in moderate extents by the difference of roughness on the upper surface of ice, and obtained 1/20-1/180 (for wind velocity 4-10m/sec) as the ratio and 18°-32° as the clock-wise deflection angle of the direction of the motions measured. from the wind direction. They considered from the above-mentioned results that the chief cause of the relative motion may be the wind pressure upon the parts of ice above the sea level. As the observed velocity of the relative motions of ice to sea water attained to the same order with those of the ice-drifts that observed by many authorities in the past, the writers noticed the necessity of taking the effects of the relative motion of ice (that is, the effects of wind-pressure drift) into consideration in the theoretical study of the drift-ice as same as the effects of the drift current of sea-water. The theoretical study may be reported in the next papers.
