The ocean tide in the southern Ross Sea

Abstract

A survey of the ocean tide in the southern Ross Sea was done by measuring tidal variations of gravity at nine locations on the floating Ross Ice Shelf. Tidal water level fluctuations were calculated from recordings between 29 days and 58 days long of the periodic variation in gravity on the ice shelf surface that is caused by tidal changes in elevation and water mass. Conventional tide gauge measurements from McMurdo Sound were included in the survey. The data indicate that the Ross Sea tide is principally diurnal. Along the northern margin of the Ross Ice Shelf the tropic (diurnal spring) tidal range is between 1 m and ; m. The range increases to more than 2 m in the southernmost part of the Ross Sea. It is more than 3 times larger than the equatorial (diurnal neap) tidal range. Amplitudes of the principal diurnal constituents K 1 P 1 and O 1 are apparently magnified by a condition of diurnal resonance in the Ross Sea. This would be expected because wavelengths of the diurnal harmonic constituents are approximately 4 times the length of the Ross Sea in the direction of propagation. The diurnal constituent amplitudes also appear to vary proportionally with the fourth root of the water depth as predicted from the theory of long wave propagation in a canal. Semidiurnal constituents M 2 , S 2 , and N 2 have small amplitudes and appear to progress clockwise around amphidromes located beneath the northwestern part of the Ross Ice Shelf.