Pressure and temperature measurements on seamounts in the North Pacific

Abstract

In 1974 and 1975 pressure gauges were placed on and records recovered from Union Seamount (49°35'N, 132°47'W), Bowie Seamount (53°18'N, 135°37'W), and Surveyor Seamount (56°08'N, 144°22'W) in the Northeast Pacific in depths of 314, 170, and 630 m, respectively. These records have been analyzed to derive harmonic constituents, and co‐phase and co‐amplitude charts have been prepared for the neighboring regions. Maximum tidal range observed was 4 m. The temperature recorded by the gauge on Surveyor Seamount revealed a predominantly semidiurnal signal of range 0.1 Celsius degree, which represents a vertical displacement of the water column of up to 50 m. Significant diurnal oscillations are not present in the temperature record. The pressure record at Union Seamount was low‐pass filtered to attenuate tidal signals. The residual pressure fluctuations at Union Seamount were up to 12 mbars in range, about one fifth of the range of the local sea‐level atmospheric pressure fluctuations. The ocean surrounding Union Seamount behaves largely as an inverted barometer, with evidence of an undershoot at periods near four days.