Synthetic Subsurface Pressure Derived from Bottom Pressure and Tide Gauge Observations

Abstract

Synthetic subsurface pressure (SSP) can be formed from tide gauge records and from bottom pressure measurements to provide a consistent and convenient basis for comparison of these two different types of observations. Common methods for this estimation are reviewed, and their accuracy is evaluated. Calculations show that subtidal SSP estimates from sea level (SSPSL) and from bottom pressure observations (SSPBP) at close sites agree only in a finite band of frequencies, corresponding to periods between 3.5 and 30 days. At the lower frequencies (periods longer than 30 days), sea level observations are subject to errors induced by the daily measure of staff height. At higher frequencies (periods between 1.5 and 3.5 days), the amplitude of fluctuations is too small to be resolved by a sea level gauge.