A Thirty-Month Seafloor Test of the A-0-A Method for Calibrating Pressure Gauges

Geodetic observations in the oceans are important for understanding plate tectonics, earthquake cycles and volcanic processes. One approach to seafloor geodesy is use of pressure gauges sense vertical changes elevation after correcting variations weight overlying atmosphere. A challenge using tendency sensors drift. The A-0-A method a new valve used periodically switch, short time, measured from external ocean inside instrument housing at atmospheric pressure. internal reading compared an accurate barometer measure drift which assumed be same low high pressures. We describe 30-months test 900 m depth on MARS cabled observatory Monterey Bay that includes two calibrated three-component accelerometer. Prior calibrations, by 6 2 hPa, respectively. After offsets corrected consistent with each other within 0.2 hPa. detided measurements show 0.5 hPa/yr trend increasing pressures during experiment. subsidence based tilt accelerometer, but may include component did not affect tilt. However, observed pressure, closely matches calculated satellite altimetry repeat conductivity, temperature casts nearby location, expected El Niño Southern Oscillation. infer corrections better than one part 10 5 per year. Additional long-term tests comparisons oceanographic methods correction will required understand if accuracy year consistency between sensors.