NOAA/National Ocean Service Platform Harvest instrumentation

Abstract

NOAA has installed two separate water level measurement systems and a suite of ancillary measurement sensors in support of the TOPEX/Poseidon Verification Experiment at Texaco Platform Harvest. The experimental measurement systems are modifications of NOAA's next‐generation water level measurement system (NGWLMS) that is being implemented into the National Water Level Observation Network of the United States. The primary system is configured with a downward looking acoustic water level sensor and the secondary system with a digital “bubbler”; pressure water level sensor (Digibub). The ancillary measurements being made are of barometric pressure, relative humidity, air temperature, water temperature, and water conductivity. Six‐minute interval measurements from each water level sensor and hourly measurements from each ancillary sensor are collected on independent remote terminal units on the platform. The data are transmitted every 3 h via GOES satellite to NOAA for processing in Silver Spring, Maryland. The installation of the measurement systems on the offshore oil platform has required a unique set of elevation corrections that are applied on an operational basis to the water level elevations. These include acoustic sound path air temperature differences for the acoustic data, and water density, nitrogen, and air column corrections to the Digibub data. NOAA field personnel have completed a platform survey in which elevation differences on the platform between the water level sensor “zeros”; and the GPS reference point were established.