New Ozone Measurement Systems for Autonomous Operation on Ocean Buoys and Towers

Abstract

Two autonomous ozone measurement systems for use on ocean buoys and towers have been built and are discussed herein. They are based on low-power atmospheric ozone sensors from Physical Sciences Inc. (PSI) and 2B Technologies. The PSI sensor operates at 1 Hz with a precision of 1 ppb but requires about 45 W with the present data system; the 2B makes a measurement every 10 s with a precision of 1?2 ppb and uses less than 4 W. The sensors have been packaged in watertight enclosures with a set of valves and filters to keep out seawater and aerosols. A controller uses data from the sensors and a meteorological system to determine whether sampling should proceed. If a sensor malfunction (such as an incorrect valve position or a temperature beyond its proper range) is detected, the controller attempts to correct it. Both sensors have been tested and used over the ocean, and one complete ozone measurement system (with the PSI sensor) has been successfully deployed on a buoy off Woods Hole, Massachusetts. In 2003, this system was operated at the Chesapeake Bay Lighthouse Tower for over a month with excellent results. The 2B system was also successfully tested in 2003 at a nearby offshore tower. The design of the systems and their testing and deployments are described, and data from some of the first experiments are presented.