A measurement system for vertical seawater profiles close to the air/sea interface
Richard P. Sims1,2, Ute Schuster2, Andrew J. Watson2, Ming Xi Yang1, Frances E. Hopkins1, John Stephens1, and Thomas G. Bell11Plymouth Marine Laboratory, Plymouth, United Kingdom 2University of Exeter, Exeter, United Kingdom
Received: 24 Feb 2017 – Accepted for review: 08 Mar 2017 – Discussion started: 16 Mar 2017
Abstract. This paper describes a Near Surface Ocean Profiler, which has been designed to precisely measure vertical gradients in the top 10 m of the ocean. Variations in the depth of seawater collection are minimised when using the profiler compared to conventional CTD/rosette deployments. The profiler consists of a remotely operated winch mounted on a tethered yet free floating buoy, which is used to raise and lower a small frame housing sensors and inlet tubing. Seawater at the inlet depth is pumped back to the ship for analysis. The profiler can be used to make continuous vertical profiles or to target a series of discrete depths. The profiler has been successfully deployed during wind speeds up to 10 m s−1 and significant wave heights up to 2 m. We demonstrate the potential of the profiler by presenting measured vertical profiles of the trace gases carbon dioxide and dimethylsulfide. Trace gas measurements use an efficient microporous membrane equilibrator to minimise the system response time. The example profiles show vertical gradients in the upper 5 m for temperature, carbon dioxide and dimethylsulfide of 0.15 °C, 4 μatm and 0.4 nM respectively.
Sims, R. P., Schuster, U., Watson, A. J., Yang, M. X., Hopkins, F. E., Stephens, J., and Bell, T. G.: A measurement system for vertical seawater profiles close to the air/sea interface, Ocean Sci. Discuss., doi:10.5194/os-2017-7, in review, 2017.