Willie is an NSF-OCE Postdoctoral Fellow working at the University of Maryland Center for Environmental Science. He is mainly interested in biological production and physical transport mechanisms in the surface ocean and their roles in the biogeochemical cycling of nutrients, such as carbon, nitrogen and oxygen. Willie typically uses geochemical tracers and sensors on autonomous vehicles to measure the magnitude and rates of these processes. During the UNOLS Chief Scientist Training Cruise, he will be using an equilibrator inlet mass spectrometer (EIMS) to measure the abundances of dissolved oxygen and argon in the underway seawater line aboard the R/V Thompson. The ratio of O₂/Ar reflects the biologically-sourced component of oxygen saturation, which in combination with an estimate of the gas transfer rate across the air/sea interface, can be used to estimate the rate of net biological oxygen production (NOP), in the surface ocean along the cruise track. NOP is stoichiometrically related to net carbon production, which represents the amount of carbon in the sunlit surface ocean available for export into the ocean’s interior via the biological pump.