Empirical algorithms to estimate water column pH in the Southern Ocean. Issue 7 (7th April 2016) - Williams, N. L.
Abstract: Empirical algorithms are developed using high‐quality GO‐SHIP hydrographic measurements of commonly measured parameters (temperature, salinity, pressure, nitrate, and oxygen) that estimate pH in the Pacific sector of the Southern Ocean. The coefficients of determination, R 2, are 0.98 for pH from nitrate (pH N ) and 0.97 for pH from oxygen (pH Ox ) with RMS errors of 0.010 and 0.008, respectively. These algorithms are applied to Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) biogeochemical profiling floats, which include novel sensors (pH, nitrate, oxygen, fluorescence, and backscatter). These algorithms are used to estimate pH on floats with no pH sensors and to validate and adjust pH sensor data from floats with pH sensors. The adjusted float data provide, for the first time, seasonal cycles in surface pH on weekly resolution that range from 0.05 to 0.08 on weekly resolution for the Pacific sector of the Southern Ocean. Key Points: Algorithms are developed for estimation of pH from biogeochemical floats in the Southern Ocean The pH algorithms can also be used to adjust pH sensor data on biogeochemical floats The seasonal cycle in surface pH ranges from 0.05 to 0.08 for the study region