L. W. Juranek

Biological production in the NE Pacific and its influence on air-sea CO2 flux: Evidence from dissolved oxygen isotopes and O2/Ar

[1] We determine rates of gross photosynthetic O2 production (GOP) and net community O2 production (NCP) using the triple oxygen isotope and O2/Ar approach on two spring and two late summer meridional transects of the NE Pacific. Observed GOP and NCP in the subtropical (89 � 9 and 8.3 � 1.3 mmol O2 m � 2 d � 1 , respectively) and subarctic (193 � 16 and 16.3 � 3.8 mmol O2 m � 2 d � 1 ) were in agreement with rates previously determined at time series stations in each region, validating the regional representativeness of these sites. At the transition zone chlorophyll front (TZCF), which migrates seasonally from 32 � N in spring to 40 � N in summer,GOPandNCPwere elevated by2–4� compared to adjacent areas. Coincident with the TZCF, increases in surface nitrate concentration and extensive changes in phytoplankton community composition were observed. HPLC pigment data indicated substantial increases in a prymnesiophyte (e.g., coccolithophore) biomarker at the TZCF on aspring and summer cruise, and a diatom biomarker on thespring cruise. Increases in remotely sensed surface particulate inorganic carbon concentration were also observed at the TZCF on all four cruises, indicating that coccolithophore production may contribute to increased productivity at the TZCF. Meridional trends in observed air-sea CO2 flux on each cruise resembled those of the biologically induced CO2 flux (NCP), but with an overprinting of the response of air-sea CO2 exchange to summer warming. A simple carbon budget based on regional CO2 flux climatology demonstrates the importance of NCP for net annual air-sea CO2 uptake, although slow air-sea equilibration and seasonal solubility effects obscure this term.

Calculating surface ocean pCO2 from biogeochemical Argo floats equipped with pH: An uncertainty analysis

U.S. National Science Foundations Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project under the NSF [PLR-1425989]; NASA [NNX14AP49G]; U.S. Argo through NOAA/JISAO grant [NA17RJ1232]; Ocean Observations and Monitoring Division, Climate Program Office, National Oceanic and Atmospheric Administration, U.S. Department of Commerce; David and Lucile Packard Foundation; NOAA Climate and Global Change postdoctoral fellowship; ARCS Foundation Oregon Chapter

Empirical algorithms to estimate water column pH in the Southern Ocean

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, R2, are 0.98 for pH from nitrate (pHN) and 0.97 for pH from oxygen (pHOx) 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.

Short-term variability in euphotic zone biogeochemistry and primary productivity at Station ALOHA: A case study of summer 2012

Time-series observations are critical to understand the structure, function, and dynamics of marine ecosystems. The Hawaii Ocean Time-series program has maintained near-monthly sampling at Station ...

Assessment of the Carbonate Chemistry Seasonal Cycles in the Southern Ocean From Persistent Observational Platforms

U.S. National Science Foundations Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project under the NSF [PLR-1425989]; NASA [NNX14AP49G]; U.S. Argo through NOAA/JISAO [NA17RJ1232]; Pacific Marine Environmental Laboratory of NOAA; Ocean Observations and Monitoring Division, Climate Program Office, National Oceanic and Atmospheric Administration, United States; ARCS Foundation Oregon Chapter