Influence of biological carbon export on ocean carbon uptake over the annual cycle across the North Pacific Ocean

Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 31 (2017): 81–95, doi:10.1002/2016GB005527.We evaluate the influences of biological carbon export, physical circulation, and temperature-driven solubility changes on air-sea CO2 flux across the North Pacific basin (35°N–50°N, 142°E–125°W) throughout the full annual cycle by constructing mixed layer budgets for dissolved inorganic carbon (DIC) and pCO2, determined on 15 container ship transects between Hong Kong and Long Beach, CA, from 2008 to 2012. Annual air-sea CO2 flux is greatest in the western North Pacific and decreases eastward across the basin (2.7 ± 0.9 mol C m−2 yr−1 west of 170°E, as compared to 2.1 ± 0.3 mol C m−2 yr−1 east of 160°W). East of 160°W, DIC removal by annual net community production (NCP) more than fully offsets the DIC increase due to air-sea CO2 flux. However, in the region west of 170°E influenced by deep winter mixing, annual NCP only offsets ~20% of the DIC increase due to air-sea CO2 flux, requiring significant DIC removal by geostrophic advection. Temperature-driven solubility changes have no net influence on pCO2 and account for <25% of annual CO2 uptake. The seasonal timing of NCP strongly affects its influence on air-sea CO2 flux. Biological carbon export from the mixed layer has a stronger influence on pCO2 in summer when mixed layers are shallow, but changes in pCO2 have a stronger influence on air-sea CO2 flux in winter when high wind speeds drive more vigorous gas exchange. Thus, it is necessary to determine the seasonal timing as well as the annual magnitude of NCP to determine its influence on ocean carbon uptake.NDSEG Fellowship from the Office of Naval Research; NSF Graduate Research Fellowship; NSF Ocean Sciences Grant Numbers: 0628663, 1259055; NOAA Climate Program Office Grant Number: A10OAR43100882017-07-2

Evidence of O2 consumption in underway seawater lines: Implications for air-sea O2 and CO2 fluxes

We observed O2 deficits of 0.5 to 2.0% (1 to 4 mol/kg) in the underway seawater lines of three different ships. Deficits in O2/Ar and isotopic enrichments in dissolved O2 observed in underway seawater lines indicate a respiratory removal process. A 1% respiratory bias in underway lines would lead to a 2.5-5 atm (2.5-5pbar) enhancement in surface water pCO2. If an underway pCO2 bias of this magnitude affectedall measurements, the global oceanic carbon uptake based on pCO 2 climatologies would be 0.5-0.8 Pg/yr higher than the present estimate of 1.6 Pg/yr. Treatment of underway lines with bleach for several hours and thorough flushing appeared to minimize O2 loss. Given the increasing interest in underway seawater measurements for the determination of surface CO2 and O2 fluxes, respiration in underway seawater lines must be identified and eliminated on all observing ships to ensure unbiased data

Redfield ratios revisited: Removing the biasing effect of anthropogenic CO2

Redfield ratios of remineralization are calculated based on chemical data analysis on isopycnal surfaces. The concentrations of dissolved inorganic carbon used in this study were corrected for the anthropogenic CO2 content as estimated with a back-calculation technique. The corrections increased the apparent carbon remineralization by 25-30%, thus proving important for the reliable estimation of Redfield carbon ratios in the presence of anthropogenic CO2. Best estimates from this study largely confirm the more recently published Redfield ratios of remineralization. The following results were obtained for the latitude range 3-41°N along 20-29°W in the Northeast Atlantic Ocean: Corg: P ratio = 123 ± 10; Corg : N ratio = 7.2 ± 0.8; -O2 :Corg ratio = 1.34 ± 0.06; -O2 : P ratio = 165 ± 15; N: P ratio = 17.5 ± 2.0. These ratios are in close agreement with the average composition of phytoplankton and represent respiration of organic matter consisting on average of 52% protein, 36% polysaccharide, and 12% lipid

Discrepant estimates of primary and export production from satellite algorithms, a biogeochemical model, and geochemical tracer measurements in the North Pacific Ocean

Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 43 (2016): 8645–8653, doi:10.1002/2016GL070226.Estimates of primary and export production (PP and EP) based on satellite remote sensing algorithms and global biogeochemical models are widely used to provide year-round global coverage not available from direct observations. However, observational data to validate these approaches are limited. We find that no single satellite algorithm or model can reproduce seasonal and annual geochemically determined PP, export efficiency (EP/PP), and EP rates throughout the North Pacific basin, based on comparisons throughout the full annual cycle at time series stations in the subarctic and subtropical gyres and basin-wide regions sampled by container ship transects. The high-latitude regions show large PP discrepancies in winter and spring and strong effects of deep winter mixed layers on annual EP that cannot be accounted for in current satellite-based approaches. These results underscore the need to evaluate satellite- and model-based estimates using multiple productivity parameters measured over broad ocean regions throughout the annual cycle.NDSEG Fellowship from the Office of Naval Research; NSF Graduate Research Fellowship; ARCS Foundation Fellowship2017-02-2

The Ursinus Weekly, December 3, 1909

Football number • Credit due coach • The scrubs • Football rules discussed • A review of the football season • Comment • Choral concert • Seminary notes • Personals • Latin-Maths and Math-Phys meet • Slonaker hurt • Football managers electedhttps://digitalcommons.ursinus.edu/weekly/2817/thumbnail.jp

Synoptic Mesoscale to Basin Scale Variability in Biological Productivity and Chlorophyll in the Kuroshio Extension Region

The Kuroshio current separates from the Japanese coast to become the eastward flowing Kuroshio Extension (KE) characterized by a strong latitudinal density front, high levels of mesoscale (eddy) energy, and high chlorophyll a (Chl). While satellite measurements of Chl show evidence of the impact of mesoscale eddies on the standing stock of phytoplankton, there have been very limited synoptic, spatially resolved in situ estimates of productivity in this region. Here, we present underway measurements of oxygen/argon supersaturation (ΔO2/Ar), a tracer of net biological productivity, for the KE made in spring, summer, and early autumn. We find large seasonal differences in the relationships between ΔO2/Ar, Chl, and sea level anomaly (SLA), a proxy for local thermocline depth deviations driven by mesoscale eddies derived from satellite observations. We show that the KE is a pronounced hotspot of high ΔO2/Ar in spring, but corresponding surface Chl values are low and have no correlation with ΔO2/Ar. In summer, there is a hotspot of productivity associated with the Oyashio front, where ΔO2/Ar and Chl are strongly positively correlated. In autumn, ΔO2/Ar and Chl are consistently low throughout the region and also positively correlated. By combining our analysis of the in situ ΔO2/Ar data with complementary Argo, BGC-Argo, repeat hydrography, and SLA observations, we infer the combination of physical and biological controls that drive the observed distributions of ΔO2/Ar and Chl. We find that the KE and Oyashio currents both act to supply nutrients laterally, fueling regions of high productivity in spring and summer, respectively