Upper Ocean Box Model which solves for the time change of Dissolved Inorganic Carbon (DIC) in single upper ocean box

Dataset: Upper Ocean Box ModelThe box model solves for the time change of Dissolved Inorganic Carbon (DIC) in single upper ocean box. The upper ocean box model is forced by observed atmospheric pCO2 and temperature. It calculates the pCO2 and air-sea CO2 flux. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/840371NSF Division of Ocean Sciences (NSF OCE) OCE-1558225, NSF Division of Ocean Sciences (NSF OCE) OCE-1558258, NSF Division of Ocean Sciences (NSF OCE) OCE-181850

Interannual variability of the air-sea flux of oxygen in the North Atlantic

In studies using timeseries observations of atmospheric O[subscript 2]/N[subscript 2] to infer the fate of fossil fuel CO[subscript 2], it has been assumed that multi-year trends in observed O[subscript 2]/N[subscript 2] are insensitive to interannual variability in air-sea fluxes of oxygen. We begin to address the validity of this assumption by investigating the magnitude and mechanisms of interannual variability in the flux of oxygen across the sea surface using a North Atlantic biogeochemical model. The model, based on the MIT ocean general circulation model, captures the gross patterns and seasonal cycle of nutrients and oxygen within the basin. The air-sea oxygen flux exhibits significant interannual variability in the North Atlantic, with a standard deviation (0.36 mol m[superscript −2] y[superscript −1]) that is a large fraction of the mean (0.85 mol m[superscript −2] y[subscript −1]). This is primarily a consequence of variability in winter convection in the subpolar gyre.Goddard Space Flight Center (Grants NGTS-30189 and NCC5-244

Global evaluation of particulate organic carbon flux parameterizations and implications for atmospheric pCO\u3csub\u3e2\u3c/sub\u3e

The shunt of photosynthetically derived particulate organic carbon (POC) from the euphotic zone and deep remineralization comprises the basic mechanism of the “biological carbon pump.” POC raining through the “twilight zone” (euphotic depth to 1 km) and “midnight zone” (1 km to 4 km) is remineralized back to inorganic form through respiration. Accurately modeling POC flux is critical for understanding the “biological pump” and its impacts on air‐sea CO2 exchange and, ultimately, long‐term ocean carbon sequestration. Yet commonly used parameterizations have not been tested quantitatively against global data sets using identical modeling frameworks. Here we use a single one‐dimensional physical‐biogeochemical modeling framework to assess three common POC flux parameterizations in capturing POC flux observations from moored sediment traps and thorium‐234 depletion. The exponential decay, Martin curve, and ballast model are compared to data from 11 biogeochemical provinces distributed across the globe. In each province, the model captures satellite‐based estimates of surface primary production within uncertainties. Goodness of fit is measured by how well the simulation captures the observations, quantified by bias and the root‐mean‐square error and displayed using “target diagrams.” Comparisons are presented separately for the twilight zone and midnight zone. We find that the ballast hypothesis shows no improvement over a globally or regionally parameterized Martin curve. For all provinces taken together, Martin\u27s b that best fits the data is [0.70, 0.98]; this finding reduces by at least a factor of 3 previous estimates of potential impacts on atmospheric pCO2 of uncertainty in POC export to a more modest range [−16 ppm, +12 ppm]

An improved comparison of atmospheric Ar/N2 time series and paired ocean-atmosphere model predictions

Ar/N2 variations in the atmosphere reflect ocean heat fluxes, air-sea gas exchange, and atmospheric dynamics. Here atmospheric Ar/N2 time series are compared to paired ocean-atmosphere model predictions. Agreement between Ar/N2 observations and simulations has improved in comparison to a previous study because of longer time series and the introduction of automated samplers at several of the atmospheric stations, as well as the refinement of the paired ocean-atmosphere models by inclusion of Ar and N2 as active tracers in the ocean component. Although analytical uncertainties and collection artifacts are likely to be mainly responsible for observed Ar/N2 outliers, air parcel back-trajectory analysis suggests that some of the variability in Ar/N2 measurements could be due to the low-altitude history of the air mass collected and, by extension, the local oceanic Ar/N2 signal. Although the simulated climatological seasonal cycle can currently be evaluated with Ar/N2 observations, longer time series and additional improvements in the signal-to-noise ratio will be required to test other model predictions such as interannual variability, latitudinal gradients, and the secular increase in atmospheric Ar/N2 expected to result from ocean warming. Copyright 2008 by the American Geophysical Union

Global ocean particulate organic carbon flux merged with satellite parameters

Particulate organic carbon (POC) flux estimated from POC concentration observations from sediment traps and 234 Th are compiled across the global ocean. The compilation includes six time series locations: CARIACO, K2, OSP, BATS, OFP, and HOT. Efficiency of the biological pump of carbon to the deep ocean depends largely on biologically mediated export of carbon from the surface ocean and its remineralization with depth; thus biologically related parameters able to be estimated from satellite observations were merged at the POC observation sites. Satellite parameters include net primary production, percent microplankton, sea surface temperature, photosynthetically active radiation, diffuse attenuation coefficient at 490 nm, euphotic zone depth, and climatological mixed layer depth. Of the observations across the globe, 85% are concentrated in the Northern Hemisphere with 44% of the data record overlapping the satellite record. Time series sites accounted for 36% of the data, while 71% of the data are measured at≥ 500m with the most common deployment depths between 1000 and 1500m. This data set is valuable for investigations of CO2 drawdown, carbon export, remineralization, and sequestration. The compiled data can be freely accessed at doi.org/10.1594/PANGAEA.855600

Mechanisms of northern North Atlantic biomass variability

In the North Atlantic Ocean north of 40&deg;&thinsp;N, intense biological productivity occurs to form the base of a highly productive marine food web. SeaWiFS satellite observations indicate trends of biomass in this region over 1998&ndash;2007. Significant biomass increases occur in the northwest subpolar gyre and there are simultaneous significant declines to the east of 30&ndash;35&deg;&thinsp;W. These short-term changes, attributable to internal variability, offer an opportunity to explore the mechanisms of the coupled physical&ndash;biogeochemical system. We use a regional biogeochemical model that captures the observed changes for this exploration. Biomass increases in the northwest are due to a weakening of the subpolar gyre and associated shoaling of mixed layers that relieves light limitation. Biomass declines to the east of 30&ndash;35&deg;&thinsp;W are due to reduced horizontal convergence of phosphate. This reduced convergence is attributable to declines in vertical phosphate supply in the regions of deepest winter mixing that lie to the west of 30&ndash;35&deg;&thinsp;W. Over the full time frame of the model experiment, 1949&ndash;2009, variability of both horizontal and vertical phosphate supply drive variability in biomass on the northeastern flank of the subtropical gyre. In the northeast subpolar gyre horizontal fluxes drive biomass variability for both time frames. Though physically driven changes in nutrient supply or light availability are the ultimate drivers of biomass changes, clear mechanistic links between biomass and standard physical variables or climate indices remain largely elusive.</p

Equatorial Pacific pCO2 Interannual Variability in CMIP6 Models

The El Niño-Southern Oscillation (ENSO) in the equatorial Pacific is the dominant mode of global air-sea carbon dioxide (CO2) flux interannual variability (IAV). Air-sea CO2 fluxes are driven by the difference between atmospheric and surface ocean pCO2, with variability of the latter driving flux variability. Previous studies found that models in Coupled Model Intercomparison Project Phase 5 (CMIP5) failed to reproduce the observed ENSO-related pattern of CO2 fluxes and had weak pCO2 IAV, which were explained by both weak upwelling IAV and weak mean vertical dissolved inorganic carbon (DIC) gradients. We assess whether the latest generation of CMIP6 models can reproduce equatorial Pacific pCO2 IAV by validating models against observations-based data products. We decompose pCO2 IAV into thermally and non-thermally driven anomalies to examine the balance between these competing anomalies, which explain the total pCO2 IAV. The majority of CMIP6 models underestimate pCO2 IAV, while they overestimate sea surface temperature IAV. Insufficient compensation of non-thermal pCO2 to thermal pCO2 IAV in models results in weak total pCO2 IAV. We compare the relative strengths of the vertical transport of temperature and DIC and evaluate their contributions to thermal and non-thermal pCO2 anomalies. Model-to-observations-based product comparisons reveal that modeled mean vertical DIC gradients are biased weak relative to their mean vertical temperature gradients, but upwelling acting on these gradients is insufficient to explain the relative magnitudes of thermal and non-thermal pCO2 anomalies

Review of US GO-SHIP (Global Oceans Shipboard Hydrographic Investigations Program) An OCB and US CLIVAR Report

The following document constitutes a review of the US GO-SHIP program, performed under the auspices of US Climate Variability and Predictability (CLIVAR) and Ocean Carbon Biogeochemistry (OCB) Programs. It is the product of an external review committee, charged and assembled by US CLIVAR and OCB with members who represent the interests of the programs and who are independent of US GO-SHIP support, which spent several months gathering input and drafting this report. The purpose of the review is to assess program planning, progress, and opportunities in collecting, providing, and synthesizing high quality hydrographic data to advance the scientific research goals of US CLIVAR and OCB

The potential for CO \u3c inf\u3e 2 -induced acidification in freshwater: A great lakes case study

Ocean acidification will likely result in a drop of 0.3–0.4 pH units in the surface ocean by 2100, assuming anthropogenic CO2 emissions continue at the current rate. Impacts of increasing atmospheric pCO2 on pH in freshwater systems have scarcely been addressed. In this study, the Laurentian Great Lakes are used as a case study for the potential for CO2-induced acidification in freshwater systems as well as for assessment of the ability of current water quality monitoring to detect pH trends. If increasing atmospheric pCO2 is the only forcing, pH will decline in the Laurentian Great Lakes at the same rate and magnitude as the surface ocean through 2100. High-resolution numerical models and one high-resolution time series of data illustrate that the pH of the Great Lakes has significant spatio-temporal variability. Because of this variability, data from existing monitoring systems are insufficient to accurately resolve annual mean trends. Significant measurement uncertainty also impedes the ability to assess trends. To elucidate the effects of increasing atmospheric CO2 in the Great Lakes requires pH monitoring by collecting more accurate measurements with greater spatial and temporal coverage