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  • 1
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    Air–sea CO〈sub〉2〈/sub〉 flux in the Pacific Ocean for the period 1990–2009
    Copernicus GmbH ; 2014
    In:  Biogeosciences Vol. 11, No. 3 ( 2014-02-06), p. 709-734
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 11, No. 3 ( 2014-02-06), p. 709-734
    Abstract: Abstract. Air–sea CO2 fluxes over the Pacific Ocean are known to be characterized by coherent large-scale structures that reflect not only ocean subduction and upwelling patterns, but also the combined effects of wind-driven gas exchange and biology. On the largest scales, a large net CO2 influx into the extratropics is associated with a robust seasonal cycle, and a large net CO2 efflux from the tropics is associated with substantial interannual variability. In this work, we have synthesized estimates of the net air–sea CO2 flux from a variety of products, drawing upon a variety of approaches in three sub-basins of the Pacific Ocean, i.e., the North Pacific extratropics (18–66° N), the tropical Pacific (18° S–18° N), and the South Pacific extratropics (44.5–18° S). These approaches include those based on the measurements of CO2 partial pressure in surface seawater (pCO2sw), inversions of ocean-interior CO2 data, forward ocean biogeochemistry models embedded in the ocean general circulation models (OBGCMs), a model with assimilation of pCO2sw data, and inversions of atmospheric CO2 measurements. Long-term means, interannual variations and mean seasonal variations of the regionally integrated fluxes were compared in each of the sub-basins over the last two decades, spanning the period from 1990 through 2009. A simple average of the long-term mean fluxes obtained with surface water pCO2 diagnostics and those obtained with ocean-interior CO2 inversions are −0.47 ± 0.13 Pg C yr−1 in the North Pacific extratropics, +0.44 ± 0.14 Pg C yr−1 in the tropical Pacific, and −0.37 ± 0.08 Pg C yr−1 in the South Pacific extratropics, where positive fluxes are into the atmosphere. This suggests that approximately half of the CO2 taken up over the North and South Pacific extratropics is released back to the atmosphere from the tropical Pacific. These estimates of the regional fluxes are also supported by the estimates from OBGCMs after adding the riverine CO2 flux, i.e., −0.49 ± 0.02 Pg C yr−1 in the North Pacific extratropics, +0.41 ± 0.05 Pg C yr−1 in the tropical Pacific, and −0.39 ± 0.11 Pg C yr−1 in the South Pacific extratropics. The estimates from the atmospheric CO2 inversions show large variations amongst different inversion systems, but their median fluxes are consistent with the estimates from climatological pCO2sw data and pCO2sw diagnostics. In the South Pacific extratropics, where CO2 variations in the surface and ocean interior are severely undersampled, the difference in the air–sea CO2 flux estimates between the diagnostic models and ocean-interior CO2 inversions is larger (0.18 Pg C yr−1). The range of estimates from forward OBGCMs is also large (−0.19 to −0.72 Pg C yr−1). Regarding interannual variability of air–sea CO2 fluxes, positive and negative anomalies are evident in the tropical Pacific during the cold and warm events of the El Niño–Southern Oscillation in the estimates from pCO2sw diagnostic models and from OBGCMs. They are consistent in phase with the Southern Oscillation Index, but the peak-to-peak amplitudes tend to be higher in OBGCMs (0.40 ± 0.09 Pg C yr−1) than in the diagnostic models (0.27 ± 0.07 Pg C yr−1).
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    DOI: 10.5194/bg-11-709-2014
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2014
    detail.hit.zdb_id: 2158181-2
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  • 2
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    Phytoplankton competition during the spring bloom in four plankton functional type models
    Copernicus GmbH ; 2013
    In:  Biogeosciences Vol. 10, No. 11 ( 2013-11-02), p. 6833-6850
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 10, No. 11 ( 2013-11-02), p. 6833-6850
    Abstract: Abstract. We investigated the mechanisms of phytoplankton competition during the spring bloom, one of the most dramatic seasonal events in lower-trophic-level ecosystems, in four state-of-the-art plankton functional type (PFT) models: PISCES, NEMURO, PlankTOM5 and CCSM-BEC. In particular, we investigated the relative importance of different ecophysiological processes on the determination of the community structure, focusing both on the bottom-up and the top-down controls. The models reasonably reproduced the observed global distribution and seasonal variation of phytoplankton biomass. The fraction of diatoms with respect to the total phytoplankton biomass increases with the magnitude of the spring bloom in all models. However, the governing mechanisms differ between models, despite the fact that current PFT models represent ecophysiological processes using the same types of parameterizations. The increasing trend in the percentage of diatoms with increasing bloom magnitude is mainly caused by a stronger nutrient dependence of diatom growth compared to nanophytoplankton (bottom-up control). The difference in the maximum growth rate plays an important role in NEMURO and PlankTOM5 and determines the absolute values of the percentage of diatoms during the bloom. In CCSM-BEC, the light dependency of growth plays an important role in the North Atlantic and the Southern Ocean. The grazing pressure by zooplankton (top-down control), however, strongly contributes to the dominance of diatoms in PISCES and CCSM-BEC. The regional differences in the percentage of diatoms in PlankTOM5 are mainly determined by top-down control. These differences in the mechanisms suggest that the response of marine ecosystems to climate change could significantly differ among models, even if the present-day ecosystem is reproduced to a similar degree of confidence. For further understanding of plankton competition and for the prediction of future change in marine ecosystems, it is important to understand the relative differences in each physiological rate and life history rate in the bottom-up and the top-down controls between PFTs.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    DOI: 10.5194/bg-10-6833-2013
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2013
    detail.hit.zdb_id: 2158181-2
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  • 3
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    iMarNet: an ocean biogeochemistry model intercomparison project within a common physical ocean modelling framework
    Copernicus GmbH ; 2014
    In:  Biogeosciences Vol. 11, No. 24 ( 2014-12-19), p. 7291-7304
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 11, No. 24 ( 2014-12-19), p. 7291-7304
    Abstract: Abstract. Ocean biogeochemistry (OBGC) models span a wide variety of complexities, including highly simplified nutrient-restoring schemes, nutrient–phytoplankton–zooplankton–detritus (NPZD) models that crudely represent the marine biota, models that represent a broader trophic structure by grouping organisms as plankton functional types (PFTs) based on their biogeochemical role (dynamic green ocean models) and ecosystem models that group organisms by ecological function and trait. OBGC models are now integral components of Earth system models (ESMs), but they compete for computing resources with higher resolution dynamical setups and with other components such as atmospheric chemistry and terrestrial vegetation schemes. As such, the choice of OBGC in ESMs needs to balance model complexity and realism alongside relative computing cost. Here we present an intercomparison of six OBGC models that were candidates for implementation within the next UK Earth system model (UKESM1). The models cover a large range of biological complexity (from 7 to 57 tracers) but all include representations of at least the nitrogen, carbon, alkalinity and oxygen cycles. Each OBGC model was coupled to the ocean general circulation model Nucleus for European Modelling of the Ocean (NEMO) and results from physically identical hindcast simulations were compared. Model skill was evaluated for biogeochemical metrics of global-scale bulk properties using conventional statistical techniques. The computing cost of each model was also measured in standardised tests run at two resource levels. No model is shown to consistently outperform all other models across all metrics. Nonetheless, the simpler models are broadly closer to observations across a number of fields and thus offer a high-efficiency option for ESMs that prioritise high-resolution climate dynamics. However, simpler models provide limited insight into more complex marine biogeochemical processes and ecosystem pathways, and a parallel approach of low-resolution climate dynamics and high-complexity biogeochemistry is desirable in order to provide additional insights into biogeochemistry–climate interactions.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-11-7291-2014
    DOI: 10.5194/bg-11-7291-2014-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2014
    detail.hit.zdb_id: 2158181-2
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  • 4
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    MAREDAT: towards a world atlas of MARine Ecosystem DATa
    Copernicus GmbH ; 2013
    In:  Earth System Science Data Vol. 5, No. 2 ( 2013-07-12), p. 227-239
    Details
    In: Earth System Science Data, Copernicus GmbH, Vol. 5, No. 2 ( 2013-07-12), p. 227-239
    Abstract: Abstract. We present a summary of biomass data for 11 plankton functional types (PFTs) plus phytoplankton pigment data, compiled as part of the MARine Ecosystem biomass DATa (MAREDAT) initiative. The goal of the MAREDAT initiative is to provide, in due course, global gridded data products with coverage of all planktic components of the global ocean ecosystem. This special issue is the first step towards achieving this. The PFTs presented here include picophytoplankton, diazotrophs, coccolithophores, Phaeocystis, diatoms, picoheterotrophs, microzooplankton, foraminifers, mesozooplankton, pteropods and macrozooplankton. All variables have been gridded onto a World Ocean Atlas (WOA) grid (1° × 1° × 33 vertical levels × monthly climatologies). The results show that abundance is much better constrained than their carbon content/elemental composition, and coastal seas and other high productivity regions have much better coverage than the much larger volumes where biomass is relatively low. The data show that (1) the global total heterotrophic biomass (2.0–4.6 Pg C) is at least as high as the total autotrophic biomass (0.5–2.4 Pg C excluding nanophytoplankton and autotrophic dinoflagellates); (2) the biomass of zooplankton calcifiers (0.03–0.67 Pg C) is substantially higher than that of coccolithophores (0.001–0.03 Pg C); (3) patchiness of biomass distribution increases with organism size; and (4) although zooplankton biomass measurements below 200 m are rare, the limited measurements available suggest that Bacteria and Archaea are not the only important heterotrophs in the deep sea. More data will be needed to characterise ocean ecosystem functioning and associated biogeochemistry in the Southern Hemisphere and below 200 m. Future efforts to understand marine ecosystem composition and functioning will be helped both by further archiving of historical data and future sampling at new locations. Microzooplankton database: doi:10.1594/PANGAEA.779970 All MAREDAT databases: http://www.pangaea.de/search?&q=maredat
    Type of Medium: Online Resource
    ISSN: 1866-3516
    URL: Article
    DOI: 10.5194/essd-5-227-2013
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2013
    detail.hit.zdb_id: 2475469-9
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  • 5
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    On the Southern Ocean CO 2 uptake and the role of the biological carbon pump in the 21st century
    American Geophysical Union (AGU) ; 2015
    In:  Global Biogeochemical Cycles Vol. 29, No. 9 ( 2015-09), p. 1451-1470
    Details
    In: Global Biogeochemical Cycles, American Geophysical Union (AGU), Vol. 29, No. 9 ( 2015-09), p. 1451-1470
    Abstract: Increase of CO 2 uptake driven by anthropogenic carbon, not by climate change A higher Revelle factor causes enhanced biologically driven CO 2 uptake in summer The southern Southern Ocean becomes more important for total CO 2 uptake
    Type of Medium: Online Resource
    ISSN: 0886-6236 , 1944-9224
    URL: Issue
    URL: Article
    DOI: 10.1002/gbc.v29.9
    DOI: 10.1002/2015GB005140
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2015
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    SSG: 12
    SSG: 13
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  • 6
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    Growth-promoting effect of thermophilic fungi on the mycelium of the edible mushroom Agaricus bisporus
    American Society for Microbiology ; 1992
    In:  Applied and Environmental Microbiology Vol. 58, No. 8 ( 1992-08), p. 2654-2659
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 58, No. 8 ( 1992-08), p. 2654-2659
    Abstract: The growth-promoting effect of the thermophilic fungus Scytalidium thermophilum in mushroom compost on the mycelium of the edible mushroom Agaricus bisporus was investigated. Results obtained by others were confirmed by showing that S. thermophilum leads to an increased hyphal extension rate of the mushroom mycelium. However, it was demonstrated that hyphal extension rates were not clearly related to mushroom biomass increase rates. A number of experiments pointed strongly towards CO2 as the determinant of hyphal extension rates. In compost, CO2 is produced mainly by thermophilic fungi. Several experiments did not reveal any other specific compound produced by S. thermophilum that increases the hyphal extension rate of the mushroom mycelium.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/aem.58.8.2654-2659.1992
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1992
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    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 7
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    Riverine influence on the tropical Atlantic Ocean biogeochemistry
    Copernicus GmbH ; 2013
    In:  Biogeosciences Vol. 10, No. 10 ( 2013-10-09), p. 6357-6373
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 10, No. 10 ( 2013-10-09), p. 6357-6373
    Abstract: Abstract. We assess the role of riverine inputs of N, Si, Fe, organic and inorganic C in the tropical Atlantic Ocean using a global ocean biogeochemistry model. We use a standard model scenario and three sensitivity tests to investigate the role of total river nutrient and carbon inputs, as well as the western (South American) and eastern (African) river inputs on the tropical Atlantic Ocean biogeochemistry, between 20° S–20° N and 70° W–20° E. Increased nutrient availability from river inputs in this area (compared to a sensitivity scenario without river nutrient inputs, NO_RIVER) leads to an increase in primary production (PP) and export production (EP), mainly in the coastal ocean area (modeled ocean area with bathymetry 〈200 m). Model results suggest an enhanced N-fixation by diazotrophs on the tropical Atlantic mainly in open ocean areas. The increased rate of N-fixation in the TODAY scenario is proportional to the increase in PP and EP relative to the NO_RIVER scenario, and may support up to 14% of the coastal ocean export production. Inputs from South American rivers have an impact in coastal PP and EP two times higher than those from African rivers. On the other hand, results suggest that the contribution of African and South American rivers to the total increase in open ocean PP and EP is similar. Considering the amount of delivered nutrients (2–3 times less nutrients and carbon inputs by African rivers) one concludes that African riverine inputs may have a larger impact on the whole tropical Atlantic Ocean biogeochemistry. This is probably due to a combination of nutrient trapping in upwelling areas off the large rivers' outflows and shallow mixed layers in the eastern tropical Atlantic, concomitantly to the differences in delivered nutrient ratios leading to alleviation in limitation conditions, mainly for diatoms. When river inputs are added to the model, we estimate a modest decrease in open ocean sea-air CO2 fluxes (−5.2 Tg C a−1) and an increase in coastal ocean CO2 fluxes, mainly provoked by the remineralization of riverine organic matter delivered by the South American rivers.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-10-6357-2013
    DOI: 10.5194/bg-10-6357-2013-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2013
    detail.hit.zdb_id: 2158181-2
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  • 8
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    Picoheterotroph (〈i〉Bacteria〈/i〉 and 〈i〉Archaea〈/i〉) biomass distribution in the global ocean
    Copernicus GmbH ; 2012
    In:  Earth System Science Data Vol. 4, No. 1 ( 2012-09-10), p. 101-106
    Details
    In: Earth System Science Data, Copernicus GmbH, Vol. 4, No. 1 ( 2012-09-10), p. 101-106
    Abstract: Abstract. We compiled a database of 39 766 data points consisting of flow cytometric and microscopical measurements of picoheterotroph abundance, including both Bacteria and Archaea. After gridding with 1° spacing, the database covers 1.3% of the ocean surface. There are data covering all ocean basins and depths except the Southern Hemisphere below 350 m or from April until June. The average picoheterotroph biomass is 3.9 ± 3.6 μg C l−1 with a 20-fold decrease between the surface and the deep sea. We estimate a total ocean inventory of about 1.3 × 1029 picoheterotroph cells. Surprisingly, the abundance in the coastal regions is the same as at the same depths in the open ocean. Using an average of published open ocean measurements for the conversion from abundance to carbon biomass of 9.1 fg cell−1, we calculate a picoheterotroph carbon inventory of about 1.2 Pg C. The main source of uncertainty in this inventory is the conversion factor from abundance to biomass. Picoheterotroph biomass is ~2 times higher in the tropics than in the polar oceans. doi:10.1594/PANGAEA.779142
    Type of Medium: Online Resource
    ISSN: 1866-3516
    URL: Article
    DOI: 10.5194/essd-4-101-2012
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 2475469-9
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  • 9
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    Simulating dimethylsulphide seasonality with the Dynamic Green Ocean Model PlankTOM5
    American Geophysical Union (AGU) ; 2010
    In:  Journal of Geophysical Research Vol. 115, No. C6 ( 2010-06-25)
    Details
    In: Journal of Geophysical Research, American Geophysical Union (AGU), Vol. 115, No. C6 ( 2010-06-25)
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/2009JC005529
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2010
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    detail.hit.zdb_id: 2969341-X
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    detail.hit.zdb_id: 2016804-4
    detail.hit.zdb_id: 3094181-7
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    detail.hit.zdb_id: 2220777-6
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    SSG: 16,13
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  • 10
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    Distribution of known macrozooplankton abundance and biomass in the global ocean
    Copernicus GmbH ; 2013
    In:  Earth System Science Data Vol. 5, No. 2 ( 2013-07-12), p. 241-257
    Details
    In: Earth System Science Data, Copernicus GmbH, Vol. 5, No. 2 ( 2013-07-12), p. 241-257
    Abstract: Abstract. Macrozooplankton are an important link between higher and lower trophic levels in the oceans. They serve as the primary food for fish, reptiles, birds and mammals in some regions, and play a role in the export of carbon from the surface to the intermediate and deep ocean. Little, however, is known of their global distribution and biomass. Here we compiled a dataset of macrozooplankton abundance and biomass observations for the global ocean from a collection of four datasets. We harmonise the data to common units, calculate additional carbon biomass where possible, and bin the dataset in a global 1 × 1 degree grid. This dataset is part of a wider effort to provide a global picture of carbon biomass data for key plankton functional types, in particular to support the development of marine ecosystem models. Over 387 700 abundance data and 1330 carbon biomass data have been collected from pre-existing datasets. A further 34 938 abundance data were converted to carbon biomass data using species-specific length frequencies or using species-specific abundance to carbon biomass data. Depth-integrated values are used to calculate known epipelagic macrozooplankton biomass concentrations and global biomass. Global macrozooplankton biomass, to a depth of 350 m, has a mean of 8.4 μg C L−1, median of 0.2 μg C L−1 and a standard deviation of 63.5 μg C L−1. The global annual average estimate of macrozooplankton biomass in the top 350 m, based on the median value, is 0.02 Pg C. There are, however, limitations on the dataset; abundance observations have good coverage except in the South Pacific mid-latitudes, but biomass observation coverage is only good at high latitudes. Biomass is restricted to data that is originally given in carbon or to data that can be converted from abundance to carbon. Carbon conversions from abundance are restricted by the lack of information on the size of the organism and/or the absence of taxonomic information. Distribution patterns of global macrozooplankton biomass and statistical information about biomass concentrations may be used to validate biogeochemical and plankton functional type models. Macrozooplankton abundance and biomass dataset doi:10.1594/PANGAEA.777398.
    Type of Medium: Online Resource
    ISSN: 1866-3516
    URL: Article
    DOI: 10.5194/essd-5-241-2013
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2013
    detail.hit.zdb_id: 2475469-9
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