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196 Research products, page 1 of 20

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  • Open Access English
    Authors: 
    Corentin Clerc; Laurent Bopp; Fabio Benedetti; Meike Vogt; Olivier Aumont;
    Publisher: Zenodo
    Project: EC | AtlantECO (862923), ANR | CIGOEF (ANR-17-CE32-0008), EC | COMFORT (820989)

    Supplementary material for "Including filter-feeding gelatinous macrozooplankton in a global marine biogeochemical model: model-data comparison and impact on the ocean carbon cycle". Clerc, C., Bopp, L., Benedetti, F., Vogt, M., and Aumont, O.: Including filter-feeding gelatinous macrozooplankton in a global marine biogeochemical model: model-data comparison and impact on the ocean carbon cycle, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2022-1282, 2022. Three directories can be downloaded: DataOBS : AtlantECO [WP2] – Traditional microscopy dataset – Thaliacea (Salpida+Doliolida+Pyromosomatida) abundance and biomass concentration data, presented in Clerc et al. (2022). FigPaper : Source code and .nc files for the figures presented in Clerc et al. (2022) (https://doi.org/10.5194/egusphere-2022-1282). MY_SRC_PISCES_NEMO_3.6 : Additional fortran routines for the compilation of PISCES-FFGM, the model developed for Clerc et al. (2022), from NEMO-3.6 (https://www.nemo-ocean.eu)

  • Open Access English
    Authors: 
    Waelbroeck, Claire; Tjiputra, Jerry; Guo, Chuncheng; Nisancioglu, Kerim H.; Jansen, Eystein; Vazquez Riveiros, Natalia; Toucanne, Samuel; Eynaud, Frédérique; Rossignol, Linda; Dewilde, Fabien; +3 more
    Project: EC | ACCLIMATE (339108), EC | ICE2ICE (610055)

    We combine consistently dated benthic carbon isotopic records distributed over the entire Atlantic Ocean with numerical simulations performed by a glacial configuration of the Norwegian Earth System Model with active ocean biogeochemistry, in order to interpret the observed Cibicides δ13C changes at the stadial-interstadial transition corresponding to the end of Heinrich Stadial 4 (HS4) in terms of ocean circulation and remineralization changes. We show that the marked increase in Cibicides δ13C observed at the end of HS4 between ~2000 and 4200 m in the Atlantic can be explained by changes in nutrient concentrations as simulated by the model in response to the halting of freshwater input in the high latitude glacial North Atlantic. Our model results show that this Cibicides δ13C signal is associated with changes in the ratio of southern-sourced (SSW) versus northern-sourced (NSW) water masses at the core sites, whereby SSW is replaced by NSW as a consequence of the resumption of deep water formation in the northern North Atlantic and Nordic Seas after the freshwater input is halted. Our results further suggest that the contribution of ocean circulation changes to this signal increases from ~40 % at 2000 m to ~80 % at 4000 m. Below ~4200 m, the model shows little ocean circulation change but an increase in remineralization across the transition marking the end of HS4. The simulated lower remineralization during stadials than interstadials is particularly pronounced in deep subantarctic sites, in agreement with the decrease in the export production of carbon to the deep Southern Ocean during stadials found in previous studies.

  • Open Access English
    Authors: 
    Crotti, Ilaria; Landais, Amaelle; Stenni, Barbara; Bazin, Lucie; Parrenin, Frédéric; Frezzotti, Massimo; Ritterbusch, Florian; Lu, Zheng-Tian; Jiang, Wei; Yang, Guo-Min; +7 more
    Publisher: PANGAEA
    Project: EC | BE-OI (730258), EC | TALDICE HOLOCENE (331615)

    TALDICE deep1 ice core chronology (years) for the TALDICE ice core for ice and gas matrix between 1438 m depth and 1548 m depth at 1 m resolution. The chronology is correlated with accumulation rate, thinning function and LIDIE (lock-in-depth in ice equivalent). The TALDICE deep1 chronology is defined for both gas and ice matrix between 1438 m depth and 1548 m depth with the application of the IceChrono1 model (Parrenin et al. 2015). The age scale is defined at 1 m resolution and gas and ice age ages (expressed in years) with their respective uncertainties. The chronology is correlated with accumulation rate, thinning function and LIDIE (lock-in-depth in ice equivalent).

  • Open Access English
    Authors: 
    Crotti, Ilaria; Landais, Amaelle; Stenni, Barbara; Bazin, Lucie; Parrenin, Frédéric; Frezzotti, Massimo; Ritterbusch, Florian; Lu, Zheng-Tian; Jiang, Wei; Yang, Guo-Min; +7 more
    Publisher: PANGAEA
    Project: EC | TALDICE HOLOCENE (331615), EC | BE-OI (730258)

    d15N (permill) measured on TALDICE ice core between 1356 and 1617 m depth. The data set includes new data published in Crotti et al. (2021), Bazin et al. (2013) and Buiron et al. (2011). The d15N, d18Oatm and dO2/N2 (permill) ratios are measured in the air extracted from 81 ice samples between 1356 m depth and 1620 m depth. The extraction of air trapped in the ice is performed at LSCE, using a semi-automatic extraction line (Capron et al., 2010), and δ18Oatm, δ15N and δO2/N2 of air are measured using a dual inlet Delta V plus (Thermo Electron Corporation) mass spectrometer.

  • Open Access English
    Authors: 
    Wong Hearing, Thomas W.; Pohl, Alexandre; Williams, Mark;
    Publisher: Zenodo
    Project: EC | BioSIGNAL (838373)

    These files contain the necessary data and R scripts for the manuscript "Quantitative comparison of geological data and climate simulations constrains early Cambrian geography and climate". The files include the NetCDF output of early Cambrian global climate simulations conducted using the coupled ocean-atmosphere FOAM general circulation model. The files include four hypothesized early Cambrian continental configurations, the topography-bathymetry files of which are also supplied. Global climate fields were simulated for each continental configuration at six greenhouse gas forcings: 4, 8, 16, 32, 64, and 128 times pre-industrial atmospheric level (PAL = 280 ppm). Simulations for all greenhouse gas forcings were run using present day orbital parameters. Additionally, there are cold and hot summer orbital parameter (CS and HS) and high and low obliquity orbital parameter (OH and OL) simulations at 32 PAL CO2. Also included is a compilation of lower Cambrian climatically sensitive lithologies. Finally, two R scripts are included: one to convert the climate model outputs to Köppen-Geiger climate classes, and the other to quantitatively compare geological data and climate simulations. The reader is referred to the associated paper for a full description of the model boundary conditions, the lithology data, and the data-model comparison methods. NERC (CENTA) PhD studentship NE/L0022493/1 BGS University Funding Initiative (BUFI) S266 Ghent University Special Research Fund (BOF) Fellowship 01P12419 Marie Sklodowska-Curie grant agreement No. 838373

  • Open Access English
    Authors: 
    Landais, Amaelle; Stenni, Barbara;
    Publisher: PANGAEA
    Project: EC | ICORDA (817493)

    We present the full dD of water and d18O of water data at 55 cm resolution on the EPICA Dome C ice core from the near surface (6.6 m) to the bottom (3190 m), hence covering the last 800 ka. The EPICA Dome C ice core has been drilled in Antarctica (-75.1°S; 123.395°E; 3233 m elevation) between 1996 and 2004 and measurements performed from 2001 to 2020. Some of the data were already published in previous published studies (Jouzel et al. 2007; Stenni et al. 2001, 2004, 2010) but corrections were performed in the present data file. dD measurements from Jouzel et al. (2007) were obtained using a uranium reduction method. In this new dataset, these results over the last 800 ka are combined with new dD measurements (760 samples) performed over the deepest 418 m using a Picarro L2130-i (cavity ring-down spectroscopy). The d18O measurements presented here were performed using a water-CO2 equilibration method. This dataset goes along with a paper published in Nature Geoscience (Landais et al., 2021).

  • Open Access English
    Authors: 
    Kiko, Rainer; Picheral, Marc; Antoine, David; Babin, Marcel; Berline, L; Biard, Tristan; Boss, Emmanuel; Brandt, Peter; Carlotti, F; Christiansen, Svenja; +32 more
    Publisher: PANGAEA
    Project: ANR | TAD (ANR-19-MPGA-0012), EC | TRIATLAS (817578)

    Particle size distribution data was collected during multiple cruises globally with several regularly intercalibrated Underwater Vision Profilers, Version 5 (UVP5; Picheral et al 2010). During the respective cruises, the UVP5 was mounted on the CTD-Rosette or as a standalone instrument and deployed in vertical mode. The UVP5 takes pictures of an illuminated watervolume of about 1 Liter every few milliseconds. Imaged items are counted, their size measured and abundance and biovolume of the particles is calculated. For different size bins, this information is summarized in the columns "Particle concentration" and "Particle biovolume". For further details please refer to Kiko et al. (in prep.) "A global marine particle size distribution dataset obtained with the Underwater Vision Profiler 5".

  • Open Access English
    Authors: 
    Rasse, Rafael; Claustre, Hervé; Poteau, Antoine;
    Project: EC | NOCEANIC (839062), EC | REMOCEAN (246777), EC | REFINE (834177)

    The shallower oxygen-poor water masses of the ocean confine a majority of the microbial communities that can produce up to 90 % of oceanic N2. This effective N2-yielding section encloses a suspended small-particle layer, inferred from particle backscattering (bbp) measurements. It is thus hypothesized that this layer (hereafter, the bbp-layer) is linked to microbial communities involved in N2 yielding such as nitrate-reducing SAR11 as well as sulfur-oxidizing, anammox, and denitrifying bacteria – a hypothesis yet to be evaluated. Here, data collected by three BGC-Argo floats deployed in the Black Sea are used to investigate the origin of this bbp-layer. To this end, we evaluate how the key drivers of N2-yielding bacteria dynamics impact the vertical distribution of bbp and the thickness of the bbp-layer. In conjunction with published data on N2 excess, our results suggest that the bbp-layer is at least partially composed of the bacteria driving N2 yielding for three main reasons: (1) strong correlations are recorded between bbp and nitrate; (2) the top location of the bbp-layer is driven by the ventilation of oxygen-rich subsurface waters, while its thickness is modulated by the amount of nitrate available to produce N2; and (3) the maxima of both bbp and N2 excess coincide at the same isopycnals where bacteria involved in N2 yielding coexist. We thus advance that bbp and O2 can be exploited as a combined proxy to delineate the N2-yielding section of the Black Sea. This proxy can potentially contribute to refining delineation of the effective N2-yielding section of oxygen-deficient zones via data from the growing BGC-Argo float network.

  • Open Access English
    Authors: 
    Lee, James E.; Brook, Edward J.; Bertler, Nancy A. N.; Buizert, Christo; Baisden, Troy; Blunier, Thomas; Ciobanu, V. Gabriela; Conway, Howard; Dahl-Jensen, Dorthe; Fudge, Tyler J.; +7 more
    Project: NSF | Collaborative Research: A... (0837883), NSF | Roosevelt Island Climate ... (1042883), NSF | Collaborative Research: D... (0944307), EC | ICE2ICE (610055), NSF | Collaborative Research: D... (0944021)

    In 2013, an ice core was recovered from Roosevelt Island in the Ross Sea, Antarctica, as part of the Roosevelt Island Climate Evolution (RICE) project. Roosevelt Island is located between two submarine troughs carved by paleo-ice-streams. The RICE ice core provides new important information about the past configuration of the West Antarctic Ice Sheet and its retreat during the most recent deglaciation. In this work, we present the RICE17 chronology and discuss preliminary observations from the new records of methane, the isotopic composition of atmospheric molecular oxygen (δ18O-Oatm), the isotopic composition of atmospheric molecular nitrogen (δ15N-N2) and total air content (TAC). RICE17 is a composite chronology combining annual layer interpretations, gas synchronization, and firn modeling strategies in different sections of the core. An automated matching algorithm is developed for synchronizing the high-resolution section of the RICE gas records (60–720 m, 1971 CE to 30 ka) to corresponding records from the WAIS Divide ice core, while deeper sections are manually matched. Ice age for the top 343 m (2635 yr BP, before 1950 C.E.) is derived from annual layer interpretations and described in the accompanying paper by Winstrup et al. (2017). For deeper sections, the RICE17 ice age scale is based on the gas age constraints and the ice age-gas age offset estimated by a firn densification model. Novel aspects of this work include: 1) stratigraphic matching of centennial-scale variations in methane for pre-anthropogenic time periods, a strategy which will be applicable for developing precise chronologies for future ice cores, 2) the observation of centennial-scale variability in methane throughout the Holocene which suggests that similar variations during the late preindustrial period need not be anthropogenic, and 3) the observation of continuous climate records dating back to ∼ 65 ka which provide evidence that the Roosevelt Island Ice Dome was a constant feature throughout the last glacial period.

  • Open Access English
    Authors: 
    Johansson, Sören; Höpfner, Michael; Kirner, Oliver; Wohltmann, Ingo; Bucci, Silvia; Legras, Bernard; Friedl-Vallon, Felix; Glatthor, Norbert; Kretschmer, Erik; Ungermann, Jörn; +1 more
    Project: EC | STRATOCLIM (603557)

    We present the first high-resolution measurements of pollutant trace gases in the Asian summer monsoon upper troposphere and lowermost stratosphere (UTLS) from the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) during the StratoClim (Stratospheric and upper tropospheric processes for better climate predictions) campaign based in Kathmandu, Nepal, 2017. Measurements of peroxyacetyl nitrate (PAN), acetylene (C2H2), and formic acid (HCOOH) show strong local enhancements up to altitudes of 16 km. More than 500 pptv of PAN, more than 200 pptv of C2H2, and more than 200 pptv of HCOOH are observed. Air masses with increased volume mixing ratios of PAN and C2H2 at altitudes up to 18 km, reaching to the lowermost stratosphere, were present at these altitudes for more than 10 d, as indicated by trajectory analysis. A local minimum of HCOOH is correlated with a previously reported maximum of ammonia (NH3), which suggests different washout efficiencies of these species in the same air masses. A backward trajectory analysis based on the models Alfred Wegener InsTitute LAgrangian Chemistry/Transport System (ATLAS) and TRACZILLA, using advanced techniques for detection of convective events, and starting at geolocations of GLORIA measurements with enhanced pollution trace gas concentrations, has been performed. The analysis shows that convective events along trajectories leading to GLORIA measurements with enhanced pollutants are located close to regions where satellite measurements by the Ozone Monitoring Instrument (OMI) indicate enhanced tropospheric columns of nitrogen dioxide (NO2) in the days prior to the observation. A comparison to the global atmospheric models Copernicus Atmosphere Monitoring Service (CAMS) and ECHAM/MESSy Atmospheric Chemistry (EMAC) has been performed. It is shown that these models are able to reproduce large-scale structures of the pollution trace gas distributions for one part of the flight, while the other part of the flight reveals large discrepancies between models and measurement. These discrepancies possibly result from convective events that are not resolved or parameterized in the models, uncertainties in the emissions of source gases, and uncertainties in the rate constants of chemical reactions.

Advanced search in Research products
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Include:
The following results are related to European Marine Science. Are you interested to view more results? Visit OpenAIRE - Explore.
196 Research products, page 1 of 20
  • Open Access English
    Authors: 
    Corentin Clerc; Laurent Bopp; Fabio Benedetti; Meike Vogt; Olivier Aumont;
    Publisher: Zenodo
    Project: EC | AtlantECO (862923), ANR | CIGOEF (ANR-17-CE32-0008), EC | COMFORT (820989)

    Supplementary material for "Including filter-feeding gelatinous macrozooplankton in a global marine biogeochemical model: model-data comparison and impact on the ocean carbon cycle". Clerc, C., Bopp, L., Benedetti, F., Vogt, M., and Aumont, O.: Including filter-feeding gelatinous macrozooplankton in a global marine biogeochemical model: model-data comparison and impact on the ocean carbon cycle, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2022-1282, 2022. Three directories can be downloaded: DataOBS : AtlantECO [WP2] – Traditional microscopy dataset – Thaliacea (Salpida+Doliolida+Pyromosomatida) abundance and biomass concentration data, presented in Clerc et al. (2022). FigPaper : Source code and .nc files for the figures presented in Clerc et al. (2022) (https://doi.org/10.5194/egusphere-2022-1282). MY_SRC_PISCES_NEMO_3.6 : Additional fortran routines for the compilation of PISCES-FFGM, the model developed for Clerc et al. (2022), from NEMO-3.6 (https://www.nemo-ocean.eu)

  • Open Access English
    Authors: 
    Waelbroeck, Claire; Tjiputra, Jerry; Guo, Chuncheng; Nisancioglu, Kerim H.; Jansen, Eystein; Vazquez Riveiros, Natalia; Toucanne, Samuel; Eynaud, Frédérique; Rossignol, Linda; Dewilde, Fabien; +3 more
    Project: EC | ACCLIMATE (339108), EC | ICE2ICE (610055)

    We combine consistently dated benthic carbon isotopic records distributed over the entire Atlantic Ocean with numerical simulations performed by a glacial configuration of the Norwegian Earth System Model with active ocean biogeochemistry, in order to interpret the observed Cibicides δ13C changes at the stadial-interstadial transition corresponding to the end of Heinrich Stadial 4 (HS4) in terms of ocean circulation and remineralization changes. We show that the marked increase in Cibicides δ13C observed at the end of HS4 between ~2000 and 4200 m in the Atlantic can be explained by changes in nutrient concentrations as simulated by the model in response to the halting of freshwater input in the high latitude glacial North Atlantic. Our model results show that this Cibicides δ13C signal is associated with changes in the ratio of southern-sourced (SSW) versus northern-sourced (NSW) water masses at the core sites, whereby SSW is replaced by NSW as a consequence of the resumption of deep water formation in the northern North Atlantic and Nordic Seas after the freshwater input is halted. Our results further suggest that the contribution of ocean circulation changes to this signal increases from ~40 % at 2000 m to ~80 % at 4000 m. Below ~4200 m, the model shows little ocean circulation change but an increase in remineralization across the transition marking the end of HS4. The simulated lower remineralization during stadials than interstadials is particularly pronounced in deep subantarctic sites, in agreement with the decrease in the export production of carbon to the deep Southern Ocean during stadials found in previous studies.

  • Open Access English
    Authors: 
    Crotti, Ilaria; Landais, Amaelle; Stenni, Barbara; Bazin, Lucie; Parrenin, Frédéric; Frezzotti, Massimo; Ritterbusch, Florian; Lu, Zheng-Tian; Jiang, Wei; Yang, Guo-Min; +7 more
    Publisher: PANGAEA
    Project: EC | BE-OI (730258), EC | TALDICE HOLOCENE (331615)

    TALDICE deep1 ice core chronology (years) for the TALDICE ice core for ice and gas matrix between 1438 m depth and 1548 m depth at 1 m resolution. The chronology is correlated with accumulation rate, thinning function and LIDIE (lock-in-depth in ice equivalent). The TALDICE deep1 chronology is defined for both gas and ice matrix between 1438 m depth and 1548 m depth with the application of the IceChrono1 model (Parrenin et al. 2015). The age scale is defined at 1 m resolution and gas and ice age ages (expressed in years) with their respective uncertainties. The chronology is correlated with accumulation rate, thinning function and LIDIE (lock-in-depth in ice equivalent).

  • Open Access English
    Authors: 
    Crotti, Ilaria; Landais, Amaelle; Stenni, Barbara; Bazin, Lucie; Parrenin, Frédéric; Frezzotti, Massimo; Ritterbusch, Florian; Lu, Zheng-Tian; Jiang, Wei; Yang, Guo-Min; +7 more
    Publisher: PANGAEA
    Project: EC | TALDICE HOLOCENE (331615), EC | BE-OI (730258)

    d15N (permill) measured on TALDICE ice core between 1356 and 1617 m depth. The data set includes new data published in Crotti et al. (2021), Bazin et al. (2013) and Buiron et al. (2011). The d15N, d18Oatm and dO2/N2 (permill) ratios are measured in the air extracted from 81 ice samples between 1356 m depth and 1620 m depth. The extraction of air trapped in the ice is performed at LSCE, using a semi-automatic extraction line (Capron et al., 2010), and δ18Oatm, δ15N and δO2/N2 of air are measured using a dual inlet Delta V plus (Thermo Electron Corporation) mass spectrometer.

  • Open Access English
    Authors: 
    Wong Hearing, Thomas W.; Pohl, Alexandre; Williams, Mark;
    Publisher: Zenodo
    Project: EC | BioSIGNAL (838373)

    These files contain the necessary data and R scripts for the manuscript "Quantitative comparison of geological data and climate simulations constrains early Cambrian geography and climate". The files include the NetCDF output of early Cambrian global climate simulations conducted using the coupled ocean-atmosphere FOAM general circulation model. The files include four hypothesized early Cambrian continental configurations, the topography-bathymetry files of which are also supplied. Global climate fields were simulated for each continental configuration at six greenhouse gas forcings: 4, 8, 16, 32, 64, and 128 times pre-industrial atmospheric level (PAL = 280 ppm). Simulations for all greenhouse gas forcings were run using present day orbital parameters. Additionally, there are cold and hot summer orbital parameter (CS and HS) and high and low obliquity orbital parameter (OH and OL) simulations at 32 PAL CO2. Also included is a compilation of lower Cambrian climatically sensitive lithologies. Finally, two R scripts are included: one to convert the climate model outputs to Köppen-Geiger climate classes, and the other to quantitatively compare geological data and climate simulations. The reader is referred to the associated paper for a full description of the model boundary conditions, the lithology data, and the data-model comparison methods. NERC (CENTA) PhD studentship NE/L0022493/1 BGS University Funding Initiative (BUFI) S266 Ghent University Special Research Fund (BOF) Fellowship 01P12419 Marie Sklodowska-Curie grant agreement No. 838373

  • Open Access English
    Authors: 
    Landais, Amaelle; Stenni, Barbara;
    Publisher: PANGAEA
    Project: EC | ICORDA (817493)

    We present the full dD of water and d18O of water data at 55 cm resolution on the EPICA Dome C ice core from the near surface (6.6 m) to the bottom (3190 m), hence covering the last 800 ka. The EPICA Dome C ice core has been drilled in Antarctica (-75.1°S; 123.395°E; 3233 m elevation) between 1996 and 2004 and measurements performed from 2001 to 2020. Some of the data were already published in previous published studies (Jouzel et al. 2007; Stenni et al. 2001, 2004, 2010) but corrections were performed in the present data file. dD measurements from Jouzel et al. (2007) were obtained using a uranium reduction method. In this new dataset, these results over the last 800 ka are combined with new dD measurements (760 samples) performed over the deepest 418 m using a Picarro L2130-i (cavity ring-down spectroscopy). The d18O measurements presented here were performed using a water-CO2 equilibration method. This dataset goes along with a paper published in Nature Geoscience (Landais et al., 2021).

  • Open Access English
    Authors: 
    Kiko, Rainer; Picheral, Marc; Antoine, David; Babin, Marcel; Berline, L; Biard, Tristan; Boss, Emmanuel; Brandt, Peter; Carlotti, F; Christiansen, Svenja; +32 more
    Publisher: PANGAEA
    Project: ANR | TAD (ANR-19-MPGA-0012), EC | TRIATLAS (817578)

    Particle size distribution data was collected during multiple cruises globally with several regularly intercalibrated Underwater Vision Profilers, Version 5 (UVP5; Picheral et al 2010). During the respective cruises, the UVP5 was mounted on the CTD-Rosette or as a standalone instrument and deployed in vertical mode. The UVP5 takes pictures of an illuminated watervolume of about 1 Liter every few milliseconds. Imaged items are counted, their size measured and abundance and biovolume of the particles is calculated. For different size bins, this information is summarized in the columns "Particle concentration" and "Particle biovolume". For further details please refer to Kiko et al. (in prep.) "A global marine particle size distribution dataset obtained with the Underwater Vision Profiler 5".

  • Open Access English
    Authors: 
    Rasse, Rafael; Claustre, Hervé; Poteau, Antoine;
    Project: EC | NOCEANIC (839062), EC | REMOCEAN (246777), EC | REFINE (834177)

    The shallower oxygen-poor water masses of the ocean confine a majority of the microbial communities that can produce up to 90 % of oceanic N2. This effective N2-yielding section encloses a suspended small-particle layer, inferred from particle backscattering (bbp) measurements. It is thus hypothesized that this layer (hereafter, the bbp-layer) is linked to microbial communities involved in N2 yielding such as nitrate-reducing SAR11 as well as sulfur-oxidizing, anammox, and denitrifying bacteria – a hypothesis yet to be evaluated. Here, data collected by three BGC-Argo floats deployed in the Black Sea are used to investigate the origin of this bbp-layer. To this end, we evaluate how the key drivers of N2-yielding bacteria dynamics impact the vertical distribution of bbp and the thickness of the bbp-layer. In conjunction with published data on N2 excess, our results suggest that the bbp-layer is at least partially composed of the bacteria driving N2 yielding for three main reasons: (1) strong correlations are recorded between bbp and nitrate; (2) the top location of the bbp-layer is driven by the ventilation of oxygen-rich subsurface waters, while its thickness is modulated by the amount of nitrate available to produce N2; and (3) the maxima of both bbp and N2 excess coincide at the same isopycnals where bacteria involved in N2 yielding coexist. We thus advance that bbp and O2 can be exploited as a combined proxy to delineate the N2-yielding section of the Black Sea. This proxy can potentially contribute to refining delineation of the effective N2-yielding section of oxygen-deficient zones via data from the growing BGC-Argo float network.

  • Open Access English
    Authors: 
    Lee, James E.; Brook, Edward J.; Bertler, Nancy A. N.; Buizert, Christo; Baisden, Troy; Blunier, Thomas; Ciobanu, V. Gabriela; Conway, Howard; Dahl-Jensen, Dorthe; Fudge, Tyler J.; +7 more
    Project: NSF | Collaborative Research: A... (0837883), NSF | Roosevelt Island Climate ... (1042883), NSF | Collaborative Research: D... (0944307), EC | ICE2ICE (610055), NSF | Collaborative Research: D... (0944021)

    In 2013, an ice core was recovered from Roosevelt Island in the Ross Sea, Antarctica, as part of the Roosevelt Island Climate Evolution (RICE) project. Roosevelt Island is located between two submarine troughs carved by paleo-ice-streams. The RICE ice core provides new important information about the past configuration of the West Antarctic Ice Sheet and its retreat during the most recent deglaciation. In this work, we present the RICE17 chronology and discuss preliminary observations from the new records of methane, the isotopic composition of atmospheric molecular oxygen (δ18O-Oatm), the isotopic composition of atmospheric molecular nitrogen (δ15N-N2) and total air content (TAC). RICE17 is a composite chronology combining annual layer interpretations, gas synchronization, and firn modeling strategies in different sections of the core. An automated matching algorithm is developed for synchronizing the high-resolution section of the RICE gas records (60–720 m, 1971 CE to 30 ka) to corresponding records from the WAIS Divide ice core, while deeper sections are manually matched. Ice age for the top 343 m (2635 yr BP, before 1950 C.E.) is derived from annual layer interpretations and described in the accompanying paper by Winstrup et al. (2017). For deeper sections, the RICE17 ice age scale is based on the gas age constraints and the ice age-gas age offset estimated by a firn densification model. Novel aspects of this work include: 1) stratigraphic matching of centennial-scale variations in methane for pre-anthropogenic time periods, a strategy which will be applicable for developing precise chronologies for future ice cores, 2) the observation of centennial-scale variability in methane throughout the Holocene which suggests that similar variations during the late preindustrial period need not be anthropogenic, and 3) the observation of continuous climate records dating back to ∼ 65 ka which provide evidence that the Roosevelt Island Ice Dome was a constant feature throughout the last glacial period.

  • Open Access English
    Authors: 
    Johansson, Sören; Höpfner, Michael; Kirner, Oliver; Wohltmann, Ingo; Bucci, Silvia; Legras, Bernard; Friedl-Vallon, Felix; Glatthor, Norbert; Kretschmer, Erik; Ungermann, Jörn; +1 more
    Project: EC | STRATOCLIM (603557)

    We present the first high-resolution measurements of pollutant trace gases in the Asian summer monsoon upper troposphere and lowermost stratosphere (UTLS) from the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) during the StratoClim (Stratospheric and upper tropospheric processes for better climate predictions) campaign based in Kathmandu, Nepal, 2017. Measurements of peroxyacetyl nitrate (PAN), acetylene (C2H2), and formic acid (HCOOH) show strong local enhancements up to altitudes of 16 km. More than 500 pptv of PAN, more than 200 pptv of C2H2, and more than 200 pptv of HCOOH are observed. Air masses with increased volume mixing ratios of PAN and C2H2 at altitudes up to 18 km, reaching to the lowermost stratosphere, were present at these altitudes for more than 10 d, as indicated by trajectory analysis. A local minimum of HCOOH is correlated with a previously reported maximum of ammonia (NH3), which suggests different washout efficiencies of these species in the same air masses. A backward trajectory analysis based on the models Alfred Wegener InsTitute LAgrangian Chemistry/Transport System (ATLAS) and TRACZILLA, using advanced techniques for detection of convective events, and starting at geolocations of GLORIA measurements with enhanced pollution trace gas concentrations, has been performed. The analysis shows that convective events along trajectories leading to GLORIA measurements with enhanced pollutants are located close to regions where satellite measurements by the Ozone Monitoring Instrument (OMI) indicate enhanced tropospheric columns of nitrogen dioxide (NO2) in the days prior to the observation. A comparison to the global atmospheric models Copernicus Atmosphere Monitoring Service (CAMS) and ECHAM/MESSy Atmospheric Chemistry (EMAC) has been performed. It is shown that these models are able to reproduce large-scale structures of the pollution trace gas distributions for one part of the flight, while the other part of the flight reveals large discrepancies between models and measurement. These discrepancies possibly result from convective events that are not resolved or parameterized in the models, uncertainties in the emissions of source gases, and uncertainties in the rate constants of chemical reactions.