Hamme
Roberta C.
Hamme
Roberta C.
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DatasetA compilation of dissolved noble gas and N2/Ar ratio measurements collected from 1999-2016 in locations spanning the globe(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-01-21) Hamme, Roberta C. ; Jenkins, William J. ; Emerson, Steven R. ; Nicholson, David P.Inert gases dissolved in the ocean are powerful tracers of the impact of physical processes on gases, particularly air-sea gas exchange (by both diffusive and bubble-meditated processes), temperature change, atmospheric pressure variation, mixing between different water masses, and ice processes. We have compiled a global ocean database of dissolved neon, argon, and krypton measurements, supplemented by helium, xenon, and nitrogen/argon (N2/Ar) ratios in some locations. Samples were collected on board multiple research cruises spanning the period 1999 through 2016 and analyzed by mass spectrometry at four different shore-based laboratories (University of Victoria, Woods Hole Oceanographic Institution, University of Washington, and Scripps Institution of Oceanography). Version 2.0 corrects an incorrect sign in the longitude for cruise 33KI20040814:HOT162 in version 1.0. The error in the database does not affect any figures in the publication (doi: 10.1146/annurev-marine-121916-063604). 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/743867
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ArticleConstraining ventilation during deepwater formation using deep ocean measurements of the dissolved gas ratios 40Ar/36Ar, N2/Ar, and Kr/Ar(American Geophysical Union, 2010-11-19) Nicholson, David P. ; Emerson, Steven ; Caillon, Nicolas ; Jouzel, Jean ; Hamme, Roberta C.The concentration of inert gases and their isotopes in the deep ocean are useful as tracers of air-sea gas exchange during deepwater formation. ΔKr/Ar, ΔN2/Ar, and δ40Ar were measured in deep profiles of samples collected in the northwest Pacific, subtropical North Pacific and tropical Atlantic oceans. For the ocean below 2000 m, we determined a mean ΔKr/Ar composition of −0.96% ± 0.16%, a mean ΔN2/Ar of 1.29% ± 0.21% relative to equilibrium saturation, and for δ40Ar a value of 1.188‰ ± 0.055‰ relative to air. These data are used to constrain high-latitude ventilation processes in the framework of three-box and seven-box ocean models. For the three-box model tracer data, we constrain the appropriate surface area of the high-latitude region in both models to be 3.6% (+2.5%, −1.7%) of ocean surface area and the bubble air injection rate to be 22.7 (+8.8, −7.3) mol air m−2 yr−1. Results for the seven-box model were similar, with a high-latitude area of 3.3% (+2.2%, −1.3%). Our results provide geochemical support for suggestions that the effective area of high-latitude ventilation is much smaller than the region of elevated preformed nutrients and demonstrate that noble gases strongly constrain the ocean solubility pump. Reducing high-latitude surface area weakens the CO2 solubility pump in the box models and limits communication between the atmosphere and deep ocean. These tracers should be useful constraints on high-latitude ventilation and the strength of the solubility pump in more complex ocean general circulation models.
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DatasetA compilation of dissolved noble gas and N2/Ar ratio measurements collected from 1999-2016 in locations spanning the globe(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2018-08-24) Hamme, Roberta C. ; Jenkins, William J. ; Emerson, Steven R. ; Nicholson, David P.Inert gases dissolved in the ocean are powerful tracers of the impact of physical processes on gases, particularly air-sea gas exchange (by both diffusive and bubble-meditated processes), temperature change, atmospheric pressure variation, mixing between different water masses, and ice processes. We have compiled a global ocean database of dissolved neon, argon, and krypton measurements, supplemented by helium, xenon, and nitrogen/argon (N2/Ar) ratios in some locations. Samples were collected on board multiple research cruises spanning the period 1999 through 2016 and analyzed by mass spectrometry at four different shore-based laboratories (University of Victoria, Woods Hole Oceanographic Institution, University of Washington, and Scripps Institution of Oceanography). For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/743867
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ArticleEvaluation of new and net community production estimates by multiple ship-based and autonomous observations in the Northeast Pacific Ocean(University of California Press, 2023-06-16) Niebergall, Alexandria K. ; Traylor, Shawnee ; Huang, Yibin ; Feen, Melanie ; Meyer, Meredith G. ; McNair, Heather M. ; Nicholson, David P. ; Fassbender, Andrea J. ; Omand, Melissa M. ; Marchetti, Adrian ; Menden-Deuer, Susanne ; Tang, Weiyi ; Gong, Weida ; Tortell, Philippe D. ; Hamme, Roberta C. ; Cassar, NicolasNew production (NP) and net community production (NCP) measurements are often used as estimates of carbon export potential from the mixed layer of the ocean, an important process in the regulation of global climate. Diverse methods can be used to measure NP and NCP, from research vessels, autonomous platforms, and remote sensing, each with its own set of benefits and uncertainties. The various methods are rarely applied simultaneously in a single location, limiting our ability for direct comparisons of the resulting measurements. In this study, we evaluated NP and NCP from thirteen independent datasets collected via in situ, in vitro, and satellite-based methods near Ocean Station Papa during the 2018 Northeast Pacific field campaign of the NASA project EXport Processes in the Ocean from RemoTe Sensing (EXPORTS). Altogether, the datasets indicate that carbon export potential was relatively low (median daily averages between −5.1 and 12.6 mmol C m−2 d−1), with most measurements indicating slight net autotrophy in the region. This result is consistent with NCP estimates based on satellite measurements of sea surface temperature and chlorophyll a. We explored possible causes of discrepancies among methods, including differences in assumptions about stoichiometry, vertical integration, total volume sampled, and the spatiotemporal extent considered. Results of a generalized additive mixed model indicate that the spatial variation across platforms can explain much of the difference among methods. Once spatial variation and temporal autocorrelation are considered, a variety of methods can provide consistent estimates of NP and NCP, leveraging the strengths of each approach.
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ArticleAn operational overview of the EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) Northeast Pacific field deployment(University of California Press, 2021-07-07) Siegel, David A. ; Cetinić, Ivona ; Graff, Jason R. ; Lee, Craig M. ; Nelson, Norman B. ; Perry, Mary J. ; Soto Ramos, Inia ; Steinberg, Deborah K. ; Buesseler, Ken O. ; Hamme, Roberta C. ; Fassbender, Andrea ; Nicholson, David P. ; Omand, Melissa M. ; Robert, Marie ; Thompson, Andrew F. ; Amaral, Vinicius ; Behrenfeld, Michael J. ; Benitez-Nelson, Claudia R. ; Bisson, Kelsey ; Boss, Emmanuel S. ; Boyd, Philip ; Brzezinski, Mark A. ; Buck, Kristen N. ; Burd, Adrian B. ; Burns, Shannon ; Caprara, Salvatore ; Carlson, Craig A. ; Cassar, Nicolas ; Close, Hilary G. ; D'Asaro, Eric A. ; Durkin, Colleen A. ; Erickson, Zachary K. ; Estapa, Margaret L. ; Fields, Erik ; Fox, James ; Freeman, Scott ; Gifford, Scott M. ; Gong, Weida ; Gray, Deric ; Guidi, Lionel ; Haëntjens, Nils ; Halsey, Kim ; Huot, Yannick ; Hansell, Dennis A. ; Jenkins, Bethany D. ; Karp-Boss, Lee ; Kramer, Sasha J. ; Lam, Phoebe J. ; Lee, Jong-Mi ; Maas, Amy E. ; Marchal, Olivier ; Marchetti, Adrian ; McDonnell, Andrew M. P. ; McNair, Heather ; Menden-Deuer, Susanne ; Morison, Francoise ; Niebergall, Alexandria K. ; Passow, Uta ; Popp, Brian N. ; Potvin, Geneviève ; Resplandy, Laure ; Roca-Martí, Montserrat ; Roesler, Collin S. ; Rynearson, Tatiana A. ; Traylor, Shawnee ; Santoro, Alyson E. ; Seraphin, Kanesa ; Sosik, Heidi M. ; Stamieszkin, Karen ; Stephens, Brandon M. ; Tang, Weiyi ; Van Mooy, Benjamin ; Xiong, Yuanheng ; Zhang, XiaodongThe goal of the EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) field campaign is to develop a predictive understanding of the export, fate, and carbon cycle impacts of global ocean net primary production. To accomplish this goal, observations of export flux pathways, plankton community composition, food web processes, and optical, physical, and biogeochemical (BGC) properties are needed over a range of ecosystem states. Here we introduce the first EXPORTS field deployment to Ocean Station Papa in the Northeast Pacific Ocean during summer of 2018, providing context for other papers in this special collection. The experiment was conducted with two ships: a Process Ship, focused on ecological rates, BGC fluxes, temporal changes in food web, and BGC and optical properties, that followed an instrumented Lagrangian float; and a Survey Ship that sampled BGC and optical properties in spatial patterns around the Process Ship. An array of autonomous underwater assets provided measurements over a range of spatial and temporal scales, and partnering programs and remote sensing observations provided additional observational context. The oceanographic setting was typical of late-summer conditions at Ocean Station Papa: a shallow mixed layer, strong vertical and weak horizontal gradients in hydrographic properties, sluggish sub-inertial currents, elevated macronutrient concentrations and low phytoplankton abundances. Although nutrient concentrations were consistent with previous observations, mixed layer chlorophyll was lower than typically observed, resulting in a deeper euphotic zone. Analyses of surface layer temperature and salinity found three distinct surface water types, allowing for diagnosis of whether observed changes were spatial or temporal. The 2018 EXPORTS field deployment is among the most comprehensive biological pump studies ever conducted. A second deployment to the North Atlantic Ocean occurred in spring 2021, which will be followed by focused work on data synthesis and modeling using the entire EXPORTS data set.