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Faculty Publications

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Articles 181 - 210 of 270

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

Effect Of The North Equatorial Counter Current On The Generation And Propagation Of Internal Solitary Waves Off The Amazon Shelf (Sar Observations), Jorge Manuel Magalhães, J.C.B. Da Silva, Maarten C. Buijsman, Carlos A.E. Gaercia Feb 2016

Effect Of The North Equatorial Counter Current On The Generation And Propagation Of Internal Solitary Waves Off The Amazon Shelf (Sar Observations), Jorge Manuel Magalhães, J.C.B. Da Silva, Maarten C. Buijsman, Carlos A.E. Gaercia

Faculty Publications

. Synthetic aperture radar (SAR) imagery from the Amazon shelf break region in the tropical west Atlantic reveals for the first time the two-dimensional horizontal structure of an intense Internal Solitary Wave (ISW) field, whose first surface manifestations are detected several hundred kilometres away from the nearest forcing bathymetry. Composite maps and an energy budget analysis (provided from the Hybrid Coordinate Ocean Model – HYCOM) help to identify two major ISW pathways emanating from the steep slopes of a small promontory (or headland) near 44◦ W and 0 ◦ N, which are seen to extend for over 500 km into …

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Relationships Between Wind Predictions And Model Resolution Over Coastal Regions, Mustafa Kemal Cambazoglu, Cheryl Ann Blain, Travis A. Smith, Robert S. Linzell Jan 2016

Relationships Between Wind Predictions And Model Resolution Over Coastal Regions, Mustafa Kemal Cambazoglu, Cheryl Ann Blain, Travis A. Smith, Robert S. Linzell

Faculty Publications

The impact of resolution on wind predictions within regions of complex coastal geometry is evaluated using a quadruple nest of COAMPS® (27 km to 1 km) to find an optimal configuration of spatial and temporal resolution. Two regions, Turkish Straits System and Chesapeake Bay, are selected because of their diverse coastal environments, the availability of wind observations and to determine if the relationships between resolution and wind prediction accuracy would be valid for geographically different regions. The coarse resolution model successfully simulates the general trend of the surface wind variation, but cannot capture peak events accurately. Increased spatial resolution …

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Size-Dependent Top-Down Control On Phytoplankton Growth By Microzooplankton In Eutrophic Lakes, Wai Hing Wong, Nancy N. Rabalais, R. Eugene Turner Jan 2016

Size-Dependent Top-Down Control On Phytoplankton Growth By Microzooplankton In Eutrophic Lakes, Wai Hing Wong, Nancy N. Rabalais, R. Eugene Turner

Faculty Publications

We hypothesized that the grazing on phytoplankton by the microzooplankton community is size-dependent and, therefore, the top-down control on phytoplankton by microzooplankton community could be one possible mechanism explaining why small phytoplankton become less abundant than large phytoplankton in eutrophic waters. We tested this hypothesis using the dilution method to measure microzooplankton grazing rates and phytoplankton growth rates in the eutrophic waters of the Barataria estuary, southeastern Louisiana. Microzooplankton grazing rates on the slower growing, small phytoplankton (\5 lm) were higher than on the large phytoplankton ([20 lm) which had relatively faster growth rates. The proportional loss of the small, …

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Examining The Potential Impact Of Swot Observations In An Ocean Analysis-Forecasting System, Matthew Carrier, Hans E. Ngodock, Scott R. Smith, Innocent Souopgui, Brent Bartels Jan 2016

Examining The Potential Impact Of Swot Observations In An Ocean Analysis-Forecasting System, Matthew Carrier, Hans E. Ngodock, Scott R. Smith, Innocent Souopgui, Brent Bartels

Faculty Publications

NASA's Surface Water and Ocean Topography (SWOT) satellite, scheduled for launch in 2020, will provide observations of sea surface height anomaly (SSHA) at a significantly higher spatial resolution than current satellite altimeters. This new observation type is expected to improve the ocean model mesoscale circulation. The potential improvement that SWOT will provide is investigated in this work by way of twin-data assimilation experiments using the Navy Coastal Ocean Model four-dimensional variational data assimilation (NCOM-4DVAR) system in its weak constraint formulation. Simulated SWOT observations are sampled from an ocean model run (referred to as the "nature" run) using an observation-simulator program …

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No Reef Is An Island: Integrating Coral Reef Connectivity Data Into The Design Of Regional-Scale Marine Protected Area Networks, Steven R. Schill, George T. Raber, Jason J. Roberts, Eric A. Treml, Jorge Brenner, Patrick N. Halpin Dec 2015

No Reef Is An Island: Integrating Coral Reef Connectivity Data Into The Design Of Regional-Scale Marine Protected Area Networks, Steven R. Schill, George T. Raber, Jason J. Roberts, Eric A. Treml, Jorge Brenner, Patrick N. Halpin

Faculty Publications

We integrated coral reef connectivity data for the Caribbean and Gulf of Mexico into a conservation decision-making framework for designing a regional scale marine protected area (MPA) network that provides insight into ecological and political contexts. We used an ocean circulation model and regional coral reef data to simulate eight spawning events from 2008–2011, applying a maximum 30-day pelagic larval duration and 20% mortality rate. Coral larval dispersal patterns were analyzed between coral reefs across jurisdictional marine zones to identify spatial relationships between larval sources and destinations within countries and territories across the region. We applied our results in Marxan, …

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Linkages Among Fluorescent Dissolved Organic Matter, Dissolved Amino Acids And Lignin-Derived Phenols In River-Influenced Ocean Margins, Youhei Yamashita, Cédric G. Fichot, Yuan Shen, Rudolf Jaffé, Ronald Benner Nov 2015

Linkages Among Fluorescent Dissolved Organic Matter, Dissolved Amino Acids And Lignin-Derived Phenols In River-Influenced Ocean Margins, Youhei Yamashita, Cédric G. Fichot, Yuan Shen, Rudolf Jaffé, Ronald Benner

Faculty Publications

Excitation emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC) is commonly used to investigate the dynamics of dissolved organic matter (DOM). However, a lack of direct comparisons with known biomolecules makes it difficult to substantiate the molecular composition of specific fluorescent components. Here, coincident surface-water measurements of EEMs, dissolved lignin, and total dissolved amino acids (TDAA) acquired in the northern Gulf of Mexico were used to investigate the relationships between specific fluorescent components and DOM biomolecules. Two terrestrial humic-like components identified by EEM-PARAFAC using samples obtained from river to offshore waters were strongly linearly correlated with dissolved …

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Abundance, Stable Isotopic Composition, And Export Fluxes Of Doc, Poc, And Dic From The Lower Mississippi River During 2006-2008, Yihua Cai, Laodong Guo, Xuri Wang, George Aiken Nov 2015

Abundance, Stable Isotopic Composition, And Export Fluxes Of Doc, Poc, And Dic From The Lower Mississippi River During 2006-2008, Yihua Cai, Laodong Guo, Xuri Wang, George Aiken

Faculty Publications

Sources, abundance, isotopic compositions, and export fluxes of dissolved inorganic carbon (DIC), dissolved and colloidal organic carbon (DOC and COC), and particulate organic carbon (POC), and their response to hydrologic regimes were examined through monthly sampling from the Lower Mississippi River during 2006–2008. DIC was the most abundant carbon species, followed by POC and DOC. Concentration and δ13C of DIC decreased with increasing river discharge, while those of DOC remained fairly stable. COC comprised 61 ± 3% of the bulk DOC with similar δ13C abundances but higher percentages of hydrophobic organic acids than DOC, suggesting its …

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Effects Of Oil-Contaminated Sediments On Submerged Vegetation: An Experimental Assessment Of Ruppia Maritima, Charles W. Martin, Lauris O. Hollis, R. Eugene Turner Oct 2015

Effects Of Oil-Contaminated Sediments On Submerged Vegetation: An Experimental Assessment Of Ruppia Maritima, Charles W. Martin, Lauris O. Hollis, R. Eugene Turner

Faculty Publications

Oil spills threaten the productivity of ecosystems through the degradation of coastal flora and the ecosystem services these plants provide. While lab and field investigations have quantified the response of numerous species of emergent vegetation to oil, the effects on submerged vegetation remain uncertain. Here, we discuss the implications of oil exposure for Ruppia maritima, one of the most common species of submerged vegetation found in the region affected by the recent Deepwater Horizon oil spill. We grew R. maritima in a range of manipulated sediment oil concentrations: 0, 0.26, 0.53, and 1.05 mL oil /L tank volume, and tracked …

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Indirect Evidence For Substantial Damping Of Low-Mode Internal Tides In The Open Ocean, Joseph K. Ansong, Brian K. Arbic, Maarten C. Buijsman, James G. Richman, Jay F. Shriver, Alan J. Wallcraft Sep 2015

Indirect Evidence For Substantial Damping Of Low-Mode Internal Tides In The Open Ocean, Joseph K. Ansong, Brian K. Arbic, Maarten C. Buijsman, James G. Richman, Jay F. Shriver, Alan J. Wallcraft

Faculty Publications

A global high-resolution ocean circulation model forced by atmospheric fields and the M2 tidal constituent is used to explore plausible scenarios for the damping of low-mode internal tides. The plausibility of different damping scenarios is tested by comparing the modeled barotropic tides with TPXO8, a highly accurate satellite-altimetry-constrained tide model, and by comparing the modeled coherent baroclinic tide amplitudes against along-track altimetry. Five scenarios are tested: (1) a topographic internal wave drag, argued here to represent the breaking of unresolved high vertical modes, applied to the bottom flow (default configuration), (2) a wave drag applied to the barotropic flow, …

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Chesapeake Bay Nitrogen Fluxes Derived From A Land-Estuarine Ocean Biogeochemical Modeling System: Model Description, Evaluation, And Nitrogen Budgets, Yang Feng, Marjorie A.M. Friedrichs, John Wilkin, Hanqin Tian, Qichun Yang, Eileen E. Hofmann, Jerry D. Wiggert, Raleigh R. Hood Aug 2015

Chesapeake Bay Nitrogen Fluxes Derived From A Land-Estuarine Ocean Biogeochemical Modeling System: Model Description, Evaluation, And Nitrogen Budgets, Yang Feng, Marjorie A.M. Friedrichs, John Wilkin, Hanqin Tian, Qichun Yang, Eileen E. Hofmann, Jerry D. Wiggert, Raleigh R. Hood

Faculty Publications

The Chesapeake Bay plays an important role in transforming riverine nutrients before they are exported to the adjacent continental shelf. Although the mean nitrogen budget of the Chesapeake Bay has been previously estimated from observations, uncertainties associated with interannually varying hydrological conditions remain. In this study, a land-estuarine-ocean biogeochemical modeling system is developed to quantify Chesapeake riverine nitrogen inputs, within-estuary nitrogen transformation processes and the ultimate export of nitrogen to the coastal ocean. Model skill was evaluated using extensive in situ and satellite-derived data, and a simulation using environmental conditions for 2001–2005 was conducted to quantify the Chesapeake Bay nitrogen …

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The Evolution Of Mode-2 Nonlinear Internal Waves Over The Northern Heng-Chun Ridge South Of Taiwan, S.R. Ramp, Y.J. Yang, D.B. Reeder, Maarten C. Buijsman, F.L. Bahr Jul 2015

The Evolution Of Mode-2 Nonlinear Internal Waves Over The Northern Heng-Chun Ridge South Of Taiwan, S.R. Ramp, Y.J. Yang, D.B. Reeder, Maarten C. Buijsman, F.L. Bahr

Faculty Publications

Two research cruises were conducted from the R/V OCEAN RESEARCHER 3 during 05–16 August 2011 to study the generation and propagation of high-frequency nonlinear internal waves (NLIWs) over the northern Heng-Chun Ridge south of Taiwan. The primary study site was on top of a smaller ridge about 15 km wide by 400 m high atop the primary ridge, with a sill depth of approximately 600 m. A single mooring was used in conjunction with shipboard observations to sample the temperature, salinity and velocity structure over the ridge. All the sensors observed a profusion of mode-2 NLIWs. Some of the waves …

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Marine Sequestration Of Carbon In Bacterial Metabolites, Oliver J. Lechtenfeld, Norbert Hertkorn, Yuan Shen, Matthias Witt, Ronald Benner Mar 2015

Marine Sequestration Of Carbon In Bacterial Metabolites, Oliver J. Lechtenfeld, Norbert Hertkorn, Yuan Shen, Matthias Witt, Ronald Benner

Faculty Publications

Linking microbial metabolomics and carbon sequestration in the ocean via refractory organic molecules has been hampered by the chemical complexity of dissolved organic matter (DOM). Here, using bioassay experiments and ultra-high resolution metabolic profiling, we demonstrate that marine bacteria rapidly utilize simple organic molecules and produce exometabolites of remarkable molecular and structural diversity. Bacterial DOM is similar in chemical composition and structural complexity to naturally occurring DOM in sea water. An appreciable fraction of bacterial DOM has molecular and structural properties that are consistent with those of refractory molecules in the ocean, indicating a dominant role for bacteria in shaping …

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Dissolved Fe And Al In The Upper 1000 M Of The Eastern Indian Ocean: A High‐Resolution Transect Along 95°E From The Antarctic Margin To The Bay Of Bengal, Maxime Grand, Christopher Measures, Mariko Hatta, William Hiscock, William Landing, Peter Morton, Clifton Buck, Pamela Barrett, Joseph Resing Mar 2015

Dissolved Fe And Al In The Upper 1000 M Of The Eastern Indian Ocean: A High‐Resolution Transect Along 95°E From The Antarctic Margin To The Bay Of Bengal, Maxime Grand, Christopher Measures, Mariko Hatta, William Hiscock, William Landing, Peter Morton, Clifton Buck, Pamela Barrett, Joseph Resing

Faculty Publications

A high‐resolution section of dissolved iron (dFe) and aluminum (dAl) was obtained along ~95°E in the upper 1000 m of the eastern Indian Ocean from the Antarctic margin (66°S) to the Bay of Bengal (18°N) during the U.S. Climate Variability and Predictability (CLIVAR) CO2 Repeat Hydrography I08S and I09N sections (February–April 2007). In the Southern Ocean, low concentrations of dAl (<1 n M) reflect the negligible dust inputs impacting the water masses subducted in the circumpolar domain. The low dAl concentrations characterizing the Southern Ocean terminate near 45°S, probably because of the advection of subtropical water masses that received dust and sedimentary inputs in their formation region. Our subsurface dFe data near the southern Kerguelen Plateau were significantly higher than historical observations in other Indian sectors of the Southern Ocean. We surmise that the offshore advection of dFe‐rich waters along the western flank of the southern Kerguelen plateau and enhanced vertical mixing could contribute to this elevated subsurface dFe inventory. Elevated subsurface particulate and dFe levels downstream of the northern Kerguelen Plateau may reflect long‐range lateral transport from the plateau's sediments and/or remineralization inputs. At the northern edge of the south Indian subtropical gyre, the deposition of Australian dust, possibly combined with the advection of dAl‐enriched waters from the Indonesian Throughflow, creates a region of elevated dAl in the upper 400 m but without a corresponding enrichment in dFe. In the northern Indian Ocean, the South Equatorial Current constitutes a remarkable biogeochemical front separating the oxygen‐rich and dFe‐poor subtropical gyre waters from the dFe‐rich and oxygen‐depleted waters of the northern Indian Ocean. By tracing the accumulation of macronutrients and dFe along the advective pathway of Indian Central Water, we show that the central waters of the northern Indian Ocean receive excess dFe in addition to that produced by remineralization inputs. The resuspension of shelf sediments and release of pore waters probably contribute to the elevated dFe and dAl levels observed below the highly stratified upper layers of the Bay of Bengal.

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Dust Deposition In The Eastern Indian Ocean: The Ocean Perspective From Antarctica To The Bay Of Bengal, Maxime Grand, Christopher Measures, Mariko Hatta, William Hiscock, Clifton Buck, William Landing Mar 2015

Dust Deposition In The Eastern Indian Ocean: The Ocean Perspective From Antarctica To The Bay Of Bengal, Maxime Grand, Christopher Measures, Mariko Hatta, William Hiscock, Clifton Buck, William Landing

Faculty Publications

Atmospheric deposition is an important but still poorly constrained source of trace micronutrients to the open ocean because of the dearth of in situ measurements of total deposition (i.e., wet + dry deposition) in remote regions. In this work, we discuss the upper ocean distribution of dissolved Fe and Al in the eastern Indian Ocean along a 95°E meridional transect spanning the Antarctic margin to the Bay of Bengal. We use the mixed layer concentration of dissolved Al in conjunction with empirical data in a simple steady state model to produce 75 estimates of total dust deposition that we compare …

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Modeling The Thermosphere As A Driven-Dissipative Thermodynamic System, William R. Frey, C. S. Lin, Matthew B. Garvin, Ariel O. Acebal Apr 2014

Modeling The Thermosphere As A Driven-Dissipative Thermodynamic System, William R. Frey, C. S. Lin, Matthew B. Garvin, Ariel O. Acebal

Faculty Publications

Thermospheric density impacts satellite position and lifetime through atmospheric drag. More accurate specification of thermospheric temperature, a key input to current models such as the High Accuracy Satellite Drag Model, can decrease model density errors. This paper improves the model of Burke et al. (2009) to model thermospheric temperatures using the magnetospheric convective electric field as a driver. In better alignment with Air Force satellite tracking operations, we model the arithmetic mean temperature, T 1/2, defined by the Jacchia (1977) model as the mean of the daytime maximum and nighttime minimum exospheric temperatures occurring in opposite hemispheres at a …

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Quantifying The Impact Of Atmospheric Deposition On The Biogeochemistry Of Fe And Al In The Upper Ocean: A Decade Of Collaboration With The Us Clivar-Co2 Repeat Hydrography Program, Maxime Grand, Clifton Buck, William Landing, Christopher Measures, Mariko Hatta, William Hiscock, Matthew Brown, Joseph Resing Mar 2014

Quantifying The Impact Of Atmospheric Deposition On The Biogeochemistry Of Fe And Al In The Upper Ocean: A Decade Of Collaboration With The Us Clivar-Co2 Repeat Hydrography Program, Maxime Grand, Clifton Buck, William Landing, Christopher Measures, Mariko Hatta, William Hiscock, Matthew Brown, Joseph Resing

Faculty Publications

The aerosol deposition of continental material and its partial dissolution in the surface ocean exerts an important control on the distribution of iron and other potentially limiting trace metal (TM) micronutrients in the open ocean. This dust deposition has implications for the regulation of global climate through the coupling of biolimiting TM cycles, marine productivity, and the global carbon cycle. Thus, it is important to determine the locations of dust deposition in the open ocean and to quantify the magnitude and subsequent dissolution of the dust. At present, there are too few dust deposition estimates and solubility measurements in the …

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Design, Development, And In-Flight Testing Of A Pointer/Tracker For In-Flight Experiments To Measure Aero-Optical Effects Over A Scaled Turret, Matthew J. Krizo, Salvatore J. Cusumano, Steven T. Fiorino, Ryan Heap, Victor Velten, Joshua Brown, Richard J. Bartell Apr 2013

Design, Development, And In-Flight Testing Of A Pointer/Tracker For In-Flight Experiments To Measure Aero-Optical Effects Over A Scaled Turret, Matthew J. Krizo, Salvatore J. Cusumano, Steven T. Fiorino, Ryan Heap, Victor Velten, Joshua Brown, Richard J. Bartell

Faculty Publications

We address the design, development, and testing of a pointer/tracker as a probe beam for the purpose of making high-speed, aero-optical measurements of the flow over a scaled beam director turret. The tracker uses retro-reflection of the probe beam off of a Reflexite annulus surrounding the turret. The constraints of the design required a near-total-commercial off the shelf system that could be quickly installed and removed in a rented aircraft. Baseline measurements of environmental vibrations are used to predict pointing performance; mitigation of line-of-sight jitter on the probe beam is achieved through passive isolation and the design of relay optics. …

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Pan-Arctic Distributions Of Continental Runoff In The Arctic Ocean, Cédric G. Fichot, Karl Kaiser, Stanford B. Hooker, Rainer M.W. Amon, Marcel Babin, Simon Bélanger, Sally A. Walker, Ronald Benner Jan 2013

Pan-Arctic Distributions Of Continental Runoff In The Arctic Ocean, Cédric G. Fichot, Karl Kaiser, Stanford B. Hooker, Rainer M.W. Amon, Marcel Babin, Simon Bélanger, Sally A. Walker, Ronald Benner

Faculty Publications

Continental runoff is a major source of freshwater, nutrients and terrigenous material to the Arctic Ocean. As such, it influences water column stratification, light attenuation, surface heating, gas exchange, biological productivity and carbon sequestration. Increasing river discharge and thawing permafrost suggest that the impacts of continental runoff on these processes are changing. Here, a new optical proxy was developed and implemented with remote sensing to determine the first pan-Arctic distribution of terrigenous dissolved organic matter (tDOM) and continental runoff in the surface Arctic Ocean. Retrospective analyses revealed connections between the routing of North American runoff and the recent freshening of …

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The Global Sustainability Transition: It Is More Than Changing Light Bulbs, Michael P. Weinstein, R. Eugene Turner, Carles Ibanez Jan 2013

The Global Sustainability Transition: It Is More Than Changing Light Bulbs, Michael P. Weinstein, R. Eugene Turner, Carles Ibanez

Faculty Publications

Current policies and norms to reconcile human demands for resources with the Earth’s ability to supply them have resulted in practices that mainly treat the symptoms of unsustainability rather than their underlying causes. Moreover, the increase in our knowledge about humankind’s role in ecosystems is not keeping pace with our understanding of the consequences of our actions, resulting in a deepening inability to address sustainability issues. The extreme complexity and intricate workings of the world require the expansion of our mental models in a systems-thinking framework if we are to realize a sustainable place for humans in it. The challenge …

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Isotopic (Δ13c, Δ14c) Analysis Of Organic Acids In Marine Samples Using Wet Chemical Oxidation, Susan Q. Lang, G. L. Früh-Green, S. M. Bernasconi, L. Wacker Jan 2013

Isotopic (Δ13c, Δ14c) Analysis Of Organic Acids In Marine Samples Using Wet Chemical Oxidation, Susan Q. Lang, G. L. Früh-Green, S. M. Bernasconi, L. Wacker

Faculty Publications

We present a method for the isolation and off-line isotope analysis of formate and acetate in marine samples. Organic acids are separated by high performance liquid chromatography and collected in glass Exetainer® screw-capped vials that have been prespiked with an oxidant and flushed with helium. The vials are subsequently heated to convert the organic compounds to CO2 for radiocarbon and δ13C analysis. Small aliquots are sampled for measurement of δ13C by isotope ratio mass spectrometry, whereas the majority of the CO2 is saved for radiocarbon analysis by accelerator mass spectrometry using a gas ion …

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Dissolved Organic Matter Composition And Bioavailability Reflect Ecosystem Productivity In The Western Arctic Ocean, Yuan Shen, Cedric Fichot, Ronald Benner Dec 2012

Dissolved Organic Matter Composition And Bioavailability Reflect Ecosystem Productivity In The Western Arctic Ocean, Yuan Shen, Cedric Fichot, Ronald Benner

Faculty Publications

Dissolved organic carbon (DOC) and total dissolved amino acids (TDAA) were measured in high (Chukchi Sea) and low (Beaufort Sea) productivity regions of the western Arctic Ocean to investigate the composition and bioavailability of dissolved organic matter (DOM). Concentrations and DOC-normalized yields of TDAA in Chukchi surface waters were relatively high, indicating an accumulation of bioavailable DOM. High concentrations and yields of TDAA were also observed in the upper halocline of slope and basin waters, indicating off-shelf transport of bioavailable DOM from the Chukchi Sea. In contrast, concentrations and yields of TDAA in Beaufort surface waters were relatively low, indicting …

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Bioactive Trace Metal Distributions And Biogeochemical Controls In The Southern Ocean, Christopher Measures, Mariko Hatta, Maxime Grand Sep 2012

Bioactive Trace Metal Distributions And Biogeochemical Controls In The Southern Ocean, Christopher Measures, Mariko Hatta, Maxime Grand

Faculty Publications

Extensive sampling in many regions of the Southern Ocean has demonstrated that surface water concentrations of dissolved Fe are low enough to limit phytoplankton growth. In contrast, there is currently no evidence that other bioactive elements (e.g., Mn, Zn, Co) are similarly limiting. Although atmospheric input of dissolved Fe to Southern Ocean surface waters appears to be low, resuspension of sediments from shallow regions around islands and the Antarctic coastline can inject significant amounts of Fe into the surrounding waters, stimulating primary production and providing a natural laboratory for studying the response of biological systems to natural Fe fertilization processes. …

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Carbon Sequestration And Sediment Accretion In San Francisco Bay Tidal Wetlands, John C. Callaway, Evyan L. Borgnis, R. Eugene Turner, Charles S. Milan Jun 2012

Carbon Sequestration And Sediment Accretion In San Francisco Bay Tidal Wetlands, John C. Callaway, Evyan L. Borgnis, R. Eugene Turner, Charles S. Milan

Faculty Publications

Tidal wetlands play an important role with respect to climate change because of both their sensitivity to sea-level rise and their ability to sequester carbon dioxide from the atmosphere. Policy-based interest in carbon sequestration has increased recently, and wetland restoration projects have potential for carbon credits through soil carbon sequestration. We measured sediment accretion, mineral and organic matter accumulation, and carbon sequestration rates using 137Cs and 210Pb downcore distributions at six natural tidal wetlands in the San Francisco Bay Estuary. The accretion rates were, in general, 0.2–0.5 cm year−1, indicating that local wetlands are keeping pace with recent rates of …

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Sustainability: More About The Toolmaker Than The Tools, R. Eugene Turner Apr 2012

Sustainability: More About The Toolmaker Than The Tools, R. Eugene Turner

Faculty Publications

A sustainable system is not necessarily a high-quality one, but it could be. We could, for example, “survive” on the desperate edge, as the remnants in a self-fouled and deteriorating environment. Why won’t a future sustainable system be just another industrial model of mass efficiency and throughput? Perhaps the incompatible outcomes are a choice between the sometimes nearly invisible civilizing aspects of culture nurturing respect, equality, and cooperation on one hand, and the greed and self-indulgences undermining social tolerance, empathy, and cooperation that ends up promoting violence and dehumanization. The human heritage is subtle, indestructible, and worth nurturing if we …

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Tracing The Transport Of Colored Dissolved Organic Matter In Water Masses Of The Southern Beaufort Sea: Relationship With Hydrographic Characteristics, A. Matsuoka, A. Bricaud, Ronald Benner, J. Para, R. Sempéré, L. Prieur, S. Bélanger, M. Babin Mar 2012

Tracing The Transport Of Colored Dissolved Organic Matter In Water Masses Of The Southern Beaufort Sea: Relationship With Hydrographic Characteristics, A. Matsuoka, A. Bricaud, Ronald Benner, J. Para, R. Sempéré, L. Prieur, S. Bélanger, M. Babin

Faculty Publications

Light absorption by colored dissolved organic matter (CDOM) [aCDOM(λ)] plays an important role in the heat budget of the Arctic Ocean, contributing to the recent decline in sea ice, as well as in biogeochemical processes. We investigated aCDOM(λ) in the Southern Beaufort Sea where a significant amount of CDOM is delivered by the Mackenzie River. In the surface layer, aCDOM(440) showed a strong and negative correlation with salinity, indicating strong river influence and conservative transport in the river plume. Below the mixed layer, a weak but positive correlation between aCDOM(440) and salinity was observed above the upper halocline, resulting from …

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Photoproduction Of Ammonium In The Southeastern Beaufort Sea And Its Biogeochemical Implications, H. Xie, S. Belanger, G. Song, Ronald Benner, A. Taalba, M. Blais, J. É. Tremblay, M. Babin Jan 2012

Photoproduction Of Ammonium In The Southeastern Beaufort Sea And Its Biogeochemical Implications, H. Xie, S. Belanger, G. Song, Ronald Benner, A. Taalba, M. Blais, J. É. Tremblay, M. Babin

Faculty Publications

Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammonium (NH4+).During the August 2009 Mackenzie Light and Carbon (MALINA) Program, the absorbed photon-based efficiency spectra of NH4+ photoproduction (i.e. photoammonification) were determined using water samples from the SE Beaufort Sea, including the Mackenzie River estuary, shelf, and Canada Basin. The photoammonification efficiency decreased with increasing wavelength across the ultraviolet and visible regimes and was higher in offshore waters …

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A Molecular Perspective On The Ageing Of Marine Dissolved Organic Matter, R. Flerus, O. J. Lechtenfeld, B. P. Koch, S. L. Mccallister, P. Schmitt-Kopplin, Ronald Benner, G. Kattner Jan 2012

A Molecular Perspective On The Ageing Of Marine Dissolved Organic Matter, R. Flerus, O. J. Lechtenfeld, B. P. Koch, S. L. Mccallister, P. Schmitt-Kopplin, Ronald Benner, G. Kattner

Faculty Publications

Dissolved organic matter (DOM) was extracted by solid-phase extraction (SPE) from 137 water samples from different climate zones and different depths along an eastern Atlantic Ocean transect. The extracts were analyzed with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with electrospray ionization (ESI). Δ14C analyses were performed on subsamples of the SPE-DOM. In addition, the amount of dissolved organic carbon was determined for all water and SPE-DOM samples as well as the yield of amino sugars for selected samples. Linear correlations were observed between the magnitudes of 43 % of the FT-ICR mass peaks and the extract Δ14C …

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Marine Snow Formation In The Aftermath Of The Deepwater Horizon Oil Spill In The Gulf Of Mexico, Uta Passow, K. Ziervogel, V. Asper, A. Diercks Jan 2012

Marine Snow Formation In The Aftermath Of The Deepwater Horizon Oil Spill In The Gulf Of Mexico, Uta Passow, K. Ziervogel, V. Asper, A. Diercks

Faculty Publications

The large marine snow formation event observed in oil-contaminated surface waters of the Gulf of Mexico (GoM) after the Deepwater Horizon accident possibly played a key role in the fate of the surface oil. We characterized the unusually large and mucus-rich marine snow that formed and conducted roller table experiments to investigate their formation mechanisms. Once marine snow lost its buoyancy, its sinking velocity, porosity and excess density were then similar to those of diatom or miscellaneous aggregates. The hydrated density of the component particles of the marine snow from the GoM was remarkably variable, suggesting a wide variety of …

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A Once And Future Gulf Of Mexico Ecosystem: Restoration Recommendations Of An Expert Working Group, Charles H. Peterson, Felicia C. Coleman, Jeremy B. C. Jackson, R. Eugene Turner, Gilbert T. Rowe, Richard T. Barber, Karen A. Bjorndal, Robert S. Carney, Robert K. Cowen, Jonathan M. Hoekstra, James T. Hollibaugh, Shirley B. Laska, Richard A. Luettich, Jr., Craig W. Osenberg, Stephen E. Roady, Stanley Senner, John M. Teal, Ping Wong Sep 2011

A Once And Future Gulf Of Mexico Ecosystem: Restoration Recommendations Of An Expert Working Group, Charles H. Peterson, Felicia C. Coleman, Jeremy B. C. Jackson, R. Eugene Turner, Gilbert T. Rowe, Richard T. Barber, Karen A. Bjorndal, Robert S. Carney, Robert K. Cowen, Jonathan M. Hoekstra, James T. Hollibaugh, Shirley B. Laska, Richard A. Luettich, Jr., Craig W. Osenberg, Stephen E. Roady, Stanley Senner, John M. Teal, Ping Wong

Faculty Publications

The Deepwater Horizon (DWH) well blowout released more petroleum hydrocarbons into the marine environment than any previous U.S. oil spill (4.9 million barrels), fouling marine life, damaging deep sea and shoreline habitats and causing closures of economically valuable fisheries in the Gulf of Mexico. A suite of pollutants—liquid and gaseous petroleum compounds plus chemical dispersants—poured into ecosystems that had already been stressed by overfishing, development and global climate change. Beyond the direct effects that were captured in dramatic photographs of oiled birds in the media, it is likely that there are subtle, delayed, indirect and potentially synergistic impacts of these …

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A Hybrid Background Error Covariance Model For Assimilating Glider Data Into A Coastal Ocean Model, Max Yaremchuk, Dmitri A. Nechaev, Chudong Pan Jun 2011

A Hybrid Background Error Covariance Model For Assimilating Glider Data Into A Coastal Ocean Model, Max Yaremchuk, Dmitri A. Nechaev, Chudong Pan

Faculty Publications

A hybrid background error covariance (BEC) model for three-dimensional variational data assimilation of glider data into the Navy Coastal Ocean Model (NCOM) is introduced. Similar to existing atmospheric hybrid BEC models, the proposed model combines low-rank ensemble covariances B(m) with the heuristic Gaussian-shaped covariances B(0) to estimate forecast error statistics. The distinctive features of the proposed BEC model are the following: (i) formulation in terms of inverse error covariances, (ii) adaptive determination of the rank m of B(m) with information criterion based on the innovation error statistics, (iii) restriction of the heuristic covariance operator B(0) to the null space of …

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