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Faculty Publications

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Articles 151 - 180 of 270

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

The Ecosystem Baseline For Particle Flux In The Northern Gulf Of Mexico, S.L.C. Giering, Beizhan Yan, Vernon Asper, Arne-R. Diercks, Jeff Chanton, Masha Pitiranggon, U. Passow Jan 2018

The Ecosystem Baseline For Particle Flux In The Northern Gulf Of Mexico, S.L.C. Giering, Beizhan Yan, Vernon Asper, Arne-R. Diercks, Jeff Chanton, Masha Pitiranggon, U. Passow

Faculty Publications

Response management and damage assessment during and after environmental disasters such as the Deepwater Horizon (DWH) oil spill require an ecological baseline and a solid understanding of the main drivers of the ecosystem. During the DWH event, a large fraction of the spilled oil was transported to depth via sinking marine snow, a routing of spilled oil unexpected to emergency response planners. Because baseline knowledge of particle export in the Northern Gulf of Mexico and how it varies spatially and temporally was limited, we conducted a detailed assessment of the potential drivers of deep (~1400 m depth) particle fluxes during …

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Understanding The Structure And Resilience Of Trophic Dynamics In The Northern Gulf Of Mexico Using Network Analysis, Megumi C. Oshima, Robert T. Leaf Jan 2018

Understanding The Structure And Resilience Of Trophic Dynamics In The Northern Gulf Of Mexico Using Network Analysis, Megumi C. Oshima, Robert T. Leaf

Faculty Publications

Network analysis is a framework that allows integration and evaluation of predator-prey interactions. In the present study, we synthesized diet composition information from 94 published studies (n = 12,335 unique predator-prey interactions) that reported food habits of teleost fishes in the northern Gulf of Mexico (nGOM). Using this information, we constructed 12 weighted trophic network models using three diet metrics and four levels of taxonomic resolution of predators and prey. We evaluated network resilience to simulated random and directed taxa loss by assessing changes in topological indices "complexity," "connectance," "efficiency," and "robustness" with respect to a priori minima. We found …

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Shelf Cross-Shore Flows Under Storm-Driven Conditions: Role Of Stratification, Shoreline Orientation, And Bathymetry., Xiaodong Wu, Nirnimesh Kumar, George Voulgaris Jan 2018

Shelf Cross-Shore Flows Under Storm-Driven Conditions: Role Of Stratification, Shoreline Orientation, And Bathymetry., Xiaodong Wu, Nirnimesh Kumar, George Voulgaris

Faculty Publications

Numerical simulations are used to study the response of Long Bay, SC (USA), a typical coastal embayment with curved coastline located on the South Atlantic Bight, to realistic, climatologically defined, synoptic storm forcing. Synoptic storms, consisting of cold and warm 25 fronts as well as tropical storms, are used as forcing under both mixed and stratified initial conditions. The analysis focuses on the development of cross-shore shelf circulation and the relative contributions of regionally defined cross-shore winds and alongshore bathymetric variation. The simulation results show that, under stratified conditions, the regionally defined offshore directed wind component promotes upwelling during the …

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Biochemical And Structural Controls On The Decomposition Dynamics Of Boreal Upland Forest Moss Tissues, Michael Philben, Sara Butler, Sharon A. Billings, Ronald Benner, Kate A. Edwards, Susan E. Ziegler Jan 2018

Biochemical And Structural Controls On The Decomposition Dynamics Of Boreal Upland Forest Moss Tissues, Michael Philben, Sara Butler, Sharon A. Billings, Ronald Benner, Kate A. Edwards, Susan E. Ziegler

Faculty Publications

Mosses contribute an average of 20 % of boreal upland forest net primary productivity and are frequently observed to degrade slowly compared to vascular plants. If this is caused primarily by the chemical complexity of their tissues, moss decomposition could exhibit high temperature sensitivity (measured as Q10) due to high activation energy, which would imply that soil organic carbon (SOC) stocks derived from moss remains are especially vulnerable to decomposition with warming. Alternatively, the physical structure of the moss cell-wall biochemical matrix could inhibit decomposition, resulting in low decay rates and low temperature sensitivity. We tested these hypotheses by …

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Dinoflagellate Cysts Track Eutrophication In The Northern Gulf Of Mexico, Andrea M. Price, Melissa M. Baustian, R. Eugene Turner, Nancy N. Rabalais, Gail L. Chmura Dec 2017

Dinoflagellate Cysts Track Eutrophication In The Northern Gulf Of Mexico, Andrea M. Price, Melissa M. Baustian, R. Eugene Turner, Nancy N. Rabalais, Gail L. Chmura

Faculty Publications

We examined organic-walled dinoflagellate cysts from one 210Pb-dated sediment core and 39 surface sediment samples from the northern Gulf of Mexico to determine the relationship between nutrient enrichment and cyst assemblages in this region characterized by oxygen deficiency. The core spans from 1962 to 1997 and its sampling location is directly influenced by the Mississippi River plume. Surface sediments were collected in 2006, 2007, 2008, and 2014 and represent approximately 1 to 4 years of accumulation. A total of 57 cyst taxa were recorded, and four heterotrophic taxa in particular were found to increase in the top section (1986–1997) of …

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Thresholds Of Sea-Level Rise Rate And Sea-Level Rise Acceleration Rate In A Vulnerable Coastal Wetland, Wei Wu, Patrick D. Biber, Matthew Bethel Dec 2017

Thresholds Of Sea-Level Rise Rate And Sea-Level Rise Acceleration Rate In A Vulnerable Coastal Wetland, Wei Wu, Patrick D. Biber, Matthew Bethel

Faculty Publications

Feedbacks among inundation, sediment trapping, and vegetation productivity help maintain coastal wetlands facing sea-level rise (SLR). However, when the SLR rate exceeds a threshold, coastal wetlands can collapse. Understanding the threshold helps address key challenges in ecology—nonlinear response of ecosystems to environmental change, promotes communication between ecologists and resource managers, and facilitates decision-making in climate change policies. We studied the threshold of SLR rate and developed a new threshold of SLR acceleration rate on sustainability of coastal wetlands as SLR is likely to accelerate due to enhanced anthropogenic forces. Deriving these two thresholds depends on the temporal scale, the interaction …

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Perspectives On Chemical Oceanography In The 21st Century: Participants Of The Come Aboard Meeting Examine Aspects Of The Field In The Context Of 40 Years Of Disco, Andrea J. Fassbender, Hilary I. Palevsky, Todd R. Martz, Anitra E. Ingalls, Martha Gledhill, Sarah E. Fawcett, Jay A. Brandes, Lihini I. Aluwihare, The Participants Of Come Aboard, Disco Xxv, Christopher T. Hayes Nov 2017

Perspectives On Chemical Oceanography In The 21st Century: Participants Of The Come Aboard Meeting Examine Aspects Of The Field In The Context Of 40 Years Of Disco, Andrea J. Fassbender, Hilary I. Palevsky, Todd R. Martz, Anitra E. Ingalls, Martha Gledhill, Sarah E. Fawcett, Jay A. Brandes, Lihini I. Aluwihare, The Participants Of Come Aboard, Disco Xxv, Christopher T. Hayes

Faculty Publications

The questions that chemical oceanographers prioritize over the coming decades, and the methods we use to address these questions, will define our field's contribution to 21st century science. In recognition of this, the U.S. National Science Foundation and National Oceanic and Atmospheric Administration galvanized a community effort (the Chemical Oceanography MEeting: A BOttom-up Approach to Research Directions, or COME ABOARD) to synthesize bottom-up perspectives on selected areas of research in Chemical Oceanography. Representing only a small subset of the community, COME ABOARD participants did not attempt to identify targeted research directions for the field. Instead, we focused on how best …

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Climate Process Team On Internal Wave-Driven Ocean Mixing, Jennifer A. Mackinnon, Zhongxiang Zhao, Caitlin B. Whalen, Amy F. Waterhouse, David S. Trossman, Oliver M. Sun, Louis C. St. Laurent, Harper L. Simmons, Kurt Polzin, Robert Pinkel, Andrew Pickering, Nancy J. Norton, Jonathan D. Nash, Ruth Musgrave, Lynne M. Merchant, Angelique V. Melet, Benjamin Mater, Sonya Legg, Willima G. Large, Eric Kunze, Jody M. Klymak, Markus Jochum, Steven R. Jayne, Robert W. Hallberg, Stephen M. Griffies, Steve Diggs, Gokhan Danabasoglu, Eric P. Chassignet, Maarten C. Buijsman, Frank O. Bryan, Bruce P. Briegleb, Andrew Barna, Brian K. Arbic, Joseph K. Ansong, Matthew H. Alford Nov 2017

Climate Process Team On Internal Wave-Driven Ocean Mixing, Jennifer A. Mackinnon, Zhongxiang Zhao, Caitlin B. Whalen, Amy F. Waterhouse, David S. Trossman, Oliver M. Sun, Louis C. St. Laurent, Harper L. Simmons, Kurt Polzin, Robert Pinkel, Andrew Pickering, Nancy J. Norton, Jonathan D. Nash, Ruth Musgrave, Lynne M. Merchant, Angelique V. Melet, Benjamin Mater, Sonya Legg, Willima G. Large, Eric Kunze, Jody M. Klymak, Markus Jochum, Steven R. Jayne, Robert W. Hallberg, Stephen M. Griffies, Steve Diggs, Gokhan Danabasoglu, Eric P. Chassignet, Maarten C. Buijsman, Frank O. Bryan, Bruce P. Briegleb, Andrew Barna, Brian K. Arbic, Joseph K. Ansong, Matthew H. Alford

Faculty Publications

The study summarizes recent advances in our understanding of internal wave–driven turbulent mixing in the ocean interior and introduces new parameterizations for global climate ocean models and their climate impacts.

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Light Rare Earth Element Depletion During Deepwater Horizon Blowout Methanotrophy, Alan M. Shiller, Eric W. Chan, D.J. Joung, Molly Redmond, John D. Kessler Sep 2017

Light Rare Earth Element Depletion During Deepwater Horizon Blowout Methanotrophy, Alan M. Shiller, Eric W. Chan, D.J. Joung, Molly Redmond, John D. Kessler

Faculty Publications

Rare earth elements have generally not been thought to have a biological role. However, recent work has demonstrated that the light REEs (LREEs: La, Ce, Pr, and Nd) are essential for at least some methanotrophs, being co-factors in the XoxF type of methanol dehydrogenase (MDH). We show here that dissolved LREEs were significantly removed in a submerged plume of methane-rich water during the Deepwater Horizon (DWH) well blowout. Furthermore, incubation experiments conducted with naturally methane-enriched waters from hydrocarbon seeps in the vicinity of the DWH wellhead also showed LREE removal concurrent with methane consumption. Metagenomic sequencing of incubation …

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A Recent Project Shows That The Microbial Carbon Pump Is A Primary Mechanism Driving Ocean Carbon Uptake, Jing M. Chen, Louis Legendre, Ronald Benner Aug 2017

A Recent Project Shows That The Microbial Carbon Pump Is A Primary Mechanism Driving Ocean Carbon Uptake, Jing M. Chen, Louis Legendre, Ronald Benner

Faculty Publications

No abstract provided.

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Temperature-Modulated Expression Of Allometric Respiration Strategies Supports A Metabolic Scaling Rule, Chet F. Rakocinski, Kelsey Burns Gillam Aug 2017

Temperature-Modulated Expression Of Allometric Respiration Strategies Supports A Metabolic Scaling Rule, Chet F. Rakocinski, Kelsey Burns Gillam

Faculty Publications

A model based on the mass-specific oxygen consumption rate of the tolerant polychaete, Capitella telata, related meaningfully to a novel metabolic scaling rule as applied to the infaunal size spectrum. Depending on temperature, C. telataexpressed divergent oxyregulating or oxyconforming strategies relative to oxygen availability. A non-linear response surface fitted to the allometric exponents of a family of VO2 curves for 12 treatment combinations of DO saturation and temperature was used to project oxygen consumption rates across the infaunal size spectrum. Plasticity in respiration strategies was evident, based on four simulated dynamic 32 d oxygen-temperature exposure scenarios and …

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A Lab-On-Chip Phosphate Analyzer For Long-Term In Situ Monitoring At Fixed Observatories: Optimization And Performance Evaluation In Estuarine And Oligotrophic Coastal Waters, Maxime Grand, Geraldine Clinton-Bailey, Alexander Beaton, Allison Schaap, Thomas Johengen, Mario Tamburri, Douglas Connelly, Matthew Mowlem, Eric Achterberg Aug 2017

A Lab-On-Chip Phosphate Analyzer For Long-Term In Situ Monitoring At Fixed Observatories: Optimization And Performance Evaluation In Estuarine And Oligotrophic Coastal Waters, Maxime Grand, Geraldine Clinton-Bailey, Alexander Beaton, Allison Schaap, Thomas Johengen, Mario Tamburri, Douglas Connelly, Matthew Mowlem, Eric Achterberg

Faculty Publications

The development of phosphate sensors suitable for long-term in situdeployments in natural waters, is essential to improve our understanding of the distribution, fluxes, and biogeochemical role of this key nutrient in a changing ocean. Here, we describe the optimization of the molybdenum blue method for in situ work using a lab-on-chip (LOC) analyzer and evaluate its performance in the laboratory and at two contrasting field sites. The in situ performance of the LOC sensor is evaluated using hourly time-series data from a 56-day trial in Southampton Water (UK), as well as a month-long deployment in the subtropical oligotrophic waters of …

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Typhoon Haiyan Overwash Sediments From Leyte Gulf Coastlines Show Local Spatial Variations With Hybrid Storm And Tsunami Signatures, Janneli Lea A. Soria, Adam D. Switzer, Jessica E. Pilarczyk, Fernando P. Siringan, Nicole S. Khan, Hermann M. Fritz Aug 2017

Typhoon Haiyan Overwash Sediments From Leyte Gulf Coastlines Show Local Spatial Variations With Hybrid Storm And Tsunami Signatures, Janneli Lea A. Soria, Adam D. Switzer, Jessica E. Pilarczyk, Fernando P. Siringan, Nicole S. Khan, Hermann M. Fritz

Faculty Publications

Marine inundation associated with the 5 to 8 m storm surge of Typhoon Haiyan in 2013 left overwash sediments inland on the coastal plains of the northwestern shores of Leyte Gulf, Philippines. The Haiyan overwash deposit provides a modern sedimentary record of storm surge deposition from a Category 5 landfalling typhoon. We studied overwash sediments at two locations that experienced similar storm surge conditions but represent contrasting sedimentological regimes, namely a siliciclastic coast and a mixed siliciclastic-carbonate coast. The contrasting local geology is significantly reflected in the differences in sediment grain size, composition and sorting at the two sites. The …

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Strong Linkages Between Surface And Deep-Water Dissolved Organic Matter In The East/Japan Sea, Tae-Hoon Kim, Guebuem Kim, Yuan Shen, Ronald Benner May 2017

Strong Linkages Between Surface And Deep-Water Dissolved Organic Matter In The East/Japan Sea, Tae-Hoon Kim, Guebuem Kim, Yuan Shen, Ronald Benner

Faculty Publications

Vertical and horizontal distributions of total dissolved amino acids (TDAAs), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) were measured in the East/Japan Sea (EJS). The euphotic zone of this sea is N-limited, and the N : P ratio is ∼ 13 below 200 m depth. Elevated TDAA concentrations (137 ± 34 nM) and DOC-normalized yields (0.8 ± 0.2 % of DOC) were observed in deep waters ( ≥  1000 m) of the EJS and compared with those in the deep North Pacific Ocean. Significantly high TDAA concentrations and yields were observed in a region of deep-water formation, indicating …

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Semidiurnal Internal Tide Energy Fluxes And Their Variability In A Global Ocean Model And Moored Observations, Joseph K. Ansong, Brian K. Arbic, Matthew H. Alford, Maarten C. Buijsman, Jay F. Shriver, Zhongxiang Zhao, James G. Richman, Harper L. Simmons, Patrick G. Timko, Alan J. Wallcraft, Luis Zamudio Mar 2017

Semidiurnal Internal Tide Energy Fluxes And Their Variability In A Global Ocean Model And Moored Observations, Joseph K. Ansong, Brian K. Arbic, Matthew H. Alford, Maarten C. Buijsman, Jay F. Shriver, Zhongxiang Zhao, James G. Richman, Harper L. Simmons, Patrick G. Timko, Alan J. Wallcraft, Luis Zamudio

Faculty Publications

We examine the temporal means and variability of the semidiurnal internal tide energy fluxes in 1/25° global simulations of the Hybrid Coordinate Ocean Model (HYCOM) and in a global archive of 79 historical moorings. Low-frequency flows, a major cause of internal tide variability, have comparable kinetic energies at the mooring sites in model and observations. The computed root-mean-square (RMS) variability of the energy flux is large in both model and observations and correlates positively with the time-averaged flux magnitude. Outside of strong generation regions, the normalized RMS variability (the RMS variability divided by the mean) is nearly independent of the …

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Climate Warming Can Accelerate Carbon Fluxes Without Changing Soil Carbon Stocks, Susan E. Ziegler, Ronald Benner, Sharon A. Billings, Kate A. Edwards, Michael Philben, Xinbiao Zhu, Jerome Laganière Feb 2017

Climate Warming Can Accelerate Carbon Fluxes Without Changing Soil Carbon Stocks, Susan E. Ziegler, Ronald Benner, Sharon A. Billings, Kate A. Edwards, Michael Philben, Xinbiao Zhu, Jerome Laganière

Faculty Publications

Climate warming enhances multiple ecosystem C fluxes, but the net impact of changing C fluxes on soil organic carbon (SOC) stocks over decadal to centennial time scales remains unclear. We investigated the effects of climate on C fluxes and soil C stocks using space-for-time substitution along a boreal forest climate gradient encompassing spatially replicated sites at each of three latitudes. All regions had similar SOC concentrations and stocks (5.6 to 6.7 kg C m−2). The three lowest latitude forests exhibited the highest productivity across the transect, with tree biomass:age ratios and litterfall rates 300 and 125% higher than those in …

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Teaching In The Age Of Humans Helping Students Think About Climate Change., Grinell Smith Jan 2017

Teaching In The Age Of Humans Helping Students Think About Climate Change., Grinell Smith

Faculty Publications

To convey the magnitude and rapidity of current climate change and the severity of predictions for the next century, I present essential climate science information using four key sets of data and contextualize that information with personal anecdotes. I then consider the reasons for the large gap between the scientific consensus about anthropogenic climate change and public perceptions of that consensus. With several known challenges to climate change education in mind, I offer four recommendations for teachers that map relevant social psychology to pedagogy: (1) establish a learning community that works to disrupt in-group favoritism and reduce attribution bias; (2) …

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Using Proxy Records To Document Gulf Of Mexico Tropical Cyclones From 1820-1915, Jordan V. Pino, Robert V. Rohli, Kristine L. Delong, Grant L. Harley, Jill C. Trepanier Nov 2016

Using Proxy Records To Document Gulf Of Mexico Tropical Cyclones From 1820-1915, Jordan V. Pino, Robert V. Rohli, Kristine L. Delong, Grant L. Harley, Jill C. Trepanier

Faculty Publications

Observations of pre-1950 tropical cyclones are sparse due to observational limitations; therefore, the hurricane database HURDAT2 (1851–present) maintained by the National Oceanic and Atmospheric Administration may be incomplete. Here we provide additional documentation for HURDAT2 from historical United States Army fort records (1820–1915) and other archived documents for 28 landfalling tropical cyclones, 20 of which are included in HURDAT2, along the northern Gulf of Mexico coast. One event that occurred in May 1863 is not currently documented in the HURDAT2 database but has been noted in other studies. We identify seven tropical cyclones that occurred before 1851, three of which …

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Sources, Distributions And Dynamics Of Dissolved Organic Matter In The Canada And Makarov Basins, Yuan Shen, Ronald Benner, Lisa L. Robbins, Jonathan G. Wynn Oct 2016

Sources, Distributions And Dynamics Of Dissolved Organic Matter In The Canada And Makarov Basins, Yuan Shen, Ronald Benner, Lisa L. Robbins, Jonathan G. Wynn

Faculty Publications

A comprehensive survey of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) was conducted in the Canada and Makarov Basins and adjacent seas during 2010–2012 to investigate the dynamics of dissolved organic matter (DOM) in the Arctic Ocean. Sources and distributions of DOM in polar surface waters were very heterogeneous and closely linked to hydrological conditions. Canada Basin surface waters had relatively low DOC concentrations (69 ± 6 μmol L−1), CDOM absorption (a325: 0.32 ± 0.07 m−1) and CDOM-derived lignin phenols (3 ± 0.4 nmol L−1), and high spectral slope values (S275–295: 31.7 ± …

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Sources, Distributions, And Dynamics Of Dissolved Organic Matter In The Canada And Makarov Basins, Yuan Shen, Ronald Benner, Lisa Robbins, Jonathan Wynn Oct 2016

Sources, Distributions, And Dynamics Of Dissolved Organic Matter In The Canada And Makarov Basins, Yuan Shen, Ronald Benner, Lisa Robbins, Jonathan Wynn

Faculty Publications

A comprehensive survey of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) was conducted in the Canada and Makarov Basins and adjacent seas during 2010–2012 to investigate the dynamics of dissolved organic matter (DOM) in the Arctic Ocean. Sources and distributions of DOM in polar surface waters were very heterogeneous and closely linked to hydrological conditions. Canada Basin surface waters had relatively low DOC concentrations (69 ± 6 μmol L−1), CDOM absorption (a325: 0.32 ± 0.07 m−1) and CDOM-derived lignin phenols (3 ± 0.4 nmol L−1), and high spectral slope values (S275–295: 31.7 ± …

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Alongcoast Structure And Interannual Variability Of Seasonal Midshelf Water Properties And Velocity In The Northern California Current System, B. Hickey, S. Geier, N. Kachel, S. Ramp, P. Kosro, Thomas Connolly Oct 2016

Alongcoast Structure And Interannual Variability Of Seasonal Midshelf Water Properties And Velocity In The Northern California Current System, B. Hickey, S. Geier, N. Kachel, S. Ramp, P. Kosro, Thomas Connolly

Faculty Publications

Moored sensors were maintained for ∼5 years on the northern California Current System (CCS) midshelf. The alongcoast sensor array spanned the area of influence of the plume from the Columbia River, several submarine canyons, as well as a coastal promontory where the equatorward coastal jet frequently separates from the shelf. Upwelling-favorable wind stress magnitude decreases poleward by more than a factor of three over the latitudinal range and shelf width varies by a factor of two. In spite of the alongcoast structure in setting, both seasonal and interannual patterns in subsurface layer water properties were remarkably similar at all sites. …

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The Changshu Declaration On Wetlands, R. Eugene Turner, Jos T. A. Verhoeven, Ania Grobicki, Jenny Davis, Shuqing An Sep 2016

The Changshu Declaration On Wetlands, R. Eugene Turner, Jos T. A. Verhoeven, Ania Grobicki, Jenny Davis, Shuqing An

Faculty Publications

No abstract provided.

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Estimation Of Temporal Variations In Path-Averaged Atmospheric Refractive Index Gradient From Time-Lapse Imagery, Santasri Basu, Jack E. Mccrae, Steven T. Fiorino, Jared Przelomski Sep 2016

Estimation Of Temporal Variations In Path-Averaged Atmospheric Refractive Index Gradient From Time-Lapse Imagery, Santasri Basu, Jack E. Mccrae, Steven T. Fiorino, Jared Przelomski

Faculty Publications

The sea level vertical refractive index gradient in the U.S. Standard Atmosphere model is −2.7×10−8  m−1 at 500 nm. At any particular location, the actual refractive index gradient varies due to turbulence and local weather conditions. An imaging experiment was conducted to measure the temporal variability of this gradient. A tripod mounted digital camera captured images of a distant building every minute. Atmospheric turbulence caused the images to wander quickly, randomly, and statistically isotropically and changes in the average refractive index gradient along the path caused the images to move vertically and more slowly. The temporal variations of …

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Systematic Bias In Baroclinic Energy Estimates In Shelf Seas, Gordon R. Stephenson, J. A. Mattias Green, Mark E. Inall Sep 2016

Systematic Bias In Baroclinic Energy Estimates In Shelf Seas, Gordon R. Stephenson, J. A. Mattias Green, Mark E. Inall

Faculty Publications

A simple model of an internal wave advected by an oscillating barotropic flow suggests flaws in standard approaches to estimating properties of the internal tide. When the M2 barotropic tidal current amplitude is of similar size to the phase speed of the M2 baroclinic tide, spectral and harmonic analysis techniques lead to erroneous estimates of the amplitude, phase, and energy in the M2 internal tide. In general, harmonic fits and bandpass or low-pass filters that attempt to isolate the lowest M2 harmonic significantly underestimate the strength of M2 baroclinic energy fluxes in shelf seas. Baroclinic …

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Wartime Construction Project Outcomes As A Function Of Contract Type, Ryan M. Hoff, Gregory D. Hammond, Peter P. Feng, Edward D. White Jul 2016

Wartime Construction Project Outcomes As A Function Of Contract Type, Ryan M. Hoff, Gregory D. Hammond, Peter P. Feng, Edward D. White

Faculty Publications

The United States has spent more than $23 billion on construction in Afghanistan since 2001. The dynamic security situation created substantial project uncertainty, and many construction projects used cost-plus-fixed-fee contracts (CPFF) instead of the firm-fixed-price (FFP) norm. Using a dataset of 25 wartime construction projects managed by the Air Force Civil Engineer Center, the authors sought to confirm that both contract types yield project outcomes consistent with the established literature. As expected, they found CPFF contracts had greater cost and schedule growth than FFP. However, they did not find differences regarding as-built quality. Additionally, the authors sought to determine whether …

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A Compilation Of Global Bio-Optical In Situ Data For Ocean-Colour Satellite Applications, André Valente, Shubba Sathyendranath, Vanda Brotas, Steve Groom, Michael Grant, Malcolm Taberner, David Antoine, Robert A. Arnone Prof, William M. Balch, Kathryn Baker, Ray Barlow, Simon Bélanger, Jean-François Berthon, Sükrü Beşiktepe, Vittorio Brando, Elisabetta Canuti, Francisco Chavez, Hervé Claustre, Richard Crout, Robert Frounin, Carlos García-Soto, Stuart W. Gibb, Richard Gould, Stanford Hooker, Mati Kahru, Holger Klein, Susanne Kratzer, Hubert Loisel, David Mckee, Brian G. Mitchell, Tiffany Moisan, Frank Muller-Karger, Leonie O'Dowd, Michael Ondrusek, Alex J. Poulton, Michel Repecaud, Timothy Smythe, Heidi M. Sosik, Michael Twardowski, Kenneth Voss, Jeremy Werdell, Marcel Wernand, Giuseppe Zibordi Jun 2016

A Compilation Of Global Bio-Optical In Situ Data For Ocean-Colour Satellite Applications, André Valente, Shubba Sathyendranath, Vanda Brotas, Steve Groom, Michael Grant, Malcolm Taberner, David Antoine, Robert A. Arnone Prof, William M. Balch, Kathryn Baker, Ray Barlow, Simon Bélanger, Jean-François Berthon, Sükrü Beşiktepe, Vittorio Brando, Elisabetta Canuti, Francisco Chavez, Hervé Claustre, Richard Crout, Robert Frounin, Carlos García-Soto, Stuart W. Gibb, Richard Gould, Stanford Hooker, Mati Kahru, Holger Klein, Susanne Kratzer, Hubert Loisel, David Mckee, Brian G. Mitchell, Tiffany Moisan, Frank Muller-Karger, Leonie O'Dowd, Michael Ondrusek, Alex J. Poulton, Michel Repecaud, Timothy Smythe, Heidi M. Sosik, Michael Twardowski, Kenneth Voss, Jeremy Werdell, Marcel Wernand, Giuseppe Zibordi

Faculty Publications

A compiled set of in situ data is important to evaluate the quality of ocean-colour satellite-data records. Here we describe the data compiled for the validation of the ocean-colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI). The data were acquired from several sources (MOBY, BOUSSOLE, AERONET-OC, SeaBASS, NOMAD, MERMAID, AMT, ICES, HOT, GeP&CO), span between 1997 and 2012, and have a global distribution. Observations of the following variables were compiled: spectral remote-sensing reflectances, concentrations of chlorophyll a, spectral inherent optical properties and spectral diffuse attenuation coefficients. The data were from multi-project archives acquired via the open internet …

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Biological Hot Spots And The Accumulation Of Marine Dissolved Organic Matter In A Highly Productive Ocean Margin, Yuan Shen, Cédric G. Fichot, Sheng-Kang Liang, Ronald Benner May 2016

Biological Hot Spots And The Accumulation Of Marine Dissolved Organic Matter In A Highly Productive Ocean Margin, Yuan Shen, Cédric G. Fichot, Sheng-Kang Liang, Ronald Benner

Faculty Publications

Concentrations of dissolved organic carbon (DOC) and major biochemicals (amino acids and carbohydrates) were measured during five cruises (2009–2010) to the Louisiana margin in the northern Gulf of Mexico. Concentrations of amino acids and carbohydrates were elevated at mid-salinities and were indicative of plankton production of dissolved organic matter (DOM) in surface waters. Hot spots of two compositionally distinct types of labile DOM were identified based on the relative abundances of amino acids and carbohydrates. Amino acid-rich hot spots occurred sporadically in regions of high phytoplankton biomass and were mostly observed between dusk and dawn, reflecting a grazing source. In …

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The Removal Kinetics Of Dissolved Organic Matter And The Optical Clarity Of Groundwater, Francis H. Chapelle, Yuan Shen, Eric W. Strom, Ronald Benner Apr 2016

The Removal Kinetics Of Dissolved Organic Matter And The Optical Clarity Of Groundwater, Francis H. Chapelle, Yuan Shen, Eric W. Strom, Ronald Benner

Faculty Publications

Concentrations of dissolved organic matter (DOM) and ultraviolet/visible light absorbance decrease systematically as groundwater moves through the unsaturated zones overlying aquifers and along flowpaths within aquifers. These changes occur over distances of tens of meters (m) implying rapid removal kinetics of the chromophoric DOM that imparts color to groundwater. A one-compartment input-output model was used to derive a differential equation describing the removal of DOM from the dissolved phase due to the combined effects of biodegradation and sorption. The general solution to the equation was parameterized using a 2-year record of dissolved organic carbon (DOC) concentration changes in groundwater at …

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Influence Of The Mississippi River On Pseudo-Nitzschia Spp. Abundance And Toxicity In Louisiana Coastal Waters, Sibel Bargu, Melissa M. Baustian, Nancy N. Rabalais, Ross Del Rio, Benjamin Von Korff, R. Eugene Turner Mar 2016

Influence Of The Mississippi River On Pseudo-Nitzschia Spp. Abundance And Toxicity In Louisiana Coastal Waters, Sibel Bargu, Melissa M. Baustian, Nancy N. Rabalais, Ross Del Rio, Benjamin Von Korff, R. Eugene Turner

Faculty Publications

The presence of domoic acid (DA) toxin from multiple species of Pseudo-nitzschia is a concern in the highly productive food webs of the northern 1,* 2,3 2 1 1,4 1 1 2 3 4 Gulf of Mexico. We documented the Pseudo-­nitzschia presence, abundance, blooms, and toxicity over 3 years along a transect ∼100 km west of the Mississippi River Delta on the continental shelf. Pseudo-nitzschia were present throughout the year and occurred in high abundances (>10 cells l ) in the early spring months during high Mississippi River (MSR) flow (∼20,000 m s ) but were most abundant ( …

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Predicting Dissolved Lignin Phenol Concentrations In The Coastal Ocean From Chromophoric Dissolved Organic Matter (Cdom) Absorption Coefficients, Cédric G. Fichot, Ronald Benner, Karl Kaiser, Yuan Shen, Rainer M. W. Amon, Hiroshi Ogawa, Chua-Jung Lu Feb 2016

Predicting Dissolved Lignin Phenol Concentrations In The Coastal Ocean From Chromophoric Dissolved Organic Matter (Cdom) Absorption Coefficients, Cédric G. Fichot, Ronald Benner, Karl Kaiser, Yuan Shen, Rainer M. W. Amon, Hiroshi Ogawa, Chua-Jung Lu

Faculty Publications

Dissolved lignin is a well-established biomarker of terrigenous dissolved organic matter (DOM) in the ocean, and a chromophoric component of DOM. Although evidence suggests there is a strong linkage between lignin concentrations and chromophoric dissolved organic matter (CDOM) absorption coefficients in coastal waters, the characteristics of this linkage and the existence of a relationship that is applicable across coastal oceans remain unclear. Here, 421 paired measurements of dissolved lignin concentrations (sum of nine lignin phenols) and CDOM absorption coefficients [ag(λ)] were used to examine their relationship along the river-ocean continuum (0–37 salinity) and across contrasting coastal oceans (sub-tropical, temperate, high-latitude). …

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