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Full-Text Articles in Physical Sciences and Mathematics

Sediment Transport Model Including Short-Lived Radioisotopes: Model Description And Idealized Test Cases, Justin J. Birchler,, Courtney K. Harris, Christopher R Sherwood, Tara A. Kniskern Dec 2018

Sediment Transport Model Including Short-Lived Radioisotopes: Model Description And Idealized Test Cases, Justin J. Birchler,, Courtney K. Harris, Christopher R Sherwood, Tara A. Kniskern

VIMS Articles

Geochronologies derived from sediment cores in coastal locations are often used to infer event bed characteristics such as deposit thicknesses and accumulation rates. Such studies commonly use naturally occurring, short-lived radioisotopes, such as Beryllium-7 (Be-7) and Thorium-234 (Th-234), to study depositional and post-depositional processes. These radioisotope activities, however, are not generally represented in sediment transport models that characterize coastal flood and storm deposition with grain size patterns and deposit thicknesses. We modified the Community Sediment Transport Modeling System (CSTMS) to account for reactive tracers and used this capability to represent the behavior of these short-lived radioisotopes on the sediment bed. …


Symbiotic Unicellular Cyanobacteria Fix Nitrogen In The Arctic Ocean, K. Harding, K. A. Turk-Kubo, Rachel E. Sipler, M. M. Mills, D. A. Bronk Dec 2018

Symbiotic Unicellular Cyanobacteria Fix Nitrogen In The Arctic Ocean, K. Harding, K. A. Turk-Kubo, Rachel E. Sipler, M. M. Mills, D. A. Bronk

VIMS Articles

Biological dinitrogen (N2) fixation is an important source of nitrogen (N) in low-latitude open oceans. The unusual N2-fixing unicellular cyanobacteria (UCYN-A)/haptophyte symbiosis has been found in an increasing number of unexpected environments, including northern waters of the Danish Straight and Bering and Chukchi Seas. We used nanoscale secondary ion mass spectrometry (nanoSIMS) to measure 15N2 uptake into UCYN-A/haptophyte symbiosis and found that UCYN-A strains identical to low-latitude strains are fixing N2 in the Bering and Chukchi Seas, at rates comparable to subtropical waters. These results show definitively that cyanobacterial N2 fixation is not constrained to subtropical waters, challenging paradigms and …


Stormsense: A Blueprint For Coastal Flood Forecast Information & Automated Alert Messaging Systems, Jon Derek Loftis, Sridhar Katragadda, Sokwoo Rhee, Cuong Nguyen Oct 2018

Stormsense: A Blueprint For Coastal Flood Forecast Information & Automated Alert Messaging Systems, Jon Derek Loftis, Sridhar Katragadda, Sokwoo Rhee, Cuong Nguyen

VIMS Articles

Increased availability of low-cost water level sensors communicating through the Internet of Things (IoT) has expanded the horizons of publicly-ingestible data streams available to modern smart cities. StormSense is an IoT-enabled inundation forecasting research initiative and an active participant in the Global City Teams Challenge seeking to enhance flood preparedness in the smart cities of Hampton Roads, VA for flooding resulting from storm surge, rain, and tides. In this study, we present the a blueprint and series of applicable protocols through the use of the new StormSense water level sensors to help establish a regional resilience monitoring network. In furtherance …


Effects Of Density‐Driven Flows On The Long‐Term Morphodynamic Evolution Of Funnel‐Shaped Estuaries, Matiane Olabarrieta, W. Rockwell Geyer, Giovanni Coco, Carl T. Friedrichs Oct 2018

Effects Of Density‐Driven Flows On The Long‐Term Morphodynamic Evolution Of Funnel‐Shaped Estuaries, Matiane Olabarrieta, W. Rockwell Geyer, Giovanni Coco, Carl T. Friedrichs

VIMS Articles

Subtidal flows driven by density gradients affect the tide‐averaged sediment transport in estuaries and, therefore, can influence their long‐term morphodynamic evolution. The three‐dimensional Coupled Ocean‐Atmosphere‐Wave‐Sediment Transport modeling system is applied to numerically analyze the effects of baroclinicity and Earth's rotation on the long‐term morphodynamic evolution of idealized funnel‐shaped estuaries. The morphodynamic evolution in all the analyzed cases reproduced structures identified in many tide‐dominated estuaries: a meandering region in the fluvial‐tidal transition zone, a tidal maximum area close to the head, and a turbidity maxima region in the brackish zone. As the morphology of the estuaries evolved, the tidal propagation (including …


Impact Of Seabed Resuspension On Oxygen And Nitrogen Dynamics In The Northern Gulf Of Mexico: A Numerical Modeling Study, Julia M. Moriarty, Courtney K. Harris, Marjorie A.M. Friedrichs, Katja Fennel, Kehui Xu Oct 2018

Impact Of Seabed Resuspension On Oxygen And Nitrogen Dynamics In The Northern Gulf Of Mexico: A Numerical Modeling Study, Julia M. Moriarty, Courtney K. Harris, Marjorie A.M. Friedrichs, Katja Fennel, Kehui Xu

VIMS Articles

Resuspension affects water quality in coastal environments by entraining seabed organic matter into the water column, which can increase remineralization, alter seabed fluxes, decrease water clarity, and affect oxygen and nutrient dynamics. Nearly all numerical models of water column biogeochemistry, however, simplify seabed and bottom boundary layer processes and neglect resuspension. Here we implemented HydroBioSed, a coupled hydrodynamic-sediment transport-biogeochemical model to examine the role of resuspension in regulating oxygen and nitrogen dynamics on timescales of a day to a month. The model was implemented for the northern Gulf of Mexico, where the extent of summertime hypoxia is sensitive to seabed …


Stoichiometric N:P Ratios, Temperature, And Iron Impact Carbon And Nitrogen Uptake By Ross Sea Microbial Communities, Jl Spackeen, Da Bronk, Rachel E. Sipler, Em Bertrand, Da Hutchins, Ae Allen Sep 2018

Stoichiometric N:P Ratios, Temperature, And Iron Impact Carbon And Nitrogen Uptake By Ross Sea Microbial Communities, Jl Spackeen, Da Bronk, Rachel E. Sipler, Em Bertrand, Da Hutchins, Ae Allen

VIMS Articles

The Southern Ocean is one of the most biologically important ecosystems on our planet. Microscopic plants, called phytoplankton, form the base of the food web in the Southern Ocean and play a direct role in regulating how much and how fast elements like nitrogen and carbon are cycled throughout the world ocean. The goal of this research was to determine how predicted changes in the environment will impact how fast phytoplankton use these elements. The conditions that we tested included elevated temperature, addition of iron, and the proportion of nitrogen to phosphorus in the seawater. These parameters were selected because …


Estimating Hypoxic Volume In The Chesapeake Bay Using Two Continuously Sampled Oxygen Profiles, Aaron J. Bever, Marjorie A.M. Friedrichs, Carl T. Friedrichs, Malcolm E. Scully Aug 2018

Estimating Hypoxic Volume In The Chesapeake Bay Using Two Continuously Sampled Oxygen Profiles, Aaron J. Bever, Marjorie A.M. Friedrichs, Carl T. Friedrichs, Malcolm E. Scully

VIMS Articles

Low levels of dissolved oxygen (DO) occur in many embayments throughout the world and have numerous detrimental effects on biota. Although measurement of in situ DO is straightforward with modern instrumentation, quantifying the volume of water in a given embayment that is hypoxic (hypoxic volume (HV)) is a more difficult task; however, this information is critical for determining whether management efforts to increase DO are having an overall impact. This paper uses output from a three‐dimensional numerical model to demonstrate that HV in Chesapeake Bay can be estimated well with as few as two vertical profiles. In addition, the cumulative …


Role Of Sediment Resuspension On Estuarine Suspended Particulate Mercury Dynamics, Ea Seelen, Grace M. Massey, Rp Mason Jul 2018

Role Of Sediment Resuspension On Estuarine Suspended Particulate Mercury Dynamics, Ea Seelen, Grace M. Massey, Rp Mason

VIMS Articles

Coastal sediments are an important site for transient and long-term mercury (Hg) storage, and they foster a geochemical environment optimal for Hg methylation. Therefore, efforts have been taken to constrain the role of sediments as a source of methylmercury (MeHg) to the estuarine water column. This study employed the Gust Microcosm Erosion Core system capable of quantifying particle removal from undisturbed cores under measurable shear stress conditions to assess particulate Hg and MeHg exchange between sediments and the water column. Samples were collected from organic-rich and organic-poor sediment types from the mid- and lower Delaware Bay. It was found that …


Impacts Of Atmospheric Nitrogen Deposition And Coastal Nitrogen Fluxes On Oxygen Concentrations In Chesapeake Bay, Fei Da, Marjorie A.M. Friedrichs, Pierre St-Laurent Jul 2018

Impacts Of Atmospheric Nitrogen Deposition And Coastal Nitrogen Fluxes On Oxygen Concentrations In Chesapeake Bay, Fei Da, Marjorie A.M. Friedrichs, Pierre St-Laurent

VIMS Articles

Although rivers are the primary source of dissolved inorganic nitrogen (DIN) inputs to the Chesapeake Bay, direct atmospheric DIN deposition and coastal DIN concentrations on the continental shelf can also significantly influence hypoxia; however, the relative impact of these additional sources of DIN on Chesapeake Bay hypoxia has not previously been quantified. In this study, the estuarine‐carbon‐biogeochemistry model embedded in the Regional‐Ocean‐Modeling‐System (ChesROMS‐ECB) is used to examine the relative impact of these three DIN sources. Model simulations highlight that DIN from the atmosphere has roughly the same impact on hypoxia as the same gram‐for‐gram change in riverine DIN …


Role Of Baroclinic Processes On Flushing Characteristics In A Highly Stratified Estuarine System, Mobile Bay, Alabama, Jiabi Du, Kyeong Park, Jian Shen, Et Al Jun 2018

Role Of Baroclinic Processes On Flushing Characteristics In A Highly Stratified Estuarine System, Mobile Bay, Alabama, Jiabi Du, Kyeong Park, Jian Shen, Et Al

VIMS Articles

Flushing of an estuary quantifies the overall water exchange between the estuary and coastal ocean and is crucially important for water quality as well as biological and geochemical processes within the system. Flushing times and freshwater age in Mobile Bay were numerically calculated under realistic and various controlled forcing conditions. Their responses to external forcing were explained by the three‐dimensional characteristics of general circulation in the system. The flushing time ranges from 10 to 33 days under the 25th–75th percentile river discharges, nearly half of the previous estimates based on barotropic processes only, suggesting the important contribution of baroclinic processes. …


Tidal Response To Sea-Level Rise In Different Types Of Estuaries: The Importance Of Length, Bathymetry, And Geometry, Jb Du, Jian Shen, Yinglong J. Zhang, Fei Ye, Z Liu, Zg Wang, Yp Wang, X Yu, M Sisson, Harry V. Wang Jan 2018

Tidal Response To Sea-Level Rise In Different Types Of Estuaries: The Importance Of Length, Bathymetry, And Geometry, Jb Du, Jian Shen, Yinglong J. Zhang, Fei Ye, Z Liu, Zg Wang, Yp Wang, X Yu, M Sisson, Harry V. Wang

VIMS Articles

Tidal response to sea-level rise (SLR) varies in different coastal systems. To provide a generic pattern of tidal response to SLR, a systematic investigation was conducted using numerical techniques applied to idealized and realistic estuaries, with model results cross-checked by analytical solutions. Our results reveal that the response of tidal range to SLR is nonlinear, spatially heterogeneous, and highly affected by the length and bathymetry of an estuary and weakly affected by the estuary convergence with an exception of strong convergence. Contrary to the common assumption that SLR leads to a weakened bottom friction, resulting in increased tidal amplitude, we …


Integrated Ocean, Earth, And Atmospheric Observations For Resilience Planning In Hampton Roads, Virginia, Jon Derek Loftis, Molly Mitchell, Larry Atkinson, Ben Hamlington, Thomas R. Allen, David R. Forrest, Et Al Jan 2018

Integrated Ocean, Earth, And Atmospheric Observations For Resilience Planning In Hampton Roads, Virginia, Jon Derek Loftis, Molly Mitchell, Larry Atkinson, Ben Hamlington, Thomas R. Allen, David R. Forrest, Et Al

VIMS Articles

Building flood resilience in coastal communities requires a precise understanding of the temporal and spatial scales of inundation and the ability to detect and predict changes in flooding. In Hampton Roads, the Intergovernmental Pilot Project's Scientific Advisory Committee recommended an integrated network of ocean, earth, and atmospheric data collection from both private and public sector organizations that engage in active scientific monitoring and observing. Since its establishment, the network has grown to include monitoring of water levels, land subsidence, wave measurements, current measurements, and atmospheric conditions. High-resolution land elevation and land cover data sets have also been developed. These products …


Stormsense: A New Integrated Network Of Iot Water Level Sensors In The Smart Cities Of Hampton Roads, Va, Jon Derek Loftis, David R. Forrest, Sridhar Katragadda, Kyle Spencer, Tammie Organski, Cuong Nguyen, Sokwoo Rhee Jan 2018

Stormsense: A New Integrated Network Of Iot Water Level Sensors In The Smart Cities Of Hampton Roads, Va, Jon Derek Loftis, David R. Forrest, Sridhar Katragadda, Kyle Spencer, Tammie Organski, Cuong Nguyen, Sokwoo Rhee

VIMS Articles

Propagation of cost-effective water level sensors powered through the Internet of Things (IoT) has expanded the available offerings of ingestible data streams at the disposal of modern smart cities. StormSense is an IoT-enabled inundation forecasting research initiative and an active participant in the Global City Teams Challenge, seeking to enhance flood preparedness in the smart cities of Hampton Roads, VA, for flooding resulting from storm surge, rain, and tides. In this study, we present the results of the new StormSense water level sensors to help establish the “regional resilience monitoring network” noted as a key recommendation from the Intergovernmental Pilot …


Effects Of Projected Changes In Wind, Atmospheric Temperature, And Freshwater Inflow On The Ross Sea, Ms Dinniman, Jm Klinck, Ee Hofmann, Walker O. Smith Jr. Jan 2018

Effects Of Projected Changes In Wind, Atmospheric Temperature, And Freshwater Inflow On The Ross Sea, Ms Dinniman, Jm Klinck, Ee Hofmann, Walker O. Smith Jr.

VIMS Articles

A 5-km horizontal resolution regional ocean-sea ice-ice shelf model of the Ross Sea is used to examine the effects of changes in wind strength, air temperature, and increased meltwater input on the formation of high-salinity shelf water (HSSW), on-shelf transport and vertical mixing of Circumpolar Deep Water (CDW) and its transformation into modified CDW (MCDW), and basal melt of the Ross Ice Shelf (RIS). A 20% increase in wind speed, with no other atmospheric changes, reduced summer sea ice minimum area by 20%, opposite the observed trend of the past three decades. Increased winds with spatially uniform, reduced atmospheric temperatures …


Multi-Decadal Trends And Variability In Temperature And Salinity In The Mid-Atlantic Bight, Georges Bank, And Gulf Of Maine, Elizabeth J. Wallace, Lev B. Looney, Donglai Gong Jan 2018

Multi-Decadal Trends And Variability In Temperature And Salinity In The Mid-Atlantic Bight, Georges Bank, And Gulf Of Maine, Elizabeth J. Wallace, Lev B. Looney, Donglai Gong

VIMS Articles

Increasing attention is being placed on the regional impact of climate change. This study focuses on the decadal scale variabilities of temperature and salinity in the Mid-Atlantic Bight (MAB), Georges Bank (GB), and Gulf of Maine (GOM) from 1977 to 2016 using hydrographic survey data from the National Oceanic and Atmospheric Administration (NOAA) Northeast Fisheries Science Center. The MAB (as defined by the shelf regions from Cape Hatteras to Cape Cod) experienced warming rates of 0.57 ◦C per decade during the Winter/Spring season (Jan–Apr) and 0.47 ◦C per decade during the Fall/Winter season (Sep–Dec). The GOM and GB, on the …