Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

2024

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 25951 - 25980 of 27055

Full-Text Articles in Entire DC Network

Integrating Climatological-Hydrodynamic Modeling And Paleohurricane Records To Assess Storm Surge Risk, Amirhosein Begmohammadi, Christine Y. Blackshaw, Ning Lin, Avantika Gori, Elizabeth Wallace, Kerry Emanuel, Jeffrey P. Donnelly Jan 2024

Integrating Climatological-Hydrodynamic Modeling And Paleohurricane Records To Assess Storm Surge Risk, Amirhosein Begmohammadi, Christine Y. Blackshaw, Ning Lin, Avantika Gori, Elizabeth Wallace, Kerry Emanuel, Jeffrey P. Donnelly

OES Faculty Publications

Sediment cores from blue holes have emerged as a promising tool for extending the record of long-term tropical cyclone (TC) activity. However, interpreting this archive is challenging because storm surge depends on many parameters including TC intensity, track, and size. In this study, we use climatological-hydrodynamic modeling to interpret paleohurricane sediment records between 1851 and 2016 and assess the storm surge risk for Long Island in The Bahamas. As the historical TC data from 1988 to 2016 is too limited to estimate the surge risk for this area, we use historical event attribution in paleorecords paired with synthetic storm modeling …

Go to article

Last Millennium Hurricane Activity Linked To Endogenous Climate Variability, Wenchang Yang, Elizabeth Wallace, Gabriel A. Vecchi, Jeffrey P. Donnelly, Julien Emile-Geay, Gregory J. Hakim, Larry W. Horowitz, Richard M. Sullivan, Robert Tardif, Peter J. Van Hengstum, Tyler S. Winkler Jan 2024

Last Millennium Hurricane Activity Linked To Endogenous Climate Variability, Wenchang Yang, Elizabeth Wallace, Gabriel A. Vecchi, Jeffrey P. Donnelly, Julien Emile-Geay, Gregory J. Hakim, Larry W. Horowitz, Richard M. Sullivan, Robert Tardif, Peter J. Van Hengstum, Tyler S. Winkler

OES Faculty Publications

Despite increased Atlantic hurricane risk, projected trends in hurricane frequency in the warming climate are still highly uncertain, mainly due to short instrumental record that limits our understanding of hurricane activity and its relationship to climate. Here we extend the record to the last millennium using two independent estimates: a reconstruction from sedimentary paleohurricane records and a statistical model of hurricane activity using sea surface temperatures (SSTs). We find statistically significant agreement between the two estimates and the late 20th century hurricane frequency is within the range seen over the past millennium. Numerical simulations using a hurricane-permitting climate model suggest …

Go to article

Integrating Climatological-Hydrodynamic Modeling And Paleohurricane Records To Assess Storm Surge Risk, Amirhosein Begmohammadi, Christine Y. Blackshaw, Ning Lin, Avantika Gori, Elizabeth Wallace, Kerry Emanuel, Jeffrey P. Donnelly Jan 2024

Integrating Climatological-Hydrodynamic Modeling And Paleohurricane Records To Assess Storm Surge Risk, Amirhosein Begmohammadi, Christine Y. Blackshaw, Ning Lin, Avantika Gori, Elizabeth Wallace, Kerry Emanuel, Jeffrey P. Donnelly

OES Faculty Publications

Sediment cores from blue holes have emerged as a promising tool for extending the record of long-term tropical cyclone (TC) activity. However, interpreting this archive is challenging because storm surge depends on many parameters including TC intensity, track, and size. In this study, we use climatological-hydrodynamic modeling to interpret paleohurricane sediment records between 1851 and 2016 and assess the storm surge risk for Long Island in The Bahamas. As the historical TC data from 1988 to 2016 is too limited to estimate the surge risk for this area, we use historical event attribution in paleorecords paired with synthetic storm modeling …

Go to article

Re-Evaluating Hydrogen Sulfide As A Sink For Cadmium And Zinc In The Oxic To Suboxic Upper Water Column Of The Pacific Ocean, N. R. Buckley, E. E. Black, J. A. Kenyon, N. T. Lanning, M. Sieber, T. M. Conway, J. N. Fitzsimmons, G. A. Cutter Jan 2024

Re-Evaluating Hydrogen Sulfide As A Sink For Cadmium And Zinc In The Oxic To Suboxic Upper Water Column Of The Pacific Ocean, N. R. Buckley, E. E. Black, J. A. Kenyon, N. T. Lanning, M. Sieber, T. M. Conway, J. N. Fitzsimmons, G. A. Cutter

OES Faculty Publications

Hydrogen sulfide is produced by heterotrophic bacteria in anoxic waters and via carbonyl sulfide hydrolysis and phytoplankton emissions under oxic conditions. Apparent losses of dissolved cadmium (dCd) and zinc (dZn) in oxygen minimum zones (OMZs) of the Atlantic and Pacific Oceans have been attributed to metal-sulfide precipitation formed via dissimilatory sulfate reduction. It has also been argued that such a removal process could be a globally important sink for dCd and dZn. However, our studies from the North Pacific OMZ show that dissolved and particulate sulfide concentrations are insufficient to support the removal of dCd via precipitation. In contrast, apparent …

Go to article

Quantifying Potential Marine Debris Sources And Potential Threats To Penguins On The West Antarctic Peninsula, Katherine L. Gallagher, Megan A. Cimino, Michael S. Dinniman, Heather J. Lynch Jan 2024

Quantifying Potential Marine Debris Sources And Potential Threats To Penguins On The West Antarctic Peninsula, Katherine L. Gallagher, Megan A. Cimino, Michael S. Dinniman, Heather J. Lynch

OES Faculty Publications

Marine pollution is becoming ubiquitous in the environment. Observations of pollution on beaches, in the coastal ocean, and in organisms in the Antarctic are becoming distressingly common. Increasing human activity, growing tourism, and an expanding krill fishing industry along the West Antarctic Peninsula all represent potential sources of plastic pollution and other debris (collectively referred to as debris) to the region. However, the sources of these pollutants from point (pollutants released from discrete sources) versus non-point (pollutants from a large area rather than a specific source) sources are poorly understood. We used buoyant simulated particles released in a high-resolution physical …

Go to article

Ratification Of The Base Of The Ics Geological Time Scale: The Global Standard Stratigraphic Age (Gssa) For The Hadean Lower Boundary, Janna Halla, Nora Noffke, Humberto Reis, Stanley Awramik, Andrey Bekker, Alexander Brasier, Flávia Callefo, Adrita Choudhury, Jan-Peter Duda, Christopher Fedo, Douglas Galante, Jessica Haddock, Peter Haines, Linda Hinnov, Axel Hofmann, Martin Homann, David Huston, Simon Johnson, Linda Kah, Martin Whitehouse, Et Al. Jan 2024

Ratification Of The Base Of The Ics Geological Time Scale: The Global Standard Stratigraphic Age (Gssa) For The Hadean Lower Boundary, Janna Halla, Nora Noffke, Humberto Reis, Stanley Awramik, Andrey Bekker, Alexander Brasier, Flávia Callefo, Adrita Choudhury, Jan-Peter Duda, Christopher Fedo, Douglas Galante, Jessica Haddock, Peter Haines, Linda Hinnov, Axel Hofmann, Martin Homann, David Huston, Simon Johnson, Linda Kah, Martin Whitehouse, Et Al.

OES Faculty Publications

The base of the ICS (International Commission on Stratigraphy) Geological Time Scale was ratified in 2022 by defining a new Global Stratigraphic Standard Age (GSSA) for the lower boundary of the Hadean Eon (formerly 4000-3600 Ma); the age of the Solar System based on the oldest solids, calcium-aluminium inclusions (CAIs), generated in the protoplanetary disk. The formal GSSA for the Hadean base is the oldest reliable, weighted mean U-corrected Pb-Pb age of 4567.30 ± 0.16 Ma obtained for CAIs in primitive meteorites Allende and Efremovka. This age is supported by the 4568-4567 Ma U-corrected Pb-Pb ages of chondrules in Northwest …

Go to article

The Impacts Of Anthropogenic Activity And Climate Change On The Formation Of Harmful Algal Blooms (Habs) And Its Ecological Consequence, Zhangxi Hu, Aifeng Li, Zhun Li, Margaret R. Mulholland Jan 2024

The Impacts Of Anthropogenic Activity And Climate Change On The Formation Of Harmful Algal Blooms (Habs) And Its Ecological Consequence, Zhangxi Hu, Aifeng Li, Zhun Li, Margaret R. Mulholland

OES Faculty Publications

No abstract provided.

Go to article

A Comparison Of Adenosine Triphosphate With Other Metrics Of Microbial Biomass In A Gradient From The North Atlantic To The Chesapeake Bay, Alexander B. Bochdansky, Amber A. Beecher, Joshua R. Calderon, Alison N. Stouffer, Nyjaee N. Washington Jan 2024

A Comparison Of Adenosine Triphosphate With Other Metrics Of Microbial Biomass In A Gradient From The North Atlantic To The Chesapeake Bay, Alexander B. Bochdansky, Amber A. Beecher, Joshua R. Calderon, Alison N. Stouffer, Nyjaee N. Washington

OES Faculty Publications

A new, simplified protocol for determining particulate adenosine triphosphate (ATP) levels allows for the assessment of microbial biomass distribution in aquatic systems at a high temporal and spatial resolution. A comparison of ATP data with related variables, such as particulate carbon, nitrogen, chlorophyll, and turbidity in pelagic samples, yielded significant and strong correlations in a gradient from the tributaries of the Chesapeake Bay (sigma-t = 8) to the open North Atlantic (sigma-t = 29). Correlations varied between ATP and biomass depending on the microscopic method employed. Despite the much greater effort involved, biomass determined by microscopy correlated poorly with other …

Go to article

Nitrogen Fixation At The Mid-Atlantic Bight Shelfbreak And Transport Of Newly Fixed Nitrogen To The Slope Sea, C. R. Selden, M. R. Mulholland, K. E. Crider, S. Clayton, A. Macías-Tapia, P. Bernhardt, D. J. Mcgillicuddy Jr., W. G. Zhang, P. D. Chappell Jan 2024

Nitrogen Fixation At The Mid-Atlantic Bight Shelfbreak And Transport Of Newly Fixed Nitrogen To The Slope Sea, C. R. Selden, M. R. Mulholland, K. E. Crider, S. Clayton, A. Macías-Tapia, P. Bernhardt, D. J. Mcgillicuddy Jr., W. G. Zhang, P. D. Chappell

OES Faculty Publications

Continental shelves contribute a large fraction of the ocean's new nitrogen (N) via N2 fixation; yet, we know little about how physical processes at the ocean's margins shape diazotroph biogeography and activity. Here, we test the hypothesis that frontal mixing favors N2 fixation at the Mid-Atlantic Bight shelfbreak. Using the 15N2 bubble release method, we measured N2 fixation rates on repeat cross-frontal transects in July 2019. N2 fixation rates in shelf waters (median = 5.42 nmol N L−1 d−1) were higher than offshore (2.48 nmol N L−1 d−1) …

Go to article

Ice-Marginal Lava Delta In Iceland Found On A Nondescript Shallow Slope: An Unexpected Record Of Ice Thickness Late In Deglacian, Audrey Putnam, Kirsten Siebach, Candice Bedford, Sarah Simpson, Elizabeth Rampe, Joseph Tamborski, Michael Thorpe Jan 2024

Ice-Marginal Lava Delta In Iceland Found On A Nondescript Shallow Slope: An Unexpected Record Of Ice Thickness Late In Deglacian, Audrey Putnam, Kirsten Siebach, Candice Bedford, Sarah Simpson, Elizabeth Rampe, Joseph Tamborski, Michael Thorpe

OES Faculty Publications

Volcanism increases when glaciers melt because isostatic rebound during deglaciation decreases the pressure on the mantle, which enhances decompression melting. Anthropogenic climate change is now causing ice sheets and valley glaciers to melt around the world and this deglaciation could stimulate volcanic activity and associated hazards in Iceland, Antarctica, Alaska, and Patagonia. However, current model predictions for volcanic activity associated with anthropogenic deglaciation in Iceland are poorly constrained, in part due to uncertainties in past volcanic output over time compared to ice sheet arrangements. Further work specifically characterizing glaciovolcanic and ice-marginal volcanoes in Iceland is needed to reconstruct volcanic output …

Go to article

Intercalibration: A Cornerstone Of The Success Of The Geotraces Program, Ana Aguilar-Islas, Hélène Planquette, Maeve C. Lohan, Walter Geibert, Gregory Cutter Jan 2024

Intercalibration: A Cornerstone Of The Success Of The Geotraces Program, Ana Aguilar-Islas, Hélène Planquette, Maeve C. Lohan, Walter Geibert, Gregory Cutter

OES Faculty Publications

The international GEOTRACES program was developed to enhance knowledge about the distribution of trace elements and their isotopes (TEIs) in the ocean and to reduce the uncertainty about their sources, sinks, and internal cycling. Recognizing the importance of intercalibration from the outset, GEOTRACES implemented intercalibration efforts early in the program, and consensus materials were generated that included the full range of TEIs dissolved in seawater, in suspended particles, and from aerosols. The GEOTRACES section cruises include “crossover station(s)” that are occupied by two or more sections and whereby all aspects of sample collection, preservation, and processing can be compared and …

Go to article

Nitrogen Uptake Rates And Phytoplankton Composition Across Contrasting North Atlantic Ocean Coastal Regimes North And South Of Cape Hatteras, Yifan Zhu, Margaret R. Mulholland, Peter W. Bernhardt, Aimee Renee Neeley, Brittany Widner, Alfonso Macías Tapia, Michael E. Echevarria Jan 2024

Nitrogen Uptake Rates And Phytoplankton Composition Across Contrasting North Atlantic Ocean Coastal Regimes North And South Of Cape Hatteras, Yifan Zhu, Margaret R. Mulholland, Peter W. Bernhardt, Aimee Renee Neeley, Brittany Widner, Alfonso Macías Tapia, Michael E. Echevarria

OES Faculty Publications

Understanding nitrogen (N) uptake rates respect to nutrient availability and the biogeography of phytoplankton communities is crucial for untangling the complexities of marine ecosystems and the physical, biological, and chemical forces shaping them. In the summer of 2016, we conducted measurements of bulk microbial uptake rates for six ¹⁵N-labeled substrates: nitrate, nitrite, ammonium, urea, cyanate, and dissolve free amino acids across distinct marine provinces, including the continental shelf of the Mid-and South Atlantic Bights (MAB and SAB), the Slope Sea, and the Gulf Stream, marking the first instance of simultaneously measuring six different N uptake rates in this dynamic region. …

Go to article

Editorial: The Marine Iodine Cycle, Past, Present, And Future, Rosie Chance, Gregory A. Cutter, Dalton S. Hardisty, Anoop S. Mahajan Jan 2024

Editorial: The Marine Iodine Cycle, Past, Present, And Future, Rosie Chance, Gregory A. Cutter, Dalton S. Hardisty, Anoop S. Mahajan

OES Faculty Publications

In this Research Topic, we bring together ten articles from the diverse research communities interested in the marine iodine cycle, including paleoceanographers, atmospheric chemists, and biogeochemists. The physical chemistry underpinning iodine’s chemical speciation and transformations in the ocean is reviewed by Luther; this paper provides a theoretical basis for the field observations presented in this Research Topic.

Go to article

An Inconsistent Enso Response To Northern Hemisphere Stadials Over The Last Deglaciation, Ryan H. Glaubke, Matthew W. Schmidt, Jennifer E. Hertzberg, Lenzie G. Ward, Franco Marcantonio, Danielle Schimmenti, Kaustubh Thirumalai Jan 2024

An Inconsistent Enso Response To Northern Hemisphere Stadials Over The Last Deglaciation, Ryan H. Glaubke, Matthew W. Schmidt, Jennifer E. Hertzberg, Lenzie G. Ward, Franco Marcantonio, Danielle Schimmenti, Kaustubh Thirumalai

OES Faculty Publications

The dynamics shaping the El Niño-Southern Oscillation's (ENSO) response to present and future climate change remain unclear, partly due to limited paleo-ENSO records spanning past abrupt climate events. Here, we measure Mg/Ca ratios on individual foraminifera to reconstruct east Pacific subsurface temperature variability, a proxy for ENSO variability, across the last 25,000 years, including the millennial-scale events of the last deglaciation. Combining these data with proxy system model output reveals divergent ENSO responses to Northern Hemisphere stadials: enhanced variability during Heinrich Stadial 1 (H1) and reduced variability during the Younger Dryas (YD), relative to the Holocene. H1 ENSO likely intensified …

Go to article

4500-Year Paleohurricane Record From The Western Gulf Of Mexico, Coastal Central Tx, Usa, Sarah B. Monica, Davin J. Wallace, Elizabeth J. Wallace, Xiaojing Du, Sylvia G. Dee, John B. Anderson Jan 2024

4500-Year Paleohurricane Record From The Western Gulf Of Mexico, Coastal Central Tx, Usa, Sarah B. Monica, Davin J. Wallace, Elizabeth J. Wallace, Xiaojing Du, Sylvia G. Dee, John B. Anderson

OES Faculty Publications

Texas receives the second-highest number of tropical cyclone (TC) landfalls per year in the United States. At present, long-term TC projections from climate models remain uncertain due to the short and biased nature of Atlantic TC observations. Sediment archives of past storms can help extend the observational record of TC strikes over the past few millennia. When a TC makes landfall along the central Texas coast, coastal downwelling channels and storm currents transport and deposit coarse sediment to a zone of rapid accumulation along the shelf, known as the Texas Mud Blanket (TMB). This “backwash” process results in expansive storm …

Go to article

A Proxy System Modeling Approach To Combining Tree-Ring And Sediment-Based Paleotempestological Records, Elizabeth J. Wallace, Sylvia Dee, Joshua Bregy, Kerry A. Emanuel Jan 2024

A Proxy System Modeling Approach To Combining Tree-Ring And Sediment-Based Paleotempestological Records, Elizabeth J. Wallace, Sylvia Dee, Joshua Bregy, Kerry A. Emanuel

OES Faculty Publications

The short and biased observational record of tropical cyclones (TCs) limits scientific understanding of how these destructive storms respond to climate forcing. Paleohurricane records use natural archives (tree rings, coarse-grained sediment) to reconstruct TC properties (frequency and intensity of rainfall, wind) over the past few hundreds to thousands of years. However, different sensitivities and sampling biases in the various paleohurricane proxies restrict our ability to compile these records into regional or basin-scale TC estimates. Here we test how well pseudo tree-ring records of paleohurricanes capture TC rainfall and occurrence. Using a large set of statistically downscaled storms forced with the …

Go to article

Submarine Groundwater Discharge At A Mega-Tidal Beach, Raymond D. Craddock, Aaron A. Mohammed, Joseph J. Tamborski, Barret L. Kurylyk Jan 2024

Submarine Groundwater Discharge At A Mega-Tidal Beach, Raymond D. Craddock, Aaron A. Mohammed, Joseph J. Tamborski, Barret L. Kurylyk

OES Faculty Publications

Tidally influenced groundwater systems in coastal environments represent important mixing zones of fresh groundwater and circulating seawater, manifesting as submarine groundwater discharge (SGD). Water circulation induced by tidal pumping enhances the exchange of chemicals between aquifers and coastal waters and thereby influences the biogeochemistry of coastal zones. Here, we report the results of an SGD field study conducted at a steep, mega-tidal sand and gravel beach along the Canadian coast of the Bay of Fundy, a region with the world's highest tides (semi-diurnal tidal ranges exceeding 10 m). Several physical and geochemical measurement techniques were employed to document the spatiotemporal …

Go to article

Contrasting Nitrogen Dynamics Across The Mid-Atlantic Bight Shelfbreak Front: Insights From Nitrate Dual Isotopes And Nitrifier Gene Abundance, Yifan Zhu, Margaret R. Mulholland, Corday R. Selden, Dennis J. Mcgillicuddy Jr., Josie Mottram, P. Dreux Chappell, Weifang Gordon Zhang, Julie Granger, Katherine E. Crider, Meredith G. Meyer, Peter W. Bernhardt, Hilde Oliver, Sophie Clayton Jan 2024

Contrasting Nitrogen Dynamics Across The Mid-Atlantic Bight Shelfbreak Front: Insights From Nitrate Dual Isotopes And Nitrifier Gene Abundance, Yifan Zhu, Margaret R. Mulholland, Corday R. Selden, Dennis J. Mcgillicuddy Jr., Josie Mottram, P. Dreux Chappell, Weifang Gordon Zhang, Julie Granger, Katherine E. Crider, Meredith G. Meyer, Peter W. Bernhardt, Hilde Oliver, Sophie Clayton

OES Faculty Publications

Observations and model studies suggest that front dynamics can enhance phytoplankton productivity. This study tested whether frontal systems also increase the abundance of nitrifying microbes and nitrogen recycling during repeat sampling transects across the Mid‐Atlantic Bight shelfbreak in July 2019. We measured ammonium concentrations, nitrate dual isotopes (δ15N, δ18O), and ammonia monooxygenase subunit A (amoA) genes of ammonia‐oxidizing archaea (AOA) and bacteria (AOB). In subsurface shelf waters, ammonium concentrations exceeded 2 μmol L−1, due to a temporary imbalance in regeneration from sinking particles and subsequent nitrification. The inverse correlation between nitrate δ15 …

Go to article

Diel Vertical Migration Rates Of The Dinoflagellate Species Margalefidinium Polykrikoides In A Lower Chesapeake Bay Tributary, S. Clayton, Jacqueline B. Chrabot, Michael Echevarria, Leah Gibala-Smith, Kathryn Mogatas, Peter Bernhardt, Margaret R. Mulholland Jan 2024

Diel Vertical Migration Rates Of The Dinoflagellate Species Margalefidinium Polykrikoides In A Lower Chesapeake Bay Tributary, S. Clayton, Jacqueline B. Chrabot, Michael Echevarria, Leah Gibala-Smith, Kathryn Mogatas, Peter Bernhardt, Margaret R. Mulholland

OES Faculty Publications

Margalefidinium polykrikoides is a mixotrophic dinoflagellate harmful algal bloom (HAB) species that blooms annually in the lower Chesapeake Bay. M. polykrikoides undertakes a diel vertical migration (DVM) which may give it a competitive advantage over purely phototrophic organisms who cannot access deeper nutrient pools and allow it to form large toxic blooms. Laboratory-based estimates of M. polykrikoides’ DVM rates suggest that it is one of the fastest known dinoflagellate swimmers and understanding this behavior is likely important for modeling and predicting M. polykrikoides blooms. However, to date, no field-derived estimates of M. polykrikoides’ DVM rates have been made in the …

Go to article

Ice-Marginal Volcanic Sequence In Iceland Found On A Nondescript Gradual Hillslope: An Unexpected Record Of Ice Thickness Late In Deglaciation, Audrey R. Putnam, Kristen L. Siebach, Candice C. Bedford, Sarah L. Simpson, Michael T. Thorpe, Joseph J. Tamborski Jan 2024

Ice-Marginal Volcanic Sequence In Iceland Found On A Nondescript Gradual Hillslope: An Unexpected Record Of Ice Thickness Late In Deglaciation, Audrey R. Putnam, Kristen L. Siebach, Candice C. Bedford, Sarah L. Simpson, Michael T. Thorpe, Joseph J. Tamborski

OES Faculty Publications

Volcanism increases when glaciers melt because isostatic rebound during deglaciation decreases the pressure on the mantle, which enhances decompression melting. Anthropogenic climate change is now causing ice sheets and valley glaciers to melt around the world and this deglaciation could stimulate volcanic activity and associated hazards in Iceland, Antarctica, Alaska, and Patagonia. However, current model predictions for volcanic activity associated with anthropogenic deglaciation in Iceland are poorly constrained, in part due to uncertainties in past volcanic output over time compared to ice sheet arrangements. Further work specifically characterizing glaciovolcanic and ice-marginal volcanoes in Iceland is needed to reconstruct volcanic output …

Go to article

Heterogeneity Of Nitrogen Fixation In The Mesopelagic Zone Of The South China Sea, Siqi Wu, Xianhui Sean Wan, Moge Du, Xirong Chen, Corday R. Selden, Mar Benavides, Sophie Bonnet, Carolin R. Löscher, M. Robert Hamersley, Margaret R. Mulholland, Xiuli Yan, Shuh-Ji Kao Jan 2024

Heterogeneity Of Nitrogen Fixation In The Mesopelagic Zone Of The South China Sea, Siqi Wu, Xianhui Sean Wan, Moge Du, Xirong Chen, Corday R. Selden, Mar Benavides, Sophie Bonnet, Carolin R. Löscher, M. Robert Hamersley, Margaret R. Mulholland, Xiuli Yan, Shuh-Ji Kao

OES Faculty Publications

Biological dinitrogen (N₂) fixation, the energetically expensive conversion of N₂ gas to ammonia, plays an essential role in balancing the nitrogen budget in the ocean. Accumulating studies show detectable N₂ fixation rates below the euphotic zone in various marine systems, revealing new insights of marine N₂ fixation. However, the reported rates are highly variable and frequently fall close to detection limits, raising the question of the ubiquity and significance of N₂ fixation in the global dark ocean. Using highly sensitive isotopic labeling incubation including a set of control incubations, we confirm the occurrence of mesopelagic N₂ fixation in the South …

Go to article

Mapping Seagrass Distribution And Abundance: Comparing Areal Cover And Biomass Estimates Between Space-Based And Airborne Imagery, Victoria J. Hill, Richard C. Zimmerman, Dorothy A. Byron, Kenneth L. Heck Jr. Jan 2024

Mapping Seagrass Distribution And Abundance: Comparing Areal Cover And Biomass Estimates Between Space-Based And Airborne Imagery, Victoria J. Hill, Richard C. Zimmerman, Dorothy A. Byron, Kenneth L. Heck Jr.

OES Faculty Publications

This study evaluated the effectiveness of Planet satellite imagery in mapping seagrass coverage in Santa Rosa Sound, Florida. We compared very-high-resolution aerial imagery (0.3 m) collected in September 2022 with high-resolution Planet imagery (~3 m) captured during the same period. Using supervised classification techniques, we accurately identified expansive, continuous seagrass meadows in the satellite images, successfully classifying 95.5% of the 11.18 km² of seagrass area delineated manually from the aerial imagery. Our analysis utilized an occurrence frequency (OF) product, which was generated by processing ten clear-sky images collected between 8 and 25 September 2022 to determine the frequency with which …

Go to article

Submarine Groundwater Discharge As A Major Nutrient Source In River-Fed Vs. Tidally Dominated Estuaries, Stephanie J. Wilson, Joseph J. Tamborski, Bongkeun Song, Peter Bernhardt, Margaret R. Mulholland Jan 2024

Submarine Groundwater Discharge As A Major Nutrient Source In River-Fed Vs. Tidally Dominated Estuaries, Stephanie J. Wilson, Joseph J. Tamborski, Bongkeun Song, Peter Bernhardt, Margaret R. Mulholland

OES Faculty Publications

The tidal tributaries of the lower Chesapeake Bay experience seasonally recurring harmful algal blooms and the significance of submarine groundwater discharge (SGD) as a nutrient vector is largely unknown. Here, we determined seasonal SGD nutrient loads in two tributaries with contrasting hydrodynamic conditions, river-fed (York River) vs. tidally dominated (Lafayette River). Radon surveys were performed in each river to quantify SGD at the embayment-scale during spring and fall 2021. Total SGD was determined from a ²²²Rn mass balance and Monte Carlo simulations. Submarine groundwater discharge rates differed by a factor of two during spring (Lafayette = 11 ± 17 cm …

Go to article

Marine Emissions Of Methanethiol Increase Aerosol Cooling In The Southern Ocean, Charel Wohl, Julián Villamayor, Martí Galí, Anoop S. Mahajan, Rafael P. Fernández, Carlos A. Cuevas, Adriana Bossolasco, Qinyi Li, Anthony J. Kettle, Tara Williams, Roland Sarda-Esteve, Valérie Gros, Rafel Simó, Alfonso Saiz-Lopez Jan 2024

Marine Emissions Of Methanethiol Increase Aerosol Cooling In The Southern Ocean, Charel Wohl, Julián Villamayor, Martí Galí, Anoop S. Mahajan, Rafael P. Fernández, Carlos A. Cuevas, Adriana Bossolasco, Qinyi Li, Anthony J. Kettle, Tara Williams, Roland Sarda-Esteve, Valérie Gros, Rafel Simó, Alfonso Saiz-Lopez

OES Faculty Publications

Ocean-emitted dimethyl sulfide (DMS) is a major source of climate-cooling aerosols. However, most of the marine biogenic sulfur cycling is not routed to DMS but to methanethiol (MeSH), another volatile whose reactivity has hitherto hampered measurements. Therefore, the global emissions and climate impact of MeSH remain unexplored. We compiled a database of seawater MeSH concentrations, identified their statistical predictors, and produced monthly fields of global marine MeSH emissions adding to DMS emissions. Implemented into a global chemistry-climate model, MeSH emissions increase the sulfate aerosol burden by 30 to 70% over the Southern Ocean and enhance the aerosol cooling effect while …

Go to article

Widespread Crab Burrows Enhance Greenhouse Gas Emissions From Coastal Blue Carbon Ecosystems, Kai Xiao, Yuchen Wu, Feng Pan, Yingrong Huang, Hebo Peng, Meiqing Lu, Yan Zhang, Hailong Li, Yan Zheng, Chunmiao Zheng, Yan Liu, Nengwan Chen, Leilei Xiao, Guangxuan Han, Yasong Li, Pei Xin, Ruili Li, Bochao Xu, Faming Wang, Joseph J. Tamborski, Alicia M. Wilson, Daniel M. Alongi, Isaac R. Santos Jan 2024

Widespread Crab Burrows Enhance Greenhouse Gas Emissions From Coastal Blue Carbon Ecosystems, Kai Xiao, Yuchen Wu, Feng Pan, Yingrong Huang, Hebo Peng, Meiqing Lu, Yan Zhang, Hailong Li, Yan Zheng, Chunmiao Zheng, Yan Liu, Nengwan Chen, Leilei Xiao, Guangxuan Han, Yasong Li, Pei Xin, Ruili Li, Bochao Xu, Faming Wang, Joseph J. Tamborski, Alicia M. Wilson, Daniel M. Alongi, Isaac R. Santos

OES Faculty Publications

Fiddler crabs, as coastal ecosystem engineers, play a crucial role in enhancing biodiversity and accelerating the flow of material and energy. Here we show how widespread crab burrows modify the carbon sequestration capacity of different habitats across a large climatic gradient. The process of crab burrowing results in the reallocation of sediment organic carbon and humus. Crab burrows can increase more greenhouse gases emissions compared to the sediment matrix (CO2: by 17-30%; CH4: by 49-141%). Straightforward calculations indicate that these increased emissions could offset 35-134% of sediment carbon burial in these two ecosystems. This research highlights the complex interactions between …

Go to article

Efficient Privacy-Preserving Spatial Data Query In Cloud Computing, Yinbin Miao, Yutao Yang, Xinghua Li, Linfeng Wei, Zhiquan Liu, Robert H. Deng Jan 2024

Efficient Privacy-Preserving Spatial Data Query In Cloud Computing, Yinbin Miao, Yutao Yang, Xinghua Li, Linfeng Wei, Zhiquan Liu, Robert H. Deng

Research Collection School Of Computing and Information Systems

With the rapid development of geographic location technology and the explosive growth of data, a large amount of spatial data is outsourced to the cloud server for reducing the local high storage and computing burdens, but at the same time causes security issues. Thus, extensive privacy-preserving spatial data query schemes have been proposed. Most of the existing schemes use Asymmetric Scalar-Product-Preserving Encryption (ASPE) to encrypt data, but ASPE has proven to be insecure against known plaintext attack. And the existing schemes require users to provide more information about query range and thus generate a large amount of ciphertexts, which causes …

Go to article

Dynamic Meta-Path Guided Temporal Heterogeneous Graph Neural Networks, Yugang Ji, Chuan Shi, Yuan Fang Jan 2024

Dynamic Meta-Path Guided Temporal Heterogeneous Graph Neural Networks, Yugang Ji, Chuan Shi, Yuan Fang

Research Collection School Of Computing and Information Systems

Graph Neural Networks (GNNs) have become the de facto standard for representation learning on topological graphs, which usually derive effective node representations via message passing from neighborhoods. Although GNNs have achieved great success, previous models are mostly confined to static and homogeneous graphs. However, there are multiple dynamic interactions between different-typed nodes in real-world scenarios like academic networks and e-commerce platforms, forming temporal heterogeneous graphs (THGs). Limited work has been done for representation learning on THGs and the challenges are in two aspects. First, there are abundant dynamic semantics between nodes while traditional techniques like meta-paths can only capture static …

Go to article

A Unified Framework For Contextual And Factoid Question Generation, Chenhe Dong, Ying Shen, Shiyang Lin, Zhenzhou Lin, Yang Deng Jan 2024

A Unified Framework For Contextual And Factoid Question Generation, Chenhe Dong, Ying Shen, Shiyang Lin, Zhenzhou Lin, Yang Deng

Research Collection School Of Computing and Information Systems

Question generation (QG) aims to automatically generate fluent and relevant questions, where the two most mainstream directions are generating questions from unstructured contextual texts (CQG), such as news articles, and generating questions from structured factoid texts (FQG), such as knowledge graphs or tables. Existing methods for these two tasks mainly face challenges of limited internal structural information as well as scarce background information, while these two tasks can benefit each other for alleviating these issues. For example, when meeting the entity mention “United Kingdom” in CQG, it can be inferred that it is a country in European continent based on …

Go to article

Demonstrating Canvas-Based Processing Of Multiple Camera Streams At The Edge, Ila Gokarn, Hemanth Sabbella, Yigong Hu, Tarek Abdelzaher, Archan Misra Jan 2024

Demonstrating Canvas-Based Processing Of Multiple Camera Streams At The Edge, Ila Gokarn, Hemanth Sabbella, Yigong Hu, Tarek Abdelzaher, Archan Misra

Research Collection School Of Computing and Information Systems

We demonstrate criticality-aware canvas-based processing of multiple concurrent camera streams at the resource constrained edge to show substantial improvement in the accuracy-throughput trade-off. The proposed system focuses the available computation resources on select Regions of Interest (RoI) across all the camera streams by (i) extracting RoI from the input camera stream (ii) 2D bin packing the RoI on a canvas frame and (iii) batching and inferring upon these constructed composite canvas frames with a YOLOv5 object detection model. Our experiments show that such canvas-based processing can (i) sustain real-time processing throughput of 23 FPS per camera across 6 concurrent input …

Go to article

Deep Learning Approach For Robust Structural Health Monitoring Using Guided Lamb Wave Responses, Sameer Gopali Jan 2024

Deep Learning Approach For Robust Structural Health Monitoring Using Guided Lamb Wave Responses, Sameer Gopali

Theses

Guided Lamb waves offer a promising solution for the early detection of internal damages in structures due to their high sensitivity to small damages. However, noise can adversely impact the development of data-driven models for damage detection, leading to inaccurate monitoring systems. This thesis explores deep learning techniques to robustly predict the location and severity of damage in cantilevered beams using noisy guided wave responses. Initially, Multi-Layer Perceptron (MLP) is trained with frequency domain features to achieve robust performance against noisy data. Further performance improvement is achieved using end-to-end learning models, which include autoencoder and one-dimensional Convolutional Neural Network (CNN). …

Go to article

First Prev Next Last