Digital Commons Network^™

Seafloor Geodesy In Shallow Water With Gps On An Anchored Spar Buoy, Surui Xie, Jason Law, Randy Russell, Timothy H. Dixon, Chad Lembke, Rocco Malservisi, Melanie Rodgers, Giovanni Iannaccone, Sergio Guardato, D. F. Naar

School of Geosciences Faculty and Staff Publications

Measuring seafloor motion in shallow coastal water is challenging due to strong and highly variable oceanographic effects. Such measurements are potentially useful for monitoring near‐shore coastal subsidence, subsidence due to petroleum withdrawal, strain accumulation/release processes in subduction zones and submerged volcanoes, and certain freshwater applications, such as volcano deformation in caldera‐hosted lakes. We have developed a seafloor geodesy system for this environment based on an anchored spar buoy topped by high‐precision GPS. Orientation of the buoy is measured using a digital compass that provides heading, pitch, and roll information. The combined orientation and GPS tracking data are used to recover …

The Record‐Setting 2018 Eastern North Pacific Hurricane Season, Kimberly M. Wood, Philip J. Klotzbach, Jennifer M. Collins, Carl J. Schreck

School of Geosciences Faculty and Staff Publications

The extremely active 2018 eastern North Pacific (ENP) hurricane season set records for number of hurricane days, major hurricane days, and accumulated cyclone energy (ACE). The Western Development Region (116°W–180°) was especially active, shattering its prior record for ACE set in 2015. In addition, Hawaii was impacted by Hurricane Lane in August and Tropical Storm Olivia in September. Despite above‐normal sea surface temperatures (SSTs) and below‐normal vertical wind shear in 2018, large‐scale conditions were generally less conducive for tropical cyclone (TC) formation than in 2015. However, the strong subtropical ridge in August and September of 2018 enhanced westward steering flow, …

Morphodynamics Of Barrier-Inlet Systems In The Context Of Regional Sediment Management, With Case Studies From West-Central Florida, Usa, Tanya Beck, Ping Wang

School of Geosciences Faculty and Staff Publications

The temporal and spatial scales controlling the morphodynamics of barrier-inlet systems are critical components of regional sediment management practice. This paper discusses regional sediment management methods employed at multiple barrier-inlet systems, with case studies from West-Central Florida. A decision-support tool is proposed for regional sediment management with discussion of its application to barrier-inlet systems. Connecting multiple barrier islands and inlets at appropriate spatio-temporal scales is critical in developing an appropriately scoped sediment management plan for a barrier-inlet system. Evaluating sediment bypassing capacity and overall inlet morphodynamics can better inform regional sand sharing along barrier-inlet coastlines; particularly where sediment resources are …

Determining The Impacts Of The Anthropocene Through Time-Calibrated Taphonomic Grading, Nicole Seiden, Gregory S. Herbert

School of Geosciences Faculty and Staff Publications

Global biodiversity loss threatens ecosystem integrity and related services for humans, but most communities lack baseline data to assess the magnitude of change. In marine conservation, molluscan death assemblages are increasingly being used as a proxy for baseline communities, and divergence between the live and the dead is assumed to reflect human impact. A drawback to partitioning an assemblage into live and dead is that inclusion of recently dead specimens in the baseline assemblage artificially reduces differences between before and after. In this study, we address this problem by using a radiocarbon- and amino acid-calibrated taphonomic grading scale to partition …

Landscape Grain Effect In Yancheng Coastal Wetland And Its Response To Landscape Changes, Peng Tian, Luodan Cao, Jialin Li, Ruiliang Pu, Xiaoli Shi, Lijia Wang, Ruiqing Liu, Hao Xu, Chen Tong, Zijing Zhou, Shuyao Shao

School of Geosciences Faculty and Staff Publications

The landscape grain effect reflects the spatial heterogeneity of a landscape and it is used as a research core of landscape ecology. The landscape grain effect can be used to not only explore spatiotemporal variation characteristics of a landscape pattern, but also to disclose variation laws of ecological structures and functions of landscapes. In this study, the sensitivity of landscape pattern indexes to grain sizes 50–1000 m was studied based on landscape data in Yancheng Coastal Wetland acquired in 1991, 2000, 2008, and 2017. Response of the grain effect to landscape changes was analyzed and an optimal grain size for …

The Multifactorial Nature Of Beak And Skull Shape Evolution In Parrots And Cockatoos (Psittaciformes), Jen A. Bright, Jesús Marugán-Lobón, Emily J. Rayfield, Samuel N. Cobb

School of Geosciences Faculty and Staff Publications

Background: The Psittaciformes (parrots and cockatoos) are characterised by their large beaks, and are renowned for their ability to produce high bite forces. These birds also possess a suite of modifications to their cranial architecture interpreted to be adaptations for feeding on mechanically resistant foods, yet the relationship between cranial morphology and diet has never been explicitly tested. Here, we provide a three-dimensional geometric morphometric analysis of the developmental and biomechanical factors that may be influencing the evolution of psittaciformes’ distinctive cranial morphologies.

Results: Contrary to our own predictions, we find that dietary preferences for more- or less- mechanically resistant …

Population Fragmentation Leads To Morpho-Functional Variation In British Red Squirrels (Sciurus Vulgaris), Philip G. Cox, Philip J.R. Morris, Andrew C. Kitchener

School of Geosciences Faculty and Staff Publications

It is well-known that population fragmentation and isolation can lead to rapid morphological and functional divergence, with the effect being particularly well-documented in rodents. Here, we investigated whether such a phenomenon could be identified in the Eurasian red squirrel (Sciurus vulgaris), which was once widespread across the majority of Great Britain, but suffered a severe population decline across the 20^th century, leaving a highly fragmented distribution. The aim was to test for morphological and biomechanical variation of the mandible between the remaining British red squirrel populations. Linear and geometric morphometric methods were used to analyse shape in …

Mechanical Significance Of Morphological Variation In Diprotodont Incisors, Philip J.R. Morris, Philip G. Cox, Samuel N. Cobb

School of Geosciences Faculty and Staff Publications

All rodents possess a single pair of enlarged incisors that grow throughout life. This condition (diprotodonty) is characteristic of Rodentia, but is also found in other mammals such as lagomorphs, hyraxes, the aye-aye and common wombat. This study surveyed lower incisor morphology across extant diprotodonts to examine shape variation within and between rodents and other diprotodonts, and to determine if tooth shape varies in a manner predictable from mechanics. Six linear and area variables were recorded from microCT scans of the mandibles of 33 diprotodont mammals. The curvature of the rodent lower incisors, as measured by the proportion of a …

Ice-Cliff Failure Via Retrogressive Slumping, Byron R. Parizek, Knut Christianson, Richard B. Alley, Denis Voytenko, Irena Vaňková, Timothy H. Dixon, Ryan T. Walker, David M. Holland

School of Geosciences Faculty and Staff Publications

Retrogressive slumping could accelerate sea-level rise if ice-sheet retreat generates ice cliffs much taller than observed today. The tallest ice cliffs, which extend roughly 100 m above sea level, calve only after ice-flow processes thin the ice to near flotation. Above some ice-cliff height limit, the stress state in ice will satisfy the material-failure criterion, resulting in faster brittle failure. New terrestrial radar data from Helheim Glacier, Greenland, suggest that taller subaerial cliffs are prone to failure by slumping, unloading submarine ice to allow buoyancy-driven full-thickness calving. Full-Stokes diagnostic modeling shows that the threshold cliff height for slumping is likely …

Time Scavengers: An Educational Website To Communicate Climate Change And Evolutionary Theory To The Public Through Blogs, Web Pages, And Social Media Platforms, Adriane R. Lam, Jennifer E. Bauer, Susanna Fraass, Sarah L. Sheffield, Maggie R. Limbeck, Rose M. Borden, Megan E. Thompson-Munson, Andrew J. Fraass, J. M. Hills, Cameron E. Muskelly, Kyle R. Hartshorn, Raquel Bryant

School of Geosciences Faculty and Staff Publications

Climate change and evolution are topics at the forefront of political discussions, debates, and the public sphere. Regardless of evidence on both topics, the public as a whole still believes they are under debate. It is imperative that the public have access to correct and easy-to-digest information on these topics to make informed environmental and ecological decisions. To date, scientifically accurate digital platforms aimed at informing the public on these topics are overly complex and jargon-ridden. Time Scavengers (www.timescavengers.blog) was created to address these issues and is maintained by a group of academics, graduate students, avocational scientists, and educators. The …

Magmatic Response To Subduction Initiation: Part 1. Fore‐Arc Basalts Of The Izu‐Bonin Arc From Iodp Expedition 352, John W. Shervais, Mark Reagan, Emily Haugen, Renat R. Almeev, Julian A. Pearce, Julie Prytulak, Jeff Ryan

School of Geosciences Faculty and Staff Publications

The Izu‐Bonin‐Mariana (IBM) fore arc preserves igneous rock assemblages that formed during subduction initiation circa 52 Ma. International Ocean Discovery Program (IODP) Expedition 352 cored four sites in the fore arc near the Ogasawara Plateau in order to document the magmatic response to subduction initiation and the physical, petrologic, and chemical stratigraphy of a nascent subduction zone. Two of these sites (U1440 and U1441) are underlain by fore‐arc basalt (FAB). FABs have mid‐ocean ridge basalt (MORB)‐like compositions, however, FAB are consistently lower in the high‐field strength elements (TiO2, P2O5, Zr) and Ni compared to MORB, with Na2O at the low …

Rapid Iceberg Calving Following Removal Of Tightly Packed Pro-Glacial Mélange, Surui Xie, Timothy Dixon, David M. Holland, Denis Voytenko, Irena Vaňková

School of Geosciences Faculty and Staff Publications

Iceberg calving is a major contributor to Greenland’s ice mass loss. Pro-glacial mélange (a mixture of sea ice, icebergs, and snow) may be tightly packed in the long, narrow fjords that front many marine-terminating glaciers and can reduce calving by buttressing. However, data limitations have hampered a quantitative understanding. We develop a new radar-based approach to estimate time-varying elevations near the mélange-glacier interface, generating a factor of three or more improvement in elevation precision. We apply the technique to Jakobshavn Isbræ, Greenland’s major outlet glacier. Over a one-month period in early summer 2016, the glacier experienced essentially no calving, and …

Tracing And Constraining Anthropogenic Aerosol Iron Fluxes To The North Atlantic Ocean Using Iron Isotopes, Tim Conway, Douglas S. Hamilton, Rachel U. Shelley, Ana M. Aguilar-Islas, William M. Landing, Natalie M. Mahowald, Seth G. John

School of Geosciences Faculty and Staff Publications

Atmospheric dust is an important source of the micronutrient Fe to the oceans. Although relatively insoluble mineral Fe is assumed to be the most important component of dust, a relatively small yet highly soluble anthropogenic component may also be significant. However, quantifying the importance of anthropogenic Fe to the global oceans requires a tracer which can be used to identify and constrain anthropogenic aerosols in situ. Here, we present Fe isotope (δ56Fe) data from North Atlantic aerosol samples from the GEOTRACES GA03 section. While soluble aerosol samples collected near the Sahara have near-crustal δ56Fe, soluble aerosols from near North America …

Research On Land Use Changes And Ecological Risk Assessment In Yongjiang River Basin In Zhejiang Province, China, Peng Tian, Jianlin Li, Hongbo Gong, Ruiliang Pu, Luodan Cao, Shuyao Shao, Zuoqi Shi, Xuili Feng, Lijia Wang, Riuqing Liu

School of Geosciences Faculty and Staff Publications

Studying land use changes and ecological risk assessment in Yongjiang River Basin in Zhejiang Province, China, provides theoretical references for optimal configuration of land resources and maintaining stability of ecosystems. Given impacts of land use changes on landscape patterns in the Yongjiang River Basin, ecological risk assessment indexes were constructed and used to analyze temporal and spatial variation characteristics of ecological risk within different periods. Results show that (1) the construction land area was increased quickly, while the cultivated area decreased sharply. A prominent characteristic of land use changes was manifested by transforming cultivated area and forestland into construction land. …

Mobile Terrestrial Photogrammetry For Street Tree Mapping And Measurements, John Roberts, Andrew Koeser, Amr Abd-Elrahman, Benjamin Wilkinson, Gail Hansen, Shawn M. Landry, Ali Perez

School of Geosciences Faculty and Staff Publications

Urban forests are often heavily populated by street trees along right-of-ways (ROW), and monitoring efforts can enhance municipal tree management. Terrestrial photogrammetric techniques have been used to measure tree biometry, but have typically used images from various angles around individual trees or forest plots to capture the entire stem while also utilizing local coordinate systems (i.e., non-georeferenced data). We proposed the mobile collection of georeferenced imagery along 100 m sections of urban roadway to create photogrammetric point cloud datasets suitable for measuring stem diameters and attaining positional x and y coordinates of street trees. In a comparison between stationary and …