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Articles 1 - 14 of 14
Full-Text Articles in Physical Sciences and Mathematics
Geological Structures And Crustal Architecture Of The Cascadia Subduction Zone From The Integration Of Multiple Geophysical Datasets, Asif Ashraf
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The Cascadia subduction zone (CSZ) has a high potential for an inevitable and devastating megathrust earthquake. This margin is characterized by a complex seismicity pattern. Particularly in Oregon, there is a seismically quiescent zone bounded by high seismicity regions to the north and south. To comprehend these variations in seismicity, it is important to study the differences in crustal architectures and physical properties (densities and magnetic susceptibilities) along the CSZ. The primary objectives are to develop two plate-scale 2D integrated models through different seismicity zones and to map major tectonic structures from filtered potential fields. The Juan de Fuca oceanic …
Auroral Heating Of Plasma Patches Due To High-Latitude Reconnection, Joaquin Diaz Pena, Joshua Semeter, Yukitoshi Nishimura, Roger Varney, Ashton Reimer, Marc Hairston, Matthew Zettergren, Michael Hirsch, Olga Verkhoglyadova, Keisuke Hosokawa, Kazuo Shiokawa
Auroral Heating Of Plasma Patches Due To High-Latitude Reconnection, Joaquin Diaz Pena, Joshua Semeter, Yukitoshi Nishimura, Roger Varney, Ashton Reimer, Marc Hairston, Matthew Zettergren, Michael Hirsch, Olga Verkhoglyadova, Keisuke Hosokawa, Kazuo Shiokawa
Publications
This study exploits the volumetric sampling capabilities of the Resolute Bay Incoherent Scatter Radar (RISR-N) in collaboration with all-sky imagery and in-situ measurements (DMSP) to examine the interplay between cold plasma transport and auroral precipitation during a high-latitude lobe reconnection event on the dawn side. The IMF had an impulsive negative excursion in B$_z$ embedded within a prolonged period of B$_z>0$ and B$_y
Drone-Based Magnetic Surveying In Eastern Nebraska, Sulaiman Albadi
Drone-Based Magnetic Surveying In Eastern Nebraska, Sulaiman Albadi
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
A magnetic survey is one of the methods used by scientists to detect subsurface features. Magnetic surveys can be carried out by walking on the surface of the earth with a magnetic field reading device called a magnetometer. Alternatively, a magnetometer can be installed on a moving platform (aircraft, boat, drone, bicycle) to conduct a more efficient magnetic survey. The geophysics team at the University of Nebraska at Lincoln assembled a drone-based magnetic survey system in 2019 (Jacobson and Filina, 2019) that has proven effective in magnetic readings over the Northern Bounding Fault (NBF) in eastern Nebraska (Jacobson and Filina, …
Inference Of Surface Velocities From Oblique Time Lapse Photos And Terrestrial Based Lidar At The Helheim Glacier, Franklyn T. Dunbar Ii
Inference Of Surface Velocities From Oblique Time Lapse Photos And Terrestrial Based Lidar At The Helheim Glacier, Franklyn T. Dunbar Ii
Graduate Student Theses, Dissertations, & Professional Papers
Using time dependent observations derived from terrestrial LiDAR and oblique
time-lapse imagery, we demonstrate that a Bayesian approach to glacial motion es-
timation provides a concise way to incorporate multiple data products into a single
motion estimation procedure effectively producing surface velocity estimates with
an associated uncertainty. This approach brings both improved computational effi-
ciency, and greater scalability across observational time-frames when compared to
existing methods. To gauge efficacy, we apply these methods to a set of observa-
tions from the Helheim Glacier, a critical actor in contemporary mass loss trends
observed in the Greenland Ice Sheet. We find that …
Impacts Of Basin-Scale Climate Modes On Coastal Sea Level: A Review, Weiqing Han, Detlef Stammer, Philip Thompson, Tal Ezer, Hindu Palanisamy, Xuebin Zhang, Catia M. Domingues, Lei Zhang, Dongliang Yuan
Impacts Of Basin-Scale Climate Modes On Coastal Sea Level: A Review, Weiqing Han, Detlef Stammer, Philip Thompson, Tal Ezer, Hindu Palanisamy, Xuebin Zhang, Catia M. Domingues, Lei Zhang, Dongliang Yuan
CCPO Publications
Global sea level rise (SLR) associated with a warming climate exerts significant stress on coastal societies and low-lying island regions. The rates of coastal SLR observed in the past few decades, however, have large spatial and temporal differences from the global mean, which to a large part have been attributed to basin-scale climate modes. In this paper, we review our current state of knowledge about climate modes’ impacts on coastal sea level variability from interannual-to-multidecadal timescales. Relevant climate modes, their impacts and associated driving mechanisms through both remote and local processes are elaborated separately for the Pacific, Indian and Atlantic …
How Dredge Pits Evolve Over Time: A Look At Their Geomorphologic Evolution And Infilling Processes, Patrick Robichaux
How Dredge Pits Evolve Over Time: A Look At Their Geomorphologic Evolution And Infilling Processes, Patrick Robichaux
LSU Master's Theses
As coastal environments become more susceptible to land loss through accelerating sea level rise and subsidence, new restoration methods harnessing borrowed sediment are more valuable than ever. Mud-capped dredge pits (MCDPs) are a relatively new source of restoration-quality sediment that has only recently been utilized for beach and barrier island restorations in Louisiana. Because MCDPs have been in use for less than two decades in only a handful sites, little is understood about their evolution over decadal timescales. To improve our understanding of MCDPs after they are dredged, we have conducted a suite of geophysical surveys including bathymetry, sidescan sonar, …
Discontinuities And Alfvenic Fluctuations In The Solar Wind, G. Paschmann, S. Haaland, B. Sonnerup, T. Knetter
Discontinuities And Alfvenic Fluctuations In The Solar Wind, G. Paschmann, S. Haaland, B. Sonnerup, T. Knetter
Dartmouth Scholarship
We examine the Alfvenicity of a set of 188 solar wind directional discontinuities (DDs) identified in the Cluster data from 2003 by Knetter (2005), with the objective of separating rotational discontinuities (RDs) from tangential ones (TDs). The DDs occurred over the full range of solar wind velocities and magnetic shear angles. By performing the Walen test in the de Hoffmann–Teller (HT) frame, we show that 77 of the 127 crossings for which a good HT frame was found had plasma flow speeds exceeding 80 % of the Alfven speed at an average angular deviation of 7.7◦; 33 cases had speeds …
The Lability Of Riverine Particulate Organic Carbon Delivered To The Ocean, Lawrence Mayer
The Lability Of Riverine Particulate Organic Carbon Delivered To The Ocean, Lawrence Mayer
University of Maine Office of Research Administration: Grant Reports
The large annual flux of organic carbon from land to the ocean largely disappears in the sea. Reasons for this loss are not clear. Under this award, the PI will examine abiotic and biotic aspects of the lability to loss of riverine particulate organic matter. Work will focus on the Mississippi, as it demonstrates the clearest loss of particulate organic material of any North American river upon deposition in the ocean. Photochemical experiments will follow up on initial work showing significant dissolution of particulate organic matter subjected to solar levels of radiation. Interactions with metal cycling will be studied, as …
The Anatomy Of A Coastal Bay/Lake System, Michelle Greene
The Anatomy Of A Coastal Bay/Lake System, Michelle Greene
LSU Master's Theses
A comprehensive and integrated approach involving sedimentology, shallow surface geophysics and radio-chemistry was used to understand lakebed sediment dynamics in Little Lake. This methodology attempted to (1) define the morphology and origin of the lake, (2) understand the variability in lake-bottom sediments, (3) assess short-term and long-term sediment accumulation rates, and (4) image lakebed features. Subbottom chirp, single beam echo sounder, and side scan sonar data were collected to define hydrographic depths, lateral variability in seabed sediment type, lakebed features, and shallow subsurface structure. Sediment samples were taken at representative locations throughout the lake and particle size distributions were determined. …
Biogeochemistry Of Arsenic And Antimony In The North Pacific Ocean, Gregory A. Cutter, Lynda S. Cutter
Biogeochemistry Of Arsenic And Antimony In The North Pacific Ocean, Gregory A. Cutter, Lynda S. Cutter
OES Faculty Publications
The biogeochemical cycles of the metalloid elements arsenic and antimony were examined along a 15,000 km surface water transect and at 9 vertical profile stations in the western North Pacific Ocean as part of the 2002 IOC Contaminant Baseline Survey. Results show that the speciation of dissolved arsenic (As III, As V, and methylated As) was subtly controlled by the arsenate (AsV)/phosphate ratio. An additional fraction of presumed organic arsenic previously reported in coastal waters was also present (~15% of the total As) in oceanic surface waters. Dissolved inorganic antimony displayed mildly scavenged behavior that was confirmed by correlations with …
Holocene Climate In Coastal Peru: Potential Implications For Climate Dynamics During The Hypsithermal Period, James D. Wright
Holocene Climate In Coastal Peru: Potential Implications For Climate Dynamics During The Hypsithermal Period, James D. Wright
University of Maine Office of Research Administration: Grant Reports
This pilot study will analyze stable isotopes in planktic foraminifera in sediment cores off the coast of Peru for the Holocene interval. In many regions of the world the early Holocene is believed to have been a time of warmer-than modern temperatures. Data derived from Peruvian middens give conflicting evidence as to whether this period was somewhat warmer or cooler than today. The foraminiferal data should provide a record of sea surface temperatures and seasonal upwelling along coastal Peru throughout the Holocene, including the period of human coastal settlement.
Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw
Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw
Faculty Publications
No abstract provided.
Basement Structure Of The Northern Ontong Java Plateau, Rick A. Hagen, Larry A. Mayer, David Mosher, Loren W. Kroenke, Tom H. Shipley, Edward L. Winterer
Basement Structure Of The Northern Ontong Java Plateau, Rick A. Hagen, Larry A. Mayer, David Mosher, Loren W. Kroenke, Tom H. Shipley, Edward L. Winterer
Affiliate Scholarship
Site surveys conducted in conjunction with Leg 130 on the Ontong Java Plateau reveal a strong seismic reflector at 0.8 to 1.0 s below the seafloor that drilling at Sites 803 and 807 confirmed is Cretaceous basalt. This reflector is generally smooth, except for the northeastern margin of the plateau, where it forms a series of small, irregularly shaped depressions. Correlatable reflectors present at the bottom of the depressions are also present on the adjacent highs, suggesting that these depressions are original volcanic topography. A strong sub-basalt reflector occurs on many seismic profiles on the northeastern portion of the plateau. …
Ocean Chlorophyll Studies From A U-2 Aircraft Platform, Hongsuk H. Kim, Charles R. Mcclain, Lamdin R. Blaine, William D. Hart, Larry P. Atkinson, James A. Yoder
Ocean Chlorophyll Studies From A U-2 Aircraft Platform, Hongsuk H. Kim, Charles R. Mcclain, Lamdin R. Blaine, William D. Hart, Larry P. Atkinson, James A. Yoder
CCPO Publications
Chlorophyll gradient maps of large ocean areas were generated from U-2/OCS data obtained over test sites in the Pacific and the Atlantic Oceans. The delineation of oceanic features using the upward radiant intensity relies on an analysis method which presupposes that radiation backscattered from the atmosphere and the ocean surface can be properly modeled by using a measurement made at 778 nm. The calculation of atmospheric radiance was performed by using a method developed by J.V. Dave. An estimation of the chlorophyll concentration is performed by properly ratioing radiances measured at 472 and 548 nm after removing the atmospheric effects. …