Hydrodynamic Modeling and Simulation of Water Residence Time in the Estuary of the Lower Amazon River
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Geologists Suggest Horseshoe Abyssal Plain May Be Start of a Subduction Zone 8 May 2019, by Bob Yirka
Geologists suggest Horseshoe Abyssal Plain may be start of a subduction zone 8 May 2019, by Bob Yirka against one another. Over by the Iberian Peninsula, the opposite appears to be happening—the African and Eurasian plates are pulling apart as the former creeps east toward the Americas. Duarte noted that back in 2012, other researchers conducting seismic wave tests found what appeared to be a dense mass of unknown material beneath the epicenter of the 1969 quake. Some in the field suggested it could be the start of a subduction zone. Then, last year, another team conducted high-resolution imaging of the area and also found evidence of the mass, confirming that it truly existed. Other research has shown that the area just above the mass experiences routine tiny earthquakes. Duarte suggests the evidence to date indicates that the bottom of the plate is peeling away. This could happen, he explained, due to serpentinization in which water percolates through plate fractures and reacts with material beneath the surface, resulting A composite image of the Western hemisphere of the in the formation of soft green minerals. The soft Earth. Credit: NASA mineral layer, he suggests, is peeling away. And if that is the case, then it is likely the area is in the process of creating a subduction zone. He reports that he and his team members built models of their A team of geologists led by João Duarte gave a ideas and that they confirmed what he suspected. presentation at this past month's European The earthquakes were the result of the process of Geosciences Union meeting that included a birthing a new subduction zone. -
James T. Kirby, Jr
James T. Kirby, Jr. Edward C. Davis Professor of Civil Engineering Center for Applied Coastal Research Department of Civil and Environmental Engineering University of Delaware Newark, Delaware 19716 USA Phone: 1-(302) 831-2438 Fax: 1-(302) 831-1228 [email protected] http://www.udel.edu/kirby/ Updated September 12, 2020 Education • University of Delaware, Newark, Delaware. Ph.D., Applied Sciences (Civil Engineering), 1983 • Brown University, Providence, Rhode Island. Sc.B.(magna cum laude), Environmental Engineering, 1975. Sc.M., Engineering Mechanics, 1976. Professional Experience • Edward C. Davis Professor of Civil Engineering, Department of Civil and Environmental Engineering, University of Delaware, 2003-present. • Visiting Professor, Grupo de Dinamica´ de Flujos Ambientales, CEAMA, Universidad de Granada, 2010, 2012. • Professor of Civil and Environmental Engineering, Department of Civil and Environmental Engineering, University of Delaware, 1994-2002. Secondary appointment in College of Earth, Ocean and the Environ- ment, University of Delaware, 1994-present. • Associate Professor of Civil Engineering, Department of Civil Engineering, University of Delaware, 1989- 1994. Secondary appointment in College of Marine Studies, University of Delaware, as Associate Professor, 1989-1994. • Associate Professor, Coastal and Oceanographic Engineering Department, University of Florida, 1988. • Assistant Professor, Coastal and Oceanographic Engineering Department, University of Florida, 1984- 1988. • Assistant Professor, Marine Sciences Research Center, State University of New York at Stony Brook, 1983- 1984. • Graduate Research Assistant, Department of Civil Engineering, University of Delaware, 1979-1983. • Principle Research Engineer, Alden Research Laboratory, Worcester Polytechnic Institute, 1979. • Research Engineer, Alden Research Laboratory, Worcester Polytechnic Institute, 1977-1979. 1 Technical Societies • American Society of Civil Engineers (ASCE) – Waterway, Port, Coastal and Ocean Engineering Division. -
Observations of Shoaling Density Current Regime Changes in Internal Wave Interactions
JUNE 2020 S O L ODOCH ET AL. 1733 Observations of Shoaling Density Current Regime Changes in Internal Wave Interactions AVIV SOLODOCH,JEROEN M. MOLEMAKER, AND KAUSHIK SRINIVASAN Department of Atmospheric and Oceanic Sciences, University of California in Los Angeles, Los Angeles, California MARISTELLA BERTA Istituto di Scienze Marine, Consiglio Nazionale delle Ricerche, La Spezia, Italy LOUIS MARIE Institut Francais de Recherche pour l’Exploitation de la Mer, Plouzané, France ARJUN JAGANNATHAN Department of Atmospheric and Oceanic Sciences, University of California in Los Angeles, Los Angeles, California (Manuscript received 1 August 2019, in final form 16 April 2020) ABSTRACT We present in situ and remote observations of a Mississippi plume front in the Louisiana Bight. The plume propagated freely across the bight, rather than as a coastal current. The observed cross-front circulation pattern is typical of density currents, as are the small width (’100 m) of the plume front and the presence of surface frontal convergence. A comparison of observations with stratified density current theory is conducted. Additionally, subcritical to supercritical transitions of frontal propagation speed relative to internal gravity wave (IGW) speed are demonstrated to occur. That is in part due to IGW speed reduction with decrease in seabed depth during the frontal propagation toward the shore. Theoretical steady-state density current propagation speed is in good agreement with the observations in the critical and supercritical regimes but not in the inherently unsteady subcritical regime. The latter may be due to interaction of IGW with the front, an effect previously demonstrated only in laboratory and numerical experiments. In the critical regime, finite- amplitude IGWs form and remain locked to the front. -
FAU Institutional Repository
FAU Institutional Repository http://purl.fcla.edu/fau/fauir This paper was submitted by the faculty of FAU’s Harbor Branch Oceanographic Institute Notice: ©2002 Elsevier Science Ltd. This is the author’s version of a work accepted for publication by Elsevier. Changes resulting from the publishing process, including peer review, editing, corrections, structural formatting and other quality control mechanisms, may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. The definitive version has been published at http://www.elsevier.com/locate/csr and may be cited as Lee, Thomas N., Ned Smith (2002) Volume transport variability through the Florida Keys tidal Channels, Continental Shelf Research 22(9):1361–1377 doi:10.1016/S0278‐4343(02)00003‐1 Continental Shelf Research 22 (2002) 1361–1377 Volume transport variability through the Florida Keys tidal channels Thomas N. Leea,*, Ned Smithb a Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA b Harbor Branch Oceanographic Institution, 5600 US Highway 1, North, Ft. Pierce, FL 34946, USA Received 28 February 2001; received in revised form 13 July 2001; accepted 18 September 2001 Abstract Shipboard measurements of volume transports through the passages of the middle Florida Keys are used together with time series of moored transports, cross-Key sea level slopes and local wind records to investigate the mechanisms controllingtransport variability. Predicted tidal transport amplitudes rangedfrom 76000 m3/s in LongKey Channel to 71500 m3/s in Channel 2. Subtidal transport variations are primarily due to local wind driven cross-Key sea level slopes. -
Redalyc.Study of Atrato River Plume in a Tropical Estuary
Dyna ISSN: 0012-7353 [email protected] Universidad Nacional de Colombia Colombia Montoya, Luis Javier; Toro-Botero, Francisco Mauricio; Gomez-Giraldo, Andrés Study of Atrato river plume in a tropical estuary: Effects of the wind and tidal regime on the Gulf of Uraba, Colombia Dyna, vol. 84, núm. 200, marzo, 2017, pp. 367-375 Universidad Nacional de Colombia Medellín, Colombia Available in: http://www.redalyc.org/articulo.oa?id=49650910043 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Study of Atrato river plume in a tropical estuary: Effects of the wind and tidal regime on the Gulf of Uraba, Colombia 1 Luis Javier Montoya a, Francisco Mauricio Toro-Botero b & Andrés Gomez-Giraldo b a Universidad de Medellin, Medellin, Colombia. [email protected] b Facultad de Minas, Universidad Nacional de Colombia, Medellin, [email protected], [email protected] Received: January 7th, 2016. Received in revised form: October 6th, 2016. Accepted. December 20th, 2016 Abstract This study focuses on the relative importance of the forcing agents of Atrato River plume as it propagates in a tropical estuary located in the Gulf of Uraba in the Colombian Caribbean Sea. Six campaigns of intensive field data collection were carried out from 2004 to 2007 to identify the main features of the plume and to calibrate and validate a numerical model. Field data and numerical models revealed high spatial and temporal plume variability according to the magnitudes of river discharges, tidal cycles, and wind stress. -
A Satellite View of Riverine Turbidity Plumes on the Ne-E Brazilian Coastal Zone
BRAZILIAN JOURNAL OF OCEANOGRAPHY, 60(3):283-298, 2012 A SATELLITE VIEW OF RIVERINE TURBIDITY PLUMES ON THE NE-E BRAZILIAN COASTAL ZONE Eduardo Negri de Oliveira1*, Bastiaan Adriaan Knoppers2, João Antônio Lorenzzetti3, Paulo Ricardo Petter Medeiros4, Maria Eulália Carneiro5 and Weber Friederichs Landim de Souza6 1Universidade Estadual do Rio de Janeiro - Departamento de Oceanografia Física (Rua São Francisco Xavier, n. 524, Maracanã, Rio de Janeiro, RJ, Brasil) 2Universidade Federal Fluminense (UFF) - Departamento de Geoquímica (Morro do Valonguinho s/n, 24020-141 Niterói, RJ, Brasil) 3Instituto Nacional de Pesquisas Espaciais (INPE) - Divisão de Sensoriamento Remoto (Av. Astronautas, 1758, 12227-010 São José dos Campos, SP, Brasil) 4Universidade Federal de Alagoas - Laboratório Natural e Ciências do Mar (Rua Aristeu de Andrade, 452, 57021-090 - Maceió / AL, Brasil) 5Petrobras SA - Monitoramento e Avaliação Ambiental (Av. Horácio de Macedo, 950, Ilha do Fundão, 21941-915 Rio de Janeiro, RJ, Brasil) 6Instituto Nacional de Tecnologia - Laboratório de Metrologia Analítica e Química (Av. Venezuela, 82, 20081-312, Rio de Janeiro, RJ, Brasil) *Corresponding author: [email protected] A B S T R A C T Turbidity plumes of São Francisco, Caravelas, Doce, and Paraiba do Sul river systems, located along the NE/E Brazilian coast, are analyzed for their dispersal patterns of Total Suspended Solids (TSS) concentration using Landsat images and a logarithmic algorithm proposed by Tassan (1987) to convert satellite reflectance values to TSS. The TSS results obtained were compared to in situ collected TSS data. The analysis of the satellite image data set revealed that each river system exhibits a distinct turbidity plume dispersal pattern. -
Wave Breaking Turbulence at the Offshore Front of the Columbia River
GeophysicalResearchLetters RESEARCH LETTER Wave breaking turbulence at the offshore front 10.1002/2014GL062274 of the Columbia River Plume 1 1 1 1 2 Key Points: Jim Thomson , Alex R. Horner-Devine , Seth Zippel , Curtis Rusch , and W. Geyer • Strong currents at fronts cause 1 2 wave breaking University of Washington, Seattle, Washington, USA, Woods Hole Oceanographic Institution, Woods Hole, • Wave breaking generates strong Massachusetts, USA turbulence • Surface turbulence (from wave breaking) can affect subsurface Abstract Observations at the Columbia River plume show that wave breaking is an important source mixing of turbulence at the offshore front, which may contribute to plume mixing. The lateral gradient of current associated with the plume front is sufficient to block (and break) shorter waves. The intense whitecapping Correspondence to: that then occurs at the front is a significant source of turbulence, which diffuses downward from the J. Thomson, [email protected] surface according to a scaling determined by the wave height and the gradient of wave energy flux. This process is distinct from the shear-driven mixing that occurs at the interface of river water and ocean water. Observations with and without short waves are examined, especially in two cases in which the background Citation: Thomson, J., A. R. Horner-Devine, conditions (i.e., tidal flows and river discharge) are otherwise identical. S. Zippel, C. Rusch, and W. Geyer (2014), Wave breaking turbu- lence at the offshore front of the Columbia River Plume, Geo- phys. Res. Lett., 41, 8987–8993, 1. Introduction doi:10.1002/2014GL062274. The local effects of waves and wave breaking on river plumes and the mixing of estuarine waters is largely unknown. -
Nearshore Drift-Cell Sediment Processes And
Journal of Coastal Research 00 0 000–000 Coconut Creek, Florida Month 0000 Nearshore Drift-Cell Sediment Processes and Ecological Function for Forage Fish: Implications for Ecological Restoration of Impaired Pacific Northwest Marine Ecosystems David Parks†, Anne Shaffer‡*, and Dwight Barry§ †Washington Department of Natural Resources ‡Coastal Watershed Institute §Western Washington University 311 McCarver Road P.O. Box 2263 Huxley Program on the Peninsula Port Angeles, Washington 98362, U.S.A. Port Angeles, Washington 98362, U.S.A. Port Angeles, Washington 98362, U.S.A. [email protected] ABSTRACT Parks, D.; Shaffer, A., and Barry, D., 0000. Nearshore drift-cell sediment processes and ecological function for forage fish: implications for ecological restoration of impaired Pacific Northwest marine ecosystems. Journal of Coastal Research, 00(0), 000–000. Coconut Creek (Florida), ISSN 0749-0208. Sediment processes of erosion, transport, and deposition play an important role in nearshore ecosystem function, including forming suitable habitats for forage fish spawning. Disruption of sediment processes is often assumed to result in impaired nearshore ecological function but is seldom assessed in the field. In this study we observed the sediment characteristics of intertidal beaches of three coastal drift cells with impaired and intact sediment processes and compared the functional metrics of forage fish (surf smelt, Hypomesus pretiosus, and sand lance, Ammodytes hexapterus) spawning and abundance to define linkages, if any, between sediment processes -
A Conceptual Model of the Strongly Tidal Columbia River Plume
Submitted to Journal of Marine Systems manuscript No. (will be inserted by the editor) Alexander R. Horner-Devine, David A. Jay, Philip M. Orton and Emily Y. Spahn A conceptual model of the strongly tidal Columbia River plume Received: date / Accepted: date Abstract The Columbia River plume is typical of large-scale, high discharge, mid-latitude plumes. In the absence of strong upwelling winds, freshwater from the river executes a rightward turn and forms an anticyclonic bulge before moving north along the Washington coast. In addition to the above A.R. Horner-Devine Civil and Environmental Engineering University of Washington Tel.: 206-685-3032 E-mail: [email protected] David Jay Civil and Environmental Engineering Portland State University E-mail: [email protected] Philip Orton Lamont-Doherty Earth Observatory Columbia University E-mail: [email protected] Emily Spahn Civil and Environmental Engineering University of Washington E-mail: [email protected] 2 dynamics, however, the river plume outflow is subject to large tides, which modify the structure of the plume in the region near the river mouth. Observations based on data acquired during a summer 2005 cruise indicate that the plume consists of four distinct water masses; source water at the lift-off point, and the tidal, re-circulating and far-field plumes. In contrast to most plume models that describe the discharge of low-salinity estuary water into ambient high-salinity coastal water, we describe the Columbia plume as the superposition of these four plume types. We focus primarily on a conceptual summary of the dynamics and mutual interaction of the tidal and re-circulating plumes. -
The Ocean Floor Word Find Activity
The Ocean Floor Word Find Activity Beneath the ocean is a landscape, which has similar features to what we see on land. The ocean floor is generally divided into the continental shelf, the continental slope and the deep ocean floor. The land from the continent or an island gently extends out underneath the water to form a large area called the continental shelf. The continental shelf is a very important area under the ocean as a lot of marine life thrives there. The area can also contain petroleum, natural gas as well as minerals under the seafloor which are very valuable. The continental slope is the point where the shelf area plunges down into the deepest parts of the oceans. This part of the ocean floor is marked with deep canyons. Below the continental slopes sediment can often collect over time to form gental slopes called continental rises. The continental shelf, slope and rises are known as the continental margin. In many parts of the bottom of the ocean there are flat areas covered with sediment. This area is called the abyssal plain. The abyssal plain is usually found at depths between 3000 and 6000 metres below sea level. The abyssal plain is broken by mid ocean ridges, which are like long mountain ranges under the ocean. The entire global mid ocean ridge system is the longest mountain chain on earth and has formed where oceanic plates are continuously separating. These areas include the Mid-Atlantic ridge, the Pacific rise, as well as trenches such as the Marina Trench in the Pacific Ocean. -
45. Sedimentary Facies and Depositional History of the Iberia Abyssal Plain1
Whitmarsh, R.B., Sawyer, D.S., Klaus, A., and Masson, D.G. (Eds.), 1996 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 149 45. SEDIMENTARY FACIES AND DEPOSITIONAL HISTORY OF THE IBERIA ABYSSAL PLAIN1 D. Milkert,2 B. Alonso,3 L. Liu,4 X. Zhao,5 M. Comas,6 and E. de Kaenel4 ABSTRACT During Leg 149, a transect of five sites (Sites 897 to 901) was cored across the rifted continental margin off the west coast of Portugal. Lithologic and seismostratigraphical studies, as well as paleomagnetic, calcareous nannofossil, foraminiferal, and dinocyst stratigraphic research, were completed. The depositional history of the Iberia Abyssal Plain is generally characterized by downslope transport of terrigenous sedi- ments, pelagic sedimentation, and contourite sediments. Sea-level changes and catastrophic events such as slope failure, trig- gered by earthquakes or oversteepening, are the main factors that have controlled the different sedimentary facies. We propose five stages for the evolution of the Iberia Abyssal Plain: (1) Upper Cretaceous and lower Tertiary gravitational flows, (2) Eocene pelagic sedimentation, (3) Oligocene and Miocene contourites, (4) a Miocene compressional phase, and (5) Pliocene and Pleistocene turbidite sedimentation. Major input of terrigenous turbidites on the Iberia Abyssal Plain began in the late Pliocene at 2.6 Ma. INTRODUCTION tured by both Mesozoic extension and Eocene compression (Pyrenean orogeny) (Boillot et al., 1979), and to a lesser extent by Miocene com- Leg 149 drilled a transect of sites (897 to 901) across the rifted mar- pression (Betic-Rif phase) (Mougenot et al., 1984). gin off Portugal over the ocean/continent transition in the Iberia Abys- Previous studies of the Cenozoic geology of the Iberian Margin sal Plain. -
Encountering Shoaling Internal Waves on the Dispersal Pathway of the Pearl River Plume in Summer Jay Lee1, James T
www.nature.com/scientificreports OPEN Encountering shoaling internal waves on the dispersal pathway of the pearl river plume in summer Jay Lee1, James T. Liu1*, I‑Huan Lee1, Ke‑Hsien Fu1,2, Rick J. Yang1, Wenping Gong3 & Jianping Gan4 Fundamentally, river plume dynamics are controlled by the buoyancy due to river efuent and mixing induced by local forcing such as winds and tides. Rarely the infuence of far‑feld internal waves on the river plume dynamics is documented. Our 5‑day fx‑point measurements and underway acoustic profling identifed hydrodynamic processes on the dispersal pathway of the Pearl River plume. The river plume dispersal was driven by the SW monsoon winds that induced the intrusion of cold water near the bottom. The river efuent occupied the surface water, creating strong stratifcation and showing on‑ofshore variability due to tidal fuctuations. However, intermittent disruptions weakened stratifcation due to wind mixing and perturbations by nonlinear internal waves (NIWs) from the northern South China Sea (NSCS). During events of NIW encounter, signifcant drawdowns of the river plume up to 20 m occurred. The EOF deciphers and ranks the contributions of abovementioned processes: (1) the stratifcation/mixing coupled by wind‑driven plume water and NIWs disruptions (81.7%); (2) the variation caused by tidal modulation (6.9%); and (3) the cold water intrusion induced by summer monsoon winds (5.1%). Our fndings further improve the understanding of the Pearl River plume dynamics infuenced by the NIWs from the NSCS. Significant physical and biogeochemical effects caused by internal waves (IWs) have been ubiquitously recognized1–3.