A computational method for the time-domain intensity scattered from rough interfaces and volume heterogeneities in deep water

As the exploration for oil and other natural resources spreads into deeper waters, traditional fixed offshore structures have become unsuitable. New technologies are being developed for deep sea exploration. Spar platforms are economical and efficient type of compliant offshore platforms in deeper waters for the drilling, production, processing and storage of ocean deposits. Although several studies have been performed on floating structures, few works have focused on spar platforms. This study gives a detailed assessment of the technical developments of the spar platform, including research on its dynamic responses, mooring systems and coupling phenomena. It addresses in detail the structural configurations, properties and characteristics of spar structures as described in existing literature along with the behaviour of spars in deep and ultra-deep ocean environments. Important practical issues which are encountered by spar platforms in various environmental loadings were also taken into consideration. Rigorous study reveals the coupled spar platform as a very innovative floating structure suitable for conducting oil and gas exploration in deeper seas. The study offers precise modelling of spar platforms for ultra-deepwater operations and improves technical parameters, economic aspects and other criteria.

Transporter proteins are a vital interface between cells and their environment. In nutrient-limited environments, microbes with transporters that are effective at bringing substrates into their cells will gain a competitive advantage over variants with reduced transport function. Microbial ammonium transporters (Amt) bring ammonium into the cytoplasm from the surrounding periplasm space, but diagnosing Amt adaptations to low nutrient environments solely from sequence data has been elusive. Here, we report altered Amt sequence amino acid distribution from deep marine samples compared to variants sampled from shallow water in two important microbial lineages of the marine water column community-Marine Group I Archaea (Thermoproteota) and the uncultivated gammaproteobacterial lineage SAR86. This pattern indicates an evolutionary pressure towards an increasing dipole in Amt for these clades in deep ocean environments and is predicted to generate stronger electric fields facilitating ammonium acquisition. This pattern of increasing dipole charge with depth was not observed in lineages capable of accessing alternative nitrogen sources, including the abundant alphaproteobacterial clade SAR11. We speculate that competition for ammonium in the deep ocean drives transporter sequence evolution. The low concentration of ammonium in the deep ocean is therefore likely due to rapid uptake by Amts concurrent with decreasing nutrient flux.

Deconvolving the controls on the deep ocean's silicon stable isotope distribution

Measurement and validation of tsunami Eigen values for the various water wave conditions

Chapter 7 - Biodiversity of deep ocean on development of biofilms: Biofouling communities and corrosion performance of materials

Paleotopographic models of the West Antarctic margin, which are essential for robust simulations of paleoclimate scenarios, lack information on sediment thickness and geodynamic conditions, resulting in large uncertainties. A new total sediment thickness grid spanning the Ross Sea–Amundsen Sea–Bellingshausen Sea basins is presented and is based on all the available seismic reflection, borehole, and gravity modeling data offshore West Antarctica. This grid was combined with NGDC's global 5 arc minute grid of ocean sediment thickness (Whittaker et al., 2013) and extends the NGDC grid further to the south. Sediment thickness along the West Antarctic margin tends to be 3–4km larger than previously assumed. The sediment volume in the Bellingshausen, Amundsen, and Ross Sea basins amounts to 3.61, 3.58, and 2.78millionkm3, respectively. The residual basement topography of the South Pacific has been revised and the new data show an asymmetric trend over the Pacific–Antarctic Ridge. Values are anomalously high south of the spreading ridge and in the Ross Sea area, where the topography seems to be affected by persistent mantle processes. In contrast, the basement topography offshore Marie Byrd Land cannot be attributed to dynamic topography, but rather to crustal thickening due to intraplate volcanism. Present-day dynamic topography models disagree with the presented revised basement topography of the South Pacific, rendering paleotopographic reconstructions with such a limited dataset still fairly uncertain.

: The long-term goal is to contribute to the understanding of long-range propagation of acoustic pulses in deep ocean environments. Emphasis is placed on broadband pulses centered at around 100 Hertz in oceans that have a well defined acoustic waveguide. This effort directly compliments the Long-range Ocean Acoustic Propagation Experiment (LOAPEX) that was performed in the fall of 2004. A primary objective is to test the hypothesis that an stochastic environmental model that includes internal waves and spice is adequate to explain the multiple forward scattering of acoustic pulses as they are propagated in range. The stochastic model is based on measurements of temperature, salinity, and pressure taken during LOAPEX. Of primary consideration is to compare model results to LOAPEX data which used source of approximately 75 Hz, but extrapolation to other source frequencies (e.g. 250 Hz) is also an objective.

The role of hydrodynamics for the spatial distribution of high-temperature hydrothermal vent-endemic fauna in the deep ocean environment

Modal group time spreads in deep ocean environments are investigated. The environments considered consist of a range-independent background on which a range-dependent perturbation, due for example to internal waves, is superimposed. Modal group time spreads are defined to be the temporal spread of acoustic energy with a fixed mode number across a nonvanishing frequency band. It is shown that there are three contributions to modal group time spreads that combine approximately in quadrature. These contributions are (1) the recriprocal bandwidth, (2) a deterministic dispersive contribution, and (3) a scattering-induced contribution. Contributions 2 and 3 are shown to be controlled by the waveguide invariant β(m,f), a property of the background sound speed structure. Numerical simulations are shown to be in good agreement with theoretical predictions. [Work supported by ONR.]

Single hydrophone passive acoustic ranging is the practice of estimating the range to an underwater sound source using acoustic recordings from a single receiver. We present a multi-path arrival-based approach to estimate the horizontal range between a submerged source:receiver pair in a deep ocean environment (in which multi-path arrivals can be resolved and modal dispersion is minimal). A cost function and optimization approach are presented that are automated and robust to some significant sources of noise (including multiple sources) and environmental uncertainty. While several multi-path ranging methods have been presented in past literature, an important contribution of our approach is that it can be fully automated, it relaxes the requirement that arrivals are labeled/identified a priori, and it can function in multiple-source scenarios. Underwater acoustic data recorded by the ALOHA Cabled Observatory (ACO) are processed using our single hydrophone ranging approach. The horizontal range to 296 airgun shots, recorded by ACO on October 5-6, 2018, is compared against the true range for each shot. Good agreement between the true and estimated ranges demonstrates the performance of the ranging approach.

A model is used to calculate this static and dynamic behavior of a marine riser supported from a floating vessel. Analysis examples demonstrate the consequences of extrapolating an existing riser design into deep water, and show that the dynamic behavior of the riser, caused primarily by vessel response to waves, is a significant design factor in all water depths. Introduction The marine riser is a conductor pipe used in floating drilling operations to convey drilling fluid and to guide tools between the drilling vessel and the wellhead at the ocean floor. The essential features of marine riser design were defined by Fischer and Ludwig who showed, with a static analysis, the importance of tensioning the riser to prevent buckling and to control deflections and stresses. An analysis by Tidwell and Ifrey further illustrated these effects. Fischer and Ludwig recognized the possible effects of dynamic behavior on the riser, but reasoned that these effects would not be a critical design factor for water depths up to 1,000 ft if the riser diameter were held to a minimum. As exploratory drilling operations move into deeper water, the dynamic effects in riser design become of increasing concern. The significance of dynamic behavior for riser design was recognized by National Engineering and Science Co. (NESCO) in their analysis of the 14,000-ft-long drilling riser for Project Mohole. Their study showed that riser Project Mohole. Their study showed that riser dynamic behavior was a significant factor in design, and that the most significant portion of the dynamic behavior was caused by motions of the drilling vessel, rather than by wave forces on the riser. The analysis model described in this paper was formulated to analyze, both statically and dynamically, the types of marine risers presently used in floating drilling operations. The analysis method employs a numerical integration scheme that differs from the series solution method employed by Fischer and Ludwig, and the finite difference methods used by Tidwell and Ifrey and by NESCO. The numerical integration method is particularly suited for an accurate representation of parameters that vary along the length of the riser and for efficient implementation on a digital computer. The purpose of this paper is to describe the mathematical model that was developed, and to illustrate the usefulness of the model with an example that shows the effects of extending a riser into deeper water. The paper is divided into two parts and an appendix. The first part describes the basis for the analysis model; the method of solving the equations in the model is described in the Appendix. The second part of the paper describes the analysis of a 16-in. riser in water depths from 400 to 2,000 ft, and discusses the effects of increasing water depth on riser design and operations. Analysis Model The analysis model of the marine riser is based on the general linear differential equation for a beam column with lateral loads in a vertical plane. A solution to the differential equation is obtained by a numerical integration method for a specified force distribution along the length and boundary conditions at each end. This section describes the equations used in the analysis model; the solution method is outlined in the Appendix. JPT P. 455

The Ocean Drilling Program (ODP) and its predecessor, the Deep Sea Drilling Project (DSDP), have completed over 30 years of scientific ocean drilling. In the early days of DSDP, drilling began in the deepest parts of the oceans, in water depths to which the oil industry is just now moving, 30 years later. ODP/DSDP technology developments have continued over the years with a special focus on high quality sampling tools and the development of seafloor observatories. One of the most successful tool developments is the advanced piston corer. This wireline tool can recover 10 m long samples and has been used successfully to recover high quality core samples in deep water (>3000 m) to 300 meters below seafloor. Other deep water coring tools have been developed to sample sedimentary and igneous rocks. Complimenting the core sample tools, ODP has developed wireline-deployed tools that measure in situ physical properties, such as pressure and temperature. The seafloor observatories have been developed for deep water science applications. These observatories are installed into boreholes, sealed from the overlying ocean water, and left to collect a variety of physical data (temperature & pressure sensors, seismometers, pore fluid samples) as time series. These ODP technologies can be used for deep water site investigations, shallow water flow assessments, and to establish fluid flow and pressure monitoring stations at deep water sites. These tools and techniques may be applied to deep water site investigations at reduced costs with high quality results. Background The Ocean Drilling Program (ODP) and its predecessor, the Deep Sea Drilling Project (DSDP), have completed over 30 years of scientific ocean drilling. These two Programs have circumnavigated the globe many times, drilling in all regions of the global ocean (Fig. 1). The Deep Sea Drilling Project officially began in 1968 when the drill ship, Glomar Challenger, sailed on its first scientific drilling expedition to the Gulf of Mexico and the Bermuda Rise. In addition to the major engineering feat of this first voyage - drilling in water depths greater than 5000 m and penetrating 700 m into the seafloor - the science successes were outstanding. Scientists recovered the oldest rocks ever found in the deep ocean and discovered deep water petroleum and salt dome cap rock. Yet scientific ocean drilling began even earlier than the Deep Sea Drilling Project. In 1961, the vessel, CUSS I, was chartered and drilled 200 m into the seafloor in 3,800 m of water off Guadeloupe Island. The recovery of basalt in this first ever deep sea borehole verified the composition of ocean crust Layer 2, and demonstrated that ocean drilling was indeed critical to the advancement of science. Drilling during the early years of the Deep Sea Drilling Project took place in the deepest parts of the oceans, in water depths to which the oil industry is just now moving, 30 years later. In addition to achieving this deep water challenge, the Project developed sampling tools to recover high quality samples of deep sea sediment, sedimentary rock, and igneous rock.

Research Article| October 01, 1995 Fallout of volcanic ash to the deep South China Sea induced by the 1991 eruption of Mount Pinatubo (Philippines) Martin G. Wiesner; Martin G. Wiesner 1Institute of Biogeochemistry and Marine Chemistry, University of Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany Search for other works by this author on: GSW Google Scholar Yubo Wang; Yubo Wang 1Institute of Biogeochemistry and Marine Chemistry, University of Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany Search for other works by this author on: GSW Google Scholar Lianfu Zheng Lianfu Zheng 2Second Institute of Oceanography, State Oceanic Administration, P.O. Box 1207, Hangzhou 310012, Peoples Republic of China Search for other works by this author on: GSW Google Scholar Geology (1995) 23 (10): 885–888. https://doi.org/10.1130/0091-7613(1995)023<0885:FOVATT>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Martin G. Wiesner, Yubo Wang, Lianfu Zheng; Fallout of volcanic ash to the deep South China Sea induced by the 1991 eruption of Mount Pinatubo (Philippines). Geology 1995;; 23 (10): 885–888. doi: https://doi.org/10.1130/0091-7613(1995)023<0885:FOVATT>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract An ongoing sediment trap experiment in the central South China Sea provided the opportunity to investigate directly the mode and rates of a medial fallout of volcanic ash following the June 15, 1991, eruption of Mount Pinatubo (Philippines). Within less than three days after the release of the major eruption plume, ash accumulation (9 kg/m2) was simultaneously recorded by traps positioned in 1190 and 3730 m water depth at a distance of 586 km to the west of the volcano. A numerical simulation of the fallout reveals that the vertical trajectories of the pyroclasts in both the atmosphere and ocean were controlled by particle aggregation. The aggregation process caused a premature subaerial fallout of fine-grained ash. After crossing the air-sea interface, vertical settling of the ash clusters was enhanced by absorption of water leading to settling rates of more than 1670 m/d. Aggregates were observed at all depths, and their rapid settling is reflected in identical pyroclast spectra in intermediate and deep water. This implies that particle sorting must have been complete in the upper water column and that the fallout was not perturbed by oceanic currents. The tephra blankets an area of 37 × 104 km2 in a fan-shaped westward distribution, which reflects the prevailing direction of the upper-level winds. Our data show that atmospheric tephra dispersal patterns are recorded almost instantaneously on the deep-sea floor and corroborate the key role of deep-sea ash layers as highly reliable chronostratigraphic markers, and as a geological tool to infer ancient wind fields. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Our knowledge of the biodiversity of the Southern Ocean (SO) deep benthos is scarce. In this review, we describe the general biodiversity patterns of meio-, macro- and megafaunal taxa, based on historical and recent expeditions, and against the background of the geological events and phylogenetic relationships that have influenced the biodiversity and evolution of the investigated taxa. The relationship of the fauna to environmental parameters, such as water depth, sediment type, food availability and carbonate solubility, as well as species interrelationships, probably have shaped present-day biodiversity patterns as much as evolution. However, different taxa exhibit different large-scale biodiversity and biogeographic patterns. Moreover, there is rarely any clear relationship of biodiversity pattern with depth, latitude or environmental parameters, such as sediment composition or grain size. Similarities and differences between the SO biodiversity and biodiversity of global oceans are outlined. The high percentage (often more than 90%) of new species in almost all taxa, as well as the high degree of endemism of many groups, may reflect undersampling of the area, and it is likely to decrease as more information is gathered about SO deep-sea biodiversity by future expeditions. Indeed, among certain taxa such as the Foraminifera, close links at the species level are already apparent between deep Weddell Sea faunas and those from similar depths in the North Atlantic and Arctic. With regard to the vertical zonation from the shelf edge into deep water, biodiversity patterns among some taxa in the SO might differ from those in other deep-sea areas, due to the deep Antarctic shelf and the evolution of eurybathy in many species, as well as to deep-water production that can fuel the SO deep sea with freshly produced organic matter derived not only from phytoplankton, but also from ice algae.

Volcanogenic effects on the rates of deposition of sediments in the Northwest Pacific Ocean