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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Multi-model Mean Nitrogen and Sulfur Deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): Evaluation of Historical and Projected Future Changes

We present multi-model global datasets of nitrogen and sulfate deposition covering time periods from 1850 to 2100, calculated within the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The computed deposition fluxes are compared to surface wet deposition and ice-core measurements. We use a new dataset of wet deposition for 2000-2002 based on critical assessment of the quality of existing regional network data. We show that for present-day (year 2000 ACCMIP time-slice), the ACCMIP results perform similarly to previously published multi-model assessments. The analysis of changes between 1980 and 2000 indicates significant differences between model and measurements over the United States, but less so over Europe. This difference points towards misrepresentation of 1980 NH3 emissions over North America. Based on ice-core records, the 1850 deposition fluxes agree well with Greenland ice cores but the change between 1850 and 2000 seems to be overestimated in the Northern Hemisphere for both nitrogen and sulfur species. Using the Representative Concentration Pathways to define the projected climate and atmospheric chemistry related emissions and concentrations, we find large regional nitrogen deposition increases in 2100 in Latin America, Africa and parts of Asia under some of the scenarios considered. Increases in South Asia are especially large, and are seen in all scenarios, with 2100 values more than double 2000 in some scenarios and reaching >1300 mgN/m2/yr averaged over regional to continental scale regions in RCP 2.6 and 8.5, ~30-50% larger than the values in any region currently (2000). Despite known issues, the new ACCMIP deposition dataset provides novel, consistent and evaluated global gridded deposition fields for use in a wide range of climate and ecological studies.

ACCMIP↗
DOE OSTI2026

Project 1: COLLECTS Project and Project 2: M&V for Saputo Cheese Project: Cooperative Research and Development (Final Report)

Project 1: Combined Power's Hyperlight Energy and NLR will collaborate on the DOE Concentrating Optics for Lower Levelized Energy CosTS (COLLECTS) project, DE-FOA-0001268. COLLECTS funding opportunity announcement (FOA) seeks to further concentrated solar power (CSP) system technologies by soliciting disruptive, transformative projects for the concentrating solar collectors in the CSP plant. These innovative projects will seek to surpass the targets set out in the SunShot Vision Study, enabling CSP to be cost-competitive with conventional forms of electric power generation. Projects will target the design and manufacturing of novel solar collectors with the ability to significantly reduce the solar field contribution to the overall levelized cost of energy (LCOE) of the CSP plant, and which have not been previously specifically targeted by CSP FOAs. Project 2: Hyperlight will perform measurement and verification (M&V) of Green House Gases and NLR will evaluate energy consumption reduction.

14 SOLAR ENERGY↗
DOE OSTI2026

CONUS-wide Projected Flood Frequency and Uncertainty Estimates, Version 1.0

This dataset presents a large-ensemble of CONUS-wide projected flood frequency and uncertainty estimates across ~2.7 million NHDPlusV2 river reaches over the CONUS. The framework producing this dataset leverages a multi-model, uncertainty-aware modeling framework that allows evaluating shifts in flood frequences at the stream reach level across the CONUS. CONUS-wide ensemble streamflow projections generated from hydrologic simulations driven by downscaled and bias-corrected Coupled Model Intercomparison Project Phase 6 (CMIP6) outputs are used to derive these flood frequency and uncertainty estimates over the period 1980 - 2099. A spatially consistent regional L-moment algorithm is applied across clusters defined by the US Hydrologic Unit Code Subregions (HUC4s and HUC8s) and NHDPlusV2 stream orders to estimate flood frequencies. The dataset also includes at-site based flood estimates that allow for the comparison between local and regional approach-based estimates, assess projected changes, and characterize their uncertainties. For more reliable estimation of rare flood frequencies such as 500 and 1000-year return periods, super-ensemble based estimates are also included in the dataset. This dataset is derived to support the "Impact-Informed Dam Safety Risk Assessment for Securing Hydropower Assests" project for the US Department of Energy (DOE) Hydropower and Hydrokinetic Office (H2O). For further details, refer to Kao et al. (2022), Ghimire et al. (2023), Ghimire et al. (2025), and Hosking and Wallis (1997).

Ghimire, Ganesh [ORNL] (ORCID:0000000242843941)↗
DOE OSTI2015

Visual exploration of high-dimensional data through subspace analysis and dynamic projections

Here, we introduce a novel interactive framework for visualizing and exploring high-dimensional datasets based on subspace analysis and dynamic projections. We assume the high-dimensional dataset can be represented by a mixture of low-dimensional linear subspaces with mixed dimensions, and provide a method to reliably estimate the intrinsic dimension and linear basis of each subspace extracted from the subspace clustering. Subsequently, we use these bases to define unique 2D linear projections as viewpoints from which to visualize the data. To understand the relationships among the different projections and to discover hidden patterns, we connect these projections through dynamic projections that create smooth animated transitions between pairs of projections. We introduce the view transition graph, which provides flexible navigation among these projections to facilitate an intuitive exploration. Finally, we provide detailed comparisons with related systems, and use real-world examples to demonstrate the novelty and usability of our proposed framework.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2012

Integrated Project Teams - An Essential Element of Project Management during Project Planning and Execution - 12155

Managing complex projects requires a capable, effective project manager to be in place, who is assisted by a team of competent assistants in various relevant disciplines. This team of assistants is known as the Integrated Project Team (IPT). he IPT is composed of a multidisciplinary group of people who are collectively responsible for delivering a defined project outcome and who plan, execute, and implement over the entire life-cycle of a project, which can be a facility being constructed or a system being acquired. An ideal IPT includes empowered representatives from all functional areas involved with a project-such as engineering design, technology, manufacturing, test and evaluation, contracts, legal, logistics, and especially, the customer. Effective IPTs are an essential element of scope, cost, and schedule control for any complex, large construction project, whether funded by DOE or another organization. By recently assessing a number of major, on-going DOE waste management projects, the characteristics of high performing IPTs have been defined as well as the reasons for potential IPT failure. Project managers should use IPTs to plan and execute projects, but the IPTs must be properly constituted and the members capable and empowered. For them to be effective, the project manager must select the right team, and provide them with the training and guidance for them to be effective. IPT members must treat their IPT assignment as a primary duty, not some ancillary function. All team members must have an understanding of the factors associated with successful IPTs, and the reasons that some IPTs fail. Integrated Project Teams should be used by both government and industry. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Design Basis Document / Owner’s Technical Specification for Nitrate Salt Systems in CSP Projects: Volume 1 Specifications for Parabolic Trough Projects, Volume 2 - Specifications for Central Receiver Projects, Volume 3 - Narrative

Design Basis Documents / Owner’s Technical Specifications are developed for parabolic trough and central receiver power plants using nitrate salt as the heat transport fluid and the thermal storage medium. The goals were to 1) distill the successful experience with nitrate salt systems from as many commercial projects as possible, 2) provide technical bases for equipment design/selection that an owner can impose on an EPC contractor, 3) compile this information in one location to provide guidance on salt systems that is as broadly applicable to as many projects as possible, and 4) work toward an industry consensus on a Design Basis Document that reflects the lessons learned from earlier commercial projects. The document allows an owner to provide design guidance, and to impose a minimum set of requirements, above and beyond those in the normal Codes and Standards, on an EPC contractor in an effort to avoid a repeat of past mistakes. If successful, this would allow salt systems to achieve the same levels of reliability and availability as commercial parabolic trough plants using diphenyl oxide / biphenyl (i.e., Dowtherm A, Therminol VP-1) as the heat transfer fluid. The report consists of 3 volumes: • Volume 1 - Specifications for Parabolic Trough Projects • Volume 2 - Specifications for Central Receiver Projects • Volume 3 - Narrative Volumes 1 and 2 include discussions of the following topics: • Plant functional requirements for the salt systems • Plant operating states, and transitions between states, for the salt systems • Risk analysis of the principal salt components • Plant requirements for the salt systems to meet the functional and the operating requirements • Type of specification for the principal salt components: functional; or prescriptive • Current state of the art for salt systems. Volume 3 discusses a number of cases in which the salt equipment at commercial parabolic trough and central receiver projects has not met the projected levels of reliability and availability. Possible reasons for the sources of the problems are discussed, as is a range of possible alternate designs that could avoid the known problems.

14 SOLAR ENERGY↗
DOE OSTI2025

Projected Urban Morphology of the Los Angeles Area by the Year 2100

This dataset provides projections of urban building morphologies for the Los Angeles urban area at 30-meter spatial resolution. It contains 192 raster files that detail two primary building attributes: building footprint fractions (ranging from 0 to 1) and average building heights (ranging from 0 to 75 meters). The projections account for a wide range of future pathways, covering two Shared Socioeconomic Pathway (SSP) scenarios (SSP3 and SSP5), two population scenarios, two developed land intensification scenarios, and four distinct levels of intensification. The dataset was created using dual Generative Adversarial Networks (GANs) trained on 2015 land cover and building properties from the National Land Cover Database (NLCD) and Model America datasets. Supporting information on the dataset has been described in the LAUrbanAreaMorphologyProjections2100_README.txt file.

Pandey, Bhartendu↗
DOE OSTI2013

Generation of virtual monochromatic CBCT from dual kV/MV beam projections

Purpose: To develop a novel on-board imaging technique which allows generation of virtual monochromatic (VM) cone-beam CT (CBCT) with a selected energy from combined kilovoltage (kV)/megavoltage (MV) beam projections. Methods: With the current orthogonal kV/MV imaging hardware equipped in modern linear accelerators, both MV projections (from gantry angle of 0°–100°) and kV projections (90°–200°) were acquired as gantry rotated a total of 110°. A selected range of overlap projections between 90° to 100° were then decomposed into two material projections using experimentally determined parameters from orthogonally stacked aluminum and acrylic step-wedges. Given attenuation coefficients of aluminum and acrylic at a predetermined energy, one set of VM projections could be synthesized from two corresponding sets of decomposed projections. Two linear functions were generated using projection information at overlap angles to convert kV and MV projections at nonoverlap angles to approximate VM projections for CBCT reconstruction. The contrast-to-noise ratios (CNRs) were calculated for different inserts in VM CBCTs of a CatPhan phantom with various selected energies and compared with those in kV and MV CBCTs. The effect of overlap projection number on CNR was evaluated. Additionally, the effect of beam orientation was studied by scanning the CatPhan sandwiched with two 5 cm solid-water phantoms on both lateral sides and an electronic density phantom with two metal bolt inserts. Results: Proper selection of VM energy [30 and 40 keV for low-density polyethylene (LDPE), polymethylpentene, 2 MeV for Delrin] provided comparable or even better CNR results as compared with kV or MV CBCT. An increased number of overlap kV and MV projection demonstrated only marginal improvements of CNR for different inserts (with the exception of LDPE) and therefore one projection overlap was found to be sufficient for the CatPhan study. It was also evident that the optimal CBCT image quality was achieved when MV beams penetrated through the heavy attenuation direction of the object. Conclusions: A novel technique was developed to generate VM CBCTs from kV/MV projections. This technique has the potential to improve CNR at selected VM energies and to suppress artifacts at appropriate beam orientations.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Hanford's 100-HX Pump and Treat Project - a Successful Blend of Science, Technology, Construction, and Project Management - 12412

CH2M Hill Plateau Remediation Company (CHPRC) recently completed construction and start-up of the $25 million 100-HX Groundwater Pump and Treat Project for the Department of Energy (DOE) at its Hanford Reservation site in Washington State. From the onset, the 100-HX Project Leadership Team was able to successfully blend the science and technology of a state-of-the-art groundwater pump and treat system with the principles, tools, and techniques of traditional industrial-type construction and project management. From the 1940's through most of the 1980's, the United States used the Hanford Site to produce nuclear material for national defense at reactor sites located along the Columbia River. While the reactors were operational, large volumes of river water were treated with sodium dichromate (to inhibit corrosion of the reactor piping) and used as a coolant for the reactors. After a single pass through the reactor and before being discharged back to the river, the coolant water was sent to unlined retention basins to cool and to allow the short-lived radioactive contaminants to decay. As a result of these operations, hexavalent chromium was introduced to the vadose zone, and ultimately into the groundwater aquifer and the adjacent Columbia River. In addition, numerous leaks and spills of concentrated sodium dichromate stock solution over the lifetime of reactor operations led to higher concentrations of chromate in the vadose zone and groundwater in localized areas. As a result, the 100 Area was included in the National Priorities List sites under the Comprehensive Environmental Response Compensation and Liability Act of 1980 (CERCLA). The mission of the 100-HX Project is to significantly reduce the concentration of hexavalent chromium in the groundwater by treating up to 3.8 billion gallons (14,300 mega-liters) of contaminated water over its first nine years of operations. In order to accomplish this mission, groundwater scientists and geologists using sophisticated scientific modeling optimized the 100-HX's approximately 0.7 square mile (181 hecto-meters) extraction and injection well field to support continuous operation of a maximum of 800 gallons (3,028 liters) per minute, 24 hours per day, and 7 days per week. The use of traditional resin technology for the plant's ion exchange system required a change out of the resin every 12 weeks and shipment to an offsite facility 1,500 miles (2,414 kilometers) away for regeneration. Instead, the project leadership pursued newer technology with a disposable resin that could be disposed of on-site and would require less frequent change outs, reducing the project's life cycle costs by more than $16 million. Constructing the facility had its own challenges. The well field location overlapped ecologically sensitive lands where bald eagles and native wildlife use the land for their mating habitat for nearly half of the year. Building locations had to be planned around historically and culturally sensitive areas, and around another contractor's remediation work zones. Also, the size of the well field required a transfer (pumping) facility and installation of more than 60 miles (97 kilometers) of high-density polypropylene pipe, 23 miles (38 kilometers) of power cable, and 28 miles (46 kilometers) of control cable. Along with schedule and budget constraints typical of any fast-track project, the project team dealt with severe resource constraints due to competing projects across the Hanford Site caused by the influx of American Recovery and Reinvestment Act stimulus funding. In addition, the project team itself was stretched between completing another $25 million dollar construction project while designing and constructing this project. In order to save money, the project schedule was compressed by three months from the original baseline schedule. This was made possible by the strong use of project management principles throughout the design, construction, and testing phases, as well as implementation of many lessons learned from a similar construction project. In summary, the 100-HX Project truly was a unique blend of science, technology, construction and project management. In summary, Hanford's 100-HX Pump and Treat Project was a successful blend of science, technology, construction, and project management. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Model reduction for hypersonic aerodynamics via conservative LSPG projection and hyper-reduction

High-speed aerospace engineering applications rely heavily on computational fluid dynamics (CFD) models for design and analysis due to the expense and difficulty of flight tests and experiments. This reliance on CFD models necessitates performing accurate and reliable uncertainty quantification (UQ) of the CFD models. However, it is very computationally expensive to run CFD for hypersonic flows due to the fine grid resolution required to capture the strong shocks and large gradients that are typically present. Furthermore, UQ approaches are “many-query” problems requiring many runs with a wide range of input parameters. One way to enable computationally expensive models to be used in such many-query problems is to employ projection-based reduced-order models (ROMs) in lieu of the (high-fidelity) full-order model. In particular, the least-squares Petrov–Galerkin (LSPG) ROM (equipped with hyper-reduction) has demonstrated the ability to significantly reduce simulation costs while retaining high levels of accuracy on a range of problems including subsonic CFD applications. This allows computationally inexpensive LSPG ROM simulations to replace the full-order model simulations in UQ studies, which makes this many-query task tractable, even for large-scale CFD models. This work presents the first application of LSPG to a hypersonic CFD application. In particular, we present results for LSPG ROMs of the HIFiRE-1 in a three-dimensional, turbulent Mach 7.1 flow, showcasing the ability of the ROM to significantly reduce computational costs while maintaining high levels of accuracy in computed quantities of interest.

Fluid Dynamics↗
DOE OSTI2015

Using Project Complexity Determinations to Establish Required Levels of Project Rigor

The concepts discussed in this paper 1) focus on using technical competencies and skills in making objective determinations regarding project complexity based on objective scoring criteria and 2) then using the complexity determinations to establish the level of rigor required in initiating, planning, executing, monitoring and controlling, and closing projects to maximize process efficiency. This paper presents a project complexity analysis methodology for defining the levels of project management process rigor a project team needs to employ to maximize project delivery efficiencies without compromising quality and performance. Methods for making project complexity determinations based on project lifecycle size, duration, organizational complexity, requirements, technology readiness, risk, and visibility are discussed. The paper correlates the levels of rigor needed by project management process groups given the determined level of project complexity. Next, the paper presents a graded approach to defining extent of team formation, planning documentation rigor, stakeholder communication rigor, requirements management rigor, acquisition planning, risk management, executing, and monitoring and controlling rigor dependent on project complexity determinations. Methods for integrating and aligning the project complexity determination methods into existing project management procedures and processes are also discussed as well as methods for training personnel in the use of the method and facilitating and monitoring effectiveness of implementation within an organization in which project delivery is a mission focus.

complexity, project, determination, management, tr↗
DOE OSTI2025

Soft costs and EVSE – Knowledge gaps as a barrier to successful projects

There has been a recent push to increase access to electric vehicle (EV) charging infrastructure. The National Electric Vehicle Infrastructure (NEVI) program, part of the Bipartisan Infrastructure Law (BIL) has made significant funding available for major charging infrastructure projects along state thruways, and many state and local incentives exist for EV owners to install chargers in their homes. However, deployment of these chargers has not kept up with demand, primarily due to issues in project planning, permitting processes, and unforeseen delays. This paper serves as a review of the current understanding of these and other non-hardware costs in EV charging infrastructure projects (collectively known as “soft costs”). We found that soft costs in EV charging infrastructure projects are not well understood. Specifically, there is little agreement on how soft costs should be categorized and tracked, and less agreement still on best practices for controlling these costs and lowering barriers to infrastructure deployment. A broader review of EV charging infrastructure cost analyses shows that these costs can have significant impacts on project outcomes. EV charging infrastructure projects may be able to examine the success of the solar industry in lowering soft costs, and a similar effort may lower project costs significantly. Further work on standardizing and collecting data on EV charging infrastructure costs is required to begin addressing and controlling these costs.

32 - ENERGY CONSERVATION, CONSUMPTION, AND UTILIZA↗
DOE OSTI2016

The Little Engine That Could: No Project is too Small for Sustainable Remediation Moab Uranium Mill Tailings Removal Project - 16427

Executive Order 13693, 'Planning for Federal Sustainability in the Next Decade', mandates the reduction of energy use and cost and greenhouse gas emissions, and the search for renewable or alternative energy solutions. DOE EM manages the Moab Uranium Mill Tailings Remedial Action Project in Utah that involves relocating a 16-million-ton uranium mill tailings pile and associated contaminated materials at the former Atlas mill site to a permanent disposal cell constructed near Crescent Junction, Utah, predominantly by rail. Project personnel strive to support the Executive Order in making preparations for the impacts of climate change. Meeting the goals of the Executive Order in light of the remote location and limited resources of the Project sites often requires an innovative approach and perseverance. The Moab Project is a 'Small Site' within EM and has a comparatively short-term completion date. As a result, large-scale sustainability projects, such as retrofits or remodels, do not offer a cost benefit over this period. Instead, less dramatic process changes are achievable. The Project purchases renewable wind energy through the local power provider to reduce Scope 2 (purchased electricity) greenhouse gas emissions. Toward its ambitious goal of achieving zero landfill waste, the Project has diverted over 50 percent of its nonhazardous solid waste from the local landfill through composting and recycling efforts. In particular, electronics must meet various sustainable criteria prior to purchase, and be recycled through donations and certified recyclers, diverting it from the waste stream. The Project has received multiple Green Buy Awards from DOE by reaching leadership goals for purchasing energy-efficient, water-efficient, bio-based, and recycled-content products. In fiscal year 2014, in response to President Obama's June 2014 memorandum, 'Sustainable Practices for Designed Landscapes and Supporting Pollinators on Federal Landscapes', the Project decided to take a proactive approach and work with a local pollinator group, hosting two beehives in a revegetation area on the Moab site. An increase in plant growth and blossoming plants in the revegetation area has been observed and is believed to be related to the added pollinators. The Project has previously seeded disturbed areas mainly with native drought-resistant species to reduce water usage. Storm water collected in sediment basins at the Crescent Junction site is used for dust control and compaction of mill tailings in the disposal cell. The Project worked with the U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service to gain support for re-contouring a remediated area adjacent to the Colorado River, which borders the Moab site on the east, to allow the area to flood at a lower river stage. This re-contouring promotes more varied vegetation growth and river water that tops the west bank brings soil nutrients to inundated areas of the site. Ponded floodwater has been pumped into revegetation plots for irrigation, reducing freshwater usage. Innovation in sustainable practices comes in many different fashions. The Moab Project demonstrates that no project is too small to implement sustainable practices. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Comparison of different numerical treatments for x-ray phase tomography of soft tissue from differential phase projections

X-ray imaging of soft tissue is made difficult by their low absorbance. The use of x-ray phase imaging and tomography can significantly enhance the detection of these tissues and several approaches have been proposed to this end. Methods such as analyzer-based imaging or grating interferometry produce differential phase projections that can be used to reconstruct the 3D distribution of the sample refractive index. We report on the quantitative comparison of three different methods to obtain x-ray phase tomography with filtered back-projection from differential phase projections in the presence of noise. The three procedures represent different numerical approaches to solve the same mathematical problem, namely phase retrieval and filtered back-projection. It is found that obtaining individual phase projections and subsequently applying a conventional filtered back-projection algorithm produces the best results for noisy experimental data, when compared with other procedures based on the Hilbert transform. The algorithms are tested on simulated phantom data with added noise and the predictions are confirmed by experimental data acquired using a grating interferometer. The experiment is performed on unstained adult zebrafish, an important model organism for biomedical studies. The method optimization described here allows resolution of weak soft tissue features, such as muscle fibers.

Pelliccia, Daniele↗
DOE OSTI2012

Siting Study for a Hydrokinetic Energy Project Located Offshore Southeastern Florida: Protocols for Survey Methodology for Offshore Marine Hydrokinetic Energy Projects

Dehlsen Associates, LLC was awarded a grant by the United States Department of Energy (DOE) Golden Field Office for a project titled 'Siting Study Framework and Survey Methodology for Marine and Hydrokinetic Energy Project in Offshore Southeast Florida,' corresponding to DOE Grant Award Number DE-EE0002655 resulting from DOE funding Opportunity Announcement Number DE-FOA-0000069 for Topic Area 2, and it is referred to herein as 'the project.' The purpose of the project was to enhance the certainty of the survey requirements and regulatory review processes for the purpose of reducing the time, efforts, and costs associated with initial siting efforts of marine and hydrokinetic energy conversion facilities that may be proposed in the Atlantic Ocean offshore Southeast Florida. To secure early input from agencies, protocols were developed for collecting baseline geophysical information and benthic habitat data that can be used by project developers and regulators to make decisions early in the process of determining project location (i.e., the siting process) that avoid or minimize adverse impacts to sensitive marine benthic habitat. It is presumed that such an approach will help facilitate the licensing process for hydrokinetic and other ocean renewable energy projects within the study area and will assist in clarifying the baseline environmental data requirements described in the U.S. Department of the Interior Bureau of Ocean Energy Management, Regulation and Enforcement (formerly Minerals Management Service) final regulations on offshore renewable energy (30 Code of Federal Regulations 285, published April 29, 2009). Because projects generally seek to avoid or minimize impacts to sensitive marine habitats, it was not the intent of this project to investigate areas that did not appear suitable for the siting of ocean renewable energy projects. Rather, a two-tiered approach was designed with the first step consisting of gaining overall insight about seabed conditions offshore southeastern Florida by conducting a geophysical survey of pre-selected areas with subsequent post-processing and expert data interpretation by geophysicists and experienced marine biologists knowledgeable about the general project area. The second step sought to validate the benthic habitat types interpreted from the geophysical data by conducting benthic video and photographic field surveys of selected habitat types. The goal of this step was to determine the degree of correlation between the habitat types interpreted from the geophysical data and what actually exists on the seafloor based on the benthic video survey logs. This step included spot-checking selected habitat types rather than comprehensive evaluation of the entire area covered by the geophysical survey. It is important to note that non-invasive survey methods were used as part of this study and no devices of any kind were either temporarily or permanently attached to the seabed as part of the work conducted under this project.

16 TIDAL AND WAVE POWER↗
DOE OSTI2016

Ocean acidification over the next three centuries using a simple global climate carbon-cycle model: projections and sensitivities

Continued oceanic uptake of anthropogenic CO 2 is projected to significantly alter the chemistry of the upper oceans over the next three centuries, with potentially serious consequences for marine ecosystems. Relatively few models have the capability to make projections of ocean acidification, limiting our ability to assess the impacts and probabilities of ocean changes. In this study we examine the ability of Hector v1.1, a reduced-form global model, to project changes in the upper ocean carbonate system over the next three centuries, and quantify the model's sensitivity to parametric inputs. Hector is run under prescribed emission pathways from the Representative Concentration Pathways (RCPs) and compared to both observations and a suite of Coupled Model Intercomparison (CMIP5) model outputs. Current observations confirm that ocean acidification is already taking place, and CMIP5 models project significant changes occurring to 2300. Hector is consistent with the observational record within both the high- (> 55°) and low-latitude oceans (< 55°). The model projects low-latitude surface ocean pH to decrease from preindustrial levels of 8.17 to 7.77 in 2100, and to 7.50 in 2300; aragonite saturation levels (Ω Ar ) decrease from 4.1 units to 2.2 in 2100 and 1.4 in 2300 under RCP 8.5. These magnitudes and trends of ocean acidification within Hector are largely consistent with the CMIP5 model outputs, although we identify some small biases within Hector's carbonate system. Of the parameters tested, changes in [H + ] are most sensitive to parameters that directly affect atmospheric CO 2 concentrations – Q 10 (terrestrial respiration temperature response) as well as changes in ocean circulation, while changes in Ω Ar saturation levels are sensitive to changes in ocean salinity and Q 10 . We conclude that Hector is a robust tool well suited for rapid ocean acidification projections and sensitivity analyses, and it is capable of emulating both current observations and large-scale climate models under multiple emission pathways.

54 ENVIRONMENTAL SCIENCES↗