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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Effects of carbon substitution on magnetic properties and magnetocaloric effects in Mn 65-x Ga 17 C 18+x compounds

This study involved the tuning of the magnetic, magnetocaloric, and room-temperature structural properties of Mn 65-x Ga 17 C 18+x (0 ≤ x ≤ 4) compounds prepared using a high-energy ball milling (HEBM) technique. This study indicates that the crystal structure of all the compounds can be described as an anti-perovskite cubic structure with the Pm-3m space group and the crystal cell volume decreases with increasing carbon concentration. The system shows a first-order structural phase transition at a temperature T=T M between two cubic phases having different magnetic structures. The phases are characterized by antiferromagnetic (AFM) and ferromagnetic (FM) -like behavior at low (T < T M ) and high (T M > T) temperature regions, respectively. A suppression of the AFM phase was observed with increasing C concentration. The temperature-induced first-order transitions (FOTs) were found to possess a small thermal hysteresis in the magnetization (~2-3 K) in an applied magnetic field of H = 50 kOe. Magnetic entropy changes estimated from isothermal magnetization curves indicate that the largest value of the magnetic entropy change of |ΔS M | = 2.1 J kg -1 K -1 for x = 4 with ΔH = 50 kOe, with a relative cooling power (RCP) of ~190 J kg -1 . Furthermore, high-energy ball milling (HEBM), a scalable technique, has been demonstrated as a viable method to synthesize magnetocaloric materials with substantial RCP values.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Structural, magnetic and magnetocaloric properties of La{sub 0.8}Ca{sub 0.2−x}Na{sub x}MnO{sub 3} manganites (0≤x≤0.2)

In this work, we report the effect of Na doping on the structural, magnetic and magnetocaloric properties in La{sub 0.8}Ca{sub 0.2−x}Na{sub x}MnO{sub 3} powder samples. Our polycristalline samples have been synthesized using the solid-state reaction method at high temperatures. The parent compound La{sub 0.8}Ca{sub 0.2}MnO{sub 3} crystallizes in the orthorhombic system with Pbnm space group. Na doping induces a structural transition from orthorhombic (Pbnm space group) to rhombohedral (R-3C space group) symmetry. Magnetization measurements versus temperature in a magnetic applied field of 50 mT showed that all our investigated samples display a paramagnetic-ferromagnetic transition with decreasing temperature. The Curie temperature T{sub C} increases with Na content from 240 K for x=0 to 330 K for x=0.2. A large magnetocaloric effect has been observed in all samples, the maximum entropy change, |∆S{sub M}|{sub max}, shifts to smaller values with increasing Na content, from4.56 J/kg K (x=0.05) to 2.3 J/kg K (x=0.2) under a magnetic field change ∆µ{sub 0}H of 2 T. For the same applied magnetic field of 2 T, the Relative Cooling Power (RCP) values are found to be constant around 91 J/kg. - Graphical abstract: Sodium doping induces an increase of T{sub C} from 240 K for x=0 to 330 K for x=0.2. - Highlights: • La{sub 0.8}Ca{sub 0.2−x}Na{sub x}MnO{sub 3} are synthesized using the ceramic method at high temperatures. • Na doping induces a structural transition from Pbnm to R-3C space group. • T{sub C} increases with Na content from 240 K for x=0 to 330 K for x=0.2. • RCP is constant around 91 J/kg for all compounds under 2 T.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Mixed rare earth oxides derived from monazite sand as an inexpensive precursor material for room temperature magnetic refrigeration applications

Highlights: • Compound is synthesized using mixed rare earth oxide derived from monazite sand. • Rietveld refinement confirms the compound is a mixture of rare earth manganites and CeO{sub 2}. • The compound exhibits a magnetic entropy change of 3.28 J kg{sup −1} K{sup −1} under 50 kOe magnetic field at 310 K. • The compound exhibit a RCP of 120 J kg{sup −1} and ΔT{sub ad} of 2.11 K at 310 K under 50 kOe field. - Abstract: An inexpensive perovskite type (RE{sub MIX}){sub 0.67}Sr{sub 0.33}MnO{sub 3} compound is synthesized via solid state method using mixed rare earth oxide precursor derived from monazite sand. Rietveld refinement of X-ray powder diffraction patterns confirms the compound is a mixture of rare earth manganites which is the major phase and CeO{sub 2} as the secondary phase. The compound shows a second order ferromagnetic to paramagnetic transition near room temperature and exhibits a magnetic entropy change (-ΔS{sub M}) of 3.28 J kg{sup −1} K{sup −1} with a relative cooling power (RCP) of 120 J kg{sup −1} and an adiabatic temperature change (ΔT{sub ad}) of 2.11 K at 310 K under 50 kOe magnetic field. The Debye temperature of the compound is found to be 543 K and room temperature thermal conductivity is 4.26 W m{sup −1} K{sup −1}. The temperature variation of electrical resistivity shows a metal to insulator transition around 180 K, which gets shifted towards higher temperature upon the application of magnetic field. The compound shows a large value of −ΔS{sub M} and this work makes an endeavor to develop low–cost materials for the magnetic refrigeration applications near the room temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Estimating the Likelihood of GHG Concentration Scenarios From Probabilistic Integrated Assessment Model Simulations

The climate scenarios that form the basis for current climate risk assessments have no assigned probabilities, and this impedes the analysis of future climate risks. This paper proposes an approach to estimate the probability of carbon dioxide (CO 2 ) concentration scenarios used in key climate change modeling experiments. It computes the CO 2 emissions compatible with the concentrations prescribed by Coupled Model Intercomparison Project Phase 5 (CMIP5) and CMIP6 experiments. The distribution of these compatible cumulative emissions is interpreted as the likelihood of future emissions given a concentration pathway. Using Bayesian analysis, the probability of each pathway can be estimated from a probabilistic sample of future emissions. The approach is demonstrated with five probabilistic CO 2 emission simulation ensembles from four Integrated Assessment Models (IAM), leading to independent estimates of the likelihood of the CO 2 concentration of Representative Concentration Pathways (RCP) and Shared Socioeconomic Pathways (SSP). Results suggest that SSP5-8.5 is unlikely for the second half of the 21st century, but offer no clear consensus on which of the remaining scenarios is most likely. Estimates of likelihoods of CO 2 concentrations associated with RCP and SSP scenarios are affected by sampling errors, differences in emission sources simulated by the IAMs, and a lack of a common experimental framework for IAM simulations. These shortcomings, along with a small IAM ensemble size, limit the applicability of the results presented here. Novel joint IAM and the Earth System Model experiments are needed to deliver actionable probabilistic climate risk assessments.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Future Intensity‐Duration‐Frequency Curves of Extreme Precipitation in the Midwest United States From Convection‐Permitting Modeling

Abstract During the last four decades, global warming has statistically significant intensified extreme precipitation events in the Midwestern United States (defined here as the region covering Illinois, Indiana, Ohio, and Kentucky), leading to increased risks to human life, property, and infrastructure. To enable climate change adaptation and resilience across various economic and social sectors in this region, updated information about future climate changes, specifically at finer spatial scales, is essential. Leveraging a new 150‐year dynamical downscaling data set at convection‐permitting resolution, this study introduces a framework to construct the projected future intensity‐duration‐frequency (IDF) curves of heavy precipitation, which are prominent tools for infrastructure design and water resources management. This framework generates IDF curves at both sub‐daily and multi‐day duration utilizing hourly in situ observations as well as quantile‐based statistical techniques in bias‐correction and return levels selection. The assumption of non‐stationarity in the distribution parameter fitting process is also implemented in this workflow. Compared to historical IDF curves for 1980–2022, future projected IDF curves for 2058–2100 under Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 scenarios indicate an average intensity increase of approximately 15% and 25%, respectively, across 74 stations, considering both annual and seasonal timescales. Future projections suggest that extreme precipitation events may become more severe across six investigated return periods, with longer return periods showing a greater increase. The frequency of future extreme precipitation events in the Midwest region is also projected to double. Furthermore, current results reveal spatial heterogeneity of future trends across stations owing to the high‐resolution input data set. Plain Language Summary This study investigates the evolving nature of extreme precipitation events in the Midwestern United States under a changing climate. By leveraging a high‐resolution dynamical downscaling data set, we construct projected intensity‐duration‐frequency (IDF) curves for future extreme rainfall events. These curves serve as vital tools for infrastructure planning and water resource management. Our analysis reveals a significant increase in both the intensity and frequency of extreme precipitation events in the region. Future projected IDF curves for the late century indicate an average intensity increase of approximately 15%–25% compared to historical values. Moreover, the frequency of such events is expected to double. Spatial heterogeneity in future trends is observed across different stations within the Midwest, highlighting the importance of high‐resolution modeling in capturing localized climate variability. These findings underscore the urgent need for climate adaptation strategies to mitigate the increasing risks associated with extreme precipitation events in the region. Key Points This study introduces a workflow to construct future intensity‐duration‐frequency (IDF) curves over the Midwest United States using a new convection‐permitting modeling data set The current IDF construction workflow reproduces well the historical observed IDF 30 curves in summer months with median relative errors of 2.4% among 74 stations and 6 investigated durations The projected IDF curves show diverse future trends of extreme precipitation across stations, with intensity increases of approximately 15% and 25% under RCP4.5 and RCP8.5 climate scenarios, respectively, and a doubling of frequency on average

Nguyen, Trung↗
DOE OSTI2019

Anisotropic magnetocaloric effect in Fe3−xGeTe2

Abstract We present a comprehensive study on anisotropic magnetocaloric porperties of the van der Waals weak-itinerant ferromagnet Fe 3− x GeTe 2 that features gate-tunable room-temperature ferromagnetism in few-layer device. Intrinsic magnetocrystalline anisotropy is observed to be temperature-dependent and most likely favors the long-range magnetic order in thin Fe 3− x GeTe 2 crsytal. The magnetic entropy change Δ S M also reveals an anisotropic characteristic between H // ab and H // c , which could be well scaled into a universal curve. The peak value $$-\Delta {S}_{M}^{{\max }}$$ − Δ S M max of 1.20 J kg −1 K −1 and the corresponding adiabatic temperature change Δ T ad of 0.66 K are deduced from heat capacity with out-of-plane field change of 5 T. By fitting of the field-dependent parameters of $$-\Delta {S}_{M}^{{\max }}$$ − Δ S M max and the relative cooling power RCP, it gives $$-{\rm{\triangle }}{S}_{M}^{{\max }}$$ − ∆ S M max ∝ H n with n = 0.603(6) and RCP ∝ H m with m = 1.20(1) when H // c . Given the high and tunable T c , Fe 3− x GeTe 2 crystals are of interest for fabricating the heterostructure-based spintronics device.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Laser propagation and soliton generation in strongly magnetized plasmas

The propagation characteristics of various laser modes with different polarization, as well as the soliton generation in strongly magnetized plasmas are studied numerically through one-dimensional (1D) particle-in-cell (PIC) simulations and analytically by solving the laser wave equation. PIC simulations show that the laser heating efficiency substantially depends on the magnetic field strength, the propagation modes of the laser pulse and their intensities. Generally, large amplitude laser can efficiently heat the plasma with strong magnetic field. Theoretical analyses on the linear propagation of the laser pulse in both under-dense and over-dense magnetized plasmas are well confirmed by the numerical observations. Most interestingly, it is found that a standing or moving soliton with frequency lower than the laser frequency is generated in certain magnetic field strength and laser intensity range, which can greatly enhance the laser heating efficiency. The range of magnetic field strength for the right-hand circularly polarized (RCP) soliton formation with high and low frequencies is identified by solving the soliton equations including the contribution of ion's motion and the finite temperature effects under the quasi-neutral approximation. In the limit of immobile ions, the RCP soliton tends to be peaked and stronger as the magnetic field increases, while the enhanced soliton becomes broader as the temperature increases. These findings in 1D model are well validated by 2D simulations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

The implications of future climate change on the blue water footprint of hydropower in the contiguous US

As the largest renewable energy source, hydropower is essential to the sustainability of the global energy market. However, a considerable amount of water can be lost in the form of evaporation from the associated multipurpose reservoirs, and hence enlarge the blue water footprint (BWF) of hydropower in a warming climate. To facilitate the sustainable management of both water and energy resources under the impact of climate change in the contiguous United States (CONUS), the BWF values of 143 major multipurpose reservoirs were evaluated during the historical period (1985–2014) and two future periods (2020–2049 and 2070–2099). The historical reservoir evaporation loss was calculated using the Landsat-based reservoir surface area and a new evaporation rate algorithm that considers the heat storage effect. Future projections of runoff availability, hydropower generation, and reservoir evaporation were estimated based on the downscaled climate model ensemble from phase 5 of the Coupled Model Intercomparison Project (CMIP5). It was found that the BWF for the CONUS is highly spatially heterogeneous, with an average value of 26.2 m 3 /MWh in the historical period. In the future, the BWF values are projected to increase under both Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. This is especially noticeable under RCP 8.5, which has an average BWF value of 30.2 m 3 /MWh for 2070–2099 (increasing by 15.3% from 26.2 m 3 /MWh). The uncertainty ranges increase even more, from 3.4 m 3 /MWh during 2020–2049 to 5.7 m 3 /MWh during 2070–2099. These findings can benefit water and energy resources management in identifying suitable environmental, economic, operational, and investment strategies for multipurpose reservoirs in a changing environment.

13 HYDRO ENERGY↗
DOE OSTI2023

Is land use producing robust signals in future projections from Earth system models, all else being equal?

Abstract We use six Earth system models (ESMs) run under SSP3-7.0, a scenario characterized by a relatively large land use change (LUC) over the 21st century, and under a variant of the same scenario where a significantly different pattern of LUC, taken from SSP1-2.6, was used, all else being equal. Our goal is to identify changes in climate extremes between the two scenarios that are statistically significant and robust across the ESMs. The motivation for this study is to test a long-held assumption of the shared socio-economic pathway-representative concentration pathway (SSP-RCP) scenario framework: that the signal from LUC can be safely disregarded when pairing different SSPs to the compatible RCPs, where compatibility only considers global radiative forcing, predominantly determined by well-mixed greenhouse gasses emissions. We analyze extremes of daily minimum and maximum temperatures and precipitation, after fitting non-stationary generalized extreme value distributions in a way that borrows strength along the length of the simulation (2015–2100) and across initial condition ensembles. We consider changes in the 20 year return levels (RL20s) of these metrics by 2100, and focus on eight locations where LUC is large within each scenario, and strongly differs between scenarios, averaging the RL20s over a neighborhood characterized by the same LUC to enhance the signal to noise. We find that precipitation extremes do not show significant differences attributable to LUC differences. For temperature extremes (cold and hot) results are mixed, with some location-index combination showing significant results for some of the ESMs but not all, and not many coherent changes appearing for indices across regions, or regions across indices. These ESMs are representative of what is typically adopted as the source of climate information for impact studies, when the SSP-RCP framework is put to use. Overall, our analysis suggests that the hypothesis to pair SSPs to RCPs in a flexible fashion is overall defensible. However, the appearance of some coherence in a few locations and for some indices invites further investigation.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

New Delhi Metallo‐Beta‐Lactamase Variants NDM‐4 and NDM‐12 from E. coli Clinical Isolates Exhibit Increased Activity and Stability

Metallo‐Beta‐Lactamases (MBLs) confer resistance to carbapenems, cephalosporins, and penicillins in several clinically relevant Gram‐negative bacteria including Acinetobacter, Pseudomonas aeruginosa, and many Enterobacteriaceae. New Delhi Metallo‐Beta‐Lactamases (NDMs) are amongst some of the most worrisome and prevalent MBLs. This family of MBLs is capable of hydrolyzing all generations of bicyclic beta‐lactams. Two new NDM variants, NDM‐4 and ‐12, have recently been identified in E. coli clinical isolates. NDM‐4 contains an M154L substitution while NDM‐12 bears both M154L and G222D mutations. Considering the clinical significance of Gram‐negative species possessing these enzymes, there is a need to characterize the structures and activities of these variants in order to provide a better basis for drug discovery efforts. We have found that NDM‐4 and NDM‐12 possess higher hydrolytic activity compared to NDM‐1. Our differential scanning fluorimetry studies suggest that the M154L mutation confers increased thermal stability and improved affinity for active site catalytic Zn metal ions. The additional G222D mutation of NDM‐12 further improves stability and Zn affinity. M154L, found in the secondary coordination sphere, accounts for changes in stability by acting as a buttress to the loop containing His 122 , a direct Zn coordinating residue. G222D, on the other hand, is a mutation located in a loop just above the active site approximately 10 Å from the active site zinc ions. Together, our crystal structures of these NDM variants, including the first known structure of NDM‐12, biochemical analyses, and biophysical analyses provide a basis for understanding the roles of key residues surrounding the active site within NDM variants. A better understanding of clinically relevant NDM variants is essential in the fight against MBL‐mediated antibiotic resistance. Our structural, biochemical, and biophysical studies will help to inform drug design efforts to develop new MBL inhibitors. Support or Funding Information The authors acknowledge financial support from the US National Institutes of Health (Award No. R01 GM111926 to RCP, DLT, MWC, and WF) and institutional support from Miami University through the Robert H. and Nancy J. Blayney Professorship (to RCP). The Advanced Light Source is supported by the US Department of Energy under contract number DE‐AC03‐76SF00098 at Lawrence Berkeley National Laboratory.

Williams, Cameron↗
DOE OSTI2020

Magnetocaloric effect in the vicinity of the magnetic phase transition in NdCo 2–x Fe x compounds

In the present paper, the magnetocaloric effect (MCE) of NdCo 2-x Fe x (x = 0, 0.2, 0.4, 0.6) compounds was investigated by magnetization measurements. Here, the temperature-dependent high-resolution synchrotron x-ray diffraction study shows a magnetostructural transition from the paramagnetic cubic phase to the ferromagnetic tetragonal phase below their Curie temperatures. Differential scanning calorimetry analysis shows the absence of thermal hysteresis, indicating the second-order nature of the magnetostructural phase transition in these compounds. The maximum values of magnetic entropy change (ΔS M ) and wide operating temperature (OT) are obtained under a field change of 5 T, which are 7.33 Jkg -1 K -1 , 6.45 Jkg -1 K -1 , 5.71 Jkg -1 K -1 , 4.70 Jkg -1 K -1 and 78 K, 82 K, 85 K, 92 K for x = 0, 0.2, 0.4, and 0.6, respectively. The corresponding values of relative cooling power (RCP) are 529.96 Jkg -1 , 497.25 Jkg -1 , 470.55 Jkg -1 , and 428.31 Jkg -1 . The observed wide OT range and large RCP values are comparable with Gd, Gd 5 Ge 2 Si 2 , and some rare-earth-based giant magnetocaloric materials, making this series of compounds suitable for magnetic refrigeration.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Phase Transitions and Magnetocaloric Properties in MnCo 1− x Zr x Ge Compounds

The structural, magnetic, and magnetocaloric properties of MnC o 1 - x Z r x Ge ( 0.01 ≤ x ≤ 0.04 ) have been studied through X-ray diffraction, differential scanning calorimetry, and magnetization measurements. Results indicate that the partial substitution of Zr for Co in MnC o 1 - x Z r x Ge decreases the martensitic transition temperature ( T M ). For x = 0.02, T M was found to coincide with the ferromagnetic transition temperature ( T C ) resulting in a first-order magnetostructural transition (MST). A further increase in zirconium concentration ( x = 0.04) showed a single transition at T C . The MST from the paramagnetic to ferromagnetic state results in magnetic entropy changes ( - Δ S M ) of 7.2 J/kgK for Δ H = 5 T at 274 K for x = 0.02. The corresponding value of the relative cooling power (RCP) was found to be 266 J/kg for Δ H = 5 T. The observed large value of MCE and RCP makes this system a promising material for magnetic cooling applications.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2023

Wavelength-tunable infrared chiral metasurfaces with phase-change materials

Optical phase-change materials exhibit tunable permittivity and switching properties during phase transition, which offers the possibility of dynamic control of optical devices. Here, a wavelength-tunable infrared chiral metasurface integrated with phase-change material GST-225 is demonstrated with the designed unit cell of parallelogram-shaped resonator. By varying the baking time at a temperature above the phase transition temperature of GST-225, the resonance wavelength of the chiral metasurface is tuned in the wavelength range of 2.33 µm to 2.58 µm, while the circular dichroism in absorption is maintained around 0.44. The chiroptical response of the designed metasurface is revealed by analyzing the electromagnetic field and displacement current distributions under left- and right-handed circularly polarized (LCP and RCP) light illumination. Moreover, the photothermal effect is simulated to investigate the large temperature difference in the chiral metasurface under LCP and RCP illumination, which allows for the possibility of circular polarization-controlled phase transition. The presented chiral metasurfaces with phase-change materials offer the potential to facilitate promising applications in the infrared regime, such as chiral thermal switching, infrared imaging, and tunable chiral photonics.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Climate Vulnerability Assessment and Resilience Planning for Idaho National Laboratory

Idaho National Laboratory’s (INL’s) mission is to discover, demonstrate, and secure innovative nuclear energy solutions, other clean energy options, and critical infrastructure. This INL’s Climate Vulnerability Assessment and Resilience Plan (VARP) was developed to enable and sustain that mission while ensuring the viability of operations considering expected climate change impacts. The VARP was developed according to the narrative requirements from the “Vulnerability Assessment and Resilience Planning Guidance, Version 1.2” document issued in February 2022. A prescribed process was used to identify mission-critical systems and components, determine historical and expected climate impacts, and develop resilient solutions. Experts from across INL, including operations staff, researchers, and climate scientists supplied input to the process. Analyses of climate modeling sources revealed that under scenarios of higher and lower greenhouse gas emissions (Representative Concentration Pathway (RCP) 4.5 and RCP 8.5), INL anticipates an increase in climate hazards, including drought, heat waves, wildfire, and precipitation. Increased frequency and duration of climatic hazards forecasts high impacts on certain mission-critical asset and infrastructure types. Utilizing the VARP Risk Assessment Tool, projected high climate hazard impacts across multiple asset and infrastructure types at the INL include energy generation and distribution systems, Site buildings, specialized or mission-critical equipment, and transportation and fleet infrastructure. Some of these mission-critical asset and infrastructure types maintain high adaptive capacity to climatic changes; however, others may need additional adaptive capacity to withstand increased frequency and duration of climate hazards. INL identified close to 300 resilient solutions that were consolidated into 11 solution categories to be tracked in the Department of Energy Sustainability Dashboard. The identified solutions are a starting point for future project development and analysis. These data are intended to inform decision makers on climate issues and potential solutions across INL and associated communities. The VARP is not intended to be a budget tool or project decision document on its own, but rather one of many tools used by decision makers to establish resilient priorities. This initial document provides the framework and foundation to resilient solutions. In the coming years, each solution needs to be fully developed, costed, and prioritized based on mission-critical risk and funding priorities.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

HDD and CDD Projections for BEND-GCAM

These are state-level annual heating and cooling degree day projections generated from downscaled climate model output for RCP 4.5 and RCP 8.5.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Stand Age and Climate Change Effects on Carbon Increments and Stock Dynamics

Carbon assimilation and wood production are influenced by environmental conditions and endogenous factors, such as species auto-ecology, age, and hierarchical position within the forest structure. Disentangling the intricate relationships between those factors is more pressing than ever due to climate change’s pressure. We employed the 3D-CMCC-FEM model to simulate undisturbed forests of different ages under four climate change (plus one no climate change) Representative Concentration Pathways (RCP) scenarios from five Earth system models. In this context, carbon stocks and increment were simulated via total carbon woody stocks and mean annual increment, which depends mainly on climate trends. We find greater differences among different age cohorts under the same scenario than among different climate scenarios under the same age class. Increasing temperature and changes in precipitation patterns led to a decline in above-ground biomass in spruce stands, especially in the older age classes. On the contrary, the results show that beech forests will maintain and even increase C-storage rates under most RCP scenarios. Scots pine forests show an intermediate behavior with a stable stock capacity over time and in different scenarios but with decreasing mean volume annual increment. These results confirm current observations worldwide that indicate a stronger climate-related decline in conifers forests than in broadleaves.

Forestry↗
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↗
DOE OSTI2023

Xanthos Output Dataset Under ISIMIP3b Selected CMIP6 Scenarios: 1850 - 2100 (Basin and Regional Scale)

Xanthos is an open-source hydrologic model, written in Python, designed to quantify and analyze global water availability. Xanthos simulates historical and future global water availability on a monthly time step at a spatial resolution of 0.5 geographic degrees. Xanthos was designed to be extensible and used by scientists that study global water supply and work with the Global Change Analysis Model (GCAM). Xanthos Output Dataset This dataset includes Xanthos outputs forced by the ISIMIP3b bias-adjusted CMIP6 climate forcing (1850 - 2100). There are 30 scenarios consists of 10 CMIP6 GCMs and 3 SSP-RCP scenarios. (1) 10 CMIP6 GCMs: GFDL-ESM4, IPSL-CM6A-LR, MPI-ESM1-2-HR, MRI-ESM2-0, UKESM1-0-LL, CanESM5, CNRM-CM6-1, CNRM-ESM2-1, EC-Earth3, and MIROC6 (2) 3 SSP-RCP Scenarios: SSP1-2.6, SSP3-7.0, and SSP5-8.5 The output variables in this dataset are aggregated to basin and regional scales. (1) Monthly runoff at basin scale (2) Annual accessible renewable water at basin scale (2) Annual actual hydropower production, hydropower potential, and exploitable hydropower potential at regional scale

Climate Change↗