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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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Characterizing Tropical Cyclones in the Energy Exascale Earth System Model Version 1
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Separating Physics and Dynamics Grids for Improved Computational Efficiency in Spectral Element Earth System Models
Previous studies have shown that atmospheric models with a spectral element grid can benefit from putting physics calculations on a relatively coarse finite volume grid. Here we demonstrate an alternative high-order, element-based mapping approach used to implement a quasi-equal-area, finite volume physics grid in E3SM. Unlike similar methods, the new method in E3SM requires topology data purely local to each spectral element, which trivially allows for regional mesh refinement. Simulations with physics grids defined by 2 × 2, 3 × 3, and 4 × 4 divisions of each element are shown to verify that the alternative physics grid does not qualitatively alter the model solution. The model performance is substantially affected by the reduction of physics columns when using the 2 × 2 grid, which can increase the throughput of physics calculations by roughly 60%–120% depending on whether the computational resources are configured to maximize throughput or efficiency. A pair of regionally refined cases are also shown to highlight the refinement capability.
Representing Socio‐Economic Uncertainty in Human System Models
Abstract Socio‐economic development pathways and their implications for the environment are highly uncertain, and energy transitions will involve complex interactions among sectors. Here, traditional Monte Carlo analysis is paired with scenario discovery techniques to provide a richer portrait of these complexities. Modeled uncertain input variables include costs of advanced energy technologies, energy efficiency trends, fossil fuel resource availability, elasticities of substitution for labor, capital, and energy across economic sectors, population growth, and labor and capital productivity. The sampled values are simulated through a multi‐sector, multi‐region, recursively dynamic model of the world economy to explore a range of possible future outcomes. We find that many patterns of energy and technology development are possible for various long‐term environmental pathways and that sectoral output for most sectors is little affected through 2050 by the long‐term temperature target, but with tight constraints on emissions, emission intensities must fall much more rapidly. Scenario discovery techniques are applied to the large uncertainty ensembles to explore if there are prevailing storylines behind outcomes of interest. An illustrative investigation focused on different levels of economic growth shows many combinations of pathways and no single storyline emerging for a given economic outcome. This method can be extended to other outcomes of interest, exploring the nature of scenarios with both tail and median outcomes. Sampling from a Monte Carlo generated ensemble provides a rich set of scenarios to investigate, and potentially aids in avoiding heuristic biases in less structured scenario approaches.
Earth System Model Overestimation of Cropland Temperatures Scales With Agricultural Intensity
Intensive crop growth can modify regional climate by partitioning energy to latent heating through transpiration, cooling growing season temperatures. Recent work shows that cooling associated with agriculture can dampen anthropogenic warming over breadbasket regions. However, it is unknown whether climate models reproduce crop influences on regional climate, and thus the future risk of extreme climate events over global breadbasket regions. Here, we show that models overestimate growing season temperatures and underestimate evapotranspiration (ET) over global croplands, and that these differences increase with cropped area. We trace this warm and dry difference through each model's representation of the surface energy budget, showing that model differences in transpiration, leaf area index, and the ratio of transpiration to total ET drive the overall effect. While the implications of these model deficiencies for future projections are uncertain, they point to the importance of improving representations of crop-climate processes to better assess breadbasket vulnerability to climate change.
Northern Hemisphere Snow Drought in Earth System Model Simulations and ERA5‐Land Data in 1980–2014
Abstract Low snow levels over the past few decades and predictions of a low‐to‐no snow future have spurred research into snow droughts, which pose a threat to water security and management. Systematic data‐model comparisons of snow drought have been lacking, hindering our understanding of the drivers of snow drought in the past. To address this gap, we analyzed snow drought events using standardized snow water equivalent index derived from monthly results of four numerical experiments using the E3SM Land Model (ELM) and ERA5‐Land data during the period of 1980–2014. Additionally, we compared snow drought duration calculated from models with those from the ERA5‐Land data during selected El Niño‐Southern Oscillation (ENSO) years. The numerical experiments were conducted with ELM driven by two prescribed atmospheric forcings, and with the coupled land‐atmosphere configuration of E3SM with and without plant hydraulics scheme feedback. Analysis reveals that 20%–30% of snow droughts occur due to factors other than above‐normal temperature and low snowfall, such as low soil moisture, warm soil temperature, and low relative humidity, etc., especially in high latitudes (50° North). Furthermore, our study highlights the exacerbating effect of ENSO events on snow drought conditions in various regions, despite some discrepancies between model and ERA5‐Land results. We also identified limitations of the coupled land‐atmosphere models in our current configuration in capturing the spatial patterns of snow droughts. This study underscores the challenge of predicting and mitigating snow drought and the need for a comprehensive understanding of the factors contributing to snow drought.
Improved representation of surface emissivity effects on longwave radiation in coupled Earth System Models
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Immobilization of single argon atoms in nano-cages of two-dimensional zeolite model systems
The confinement of noble gases on nanostructured surfaces, in contrast to bulk materials, at non-cryogenic temperatures represents a formidable challenge. Here, individual Ar atoms are trapped at 300 K in nano-cages consisting of (alumino)silicate hexagonal prisms forming a two-dimensional array on a planar surface. The trapping of Ar atoms is detected in situ using synchrotron-based ambient pressure X-ray photoelectron spectroscopy. The atoms remain in the cages upon heating to 400 K. The trapping and release of Ar is studied combining surface science methods and density functional theory calculations. While the frameworks stay intact with the inclusion of Ar atoms, the permeability of gasses (for example, CO) through them is significantly affected, making these structures also interesting candidates for tunable atomic and molecular sieves. Our findings enable the study of individually confined noble gas atoms using surface science methods, opening up new opportunities for fundamental research.
Picochlorum celeri as a model system for robust outdoor algal growth in seawater
Abstract With fast growth rates, broad halotolerance and the ability to thrive at high temperatures, algae in the genus Picochlorum are emerging as promising biomass producers. Recently, we isolated a remarkably productive strain, Picochlorum celeri , that attains > 40 g m −2 day −1 productivities using simulated outdoor light. To test outdoor productivities, Picochlorum celeri was cultivated in 820 L raceway ponds at the Arizona Center for Algae Technology and Innovation. Picochlorum celeri demonstrated the highest outdoor biomass productivities reported to date at this testbed averaging ~ 31 g m −2 day −1 over four months with a monthly (August) high of ~ 36 g m −2 day −1 . Several single day productivities were > 40 g m −2 day −1 . Importantly for sustainability, Picochlorum celeri achieved these productivities in saline water ranging from seawater to 50 parts per thousand sea salts, without any biocides or pond crashes, for over 143 days. Lastly, we report robust genetic engineering tools for future strain improvements.
Context-aware implicit neural representations to compress Earth systems model data
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Finer resolutions and targeted process representations in earth system models improve hydrologic projections and hydroclimate impacts
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Polarity-tunable and wavelength-tunable bacteriochlorins bearing a single carboxylic acid or NHS ester. Use in a protein bioconjugation model system
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Electronic and relativistic contributions to ion-pairing in polyoxometalate model systems
Experiment and theory delineate covalency, electrostatic association, and relativistic effect contributions to polyoxometalate-alkali ion-pairs in water.
Crystallographic and electronic evolution of lanthanum strontium ferrite (La 0.6 Sr 0.4 FeO 3-δ ) thin film and bulk model systems during iron exsolution
In this work, we study the changes in the crystallographic phases and in the chemical states during the iron exsolution process of lanthanum strontium ferrite (LSF, La 0.6 Sr 0.4 FeO 3-δ ). By using thin films of orthorhombic LSF, grown epitaxially on NaCl(001) and rhombohedral LSF powder, the materials gap is bridged. Furthermore, the orthorhombic material transforms into a fluorite structure after the exsolution has begun, which further hinders this process. Additionally, for the powder material, by a combination of in situ core level spectroscopy and ex situ neutron diffraction, we could directly highlight differences in the Fe chemical nature between surface and bulk: whereas the bulk contains Fe(IV) in the fully oxidized state, the surface spectra can be described perfectly by the sole presence of Fe(III). We also present corresponding magnetic and oxygen vacancy concentration data of reduced rhombohedral LSF that did not undergo a phase transformation to the cubic perovskite system based on neutron diffraction data.
X-ray fluorescence microscopy and X-ray absorption spectroscopy reveal the stability of the plecstatin-1 scaffold in biological model systems: comparison of Ru, Os and Ir analogues
Ligand exchange reactions often impact our understanding of metal-based cancer drug prototype actions. Here we makein situmeasurements of metal distribution and speciation to show that these are limited for plecstatin analogues.
Structure and tunneling dynamics in a model system of peptide co-solvents: Rotational spectroscopy of the 2,2,2-trifluoroethanol⋯water complex
The hydrogen-bonding topology and tunneling dynamics of the binary adduct, 2,2,2-trifluoroethanol (TFE)⋯water, were investigated using chirped pulse and cavity based Fourier transform microwave spectroscopy with the aid of high level ab initio calculations. Rotational spectra of the most stable binary TFE⋯water conformer and five of its deuterium isotopologues were assigned. A strong preference for the insertion binding topology where water is inserted into the existing intramolecular hydrogen-bonded ring of TFE was observed. Tunneling splittings were detected in all of the measured rotational transitions of TFE⋯water. Based on the relative intensity of the two tunneling components and additional isotopic data, the splitting can be unambiguously attributed to the tunneling motion of the water subunit, i.e., the interchange of the bonded and nonbonded hydrogen atoms of water. The absence of any other splitting in the rotational transitions of all isotopologues observed indicates that the tunneling between g+ and g− TFE is quenched in the TFE⋯H{sub 2}O complex.
Microwave Interrogation of an Air Plasma Plume as a Model System for Hot Spots in Explosives
Abstract not provided