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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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11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Cyclone Fani: the tug-of-war between regional warming and anthropogenic aerosol effects

Before Cyclone Amphan took place in 2020, Cyclone Fani (May 2019) is the strongest pre-monsoon cyclone in the Bay of Bengal (BOB) since 1991, killing 90 people in eastern India and Bangladesh while causing US$1.81 billion of damages. Fani developed during a period of high concentration of anthropogenic aerosols in the BOB with abnormally high sea surface temperature (SST), thereby presenting an opportunity to understand the compound effects of atmospheric aerosols and regional climate warming on a tropical cyclone. A quantitative attribution analysis was conducted using the Weather Research and Forecasting model with chemistry (WRF-Chem) run at the convection-permitting (4 km) grid spacing, accompanied by an ensemble of coarser-resolution simulations to quantify the uncertainty. The removal of post-1990 trends in the tropospheric variables and SST from WRF-Chem's initial conditions (IC) and boundary conditions (BC, including the lateral and lower boundary conditions) resulted in a reduction of cyclone precipitation by about 51% during the 5 d of April 28-May 2. The removal of tropospheric warming shows approximately twice as strong an effect on Fani (39% reduction in precipitation) as that of SST warming (22% reduction). When aerosol's direct and indirect effects were removed from the simulations, i.e., no aerosol influence on radiation and cloud microphysics, Fani initially strengthened but later weakened, as measured by geopotential height and precipitation amounts. These results suggest that aerosol and its interaction with the atmosphere acted to mitigate the strengthening effect of anthropogenic warming on Fani, but was not strong enough to entirely counteract it. Although the ensemble of coarser simulations appears to overestimate Cyclone Fani in terms of precipitation, the direction of the effects is in agreement with that obtained from the 4 km simulations. Given the increasing anthropogenic aerosols in the BOB, future attribution studies using more sophisticated dynamical aerosol models on BOB tropical cyclones are urged.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Recurrent pattern of extreme fire weather in California

Abstract Historical wildfire events in California have shown a tendency to occur every five to seven years with a rapidly increasing tendency in recent decades. This oscillation is evident in multiple historical climate records, some more than a century long, and appears to be continuing. Analysis shows that this 5–7 year oscillation is linked to a sequence of anomalous large-scale climate patterns with an eastward propagation in both the ocean and atmosphere. While warmer temperature emerges from the northern central Pacific to the west coast of California, La Niña pattern develops simultaneously, implying that the lifecycle of the El Niño-Southern Oscillation that takes multiple years to form could be a trigger. The evolving patterns of the Pacific-to-North America atmospheric teleconnection suggest the role of tropical and subtropical forcing embedded in this lifecycle. These results highlight the semi-cyclical hydrological behavior as a climate driver for wildfire variability in California.

Environmental Sciences & Ecology↗
DOE OSTI2023

Interannual variability and trends of summertime PM2.5-based air quality in the Intermountain West

Abstract Summertime air quality is a growing public health concern in the populated region of Northern Utah. Whereas winter air pollution is highly linked with local atmospheric temperature inversions associated with upper atmospheric high-pressure and radiational cooling in valleys, the relationship between climate factors and the frequency of poor air quality during summer is still unknown. Analyzing the last 20 years of data, we demonstrated that summertime unhealthy days (as defined by PM2.5 air quality index level) in Northern Utah highly correlate with the number of dry-hot days, wildfire size, and an upper atmospheric ridge over the Northwestern United States. The persistent atmospheric ridge enhances lightning-caused fire burned areas in northwestern states and then transports the wildfire smoke toward Northern Utah. Similarly, climate model simulations confirm observational findings, such as an increasing trend of the upper atmospheric ridge and summertime dry days in the northwestern states. Such metrics developed in this study could be used to establish longer-term monitoring and seasonal forecasting for air quality and its compounding factors, which is currently limited to forecasting products for only several days.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

A weather pattern responsible for increasing wildfires in the western United States

Abstract The western United States (U.S.) has been experiencing more severe wildfires, in part due to climate change, but the underlying synoptic patterns and their modulation in driving fire weather is unclear. Here we investigated the relationship between weather regimes (WRs) and fire weather indices, specifically vapor pressure deficit (VPD) and the Canadian Forest Fire Weather Index. By identifying five singular WRs using k-means clustering, we found that a particular regime (WR-2), one characterized by a distinct tripolar wave train pattern over the continental U.S., has exhibited an increased frequency since 1980. The ascribed WR-2 regime was found to be mainly responsible for rising trends in the fire weather indices, especially VPD. Further, the average fire indices of the WR-2 regime played a more important role than the frequency in shaping the rising trends in the fire weather indices. The increased frequency of the WR-2 WR was mainly attributed to anthropogenic forcing and, the year-to-year variation of the frequency was associated with sea surface temperature anomalies over the subtropical eastern Pacific. Human-induced climate change might have furthered the exacerbation of wildfire danger in the western U.S. by modulating the behaviors of WRs and fire weather indices.

Zhang, Wei (ORCID:0000000221698749)↗
DOE OSTI2020

Materials Data on YS by Materials Project

SY1 is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Y is bonded to six equivalent S atoms to form a mixture of edge and corner-sharing YS6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Y–S bond lengths are 2.77 Å. S is bonded to six equivalent Y atoms to form a mixture of edge and corner-sharing SY6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y5S7 by Materials Project

Y5S7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Y sites. In the first Y site, Y is bonded to six S atoms to form YS6 octahedra that share corners with three YS6 octahedra, corners with six equivalent YS7 pentagonal bipyramids, edges with five equivalent YS6 octahedra, and an edgeedge with one YS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 0–56°. There are a spread of Y–S bond distances ranging from 2.69–2.83 Å. In the second Y site, Y is bonded to seven S atoms to form distorted YS7 pentagonal bipyramids that share corners with eight YS6 octahedra, edges with four YS6 octahedra, edges with two equivalent YS7 pentagonal bipyramids, and faces with two equivalent YS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 22–67°. There are a spread of Y–S bond distances ranging from 2.75–2.95 Å. In the third Y site, Y is bonded to six S atoms to form YS6 octahedra that share corners with two equivalent YS6 octahedra, corners with four equivalent YS7 pentagonal bipyramids, edges with two equivalent YS6 octahedra, and edges with six equivalent YS7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 56°. There are two shorter (2.69 Å) and four longer (2.75 Å) Y–S bond lengths. There are four inequivalent S sites. In the first S site, S is bonded to five Y atoms to form SY5 trigonal bipyramids that share corners with five equivalent SY4 tetrahedra, corners with four equivalent SY5 trigonal bipyramids, an edgeedge with one SY4 tetrahedra, and edges with five SY5 trigonal bipyramids. In the second S site, S is bonded to four Y atoms to form distorted SY4 tetrahedra that share corners with three equivalent SY4 tetrahedra, corners with nine SY5 trigonal bipyramids, and edges with four SY5 trigonal bipyramids. In the third S site, S is bonded to five Y atoms to form distorted SY5 trigonal bipyramids that share corners with four equivalent SY4 tetrahedra, corners with six SY5 trigonal bipyramids, edges with three equivalent SY4 tetrahedra, and edges with six SY5 trigonal bipyramids. In the fourth S site, S is bonded in a square co-planar geometry to four equivalent Y atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YS2 by Materials Project

YS2 is Cubic Laves structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Y3+ is bonded in a 12-coordinate geometry to twelve equivalent S+1.50- atoms. All Y–S bond lengths are 3.25 Å. S+1.50- is bonded to six equivalent Y3+ and six equivalent S+1.50- atoms to form a mixture of edge, face, and corner-sharing SY6S6 cuboctahedra. All S–S bond lengths are 2.77 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YS by Materials Project

SY1 is BCT5-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two SY1 sheets oriented in the (0, 0, 1) direction. Y is bonded to five equivalent S atoms to form a mixture of distorted edge and corner-sharing YS5 square pyramids. There are four shorter (2.75 Å) and one longer (2.79 Å) Y–S bond lengths. S is bonded to five equivalent Y atoms to form a mixture of edge and corner-sharing SY5 square pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y2S3 by Materials Project

Y2S3 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. there are three inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Y–S bond distances ranging from 2.73–3.20 Å. In the second Y3+ site, Y3+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Y–S bond distances ranging from 2.76–3.01 Å. In the third Y3+ site, Y3+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Y–S bond distances ranging from 2.77–3.08 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to six Y3+ atoms. In the second S2- site, S2- is bonded to five Y3+ atoms to form a mixture of distorted edge, face, and corner-sharing SY5 trigonal bipyramids. In the third S2- site, S2- is bonded to five Y3+ atoms to form a mixture of distorted edge, face, and corner-sharing SY5 square pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y2S3 by Materials Project

Y2S3 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are six inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to seven S2- atoms to form distorted YS7 pentagonal bipyramids that share corners with two YS6 octahedra, corners with two equivalent YS7 pentagonal bipyramids, edges with two equivalent YS6 octahedra, edges with six YS7 pentagonal bipyramids, and a faceface with one YS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 33–34°. There are a spread of Y–S bond distances ranging from 2.74–2.99 Å. In the second Y3+ site, Y3+ is bonded to seven S2- atoms to form distorted YS7 pentagonal bipyramids that share corners with five YS6 octahedra, edges with four YS6 octahedra, edges with four equivalent YS7 pentagonal bipyramids, and a faceface with one YS6 octahedra. The corner-sharing octahedra tilt angles range from 31–49°. There are a spread of Y–S bond distances ranging from 2.70–2.94 Å. In the third Y3+ site, Y3+ is bonded to six S2- atoms to form YS6 octahedra that share corners with four YS6 octahedra, corners with three YS7 pentagonal bipyramids, edges with three YS6 octahedra, and edges with four YS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 14–68°. There are a spread of Y–S bond distances ranging from 2.65–2.84 Å. In the fourth Y3+ site, Y3+ is bonded to six S2- atoms to form YS6 octahedra that share corners with four YS6 octahedra, corners with two YS7 pentagonal bipyramids, edges with three YS6 octahedra, and edges with four YS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 14–63°. There are a spread of Y–S bond distances ranging from 2.70–2.87 Å. In the fifth Y3+ site, Y3+ is bonded to six S2- atoms to form YS6 octahedra that share corners with four YS6 octahedra, corners with five YS7 pentagonal bipyramids, edges with four equivalent YS6 octahedra, and a faceface with one YS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 63–68°. There are a spread of Y–S bond distances ranging from 2.70–2.85 Å. In the sixth Y3+ site, Y3+ is bonded to seven S2- atoms to form distorted YS7 pentagonal bipyramids that share corners with three YS6 octahedra, corners with two equivalent YS7 pentagonal bipyramids, edges with two equivalent YS6 octahedra, edges with six YS7 pentagonal bipyramids, and a faceface with one YS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 49–51°. There are a spread of Y–S bond distances ranging from 2.74–2.95 Å. There are nine inequivalent S2- sites. In the first S2- site, S2- is bonded to four Y3+ atoms to form distorted SY4 tetrahedra that share a cornercorner with one SY5 square pyramid, corners with two equivalent SY4 tetrahedra, corners with four equivalent SY5 trigonal bipyramids, corners with four SY4 trigonal pyramids, edges with two equivalent SY5 square pyramids, edges with two equivalent SY4 tetrahedra, and an edgeedge with one SY5 trigonal bipyramid. In the second S2- site, S2- is bonded to four Y3+ atoms to form distorted SY4 trigonal pyramids that share corners with two equivalent SY5 square pyramids, a cornercorner with one SY4 tetrahedra, corners with two equivalent SY5 trigonal bipyramids, corners with eight SY4 trigonal pyramids, and edges with three equivalent SY5 trigonal bipyramids. In the third S2- site, S2- is bonded to five Y3+ atoms to form distorted SY5 trigonal bipyramids that share corners with seven SY4 trigonal pyramids, edges with four equivalent SY5 trigonal bipyramids, and edges with six SY4 trigonal pyramids. In the fourth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to four Y3+ atoms. In the fifth S2- site, S2- is bonded to five Y3+ atoms to form SY5 square pyramids that share a cornercorner with one SY4 tetrahedra, corners with seven SY4 trigonal pyramids, edges with two equivalent SY5 square pyramids, edges with two equivalent SY4 tetrahedra, edges with two equivalent SY5 trigonal bipyramids, and an edgeedge with one SY4 trigonal pyramid. In the sixth S2- site, S2- is bonded to five Y3+ atoms to form distorted SY5 trigonal bipyramids that share corners with four equivalent SY4 tetrahedra, corners with five SY4 trigonal pyramids, edges with two equivalent SY5 square pyramids, an edgeedge with one SY4 tetrahedra, edges with two equivalent SY5 trigonal bipyramids, and edges with three equivalent SY4 trigonal pyramids. In the seventh S2- site, S2- is bonded to four Y3+ atoms to form distorted SY4 trigonal pyramids that share corners with two equivalent SY5 square pyramids, corners with five SY5 trigonal bipyramids, corners with six SY4 trigonal pyramids, an edgeedge with one SY5 trigonal bipyramid, and edges with four SY4 trigonal pyramids. In the eighth S2- site, S2- is bonded to four Y3+ atoms to form distorted SY4 trigonal pyramids that share corners with two equivalent SY5 square pyramids, corners with three SY5 trigonal bipyramids, corners with six SY4 trigonal pyramids, an edgeedge with one SY5 square pyramid, edges with two equivalent SY5 trigonal bipyramids, and edges with two equivalent SY4 trigonal pyramids. In the ninth S2- site, S2- is bonded to four Y3+ atoms to form SY4 trigonal pyramids that share a cornercorner with one SY5 square pyramid, corners with three equivalent SY4 tetrahedra, corners with two equivalent SY5 trigonal bipyramids, corners with two equivalent SY4 trigonal pyramids, edges with three equivalent SY5 trigonal bipyramids, and edges with two equivalent SY4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y2S3 by Materials Project

Y2S3 is Stibnite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to seven S2- atoms to form a mixture of distorted edge and corner-sharing YS7 pentagonal bipyramids. There are a spread of Y–S bond distances ranging from 2.76–2.82 Å. In the second Y3+ site, Y3+ is bonded in a 7-coordinate geometry to eight S2- atoms. There are a spread of Y–S bond distances ranging from 2.83–3.35 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded to five Y3+ atoms to form a mixture of distorted edge and corner-sharing SY5 trigonal bipyramids. In the second S2- site, S2- is bonded to five Y3+ atoms to form a mixture of distorted edge and corner-sharing SY5 square pyramids. In the third S2- site, S2- is bonded in a 4-coordinate geometry to five Y3+ atoms.

36 MATERIALS SCIENCE↗