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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Precise orbit analysis and global verification results from ERS-1 altimetry

A technique which employs dual satellite crossover measurements from ERS-1 and Topology Ocean Experiment (TOPEX)/Poseidon together with laser tracking data and single satellite crossover measurements for ERS-1 precision orbit determination is described. The accuracy assessment of the resulting ERS-1 orbit is provided. Results of global verification of the ERS-1 Ocean Products (OPR02) and the Interim Geophysical Data Records (IGDR) data products in terms of altimeter bias, time lag bias and sea state bias are presented.

Shum, C. K.↗
NASA NTRS1996

A Comparison of Measurements from ATMOS and Instruments Aboard the ER-2 Aircraft: Tracers of Atmospheric Transport and Halogenated Gases

We compare volume mixing ratio profiles of N2O, O3, NO(y), H2O, CH4, and CO in the mid-latitude lower stratosphere measured by the ATMOS Fourier transform spectrometer on the ATLAS-3 Space Shuttle Mission with in situ measurements acquired from the NASA ER-2 aircraft during Nov 1994. ATMOS and ER-2 observations of (N2O) show good agreement, as do measured correlations of (O3), (NO(y)), (H2O), and (CH4) with (N2O). Thus a consistent measure of the hydrogen (H2O, CH4) content of the lower stratosphere is provided by the two platforms. The similarity of (NO(y)) determined by detection of individual species by ATMOS and the total (NOy) measurement on the ER-2 provides strong corroboration for the accuracy of both techniques. A 25% discrepancy in lower stratospheric (CO) observed by ATMOS and the ER-2 remains unexplained. Otherwise, the agreement for measurements of long-lived tracers demonstrates the ability to combine ATMOS data with in situ observations for quantifying atmospheric transport.

Chang, A. Y.↗
NASA NTRS1997

Biweekly Maps of Wind Stress for the North Pacific from the ERS-1 Scatterometer

The European Remote-sensing Satellite (ERS-1) was launched in July 1991 and contained several instruments for observing the Earth's ocean including a wind scatterometer. The scatterometer measurements were processed by the European Space Agency (ESA) and the Jet Propulsion Laboratory (JPL). JPL reprocessed (Freilich and Dunbar, 1992) the ERS-1 backscatter measurements to produced a 'value added' data set that contained the ESA wind vector as well as a set of up to four ambiguities. These ambiguities were further processed using a maximum-likelihood estimation (MLE) and a median filter to produce a 'selected vector.' This report describes a technique developed to produce time-averaged wind field estimates with their expected errors using only scatterometer wind vectors. The processing described in this report involved extracting regions of interest from the data tapes, checking the quality and creating the wind field estimate. This analysis also includes the derivation of biweekly average wind vectors over the North Pacific Ocean at a resolution of 0.50 x 0.50. This was done with an optimal average algorithm temporally and an over-determined biharmonic spline spatially. There have been other attempts at creating gridded wind files from ERS-1 winds, e.g., kriging techniques (Bentamy et al., 1996) and successive corrections schemes (Tang and Liu, 1996). There are several inherent problems with the ERS-1 scatterometer. Since this is a multidisciplinary mission, the satellite is flown in different orbits optimized for each phase of the mission. The scatterometer also shares several sub-systems with the Synthetic Aperture Radar (SAR) and cannot be operated while the SAR is in operation. The scatterometer is also a single-sided instrument and only measures backscatter along the right side of the satellite. The processing described here generates biweekly wind maps during the wktwo years analysis period regardless of the satellite orbit or missing data.

SYNTHETIC APERTURE RADAR↗
NASA NTRS1996

A Comparison of Measurements from ATMOS and Instruments Aboard the ER-2 Aircraft: Tracers of Atmospheric Transport

We compare volume mixing ratio profiles of N2O, O3, NO(y) H2O, CH4, and CO in the mid-latitude lower stratosphere measured by the ATMOS Fourier transform spectrometer on the ATLAS-3 Space Shuttle Mission with in situ measurements acquired from the NASA ER-2 aircraft during Nov 1994. ATMOS and ER-2 observations of [N2O] show good agreement, as do measured correlations of [O3], [NO(y)], [H2O], and [CH4] with [N2O]. Thus a consistent measure of the hydrogen (H2O, CH4) content of the lower stratosphere is provided by the two platforms. The similarity of [NO(y)] determined by detection of individual species by ATMOS and the total [NO(y)] measurement on the ER-2 provides strong corroboration for the accuracy of both techniques. A 25% discrepancy in lower stratospheric [CO] observed by ATMOS and the ER-2 remains unexplained. Otherwise, the agreement for measurements of long-lived tracers demonstrates the ability to combine ATMOS data with in situ observations for quantifying atmospheric transport.

Chang, A. Y.↗
NASA NTRS2000

Hurricane Bonnie Landfalling Observed from ER-2 Doppler Radar on 26 August 1998 During CAMEX-3

The NASA ER-2 and DC-8 aircraft collected remote sensing and in situ data sets from Hurricane Bonnie (23, 24, and 26 August 1998) during the Convection And Moisture Experimental-3 (CAMEX-3). Bonnie was an exceptional case where NASA and NOAA had five aircraft sampling both upper levels and lower altitudes. The ER-2 was instrumented with the ER-2 Doppler XBand radar (EDOP) and several radiometers ranging from visible to lower frequency microwaves. EDOP is a fixed dual-beam radar (nadir and forward-looking beams) which allows computation of both vertical and alongtrack horizontal winds. The hurricane secondary circulation is typically difficult to measure at upper levels due to aircraft altitude limitations and sensitivity of the lower altitude airborne radars. EDOP is in principle, well suited to measure these components of the wind. When ER-2 flies across the approximate center of the hurricane circulation, the along-track winds derived from EDOP, are approximately equal to the hurricane radial flow comprising the secondary circulation. Assuming that the hydrometeor fallspeeds can be approximated, the radial and vertical wind components of the secondary circulation can be measured. Since the hydrometeor motions can be estimated with more confidence in the higher altitude ice regions (i.e., graupel and mixed phase are complicated at lower altitudes), the derived radial and vertical winds have higher accuracy at upper levels. On the other hand, the reflectivities are extremely low at higher altitudes, resulting in fewer Doppler velocity estimates.

Heymsfield, G. M.↗
NASA NTRS1993

Calibration Results for J-ERS-1 SAR Data Produced by the Alaska SAR Facility

The Alaska SAR Facility has been receiving and processing SAR data from the J-ERS-1 satellite since Spring 1992. Corner reflectors have been set up for J-ERS-1 SAR calibration at a site near Delta Junction, in central Alaska. Image quality and calibration analysis results from the Delta Junction site and others will be presented in this paper. The impact of the 3-bit Analog-to-Digital Converter and the automatic stepping of the gain as a function of range in the J-ERS-1 radar receiver on calibration performance has been assessed. Preliminary observations on J-ERS-1 SAR data are that the average Signal-to-Noise ratio is generally fairly low, in the range 5-6dB. Azimuth ambiguity levels are higher than preflight analysis indicated. Over land, the dynamic range in the backscatter at L-band for approximately 36 degree incidence angle is often fairly high.

Freeman, A.↗
NASA NTRS1993

Calibration Results for J-ERS-1 SAR Data Produced by the Alaska SAR Facility

The Alaska SAR Facility has been receiving and processing SAR data from the J-ERS-1 satellite since Spring 1992. Corner reflectors have been set up for J-ERS-1 SAR calibration at a site near Delta Junction, in central Alaska. Image quality and calibration analysis results from the Delta Junction site and others will be presented in this paper. The impact of the 3-bit Analog-to-Digital Converter and the automatic stepping of the gain as a function of range in the J-ERS-1 radar receiver on calibration performance has been assessed. Preliminary observations on J-ERS-1 SAR data are that the average Signal-to-Noise ratio is generally fairly low, in the range 5-6 dB. Azimuth ambiguity levels are higher than preflight analysis indicated. Over land, the dynamic range in the backscatter at L-band for approximately 36 degree incidence angle is often fairly high...

Freeman, A.↗
DOE OSTI2020

Materials Data on Er(AlGe)2 by Materials Project

Al2ErGe2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Er is bonded to six equivalent Ge atoms to form distorted ErGe6 octahedra that share corners with twelve equivalent AlGe4 tetrahedra, edges with six equivalent ErGe6 octahedra, and edges with six equivalent AlGe4 tetrahedra. All Er–Ge bond lengths are 2.98 Å. Al is bonded to four equivalent Ge atoms to form distorted AlGe4 tetrahedra that share corners with six equivalent ErGe6 octahedra, corners with six equivalent AlGe4 tetrahedra, edges with three equivalent ErGe6 octahedra, and edges with three equivalent AlGe4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–56°. There are three shorter (2.55 Å) and one longer (2.57 Å) Al–Ge bond lengths. Ge is bonded to three equivalent Er and four equivalent Al atoms to form a mixture of distorted corner and edge-sharing GeEr3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(IO3)3 by Materials Project

Er(IO3)3 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one Er(IO3)3 sheet oriented in the (-1, 0, 2) direction. Er3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Er–O bond distances ranging from 2.28–2.41 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Er3+ and one I5+ atom. The O–I bond length is 1.85 Å. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Er3+ and one I5+ atom. The O–I bond length is 1.85 Å. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one I5+ atom. The O–I bond length is 1.86 Å. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Er3+ and one I5+ atom. The O–I bond length is 1.84 Å. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Er3+ and one I5+ atom. The O–I bond length is 1.86 Å. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one I5+ atom. The O–I bond length is 1.84 Å. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Er3+ and one I5+ atom. The O–I bond length is 1.82 Å. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to one Er3+ and one I5+ atom. The O–I bond length is 1.84 Å. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Er3+ and one I5+ atom. The O–I bond length is 1.84 Å. There are three inequivalent I5+ sites. In the first I5+ site, I5+ is bonded in a 5-coordinate geometry to three O2- atoms. In the second I5+ site, I5+ is bonded in a 3-coordinate geometry to three O2- atoms. In the third I5+ site, I5+ is bonded in a 6-coordinate geometry to three O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(MnGe)2 by Materials Project

ErMn2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Er is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Er–Ge bond lengths are 3.05 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of edge and corner-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.43 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Er, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.56 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(BiO2)3 by Materials Project

Er(BiO2)3 is Ilmenite-like structured and crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded in an octahedral geometry to six equivalent O2- atoms. All Er–O bond lengths are 2.27 Å. In the second Er3+ site, Er3+ is bonded in an octahedral geometry to six equivalent O2- atoms. All Er–O bond lengths are 2.26 Å. Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.22–2.63 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to one Er3+ and three equivalent Bi3+ atoms to form a mixture of distorted edge and corner-sharing OErBi3 trigonal pyramids. In the second O2- site, O2- is bonded to one Er3+ and three equivalent Bi3+ atoms to form a mixture of distorted edge and corner-sharing OErBi3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(ReO4)2 by Materials Project

Er(ReO4)2 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one Er(ReO4)2 sheet oriented in the (0, 0, 1) direction. Er3+ is bonded to six O2- atoms to form ErO6 octahedra that share corners with six equivalent ReO4 tetrahedra. There are three shorter (2.23 Å) and three longer (2.24 Å) Er–O bond lengths. Re+6.50+ is bonded to four O2- atoms to form ReO4 tetrahedra that share corners with three equivalent ErO6 octahedra. The corner-sharing octahedra tilt angles range from 19–20°. There is one shorter (1.75 Å) and three longer (1.78 Å) Re–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Er3+ and one Re+6.50+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Er3+ and one Re+6.50+ atom. The O–Re bond length is 1.78 Å. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Er3+ and one Re+6.50+ atom. The O–Re bond length is 1.78 Å. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Re+6.50+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one Re+6.50+ atom. The O–Re bond length is 1.75 Å. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Er3+ and one Re+6.50+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Er3+ and one Re+6.50+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Er3+ and one Re+6.50+ atom. The O–Re bond length is 1.78 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er(Ni2P)2 by Materials Project

ErNi4P2 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Er is bonded in a 6-coordinate geometry to six equivalent P atoms. There are two shorter (2.80 Å) and four longer (2.83 Å) Er–P bond lengths. Ni is bonded in a 3-coordinate geometry to three equivalent P atoms. There are two shorter (2.30 Å) and one longer (2.31 Å) Ni–P bond lengths. P is bonded in a 9-coordinate geometry to three equivalent Er and six equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

MODFLOW6 models used to evaluate potential stresses and hydrologic conditions driving water-level fluctuations in well ER-5-3-2, Frenchman Flat, Southern Nevada

The hydrograph for well ER-5-3-2 in Frenchman Flat, southern Nevada, has previously unexplained water-level fluctuations. Four, three-dimensional, groundwater models (MODFLOW 6) were developed to evaluate potential stresses and hydrologic conditions affecting the well ER-5-3-2 hydrograph. Four model scenarios were developed that simulated: (1) wellbore leakage without recharge, (2) wellbore leakage with recharge, (3) shallow (low transmissivity) and deep (high transmissivity) carbonate rocks, and (4) lateral heterogeneity of carbonate rocks. Input and output files for the four model scenarios are in the model and output directories, respectively. Hydraulic conductivity, specific storage, and wellbore-leakage rates (when simulated) were estimated with parameter estimation (PEST) by minimizing a weighted composite, sum-of-squares objective function. The objective function was informed by measurement and Tikhonov regularization observations. Measurement observations included drawdowns from the constant-rate aquifer test and water-level altitudes measured in well ER-5-3-2 from 2001-2021. Tikhonov regularization informed hydraulic conductivity and specific storage parameters that were insensitive to measurement observations, where homogeneity was the preferred relation. Batch files, executables, and MODFLOW 6, PEST, and post-processing utilities are in the ancillary directory. Supplementary data also are included in the ancillary directory, including site information, high-frequency water-level and aquifer-test data, transmissivity estimates, water-chemistry data, and water-temperature analyses. This USGS data release contains data, analyses, and model files for the simulations and analysis results described in U.S. Geological Survey Scientific Investigations Report (https://doi.org/10.3133/sir20225132).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Multi-omics Resources for Understanding Gene Regulation in Response to ER Stress in Plants

Proteotoxic stress of the endoplasmic reticulum (ER) is a potentially lethal condition that ensues when the biosynthetic capacity of the ER is overwhelmed. A sophisticated and largely conserved signaling, known as the unfolded protein response (UPR), is designed to monitor and alleviate ER stress. In plants, the emerging picture of gene regulation by the UPR now appears to be more complex than ever before, requiring multi-omics-enabled network-level approaches to be untangled. In the past decade, with an increasing access and decreasing costs of next-generation sequencing (NGS) and high-throughput protein–DNA interaction (PDI) screening technologies, multitudes of global molecular measurements, known as omics, have been generated and analyzed by the research community to investigate the complex gene regulation of plant UPR. In this chapter, we present a comprehensive catalog of omics resources at different molecular levels (transcriptomes, protein–DNA interactomes, and networks) along with the introduction of key concepts in experimental and computational tools in data generation and analyses. Finally, this chapter will serve as a starting point for both experimentalists and bioinformaticians to explore diverse omics datasets for their biological questions in the plant UPR, with likely applications also in other species for conserved mechanisms.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

Quaternary i-MAX Phases (Mo 2/3 RE 1/3 ) 2 AlC (RE: Dy, Tb, Er): Experimental Characterization and First-Principles Insights into their Fundamental Properties

Rare earth (RE)-based materials have unique electronic, magnetic, and optical properties, leading to the recent discovery of atomically layered solids with the chemical formula (M' 2/3 RE 1/3 ) 2 AlC, which have since garnered significant attention in the scientific community. This study aims to synthesize, characterize, and investigate the structural and thermal stability of the RE i-MAX phases. We prepared i-MAX phases using molybdenum (Mo) as M′ and RE elements as Dy, Tb, and Er, namely (Mo 2/3 Dy 1/3 ) 2 AlC, (Mo 2/3 Tb 1/3 ) 2 AlC, and (Mo 2/3 Er 1/3 ) 2 AlC. Structural characterization through x-ray diffraction (XRD) and Raman spectroscopy confirms the formation of the RE-based i-MAX phase, along with the presence of minor impurity phases in the alloys. Thermogravimetric analysis (TGA) conducted up to 1000°C under ambient conditions reveals that the i-MAX phases remain thermally stable up to approximately 450°C, beyond which oxidation leads to a noticeable weight gain in all samples. Differential scanning calorimetry (DSC) measurements during heating and cooling cycles show endothermic and exothermic peaks for (Mo 2/3 Dy 1/3 ) 2 AlC i-MAX in the 410–420°C range, indicating a temperature-induced minor atomic arrangement. In contrast, these peaks are absent in the Tb- and Er-based i-MAX phases. These findings offer valuable insights into the thermal behavior and stability of these i-MAX phases under thermal stress, contributing to a deeper understanding of their unique properties. Furthermore, first-principles density functional theory (DFT) calculations were performed to investigate the electronic and optical properties of the i-MAX phases. The results reveal their metallic nature, with pronounced contributions from Mo and RE elements near the Fermi level and within the conduction band.

Rare earth↗
DOE OSTI2022

Transcriptional competition shapes proteotoxic ER stress resolution

Through dynamic activities of conserved master transcription factors (mTFs), the unfolded protein response (UPR) relieves proteostasis imbalance of the endoplasmic reticulum (ER), a condition known as ER stress. Because dysregulated UPR is lethal, the competence for fate changes of the UPR mTFs must be tightly controlled. However, the molecular mechanisms underlying regulatory dynamics of mTFs remain largely elusive. Here, we identified the abscisic acid-related regulator G-class bZIP TF2 (GBF2) and the cis-regulatory element G-box as regulatory components of the plant UPR led by the mTFs, bZIP28 and bZIP60. We demonstrate that, by competing with the mTFs at G-box, GBF2 represses UPR gene expression. Conversely, a gbf2 null mutation enhances UPR gene expression and suppresses the lethality of a bzip28 bzip60 mutant in unresolved ER stress. Here, by demonstrating that GBF2 functions as a transcriptional repressor of the UPR, we address the long-standing challenge of identifying shared signalling components for a better understanding of the dynamic nature and complexity of stress biology. Furthermore, our results identify a new layer of UPR gene regulation hinged upon an antagonistic mTFs-GFB2 competition for proteostasis and cell fate determination.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

UV-Vis spectrophotometric determination of rare earth elements (REE) speciation at near-neutral to alkaline pH. Part II: hydrolysis of Er from 25 to 75 °C

Aqueous speciation of rare earth elements (REE) controls their mobilization, fractionation, and enrichment in the natural waters. Geochemical modeling of their speciation is key to improve our understanding of the formation of economic mineral deposits, for developing mineral separation and mine tailing recovery technologies, and for characterizing the geochemistry of thermal water. However, our ability to predict the fate of REE in a wide pH and temperature range is limited by the scarcity of thermodynamic data for the REE hydroxyl complexes. In part I of this study (H. J. Han and A. P. Gysi, Dalton Trans., 2024, 53, 13129–13141), the optical properties of m-cresol purple (mCP) were determined using UV-Vis spectrophotometry between 25 and 75 °C in order to develop a method for deriving the hydrolysis constants of erbium (Er). Here, UV-Vis spectrophotometry experiments were conducted as a function of temperature between 35 and 75 °C to determine the hydrolysis of Er in near-neutral to alkaline solutions using mCP as an in situ pH color indicator. Here, the experiments were conducted with Er concentrations from 0 to ~0.253 mmol kg –1 in low ionic strength solutions (≤0.001 mol kg –1 ).

58 GEOSCIENCES↗