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Sample records for al atmos chem

  1. Corrigendum to Aerosol impacts on California winter clouds and precipitation during CalWater 2011: local pollution versus long-range transported dust published in Atmos. Chem. Phys., 14, 81–101, 2014

    SciTech Connect

    Fan, Jiwen; Leung, Lai-Yung R.; DeMott, Paul J.; Comstock, Jennifer M.; Singh, Balwinder; Rosenfeld, Daniel; Tomlinson, Jason M.; White, A.; Prather, Kimberly; Minnis, Patrick; Ayers, J. K.; Min, Qilong

    2014-05-01

    In the paper “Aerosol impacts on California winter clouds and precipitation during CalWater 2011: local pollution versus long-range transported dust” by J. Fan et al., wrong versions of Fig. 8 and Fig. 12 were published. Please find the correct figures below.

  2. Corrigendum to "Aerosol indirect effects from shipping emissions: sensitivity studies with the global aerosol-climate model ECHAM-HAM" published in Atmos. Chem. Phys., 12, 5985-6007, 2012

    NASA Astrophysics Data System (ADS)

    Peters, K.; Stier, P.; Quaas, J.; Graßl, H.

    2013-07-01

    An error in the calculation of the emitted number of primary sulfate particles for a given mass of emitted elementary sulfur has recently been identified in HAM, i.e. the aerosol module utilised in the ECHAM-HAM aerosol climate model. Correcting for this error substantially alters the estimates of top-of-atmosphere radiative forcing due to aerosol indirect effects from global shipping emissions (year 2000) as presented in Peters et al. (2012). Here, we shortly present these new results.

  3. Advanced Multimission Operations System (ATMO)

    NASA Technical Reports Server (NTRS)

    Mandrake, Lucas; Thompson, David R.

    2013-01-01

    The HiiHat toolbox developed for CAT/ENVI provides principal investigators direct, immediate, flexible, and seamless interaction with their instruments and data from any location. Offering segmentation and neutral region division, it facilitates the discovery of key endmembers and regions of interest larger than a single pixel. Crucial to the analysis of hyperspectral data from Mars or Earth is the removal of unwanted atmospheric signatures. For Mars and the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), residual atmospheric CO2 absorption is both directly problematic and indicative of processing errors with implications to the scientific utility of any particular image region. Estimating this residual error becomes key both in selecting regions of low distortion, and also to select mitigating methods, such as neutral region division. This innovation, the ATMO estimator, provides a simple, 0-1 normalized scalar that estimates this distortion (see figure). The metric is defined as the coefficient of determination of a quadratic fit in the region of distorting atmospheric absorption (approx 2 micron). This mimics the behavior of existing CRISM team mineralogical indices to estimate the presence of known, interesting mineral signatures. This facilitates the ATMO metric's assimilation into existing planetary geology workflows.

  4. Characterising Biomass Burning Aerosol in WRF-Chem using the Volatility Basis Set, with Evaluation against SAMBBA Flight Data

    NASA Astrophysics Data System (ADS)

    Lowe, D.; Topping, D. O.; Archer-Nicholls, S.; Darbyshire, E.; Morgan, W.; Liu, D.; Allan, J. D.; Coe, H.; McFiggans, G.

    2015-12-01

    The burning of forests in the Amazonia region is a globally significant source of carbonaceous aerosol, containing both absorbing and scattering components [1]. In addition biomass burning aerosol (BBA) are also efficient cloud condensation nuclei (CCN), modifying cloud properties and influencing atmospheric circulation and precipitation tendencies [2]. The impacts of BBA are highly dependent on their size distribution and composition. A bottom-up emissions inventory, the Brazilian Biomass Burning Emissions Model (3BEM) [3], utilising satellite products to generate daily fire emission maps is used. Injection of flaming emissions within the atmospheric column is simulated using both a sub-grid plume-rise parameterisation [4], and simpler schemes, within the Weather Research and Forecasting Model with Chemistry (WRF-Chem, v3.4.1) [5]. Aerosol dynamics are simulated using the sectional MOSAIC scheme [6], incorporating a volatility basis set (VBS) treatment of organic aerosol [7]. For this work we have modified the 9-bin VBS to use the biomass burning specific scheme developed by May et al. [8]. The model has been run for September 2012 over South America (at a 25km resolution). We will present model results evaluating the modelled aerosol vertical distribution, size distribution, and composition against measurements taken by the FAAM BAe-146 research aircraft during the SAMBBA campaign. The main focus will be on investigating the factors controlling the vertical gradient of the organic mass to black carbon ratio of the measured aerosol. This work is supported by the Nature Environment Research Council (NERC) as part of the SAMBBA project under grant NE/J010073/1. [1] D. G. Streets et al., 2004, J. Geophys. Res., 109, D24212. [2] M. O. Andreae et al., 2004, Science, 303, 1337-1342. [3] K. Longo et al., 2010, Atmos. Chem. Phys., 10, 5,785-5,795. [4] S. Freitas et al., 2007, Atmos. Chem. Phys., 7, 3,385-3,398. [5] S. Archer-Nicholls et al., 2015, Geosci. Model Dev., 8

  5. Charactering biomass burning aerosol in the Weather Research and Forecasting model with Chemistry (WRF-Chem), with evaluation against SAMBBA flight data.

    NASA Astrophysics Data System (ADS)

    Archer-Nicholls, S.; Lowe, D.; Darbyshire, E.; Morgan, W.; Freitas, S. R.; Longo, K.; Coe, H.; McFiggans, G.

    2014-12-01

    . Longo et al., 2010, Atmos. Chem. Phys., 10, 5785-5795. 2. M. O. Andreae and P. Merlot, 2001, Global Biogeochem. Cy., 15(4), 955-966. 3. S. Freitas et al., 2007, Atmos. Chem. Phys., 7, 3385-3398. 4. G. Grell et al., 2011, Atmos. Chem. Phys., 11, 5289-5303. 5. R. Zavari et al., 2008, J. Geophys. Res., 113, D132024.

  6. 77 FR 15748 - Atmos Energy Corporation/Atmos Energy-Kentucky/Mid-States Division; Notice of Motion for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-16

    ... of Motion for Extension of Rate Case Filing Deadline Take notice that on March 9, 2012, Atmos Energy Corporation filed on behalf of Atmos Energy--Kentucky/Mid-States Division (Atmos) a motion requesting an... a motion to intervene or to protest this filing must file in accordance with Rules 211 and 214...

  7. Web portal on environmental sciences "ATMOS''

    NASA Astrophysics Data System (ADS)

    Gordov, E. P.; Lykosov, V. N.; Fazliev, A. Z.

    2006-06-01

    The developed under INTAS grant web portal ATMOS (http://atmos.iao.ru and http://atmos.scert.ru) makes available to the international research community, environmental managers, and the interested public, a bilingual information source for the domain of Atmospheric Physics and Chemistry, and the related application domain of air quality assessment and management. It offers access to integrated thematic information, experimental data, analytical tools and models, case studies, and related information and educational resources compiled, structured, and edited by the partners into a coherent and consistent thematic information resource. While offering the usual components of a thematic site such as link collections, user group registration, discussion forum, news section etc., the site is distinguished by its scientific information services and tools: on-line models and analytical tools, and data collections and case studies together with tutorial material. The portal is organized as a set of interrelated scientific sites, which addressed basic branches of Atmospheric Sciences and Climate Modeling as well as the applied domains of Air Quality Assessment and Management, Modeling, and Environmental Impact Assessment. Each scientific site is open for external access information-computational system realized by means of Internet technologies. The main basic science topics are devoted to Atmospheric Chemistry, Atmospheric Spectroscopy and Radiation, Atmospheric Aerosols, Atmospheric Dynamics and Atmospheric Models, including climate models. The portal ATMOS reflects current tendency of Environmental Sciences transformation into exact (quantitative) sciences and is quite effective example of modern Information Technologies and Environmental Sciences integration. It makes the portal both an auxiliary instrument to support interdisciplinary projects of regional environment and extensive educational resource in this important domain.

  8. Orbital analysis for atmospheric trace molecule spectroscopy (ATMOS) Shuttle missions

    NASA Technical Reports Server (NTRS)

    Harrison, Edwin F.; Denn, Frederick M.; Gibson, Gary G.

    1988-01-01

    An orbital analysis was carried out to define the geographical coverage capabilities of an ATMOS solar occultation experiment on Space Shuttle/Spacelab missions. Particular attention was given to the effects of launch time, orbit inclination, altitude, and season on latitude-longitude coverage. It is shown that the widest band of latitude coverage in the tropics and temperate zones can be achieved with a midinclined orbit and a midmorning or late-night launch time. The use of ATMOS Shuttle underflights to provide coincident measurements with a solar occultation experiment on the Upper Atmospheric Research Satellite is also examined.

  9. 78 FR 39720 - Atmos Pipeline and Storage, LLC; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-02

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Atmos Pipeline and Storage, LLC; Notice of Application Take notice that on June 14, 2013, Atmos Pipeline and Storage, LLC. (Atmos), filed with the Federal Energy Regulatory Commission an application under section 7(b)...

  10. 77 FR 21760 - Atmos Energy Colorado/Kansas Division; Notice of Baseline Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-11

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Atmos Energy Colorado/Kansas Division; Notice of Baseline Filing Take notice that on March 30, 2012, Atmos Energy Colorado/Kansas Division (Atmos) submitted a baseline...

  11. 77 FR 23244 - Atmos Energy Colorado/Kansas Division; Notice of Revised Baseline Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-18

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Atmos Energy Colorado/Kansas Division; Notice of Revised Baseline Filing Take notice that on April 10, 2012, Atmos Energy Colorado/Kansas Division (Atmos) filed a...

  12. ATMOS: Long term atmospheric measurements for mission to planet Earth

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A long-term, space-based measurement program, together with continued balloon and aircraft-borne investigations, is essential to monitor the predicted effects in the atmosphere, to determine to what extent the concentration measurements agree with current models of stratospheric chemistry, and to determine the condition of the ozone layer. The Atmospheric Trace Molecule Spectroscopy (ATMOS) Experiment is currently making comprehensive, global measurements of Earth's atmosphere as part of the Atmospheric Laboratory for Applications and Science (ATLAS) program on the Space Shuttle. Part of NASA's Mission to Planet Earth, ATLAS is a continuing series of missions to study Earth and the Sun and provide a more fundamental understanding of the solar influences on Earth's atmosphere. The ATMOS program, instruments, and science results are presented.

  13. AdapChem

    NASA Technical Reports Server (NTRS)

    Oluwole, Oluwayemisi O.; Wong, Hsi-Wu; Green, William

    2012-01-01

    AdapChem software enables high efficiency, low computational cost, and enhanced accuracy on computational fluid dynamics (CFD) numerical simulations used for combustion studies. The software dynamically allocates smaller, reduced chemical models instead of the larger, full chemistry models to evolve the calculation while ensuring the same accuracy to be obtained for steady-state CFD reacting flow simulations. The software enables detailed chemical kinetic modeling in combustion CFD simulations. AdapChem adapts the reaction mechanism used in the CFD to the local reaction conditions. Instead of a single, comprehensive reaction mechanism throughout the computation, a dynamic distribution of smaller, reduced models is used to capture accurately the chemical kinetics at a fraction of the cost of the traditional single-mechanism approach.

  14. AutoChem

    NASA Technical Reports Server (NTRS)

    Lary, David John

    2005-01-01

    AutoChem is a suite of Fortran 90 computer programs for the modeling of kinetic reaction systems. AutoChem performs automatic code generation, symbolic differentiation, analysis, and documentation. It produces a documented stand-alone system for the modeling and assimilation of atmospheric chemistry. Given databases of chemical reactions and a list of constituents defined by the user, AutoChem automatically does the following: 1. Selects the subset of reactions that involve a user-defined list of constituents and automatically prepares a document listing the reactions; 2. Constructs the ordinary differential equations (ODEs) that describe the reactions as functions of time and prepares a document containing the ODEs; 3. Symbolically differentiates the time derivatives to obtain the Jacobian and prepares a document containing the Jacobian; 4. Symbolically differentiates the Jacobian to obtain the Hessian and prepares a document containing the Hessian; and 5. Writes all the required Fortran 90 code and datafiles for a stand-alone chemical modeling and assimilation system (implementation of steps 1 through 5). Typically, the time taken for steps 1 through 5 is about 3 seconds. The modeling system includes diagnostic components that automatically analyze each ODE at run time, the relative importance of each term, time scales, and other attributes of the model.

  15. Heavy ozone enrichments from ATMOS infrared solar spectra

    NASA Astrophysics Data System (ADS)

    Irion, F. W.; Gunson, M. R.; Rinsland, C. P.; Yung, Y. L.; Abrams, M. C.; Chang, A. Y.; Goldman, A.

    Vertical enrichment profiles of stratospheric 16O16Ol8O and 16O18O16O (hereafter referred to as 668O3 and 686O3 respectively) have been derived from space-based solar occultation spectra recorded at 0.01 cm-1 resolution by the ATMOS (Atmospheric Trace MOlecule Spectroscopy) Fourier-transform infrared (FTIR) spectrometer. The observations, made during the Spacelab 3 and ATLAS-1, -2, and -3 shuttle missions, cover polar, mid-latitude and tropical regions between 26 to 2.6 mb inclusive (≈ 25 to 41 km). Average enrichments, weighted by molecular 48O3 density, of (15±6)% were found for 668O3 and (10±7)% for 686O3. Defining the mixing ratio of 50O3 as the sum of those for 668O3 and 686O3, an enrichment of (13±5)% was found for 50O3 (1σ standard deviation). No latitudinal or vertical gradients were found outside this standard deviation. From a series of ground-based measurements by the ATMOS instrument at Table Mountain, California (34.4°N), an average total column 668O3 enrichment of (17±4)% (1σ standard deviation) was determined, with no significant seasonal variation discernable. Possible biases in the spectral intensities that affect the determination of absolute enrichments are discussed.

  16. Using WRF-Chem to investigate the impact of night time nitrate radical chemistry and N2O5 heterogeneous chemistry on the chemical composition of the UK troposphere.

    NASA Astrophysics Data System (ADS)

    Archer-Nicholls, S.; Lowe, D.; Utembe, S.; McFiggans, G.

    2012-04-01

    of two flight periods: one during July 2010; the other during January 2011. We have run five model scenarios for both these periods: a base case, with standard emissions and chemistry; two scenarios with standard chemistry, but with halved and doubled NOx transport emissions respectively; and two scenarios with standard emissions, but one without N2O5 heterogeneous chemistry, and the other with the Cl- reaction pathway disabled. We will present results from the application of WRF-Chem to model the regional chemical composition of the atmosphere about the UK. Sensitivities to changing emission profiles and the impact of N2O5 heterogeneous chemistry will be discussed. Preliminary comparisons between model results and aircraft data will be shown. The strengths and weaknesses of our modelling approach, in particular the gains and drawbacks of using a fully coupled online model for use in this campaign, will be highlighted. The wider impacts of the processes investigated on the regional climate and air quality will be further discussed. Allan, B., et. al. (2000); J. Geophys. Res., 105, doi: 10.1046/j.1365-2370.2000.00208. Bertram, T. H., Thornton, J. A. (2009); Atmos. Chem. Phys., 9, 8351-8363, doi: 10.5194/acp-9-8351-2009 Grell, G., et. al. (2005); Atmos. Environ., 39, 6957- 6975. doi: 10.1016/j.atmosenv.2005.04.027 Topping, D., Lowe, D. & McFiggans, G. (2012); Geosci. Model Dev., 5, 1-13. doi:10.5194/gmd-5-1-2012 Watson, L., et. al. (2008); Atmos. Environ., 42, 7196- 7204, doi: 10.1016/j.atmosenv.2008.07.034 Zaveri, R. A., et. al. (2008); J. Geophys. Res., 113, doi:10.1029/2007JD008782

  17. Optical design of the ATMOS Fourier transform spectrometer

    NASA Technical Reports Server (NTRS)

    Abel, I. R.; Reynolds, B. R.; Breckinridge, J. B.; Pritchard, J.

    1979-01-01

    The optical system design of the ATMOS Fourier transform spectrometer to be operated from Spacelab for the measurement of stratospheric trace molecules is described. The design contains features which can achieve the required fringe contrast of 80% and spectral resolution of 0.02/cm over a spectral range of 2-16 microns. In particular, the design is based on the following features which alleviate the usual requirements for alignment precision: (1) 'cat's eye' mirror configuration in the two arms of the interferometer for retroreflection stability, (2) tilt-compensated system of beamsplitter, compensator, and fold mirrors for wavefront directional stability, (3) paraboloidal 'cat's eye' primary mirror for wavefront stability against shear, (4) rotatable compensator for matching chromatic dispersion, and (5) wedged refractive components to avoid channel spectra due to the Fabry-Perot effect.

  18. 75 FR 31429 - Atmos Pipeline-Texas; Notice of Baseline Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-03

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Atmos Pipeline--Texas; Notice of Baseline Filing May 27, 2010. Take notice that on May 27, 2010, Atmos Pipeline--Texas submitted a baseline filing of its Statement of...

  19. X-ray computed microtomography of sea ice - comment on "A review of air-ice chemical and physical interactions (AICI): liquids, quasi-liquids, and solids in snow" by Bartels-Rausch et al. (2014)

    NASA Astrophysics Data System (ADS)

    Obbard, R. W.

    2015-07-01

    This comment addresses a statement made in "A review of air-ice chemical and physical interactions (AICI): liquids, quasi-liquids, and solids in snow" by Bartels-Rausch et al. (Atmos. Chem. Phys., 14, 1587-1633, doi:10.5194/acp-14-1587-2014, 2014). Here we rebut the assertion that X-ray computed microtomography of sea ice fails to reveal liquid brine inclusions by discussing the phases present at the analysis temperature.

  20. Stratospheric infrared continuum absorptions observed by the ATMOS instrument

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Zander, R.; Namkung, J. S.; Farmer, C. B.; Norton, R. H.

    1989-01-01

    A quantitative analysis of infrared continuum absorption features observed in ATMOS/Spacelab 3 (1985) spectra of the lower stratosphere is reported. Continuous absorption produced primarily by the collision-induced fundamental vibration-rotation band of O2 and to a lesser extent by the superposition of H2O far line wings has been observed in the 1400 to 1800/cm interval below tangent heights of about 25 km. Continuum optical depths measured in microwindows nearly free of atmospheric line absorption are 0.78 + or - 0.06 times those calculated with the O2 absorption coefficients of Timofeyev and Tonkov (1978). Transmittance measurements in microwindows between 2395 and 2535/cm have been used to study continuous absorption from the collision induced fundamental vibration-rotation band of N2 and the far wings of strong CO2 lines. The measured transmittances have been analyzed to derive best fit absorption coefficients for the N2 pressure-induced band at lower stratospheric temperatures (about 210 K).

  1. ChemCam video footage

    NASA Video Gallery

    ChemCam is a rock-zapping laser instrument that can hit rocks with a laser then observes the flash through a telescope and analyzes the spectrum of light to identify the chemical elements in the ta...

  2. The ChemEcology Portfolio.

    ERIC Educational Resources Information Center

    Wygoda, Linda J.

    1996-01-01

    Presents activities based on readings from ChemEcology that incorporate student writing with thinking skills as part of a reading/writing portfolio. Helps students to develop a broader understanding of chemistry, the chemical industry, and the environment. (JRH)

  3. A Comparison of Measurements from ATMOS and Instruments Aboard the ER-2 Aircraft: Halogenated Gases

    NASA Technical Reports Server (NTRS)

    Chang, A. Y.; Salawitch, R. J.; Michelsen, H. A.; Gunson, M. R.; Abrams, M. C.; Zander, R.; Rinsland, C. P.; Elkins, J. W.; Dutton, G. S.; Volk, C. M.; Webster, C. R.; May, R. D.; Fahey, D. W.; Gao, R.-S.; Loewenstein, M.

    1996-01-01

    We compare volume mixing ratio profiles of N2O, CFC-11, CFC-12, CCl4, SF6, and HCl 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. Good agreement is found between ATMOS and in situ correlations of [CFC-11], [CFC-12], and [SF6] with [N2O]. ATMOS measurements of [CCl4] are 15% high compared to ER-2 data, but agree within the systematic uncertainties. ATMOS observations of [HCl] vs [N2O] are within approximately 10% of ER-2 data for [HCl] > 1 ppbv, but exceed in situ measurements by larger fractional amounts for smaller [HCl]. ATMOS measurements of [ClONO2] agree well with values inferred from in situ observations of [ClO], [NO], and [O3]. The sum of [HCl] and [ClONO2] observed by ATMOS, supplemented by a minor contribution from [ClO] estimated with a photochemical model, is consistent with the levels of inorganic chlorine inferred from in situ measurements of chlorine source gases.

  4. The Atmospheric Trace Molecule Spectroscopy (ATMOS) Experiment: Deployment on the ATLAS Space Shuttle Missions

    NASA Technical Reports Server (NTRS)

    Gunson, M. R.; Abbas, M. M.; Abrams, M. C.; Allen, M.; Brown, L. R.; Brown, T. L.; Chang, A. Y.; Goldman, A.; Irion, F. W.; Lowes, L. L..; Mahieu, E.; Manney, G. L.; Michelsen, H. A.; Newchurch, M. J.; Rinsland, C. P.; Salawitch, R. J.; Stiller, G. P.; Toon, G. C.; Yung, Y. L.; Zander, R.

    1996-01-01

    The ATMOS Fourier transform spectrometer was flown for a fourth time on the Space Shuttle as part of the ATLAS-3 instrument payload in November 1994. More than 190 sunrise and sunset occultation events provided measurements of more than 30 atmospheric trace gases at latitudes 3 - 49 deg N and 65 - 72 deg S, including observations both inside and outside the Antarctic polar vortex. The instrument configuration, data retrieval methodology, and mission background are described to place in context analyses of ATMOS data presented in this issue.

  5. The ATMOS (Atmospheric Trace MOlecule Spectroscopy) experiment - A tool for global monitoring of the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Zander, R.; Gunson, M. R.; Farmer, C. B.; Norton, R. H.; Rinsland, C. P.

    1990-01-01

    A review is presented of the objectives, instrumentation, performance and results of the ATMOS program developed by NASA-JPL as part of the Spacelab 3 shuttle payload. ATMOS was developed to obtain high-resolution spectroscopic information of the middle atmosphere, from which the vertical distribution of the most possible trace and minor molecules could be retrieved. A complete occultation included not only data recorded when the optical path traversed the earth's atmosphere, but also many spectra with tangent heights big enough for no more telluric absorptions to be detected. The averaging of such 'high sun' observations has provided high quality solar spectra totally free of atmospheric absorption features.

  6. Automated CO2 extraction from air for clumped isotope analysis in the atmo- and biosphere

    NASA Astrophysics Data System (ADS)

    Hofmann, Magdalena; Ziegler, Martin; Pons, Thijs; Lourens, Lucas; Röckmann, Thomas

    2015-04-01

    The conventional stable isotope ratios 13C/12C and 18O/16O in atmospheric CO2 are a powerful tool for unraveling the global carbon cycle. In recent years, it has been suggested that the abundance of the very rare isotopologue 13C18O16O on m/z 47 might be a promising tracer to complement conventional stable isotope analysis of atmospheric CO2 [Affek and Eiler, 2006; Affek et al. 2007; Eiler and Schauble, 2004; Yeung et al., 2009]. Here we present an automated analytical system that is designed for clumped isotope analysis of atmo- and biospheric CO2. The carbon dioxide gas is quantitatively extracted from about 1.5L of air (ATP). The automated stainless steel extraction and purification line consists of three main components: (i) a drying unit (a magnesium perchlorate unit and a cryogenic water trap), (ii) two CO2 traps cooled with liquid nitrogen [Werner et al., 2001] and (iii) a GC column packed with Porapak Q that can be cooled with liquid nitrogen to -30°C during purification and heated up to 230°C in-between two extraction runs. After CO2 extraction and purification, the CO2 is automatically transferred to the mass spectrometer. Mass spectrometric analysis of the 13C18O16O abundance is carried out in dual inlet mode on a MAT 253 mass spectrometer. Each analysis generally consists of 80 change-over-cycles. Three additional Faraday cups were added to the mass spectrometer for simultaneous analysis of the mass-to-charge ratios 44, 45, 46, 47, 48 and 49. The reproducibility for δ13C, δ18O and Δ47 for repeated CO2 extractions from air is in the range of 0.11o (SD), 0.18o (SD) and 0.02 (SD)o respectively. This automated CO2 extraction and purification system will be used to analyse the clumped isotopic signature in atmospheric CO2 (tall tower, Cabauw, Netherlands) and to study the clumped isotopic fractionation during photosynthesis (leaf chamber experiments) and soil respiration. References Affek, H. P., Xu, X. & Eiler, J. M., Geochim. Cosmochim. Acta 71, 5033

  7. Profiles of Stratospheric Chlorine Nitrate from ATMOS/ATLAS 1 Infrared Solar Occultation Spectra

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Abrams, M. C.; Zander, R.; Mahieu, E.; Goldman, A.; Ko, M. K. W.; Rodriguez, J. M.; Sze, N. D.

    1994-01-01

    Stratospheric volume mixing ration profiles of chlorine nitrate have been retrieved from 0.01-cm(sub -1) resolution infrared solar occutation spectra recorded at latitudes between 14 degrees N and 54 degrees S by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS 1 shuttle mission (March 24 to April 2, 1992).

  8. PubChem Substance and Compound databases

    PubMed Central

    Kim, Sunghwan; Thiessen, Paul A.; Bolton, Evan E.; Chen, Jie; Fu, Gang; Gindulyte, Asta; Han, Lianyi; He, Jane; He, Siqian; Shoemaker, Benjamin A.; Wang, Jiyao; Yu, Bo; Zhang, Jian; Bryant, Stephen H.

    2016-01-01

    PubChem (https://pubchem.ncbi.nlm.nih.gov) is a public repository for information on chemical substances and their biological activities, launched in 2004 as a component of the Molecular Libraries Roadmap Initiatives of the US National Institutes of Health (NIH). For the past 11 years, PubChem has grown to a sizable system, serving as a chemical information resource for the scientific research community. PubChem consists of three inter-linked databases, Substance, Compound and BioAssay. The Substance database contains chemical information deposited by individual data contributors to PubChem, and the Compound database stores unique chemical structures extracted from the Substance database. Biological activity data of chemical substances tested in assay experiments are contained in the BioAssay database. This paper provides an overview of the PubChem Substance and Compound databases, including data sources and contents, data organization, data submission using PubChem Upload, chemical structure standardization, web-based interfaces for textual and non-textual searches, and programmatic access. It also gives a brief description of PubChem3D, a resource derived from theoretical three-dimensional structures of compounds in PubChem, as well as PubChemRDF, Resource Description Framework (RDF)-formatted PubChem data for data sharing, analysis and integration with information contained in other databases. PMID:26400175

  9. PubChem Substance and Compound databases.

    PubMed

    Kim, Sunghwan; Thiessen, Paul A; Bolton, Evan E; Chen, Jie; Fu, Gang; Gindulyte, Asta; Han, Lianyi; He, Jane; He, Siqian; Shoemaker, Benjamin A; Wang, Jiyao; Yu, Bo; Zhang, Jian; Bryant, Stephen H

    2016-01-01

    PubChem (https://pubchem.ncbi.nlm.nih.gov) is a public repository for information on chemical substances and their biological activities, launched in 2004 as a component of the Molecular Libraries Roadmap Initiatives of the US National Institutes of Health (NIH). For the past 11 years, PubChem has grown to a sizable system, serving as a chemical information resource for the scientific research community. PubChem consists of three inter-linked databases, Substance, Compound and BioAssay. The Substance database contains chemical information deposited by individual data contributors to PubChem, and the Compound database stores unique chemical structures extracted from the Substance database. Biological activity data of chemical substances tested in assay experiments are contained in the BioAssay database. This paper provides an overview of the PubChem Substance and Compound databases, including data sources and contents, data organization, data submission using PubChem Upload, chemical structure standardization, web-based interfaces for textual and non-textual searches, and programmatic access. It also gives a brief description of PubChem3D, a resource derived from theoretical three-dimensional structures of compounds in PubChem, as well as PubChemRDF, Resource Description Framework (RDF)-formatted PubChem data for data sharing, analysis and integration with information contained in other databases. PMID:26400175

  10. Predicting the thermal/structural performance of the atmospheric trace molecules spectroscopy /ATMOS/ Fourier transform spectrometer

    NASA Technical Reports Server (NTRS)

    Miller, J. M.

    1980-01-01

    ATMOS is a Fourier transform spectrometer to measure atmospheric trace molecules over a spectral range of 2-16 microns. Assessment of the system performance of ATMOS includes evaluations of optical system errors induced by thermal and structural effects. In order to assess the optical system errors induced from thermal and structural effects, error budgets are assembled during system engineering tasks and line of sight and wavefront deformations predictions (using operational thermal and vibration environments and computer models) are subsequently compared to the error budgets. This paper discusses the thermal/structural error budgets, modelling and analysis methods used to predict thermal/structural induced errors and the comparisons that show that predictions are within the error budgets.

  11. Trace Gas Transport in the Arctic Vortex Inferred from ATMOS ATLAS-2 Observations During April 1993

    NASA Technical Reports Server (NTRS)

    Abrams, M. C.; Manney, G. L.; Gunson, M. R.; Abbas, M. M.; Chang, A. Y.; Goldman, A.; Irion, F. W.; Michelsen, H. A.; Newchurch, M. J.; Rinsland, C, P,; Salawitch, R. J.; Stiller, G. P.; Zander, R.

    1996-01-01

    Measurements of the long-lived tracers CH4, N2O, and HF from the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during the Atmospheric Laboratory for Science and Applications-2 (ATLAS-2) Space Shuttle mission in April 1993 are used to infer average winter descent rates ranging from 0.8 km/month at 20 km to 3.2 km/month at 40 km in the Arctic polar vortex during the 1992-93 winter. Descent rates in the mid-stratosphere are similar to those deduced for the Antarctic vortex using ATMOS/ATLAS-3 measurements in November 1994, but the shorter time period of descent in the Arctic leads to smaller total distances of descent. Strong horizontal gradients observed along the vortex edge indicate that the Arctic vortex remains a significant barrier to transport at least until mid-April in the lower to middle stratosphere.

  12. Measurement of atmospheric composition by the ATMOS instrument from Table Mountain Observatory

    NASA Astrophysics Data System (ADS)

    Gunson, Michael R.; Irion, Fredrick W.

    1991-09-01

    Following its first flight on board the Space Shuttle 'Challenger' as part of the Spacelab 3 payload, the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument has been operated at the Jet Propulsion Laboratory's Table Mountain Observatory (TMO; 34.4 deg N, 117.7 deg W, 2.23 km altitude) in the San Gabriel Mountains of Southern California. With the delay in the resumption of regular Shuttle flights, ATMOS has acquired a large number of high-quality, high-resolution infrared solar absorption spectra, spanning a period between late-1985 and mid-1990. These spectra are being analyzed to derive the column abundances of several atmospheric species including O3, HCl, HF, and HNO3. Although limited in temporal coverage, the preliminary results for these gases are discussed here in the context of the requirement and contribution to be made by similar instruments in detecting long term changes in stratospheric composition.

  13. Increase of Stratospheric Carbon Tetrafluoride (CF4) Based on ATMOS Observations from Space

    NASA Technical Reports Server (NTRS)

    Zander, R.; Solomon, S.; Mahieu, E.; Goldman, A.; Rinsland, C. P.; Gunson, M. R.; Abrams, M. C.; Chang, A. Y.; Michelsen, H. A.; Newchurch, M. J.; Stiller, G. P.

    1996-01-01

    Stratospheric volume mixing ratio profiles of carbon tetrafluoride, CF4, obtained with the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during the ATLAS (Atmospheric Laboratory for Applications and Science) -3 mission of 1994 are reported. Overall the profiles are nearly constant over the altitude range 20 to 50 km, indicative of the very long lifetime of CF4 in the atmosphere. In comparison to the stratospheric values of CF4 inferred from the ATMOS/Spacelab 3 mission of 1985, the 1994 concentrations are consistent with an exponential increase of (1.6 +/- 0.6)% yr(exp -1). This increase is discussed with regard to previous results and likely sources of CF4 at the ground. Further, it is shown that simultaneous measurements of N2O and CF4 provide a means of constraining the lower limit of the atmospheric lifetime of CF4 at least 2,300 years, two sigma.

  14. Stratospheric sulfuric acid aerosols: composition and temperature discrimination with the ATMOS data set

    NASA Technical Reports Server (NTRS)

    Eldering, A.; Irion, F. W.; Mills, F. P.; Steele, H. M.; Kahn, B. H.; Gunson, M. R.

    2000-01-01

    The ATMOS Fourier transform spectrometer was flown for a fourth time on the Space Shuttle as part of the ATLAS-3 instrument payload in November 1994. More than 190 sunrise and sunset occultation events provided measurements of more than 30 atmospheric trace gases at latitudes 3-49(deg)N and 65-72(deg)S, including observations both inside and outside the Antarctic polar vortex.

  15. Synthetic Solar Spectra Out Of Atmos Data For The Near- And Mid-infrared Ranges

    NASA Astrophysics Data System (ADS)

    Seo, Haing Ja; Kim, S.; Kim, J.; Jang, M.

    2006-09-01

    We have constructed synthetic solar spectra for the 2.5 - 3.0 μm, 4.1 - 4.4 μm, and 5.1 - 7.7 μm ranges using Voigt line profiles, and with solar line identifications compiled by Geller (1992), who derived solar line positions and intensities from contaminated high-resolution solar spectra obtained by ATMOS (Atmospheric Trace Molecule Spectroscopy), a spaceborne observatory. Because the ATMOS spectra in these wavelength ranges are contaminated by absorption lines of molecules existing in Earth's high-altitude atmosphere, the direct use of this high-resolution solar spectra has been inconvenient for planetary scientists. We compared the synthetic solar spectra with the ATMOS spectra, and obtained satisfactory fits with the exception of a few abnormal lines. From the satisfactory comparisons, we were able to determine Voigt line parameters for each solar line. These synthetic solar spectra will be useful to eliminate solar continua from spectra of planetary objects to extract their own spectral characteristics. Reference Geller, M., 1992, A High-Resolution Atlas of the Infrared Spectrum of the Sun and the Earth Atmosphere from Space, Vol. III. Key to Identification of Solar Features, NASA Reference Pub. 1224.

  16. Corrigendum to "Impact of cloud-borne aerosol representation on aerosol direct and indirect effects" published in Atmos. Chem. Phys., 6, 4163-4174, 2006

    SciTech Connect

    Ghan, Steven J; Easter, Richard C

    2007-01-19

    Ghan and Easter (2006) (hereafter referred to as GE2006) used a global aerosol model to estimate the sensitivity of aerosol direct and indirect effects to a variety of simplified treatments of the cloud-borne aerosol. They found that neglecting transport of cloud-borne particles introduces little error, but that diagnosing cloud-borne particles produces global mean biases of 20% and local errors of up to 40% for aerosol, droplet number, and direct and indirect radiative forcing However, we have recently found that in those experiments we had inadvertently turned off the first aerosol indirect effect. In the radiation module, the droplet effective radius was prescribed at 10 microns rather than related to the droplet number concentration. The second indirect effect, in which droplet number influences droplet collision and coalescence, was treated, so that the simulations produced an aerosol indirect effect, albeit one that is much smaller (about -0.2Wm-2 for anthropogenic sulfate) than other previous estimates.

  17. Exploiting PubChem for Virtual Screening

    PubMed Central

    Xie, Xiang-Qun

    2011-01-01

    Importance of the field PubChem is a public molecular information repository, a scientific showcase of the NIH Roadmap Initiative. The PubChem database holds over 27 million records of unique chemical structures of compounds (CID) derived from nearly 70 million substance depositions (SID), and contains more than 449,000 bioassay records with over thousands of in vitro biochemical and cell-based screening bioassays established, with targeting more than 7000 proteins and genes linking to over 1.8 million of substances. Areas covered in this review This review builds on recent PubChem-related computational chemistry research reported by other authors while providing readers with an overview of the PubChem database, focusing on its increasing role in cheminformatics, virtual screening and toxicity prediction modeling. What the reader will gain These publicly available datasets in PubChem provide great opportunities for scientists to perform cheminformatics and virtual screening research for computer-aided drug design. However, the high volume and complexity of the datasets, in particular the bioassay-associated false positives/negatives and highly imbalanced datasets in PubChem, also creates major challenges. Several approaches regarding the modeling of PubChem datasets and development of virtual screening models for bioactivity and toxicity predictions are also reviewed. Take home message Novel data-mining cheminformatics tools and virtual screening algorithms are being developed and used to retrieve, annotate and analyze the large-scale and highly complex PubChem biological screening data for drug design. PMID:21691435

  18. Stratospheric NO and NO2 Abundances from ATMOS Solar-Occultation Measurements

    NASA Technical Reports Server (NTRS)

    Newchurch, M. J.; Allen, M.; Gunson, M. R.; Salawitch, R. J.; Collins, G. B.; Huston, K. H.; Abbas, M. M.; Abrams, M. C.; Chang, A. Y.; Fahey, D. W.; Gao, R. S.; Irion, F. W.; Lowenstein, M.; Manney, G. L.; Michelsen, H. A.; Podolske, J. R.; Rinsland, C. P.; Zander, R.

    1996-01-01

    Using results from a time-dependent photochemical model to calculate the diurnal variation of NO and NO2, we have corrected Atmospheric Trace MOlecule Spectroscopy (ATMOS) solar-occultation retrievals of the NO and NO2 abundances at 90' solar zenith angle. Neglecting to adjust for the rapid variation of these gases across the terminator results in potential errors in retrieved profiles of approximately 20% for NO2 and greater than 100% for NC at altitudes below 25 km. Sensitivity analysis indicates that knowledge of the local 03 and temperature profiles, rather than zonal mean or climatological conditions of these quantities, is required to obtain reliable retrievals of NO and NO2 in the lower stratosphere. Extremely inaccurate 03 or temperature values at 20 km can result in 50% errors in retrieved NO or NO2. Mixing ratios of NO in the mid-latitude, lower stratosphere measured by ATMOS during the November 1994 ATLAS-3 mission compare favorably with in situ ER-2 observations, providing strong corroboration of the reliability of the adjusted space-borne measurements.

  19. [The ATMO index: an air quality indicator for developed areas in France].

    PubMed

    2003-05-01

    The LAURE (5) of 30 december, 1996, sets the preventive, monitoring, reduction or suppression of atmospheric pollution objectives and the goals for preserving air quality. Heading 1--Article 4 of the law states in particular that the right to information on air quality and its impact on the environment is recognised as the right of every person on French territory. The decree of 10 january, 2000, about the air-quality index is derived from this determination to information for all, stated as an important element in the policy for air-quality management. This decree provides definitions of the ATMO index with "standards 2000" and the recommendations required for its calculation. Previously (1992 and before), certain local agencies had developed their own index. Naturally these indices showed sizeable differences. The effort provided by the Ministry of the Environment, ADEME and the monitoring agencies, enabled the definition of a single index for the whole of the large urban areas (> 100,000 inhabitants). The index gives a common language to the non-specialist public, which can now understand the overall air quality in different urban areas. As all aggregate indicators of the same kind, the ATMO index is designed as a tool that makes it possible to translate in a quantitative and simple way the synthesis of numerous measurement data recorded daily by official air-quality monitoring agencies (AASQA). PMID:12838780

  20. ATMOS/ATLAS 3 Infrared Profile Measurements of Clouds in the Tropical and Subtropical Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Wang, P.-H.; Arduini, R. F.; Baum, B. A.; Minnis, P.; Goldman, A.; Abrams, M. C.; Zander, R.; Mahieu, E.; Salawitch, R. J.; Michelsen, H. A.; Irion, F. W.; Newchurch, M. J.

    1998-01-01

    Vertical profiles of infrared cirrus extinction have been derived from tropical and subtropical upper tropospheric solar occultation spectra. The measurements were recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the Atmospheric Laboratory for Applications and Sciences (ATLAS) 3 shuttle flight in November 1994. The presence of large numbers of small ice crystals is inferred from the appearance of broad extinction features in the 8-12 micron region. These features were observed near the tropopause and at lower altitudes. Vertical profiles of the ice extinction (/km) in microwindows at 831, 957, and 1204/cm have been retrieved from the spectra and analyzed with a model for randomly oriented spheroidal ice crystals. An area-equivalent spherical radius of 6 microns is estimated from the smallest ice crystals observed in the 8-12 gm region. Direct penetration of clouds into the lower stratosphere is inferred from observations of cloud extinction extending from the upper troposphere to 50 mbar (20 km altitude). Cloud extinction between 3 and 5 microns shows very little wavelength dependence, at least for the cases observed by the ATMOS instrument in the tropics and subtropics during ATLAS 3.

  1. Atmos/Atlas 3 Infrared Profile Measurements of Clouds in the Tropical and Subtropical Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Wang, P.-H.; Arduini, R. F.; Baum, B. A.; Minnis, P.; Goldman, A.; Abrams, M. C.; Zander, R.; Mahieu, E.; Salawitch, R. J.; Michelsen, H. A.; Irions, F. W.; Newchurch, M. J.

    1998-01-01

    Vertical profiles of infrared cirrus extinction have been derived from tropical and subtropical upper tropospheric solar occultation spectra. The measurements were recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the Atmospheric Laboratory for Applications and Sciences (ATLAS) 3 shuttle flight in November 1994. The presence of large numbers of small ice crystals is inferred from the appearance of broad extinction features in the 8-12 micron region. These features were observed near the tropopause and at lower altitudes. Vertical profiles of the ice extinction (/km) in microwindows at 831, 957, and 1204/cm have been retrieved from the spectra and analyzed with a model for randomly oriented spheroidal ice crystals. An area-equivalent spherical radius of 6 gm is estimated from the smallest ice crystals observed in the 8-12 micron region. Direct penetration of clouds into the lower stratosphere is inferred from observations of cloud extinction extending from the upper troposphere to 50 mbar (20 km altitude). Cloud extinction between 3 and 5 micron shows very little wavelength dependence, at least for the cases observed by the ATMOS instrument in the tropics and subtropics during ATLAS 3.

  2. ChemCam Passive Spectroscopy of the Martian Atmosphere

    NASA Astrophysics Data System (ADS)

    McConnochie, T. H.; Smith, M. D.; Wolff, M. J.; Bender, S. C.; Johnson, J. R.; Wiens, R. C.; Maurice, S.; Gasnault, O.; Barraclough, B. L.; Blaney, D. L.; DeFlores, L.; Team, M.

    2013-12-01

    The design priority of the Laser-Induced Breakdown Spectrometer (LIBS) portion of the ChemCam instrument (Wiens et al. 2012, Space Sci, Rev. 170) on the Mars Science Laboratory (MSL) Curiosity rover is its active mode, which acquires spectra of a laser induced plasma using three spectrometers. However these same spectrometers have excellent sensitivity to ambient light and so are also used independent of the laser in 'passive' mode to acquire spectra of the Martian surface (Johnson et al., 2013, LPSC #1372) and, as we will describe here, the Martian sky. Using ChemCam passive sky observations, we have successfully measured the column abundance of water vapor, molecular oxygen, and carbon dioxide gas, and with further analysis will likely be able to constrain the column abundance of ozone as well as aerosol and cloud particle properties. Although data analysis is ongoing, we currently estimate a 2 sigma precision of < +/- 1 precipitable microns for water vapor, < +/- 30 ppm for molecular oxygen, and < +/- 4 % for carbon dioxide. The three ChemCam spectrometers span 240-342 nm, 382-469 nm, and 474-906 nm, respectively, with a resolution of 0.6 nm FWHM or better. Passive sky observations were obtained on sols 131, 230, and then at regular ~7 sol intervals starting on sol 278. The observation consists of acquiring spectra of light scattered by the atmosphere at two elevation angles so that the ratio of the two resulting radiance spectra yields (after removing the continuum) an extremely precise absorption spectrum with both the solar spectrum and instrument response uncertainties removed. To yield column abundances, the spectra are modeled with a discrete ordinates multiple scattering radiative transfer code that incorporates gas absorption via the correlated-k method.

  3. Science applications of the multi-FOV lidar for ATMOS-B1/ERM

    NASA Astrophysics Data System (ADS)

    Sugimoto, Nobuo; Liu, Zhaoyan; Voelger, Peter; Shimizu, Atsushi; Sasano, Yasuhiro; Asai, Kazuhiro; Ishizu, Mitsuo; Itabe, Toshikasu; Imai, Tadashi

    2001-02-01

    A new multi-FOV space-borne lidar named "A-lidar" is being studied by the National Space Development Agency of Japan (NASDA) for the earth radiation mission proposed as a joint program with the European Space Agency (ESA). The mission is named "EarthCARE". It was formerly called ATMOS-B1 or ERM. The lidar has a two-wavelength transmitter (1064 nm and 532 nm), a dual polarization receiver at 1064 nm, and a multi-field-of-view (multi-FOV) receiver at 532 nm. The multi-FOV feature of A-lidar will enable us to solve the multiple scattering problems with space lidar measurements of profiles of clouds and aerosols. The multi-FOV feature can also be used for characterization of aerosols.

  4. The 1994 northern midlatitude budget of stratospheric chlorine derived from ATMOS/ATLAS-3 observations

    NASA Astrophysics Data System (ADS)

    Zander, R.; Mahieu, E.; Gunson, M. R.; Abrams, M. C.; Chang, A. Y.; Abbas, M.; Aellig, C.; Engel, A.; Goldman, A.; Irion, F. W.; Kämpfer, N.; Michelson, H. A.; Newchurch, M. J.; Rinsland, C. P.; Salawitch, R. J.; Stiller, G. P.; Toon, G. C.

    Volume mixing ratio (VMR) profiles of the chlorine-bearing gases HCl, ClONO2, CCl3F, CCl2F2, CHClF2, CCl4, and CH3Cl have been measured between 3 and 49° northern- and 65 to 72° southern latitudes with the Atmospheric Trace MOlecule Spectroscopy (ATMOS) instrument during the ATmospheric Laboratory for Applications and Science (ATLAS)-3 shuttle mission of 3 to 12 November 1994. A subset of these profiles obtained between 20 and 49°N at sunset, combined with ClO profiles measured by the Millimeter-wave Atmospheric Sounder (MAS) also from aboard ATLAS-3, measurements by balloon for HOCl, CH3CCl3 and C2Cl3F3, and model calculations for COClF indicates that the mean burden of chlorine, ClTOT, was equal to (3.53±0.10) ppbv (parts per billion by volume), 1-sigma, throughout the stratosphere at the time of the ATLAS 3 mission. This is some 37% larger than the mean 2.58 ppbv value measured by ATMOS within the same latitude zone during the Spacelab 3 flight of 29 April to 6 May 1985, consitent with an exponential growth rate of the chlorine loading in the stratosphere equal to 3.3%/yr or a linear increase of 0.10 ppbv/yr over the Spring-1985 to Fall-1994 time period. These findings are in agreement with both the burden and increase of the main anthropogenic Cl-bearing source gases at the surface during the 1980s, confirming that the stratospheric chlorine loading is primarily of anthropogenic origin.

  5. PubChemSR: A search and retrieval tool for PubChem

    PubMed Central

    Hur, Junguk; Wild, David J

    2008-01-01

    Background Recent years have seen an explosion in the amount of publicly available chemical and related biological information. A significant step has been the emergence of PubChem, which contains property information for millions of chemical structures, and acts as a repository of compounds and bioassay screening data for the NIH Roadmap. There is a strong need for tools designed for scientists that permit easy download and use of these data. We present one such tool, PubChemSR. Implementation PubChemSR (Search and Retrieve) is a freely available desktop application written for Windows using Microsoft .NET that is designed to assist scientists in search, retrieval and organization of chemical and biological data from the PubChem database. It employs SOAP web services made available by NCBI for extraction of information from PubChem. Results and Discussion The program supports a wide range of searching techniques, including queries based on assay or compound keywords and chemical substructures. Results can be examined individually or downloaded and exported in batch for use in other programs such as Microsoft Excel. We believe that PubChemSR makes it straightforward for researchers to utilize the chemical, biological and screening data available in PubChem. We present several examples of how it can be used. PMID:18482452

  6. Chem 13 News: A Valuable Resource

    NASA Astrophysics Data System (ADS)

    Thorsen, Kathy

    2002-02-01

    This column provides a brief description of material pertinent to high school chemistry teaching appearing in Chem 13 News, a periodical published by the University of Waterloo in Canada. Featured articles, demonstrations, laboratory experiences, and special features from the January through May 2001 issues are discussed.

  7. "CHEM"opera for Chemistry Education

    ERIC Educational Resources Information Center

    Chung, Yong Hee

    2013-01-01

    "CHEM"opera is an opera blended with demonstrations of chemical reactions. It has been produced and performed twice by chemistry undergraduate students at Hallym University in South Korea. It aims to demonstrate interesting chemical reactions to chemistry students, children and the public and to facilitate their understanding of the role…

  8. A History of ChemMatters Magazine

    ERIC Educational Resources Information Center

    Tinnesand, Michael J.

    2007-01-01

    ChemMatters, the chemistry magazine published since 1983, has always provided interesting topics for chemistry students. The American Chemical Society publishes the magazine and many well-known authors like Isaac Asimov, Glen Seaborg and Derek Davenport have contributed to the magazine and the magazine has succeeded in its goal of demystifying…

  9. The Best of Chem 13 News

    NASA Astrophysics Data System (ADS)

    Thorsen, Kathy

    1999-07-01

    This column is designed to give JCE readers a few highlights from Chem 13 News, a monthly publication for chemistry educators from the University of Waterloo in Ontario, Canada, and provides annotations describing a particular activity or a variety of sources from which new and creative ideas can be extracted.

  10. PubChem promiscuity: a web resource for gathering compound promiscuity data from PubChem

    PubMed Central

    Canny, Stephanie A.; Cruz, Yasel; Southern, Mark R.; Griffin, Patrick R.

    2012-01-01

    Summary: Promiscuity counts allow for a better understanding of a compound's assay activity profile and drug potential. Although PubChem contains a vast amount of compound and assay data, it currently does not have a convenient or efficient method to obtain in-depth promiscuity counts for compounds. PubChem promiscuity fills this gap. It is a Java servlet that uses NCBI Entrez (eUtils) web services to interact with PubChem and provide promiscuity counts in a variety of categories along with compound descriptors, including PAINS-based functional group detection. Availability: http://chemutils.florida.scripps.edu/pcpromiscuity Contact: southern@scripps.edu PMID:22084255

  11. ChemCam Targeted Science at Gale Crater

    NASA Astrophysics Data System (ADS)

    Wiens, R. C.; Blaney, D. L.; Clark, B. C.; Bridges, N. T.; Clegg, S. M.; Maurice, S.; Newsom, H. E.; Vaniman, D. T.; Herkenhoff, K. E.; Ollila, A. M.; Gasnault, O.; Pinet, P. C.; Dromart, G.; Barraclough, B. L.; Lasue, J.

    2011-12-01

    The MSL rover, Curiosity, uses a novel remote-sensing instrument, ChemCam, which combines laser-induced breakdown spectroscopy (LIBS) with a high resolution remote micro-imager (RMI). ChemCam uses a focused, pulsed laser beam at targets up to 7 m away to excite a light-emitting plasma. Spectral analysis identifies elements present and provides rapid semi-quantitative analyses. Repeated laser pulses remove dust and weathering coatings from rock samples to depths >0.5 mm and ~0.4 mm in diameter. The RMI, with ~20x20 mrad field of view, provides a broad-band image with 100 μm resolution. LIBS yields abundances of H, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, Cl, K, Ca, Ti, V, Cr, Fe, Ni, Zr, Rb, Sr, As, Ba, and Pb. Interference from atmospheric constituents raises the detection limits of C, N, and O (e.g., >2% wt for C). LIBS is very sensitive to alkali and alkali earth elements, with some detection limits to ~1 ppm at close range. Conversely, LIBS is insensitive to F, Cl, S, P, and N, with detection limits of several wt. %. Pointing accuracy is ~3 mrad, however relative pointing accuracy is better, so line scans and rasters will enable analyses of targeted features to ~1 mm. At Gale Crater, determination of elements not previously analyzed in-situ, i.e., H, Li, Rb, Sr, and Ba, along with other elements will constrain aqueous, hydrothermal and vapor geochemical transport processes. Initial analyses after landing will characterize air fall dust and weathering coatings on local rocks, and profile the soil and surfacial materials including bedforms to investigate compositional differences in near-surface layers. Targets within the landing ellipse include fan and inverted channel deposits derived from the crater rim, which may contain alteration minerals produced by impact hydrothermal processes. Enigmatic deposits with bright fracture fill could represent lake sediments modified by injection of deposits from groundwater. During the drive to the Gale mound, ChemCam will

  12. ChemMatCARS Data Archive

    DOE Data Explorer

    ChemMatCARS is a high-brilliance national synchrotron x-ray facility dedicated primarily to static and dynamic condensed matter chemistry and materials science. The scientific focus of the facility includes the study of surface and interfacial properties of liquids and solids as well as their bulk structure at atomic, molecular and mesoscopic length scales with high spatial and energy resolution. Experimental techniques supported by the facility include: 1) Liquid Surface X-ray Scattering; 2) Solid Surface X-ray Scattering; 3) Time-Resolved Crystallography; 4) Micro-Crystal Diffraction; 5) Small and Wide-angle X-ray Scattering. The data archive referenced here contains data for various components along the beamline within the First Optics Enclosure and is intended to be input or parameter data. See the Science Nuggets at http://cars9.uchicago.edu/chemmat/pages/nuggets.html for leads to some of the research conducted at the ChemMatCARS beamline.

  13. ChemDoodle 6.0.

    PubMed

    Todsen, William L

    2014-08-25

    ChemDoodle 6.0 is an advanced software suite for drawing chemical structure diagrams. The program's capabilities extend far beyond mere structures, however, including the ability to calculate NMR spectra, generate IUPAC names and line notations for structures, manipulate structures imported from the Internet, interpret and interconvert files generated by other chemical drawing software programs, illustrate glassware and equipment setups, and draw TLC plates. This latest version supports full round-trip editing, so that structures produced with the program can be used in standard office software and reimported into ChemDoodle if modifications are needed. These features and more are included in the basic package, which is very affordable. PMID:25072815

  14. Building the EarthChem System for Advanced Data Management in Igneous Geochemistry

    NASA Astrophysics Data System (ADS)

    Lehnert, K.; Walker, J. D.; Carlson, R. W.; Hofmann, A. W.; Sarbas, B.

    2004-12-01

    Several mature databases of geochemical analyses for igneous rocks are now available over the Internet. The existence of these databases has revolutionized access to data for researchers and students allowing them to extract data sets customized to their specific problem from global data compilations with their desktop computer within a few minutes. Three of the database efforts - PetDB, GEOROC, and NAVDAT - have initiated a collaborative effort called EarthChem to create better and more advanced and integrated data management for igneous geochemistry. The EarthChem web site (http://www.earthchem.org/) serves as a portal to the three databases and information related to EarthChem activities. EarthChem participants agreed to establish a dialog to minimize duplication of effort and share useful tools and approaches. To initiate this dialog, a workshop was run by EarthChem in October, 2003 to discuss cyberinfrastructure needs in igneous geochemistry (workshop report available at the EarthChem site). EarthChem ran an information booth with database and visualization demonstrations at the Fall 2003 AGU meeting (and will have one in 2004) and participated in the May 2003 GERM meeting in Lyon, France where we provided the newly established Publishers' Round Table a list of minimum standards of data reporting to ease the assimilation of data into the databases. Aspects of these suggestions already have been incorporated into new data policies at Geochimica et Cosmochimica Acta and Chemical Geology (Goldstein et al. 2004), and are under study by the Geological Society of America. EarthChem presented its objectives and activities to the Solid Earth Sciences community at the Annual GSA Meeting 2003 (Lehnert et al, 2003). Future plans for EarthChem include expanding the types and amounts of data available from a single portal, giving researchers, faculty, students, and the general public the ability to search, visualize, and download geochemical and geochronological data for a

  15. A Comparison of Ozone Measurements Made by the ATMOS, MAS, and SSBUV Instruments During ATLAS 1,2, and 3

    NASA Technical Reports Server (NTRS)

    Kriebel, D. L.; Bevilacqua, R. M.; Hilsenrath, E.; Gunson, M.; Hartmann, G. K.; Abrams, M.; Daehler, M.; Pauls, T. A.; Newchurch, M.; Aellig, C. P.; Bories, M. C.

    1996-01-01

    Ozone profile measurements were made by three instruments, ATMOS, MAS, and SSBUV, using distinctly different observing techniques, as part of the ATLAS Space Shuttle missions in March 1992, April 1993, and November 1994. ATMOS makes solar-occultation observations of infrared spectra using a Fourier transform interferometer. MAS uses a limb-scanning antenna to measure emission spectra at millimeter wavelengths. SSBUV is a nadir-viewing instrument measuring the transmission of scattered solar ultraviolet radiation modified by ozone absorption. A sample of zonal-mean mixing ratio profiles indicates that these three ATLAS instruments generally agree to within 10%, although a few potential biases have been noted. There are significant differences in the character of the agreement between ATLAS 1 and ATLAS 2 which will require further study.

  16. ChemCam Science Objectives for the Mars Science Laboratory (MSL) Rover

    NASA Technical Reports Server (NTRS)

    Wiens, R.; Maurice, S.; Bridges, N.; Clark, B.; Cremers, D.; Herkenhoff, K.; Kirkland, L.; Mangold, N.; Manhes, G.; Mauchien, P.

    2005-01-01

    ChemCam consists of two remote sensing instruments. One, a Laser-Induced Breakdown Spectroscopy (LIBS) instrument provides rapid elemental composition data on rocks and soils within 13 m of the rover. By using laser pulses, it can remove dust or profile through weathering layers remotely. The other instrument, the Remote Micro-Imager (RMI), provides the highest resolution images between 2 m and infinity. At approximately 80 Rad field of view, its resolution exceeds that of MER Pancam by at least a factor of four. The ChemCam instruments are described in a companion paper by Maurice et al. [1]. Here we present the science objectives for the ChemCam instrument package.

  17. ChemCam Science Objectives for the Mars Science Laboratory (MSL) Rover

    NASA Technical Reports Server (NTRS)

    Wiens, R.; Maurice, S.; Bridges, N.; Clark, B.; Cremers, D.; Herkenhoff, K.; Kirkland, L.; Mangold, N.; Manhes, G.; Mauchien, P.

    2005-01-01

    ChemCam consists of two remote sensing instruments. One, a Laser-Induced Breakdown Spectroscopy (LIBS) instrument provides rapid elemental composition data on rocks and soils within 13 m of the rover. By using laser pulses, it can remove dust or profile through weathering layers remotely. The other instrument, the Remote Micro-Imager (RMI), provides the highest resolution images between 2 m and infinity. At approximately 80 Rad field of view, its resolution exceeds that of MER Pancam by at least a factor of four. The ChemCam instruments are described in a companion paper by Maurice et al. Here we present the science objectives for the ChemCam instrument package.

  18. The Best of Chem 13 News

    NASA Astrophysics Data System (ADS)

    Thorsen, Kathy

    1998-11-01

    This column is designed to give JCE readers highlights from Chem 13 News, a monthly publication from the University of Waterloo (Ontario, Canada) for chemistry educators. I have selected a variety of articles appearing from January through May 1998 that captured my interest as a chemistry teacher. I would like to share them with others. The following paragraphs provide references to innovative ways of introducing students to general chemistry concepts and engaging them in experimental design. Through these methods they begin to develop a better understanding of concepts discussed in class.

  19. ConfChem Conference on Flipped Classroom: Spring 2014 ConfChem Virtual Poster Session

    ERIC Educational Resources Information Center

    Belford, Robert E.; Stoltzfus, Matthew; Houseknecht, Justin B.

    2015-01-01

    This communication describes the virtual poster session of the Flipped Classroom online ConfChem conference that was hosted by the ACS CHED Committee on Computers in Chemical Education (CCCE) from May 9 to June 12, 2014. During the conference's online discussions, it became evident that multiple participants who were not presenting papers had been…

  20. Chem-2-Chem: A One-to-One Supportive Learning Environment for Chemistry

    NASA Astrophysics Data System (ADS)

    Báez-Galib, Rosita; Colón-Cruz, Héctor; Resto, Wilfredo; Rubin, Michael R.

    2005-12-01

    The Chem-2-Chem (C2C) tutoring mentoring program was developed at the University of Puerto Rico at Cayey, an undergraduate institution serving Hispanic students, to increase student retention and help students achieve successful general chemistry course outcomes. This program provides a supportive learning environment designed to address students' academic and emotional needs in a holistic way. Advanced chemistry students offered peer-led, personalized, and individualized learning experiences through tutoring and mentoring to approximately 21% of students enrolled in the general chemistry course. Final grades from official class lists of all general chemistry course sections were analyzed using Student's t -test, paired t -test, and χ 2 analysis. Results during the seven semesters studied show an increase of 29% in successful course outcomes defined as final letter grades of A, B, and C obtained by Chem-2-Chem participants. For each final grade, highly statistically significant differences between participants and nonparticipants were detected. There were also statistically significant differences between successful course outcomes obtained by participants and nonparticipants for each of the semesters studied. This research supports recent trends in chemical education to provide a social context for learning experiences. This peer-led learning strategy can serve as an effective model to achieve excellence in science courses at a wide range of educational institutions.

  1. Using ChemBank to probe chemical biology.

    PubMed

    Petri Seiler, Kathleen; Kuehn, Heidi; Pat Happ, Mary; Decaprio, Dave; Clemons, Paul A

    2008-06-01

    ChemBank (http://chembank.broad.harvard.edu/) is a public, Web-based informatics environment. ChemBank stores and makes freely available data derived from small molecules and small-molecule screens and has resources for relating and studying these data. Currently, ChemBank stores information on hundreds of thousands of small molecules and hundreds of biomedically relevant assays performed at the Broad Institute screening center. Web-based analysis tools are available within ChemBank to study the relationships between small molecules, cell measurements, and cell states. This unit demonstrates the use of ChemBank data to ask and answer questions relating to chemical biology and screening experiments contained within ChemBank. PMID:18551413

  2. LANL Researcher Roger Wiens Discusses ChemCam

    ScienceCinema

    Wiens, Roger

    2014-08-12

    Discussion of the ChemCam instrument on the Curiosity Rover that occurred during the NASA press conference prior to launch of the Mars Science Laboratory. The ChemCam instrument was developed by Los Alamos National Laboratory and the French Space Institute. Los Alamos National Laboratory researcher Roger Wiens discusses the instrument on this video. ChemCam uses a laser to "zap" features of the Martian landscape and then uses a spectrometer to gather information about the composition of the sample. ChemCam will help the Curiosity Rover determine whether Mars is or was habitable. The Rover is expected to touch down on the Red Planet on August 5, 2012.

  3. LANL Researcher Roger Wiens Discusses ChemCam

    SciTech Connect

    Wiens, Roger

    2012-02-15

    Discussion of the ChemCam instrument on the Curiosity Rover that occurred during the NASA press conference prior to launch of the Mars Science Laboratory. The ChemCam instrument was developed by Los Alamos National Laboratory and the French Space Institute. Los Alamos National Laboratory researcher Roger Wiens discusses the instrument on this video. ChemCam uses a laser to "zap" features of the Martian landscape and then uses a spectrometer to gather information about the composition of the sample. ChemCam will help the Curiosity Rover determine whether Mars is or was habitable. The Rover is expected to touch down on the Red Planet on August 5, 2012.

  4. Pressure Sounding of the Middle Atmosphere from ATMOS Solar Occultation Measurements of Atmospheric CO(sub 2) Absorption Lines

    NASA Technical Reports Server (NTRS)

    Abrams, M.; Gunson, M.; Lowes, L.; Rinsland, C.; Zander, R.

    1994-01-01

    A method for retrieving the atmospheric pressure corresponding to the tangent point of an infrared spectrum recorded in the solar occultation mode is described and applied to measurements made by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer. Tangent pressure values are inferred from measurements of isolated CO(sub 2) lines with temperature-insensitive intensities. Tangent pressures are determined with a spectroscopic precision of 1-3%, corresponding to a tangent point height precision, depending on the scale height, of 70-210 meters.

  5. NARSTO EPA SS ST LOUIS AIR CHEM PM MET DATA

    Atmospheric Science Data Center

    2014-05-07

    NARSTO EPA SS ST LOUIS AIR CHEM PM MET DATA Project Title:  NARSTO ... Amount Surface Pressure Solar Radiation Surface Air Temperature Particulates Trace Metals Order Data:  ... Data Guide Documents:  St Louis Air Chem Guide St Louis Final Report  (PDF) St Louis QA ...

  6. NARSTO EPA SS NEW YORK AIR CHEM PM MET DATA

    Atmospheric Science Data Center

    2014-04-25

    NARSTO EPA SS NEW YORK AIR CHEM PM MET DATA Project Title:  NARSTO ... Thermooptical Transmission Location:  New York Spatial Resolution:  Point Measurements ...   Order Data Guide Documents:  New York Air Chem Guide CPM Summary Report  (PDF) ...

  7. ChemOkey: A Game to Reinforce Nomenclature

    ERIC Educational Resources Information Center

    Kavak, Nusret

    2012-01-01

    Learning the symbolic language of chemistry is a difficult task that can be frustrating for students. This article introduces a game, ChemOkey, that can help students learn the names and symbols of common ions and their compounds in a fun environment. ChemOkey, a game similar to Rummikub, is played with a set of 106 plastic or wooden tiles. The…

  8. Engineering Analysis in the Chem-E-Car Competition

    ERIC Educational Resources Information Center

    Lewis, Randy S.; Moshfeghian, Aliakbar; Madihally, Sundararajan V.

    2006-01-01

    The AIChE Chem-E-Car competition provides students an opportunity to demonstrate their design and teamwork skills. Engineering analysis is not required at the national competition and is often not applied. This work describes an engineering analysis of a Chem-E-Car to predict the distance traveled by the car. Engineering analysis is advantageous…

  9. High Excitation Rydberg Levels of Fe I from the ATMOS Solar Spectrum at 2.5 and 7 microns

    NASA Technical Reports Server (NTRS)

    Schoenfeld, W. G.; Chang, E. S.; Geller, M.; Johansson, S.; Nave, G.; Sauval, A. J.; Grevesse, N.

    1995-01-01

    The quadrupole-polarization theory has been applied to the 3d(sup 6)4S(D-6)4f and 5g subconfigurations of Fe I by a parametric fit, and the fitted parameters are used to predict levels in the 6g and 6h subconfigurations. Using the predicted values, we have computed the 4f-6g and 5g-6h transition arrays and made identifications in the ATMOS infrared solar spectrum. The newly identified 6g and 6h levels, based on ATMOS wavenumbers, are combined with the 5g levels and found to agree with the theoretical values with a root mean-squared-deviation of 0.042/ cm. Our approach yields a polarizability of 28.07 a(sub o, sup 2) and a quadrupole moment of 0.4360 +/- 0.0010 ea(sup 2, sub o) for Fe II, as well as an improved ionization potential of 63737.700 +/- 0.010/ cm for Fe I.

  10. ATMOS/ATLAS-3 Observations of Long-Lived Tracers and Descent in the Antarctic Vortex in November 1994

    NASA Technical Reports Server (NTRS)

    Abrams, M. C.; Manney, G. L.; Gunson, M. R.; Abbas, M. M.; Chang, A. Y.; Goldman, A.; Irion, F. W.; Michelsen, H. A.; Newchurch, M. J.; Rinsland, C. P.; Salawitch, R. J.; Stiller, G. P.; Zander, R.

    1996-01-01

    Observations of the long-lived tracers N2O, CH4 and HF obtained by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument in early November 1994 are used to estimate average descent rates during winter in the Antarctic polar vortex of 0.5 to 1.5 km/month in the lower stratosphere, and 2.5 to 3.5 km/month in the middle and upper stratosphere. Descent rates inferred from ATMOS tracer observations agree well with theoretical estimates obtained using radiative heating calculations. Air of mesospheric origin (N2O less than 5 ppbV) was observed at altitudes above about 25 km within the vortex. Strong horizontal gradients of tracer mixing ratios, the presence of mesospheric air in the vortex in early spring, and the variation with altitude of inferred descent rates indicate that the Antarctic vortex is highly isolated from midlatitudes throughout the winter from approximately 20 km to the stratopause. The 1994 Antarctic vortex remained well isolated between 20 and 30 km through at least mid-November.

  11. ATMOS/ATLAS 1 measurements of sulfur hexafluoride (SF6) in the lower stratosphere and upper troposphere

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Abrams, M. C.; Lowes, L. L.; Zander, R.; Mahieu, E.

    1993-01-01

    Vertical profiles of sulfur hexafluoride (SF6) in the lower stratosphere and upper troposphere have been retrieved from 0.01/cm resolution infrared solar occultation spectra recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS (Atmospheric Laboratory for Applications and Science) 1 shuttle mission of March 24 to April 2, 1992. Based on measurements of the unresolved absorption by the SF6 mu(sub 3) band Q branch at 947.9/cm, average SF6 volume mixing ratios and 1-sigma uncertainties of 3.20 +/- 0.54 parts per trillion by volume (pptv; 10(exp -12) ppv) at 200 mbar (approximately 11.8 km) declining to 2.86 +/- 0.29 pptv at 100 mbar (approximately 16.2 km) and 1.95 +/- 0.50 pptv at 30 mbar (approximately 23.9 km) have been retrieved. The profiles show no obvious dependence with latitude over the range of the measurements (eight occultations spanning 28 deg S to 54 deg S). Assuming an exponential growth model and applying a correction for the interhemispheric concentration difference, an average SF6 rate of increase of 8.7 +/- 2.2% per year, 2 sigma, between 12 and 18 km has been derived by fitting the present measurements, ATMOS measurements from the April-May 1985 Spacelab 3 mission, and balloon-borne IR measurements obtained in March 1981 and June 1988.

  12. Chem-nuclear's midwest volume reduction facility

    SciTech Connect

    Loiselle, V.

    1987-01-01

    The 1985 amendments to the Low-Level Waste Policy Act mandated volume allocation limits for nuclear utilities over a 7-yr period ending December 31, 1992. Under the provisions of the act, nonsited regions of the US, such as the Midwest, have received more stringent volume limitations than the sited regions. Restrictions, however severe, are causing all nuclear utilities to carefully examine the source and volume generation of low-level wastes at their respective plants. Nuclear utilities dry active wastes (DAW), as compared to wet wastes, amount to 50 to 75% of wastes generated. The progress in reducing DAW can now be achieved with volume reduction by supercompaction. Chem-Nuclear established and licensed its Midwest Volume Reduction Facility (MWVRF) to provide an integrated volume reduction service. Although compaction of DAW is not new, supercompaction is. Through millions of pounds-force (as compared to tens of thousands pounds-force currently available from conventional equipment) much greater volume reduction can be achieved. The results of supercompaction is a product that approaches the theoretical density of its solid constituents - a logical and ultimate end point for compaction capability and volume reduction overall. The reduction service, equipment, and the facility interfacing with other services of transportation and disposal and the generator are discussed in detail. As a result of the integrated service, significant savings in waste management and volume allocation can be achieved.

  13. One year of chemical diversity seen by ChemCam at Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Gasnault, Olivier; Wiens, Roger; Maurice, Sylvestre; Meslin, Pierre-Yves; Forni, Olivier; Leveillé, Richard; Bridges, Nathan; Lasue, Jérémie; Le Mouélic, Stéphane; Mangold, Nicolas; Sautter, Violaine

    2014-05-01

    evidences are provided by the discovery with ChemCam of three rocks with Mn-enriched coatings [11]. There are also some indications through the measurement of lithium abundance for a low level aqueous alteration pulling the alkalis out to the surface [12]. The influx of subsurface water must have been limited though otherwise the Li concentration in the soils should be higher than what ChemCam measured (first detection on Mars [12]). References: [1] Meslin et al. (2013) Science, 341, doi:10.1126/science.1238670 ; [2] Schröder et al. (2013) Europ. Planet. Sci. Congress, 120 ; [3] Cousin et al. (2014) Lunar Planet. Conf., 1278; [4] Sautter et al. (2014) J. Geophys. Res., doi:10.1002/2013JE004472; [5] Grotzinger et al. (2013) Science, doi:10.1126/science.1242777; [6] McLennan et al. (2013) Science, doi:10.1126/science.1244734; [7] Vaniman et al. (2013) Science, doi:10.1126/science.1243480; [8] Siebach et al. (2013) Am. Geophys. Union Assembly, P13D-07; [9] Leveillé et al. (2013) Am. Geophys. Union Assembly, P13D-08; [10] Nachon et al. (2014) Lunar Planet. Conf.; [11] Lanza et al. (2014) Lunar Planet. Conf.; [12] Ollila et al. (2013) J. Geophys. Res., doi:10.1002/2013JE004517.

  14. Comment on "Replica-exchange-with-tunneling for fast exploration of protein landscapes" [J. Chem. Phys. 143, 224102 (2015)

    NASA Astrophysics Data System (ADS)

    Sakuraba, Shun

    2016-08-01

    In "Replica-exchange-with-tunneling for fast exploration of protein landscapes" [F. Yaşar et al., J. Chem. Phys. 143, 224102 (2015)], a novel sampling algorithm called "Replica Exchange with Tunneling" was proposed. However, due to its violation of the detailed balance, the algorithm fails to sample from the correct canonical ensemble.

  15. Concentrations of carbonyl sulfide and hydrogen cyanide in the free upper troposphere and lower stratosphere deduced from ATMOS/Spacelab 3 infrared solar occultation spectra

    NASA Technical Reports Server (NTRS)

    Zander, R.; Rinsland, C. P.; Russell, J. M., III; Farmer, C. B.; Norton, R. H.

    1988-01-01

    This paper presents the results on the volume mixing ratio profiles of carbonyl sulfide and hydrogen cyanide, deduced from the spectroscopic analysis of IR solar absorption spectra obtained in the occultation mode with the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during its mission aboard Spacelab 3. A comparison of the ATMOS measurements for both northern and southern latitudes with previous field investigations at low midlatitudes shows a relatively good agreement. Southern Hemisphere volume mixing ratio profiles for both molecules were obtained for the first time, as were the profiles for the Northern Hemisphere covering the upper troposphere and the lower stratosphere simultaneously.

  16. RESRAD-CHEM: A computer code for chemical risk assessment

    SciTech Connect

    Cheng, J.J.; Yu, C.; Hartmann, H.M.; Jones, L.G.; Biwer, B.M.; Dovel, E.S.

    1993-10-01

    RESRAD-CHEM is a computer code developed at Argonne National Laboratory for the U.S. Department of Energy to evaluate chemically contaminated sites. The code is designed to predict human health risks from multipathway exposure to hazardous chemicals and to derive cleanup criteria for chemically contaminated soils. The method used in RESRAD-CHEM is based on the pathway analysis method in the RESRAD code and follows the U.S. Environmental Protection Agency`s (EPA`s) guidance on chemical risk assessment. RESRAD-CHEM can be used to evaluate a chemically contaminated site and, in conjunction with the use of the RESRAD code, a mixed waste site.

  17. Comment on ``The application of the thermodynamic perturbation theory to study the hydrophobic hydration'' [J. Chem. Phys. 139, 024101 (2013)

    NASA Astrophysics Data System (ADS)

    Graziano, Giuseppe

    2013-09-01

    It is shown that the behaviour of the hydration thermodynamic functions obtained in the 3D Mercedes-Benz model of water by Mohoric et al. [J. Chem. Phys. 139, 024101 (2013)] is not qualitatively correct with respect to experimental data for a solute whose diameter is 1.5-fold larger than that of a water molecule. It is also pointed out that the failure is due to the fact that the used 3D Mercedes-Benz model of water [A. Bizjak, T. Urbic, V. Vlachy, and K. A. Dill, J. Chem. Phys. 131, 194504 (2009)] does not reproduce in a quantitatively correct manner the peculiar temperature dependence of water density.

  18. First flight of the ATMOS instrument during the Spacelab 3 Mission, April 29 through May 6, 1985

    NASA Technical Reports Server (NTRS)

    Farmer, Crofton B.; Raper, Odell F.; Ocallaghan, Fred G.

    1987-01-01

    The underlying rationale and the implementation of the Atmospheric Trace Molecule Spectroscopy (ATMOS) investigation are discussed, a description of the sensor is given, and the ground tests and integration procedures leading to the Spacelab 3 flight are described. The data reduction and analysis procedures used after the flight are discussed, a number of examples of the spectra obtained are shown, and the concentration profiles as a function of altitude for the minor and trace gases measured during the mission are presented. On the basis of the instrument's ability to survive both the launch and the reentry of the shuttle and its flawless performance while on orbit, the concepts involved in the investigation have been proved by the Spacelab 3 flight, and an extended series of reflights is currently being planned as a part of the Atmospheric Laboratory for Applications and Science (ATLAS) Missions. The goals for the investigation during these missions are also discussed.

  19. Comparing UCLALES-SALSA and WRF-Chem LES

    NASA Astrophysics Data System (ADS)

    Tonttila, Juha; Dunne, Eimear; Ahola, Jaakko; Korhonen, Hannele; Kokkola, Harri; Romakkaniemi, Sami

    2016-04-01

    The new UCLALES-SALSA model, which uses a sectional representation of aerosols and cloud droplets, is compared against the LES configuration of the established WRF-Chem model. Two configurations of WRF-Chem are compared: the first using the sectional MOSAIC aerosol representation, and the second using the modal MADE/SORGAM representation. Both sets of WRF-Chem simulations use the two-moment Morrisson bulk cloud scheme. Wherever possible, the three sets of simulations have identical processes and initial conditions. By comparing UCLALES-SALSA against an established model in an ideal scenario, we demonstrate that the new model provides a realistic representation of warm cloud processes. The two configurations of WRF-Chem make it possible (to an extent) to isolate whether differences in model outputs are due to meteorological or microphysical effects.

  20. PubChem BioAssay: 2014 update.

    PubMed

    Wang, Yanli; Suzek, Tugba; Zhang, Jian; Wang, Jiyao; He, Siqian; Cheng, Tiejun; Shoemaker, Benjamin A; Gindulyte, Asta; Bryant, Stephen H

    2014-01-01

    PubChem's BioAssay database (http://pubchem.ncbi.nlm.nih.gov) is a public repository for archiving biological tests of small molecules generated through high-throughput screening experiments, medicinal chemistry studies, chemical biology research and drug discovery programs. In addition, the BioAssay database contains data from high-throughput RNA interference screening aimed at identifying critical genes responsible for a biological process or disease condition. The mission of PubChem is to serve the community by providing free and easy access to all deposited data. To this end, PubChem BioAssay is integrated into the National Center for Biotechnology Information retrieval system, making them searchable by Entrez queries and cross-linked to other biomedical information archived at National Center for Biotechnology Information. Moreover, PubChem BioAssay provides web-based and programmatic tools allowing users to search, access and analyze bioassay test results and metadata. In this work, we provide an update for the PubChem BioAssay resource, such as information content growth, new developments supporting data integration and search, and the recently deployed PubChem Upload to streamline chemical structure and bioassay submissions. PMID:24198245

  1. Chemerin-ChemR23 Signaling in Tooth Development

    PubMed Central

    Ohira, T.; Spear, D.; Azimi, N.; Andreeva, V.; Yelick, P.C.

    2012-01-01

    Our long-term goal is to identify and characterize molecular mechanisms regulating tooth development, including those mediating the critical dental epithelial-dental mesenchymal (DE-DM) cell interactions required for normal tooth development. The goal of this study was to investigate Chemerin (Rarres2)/ChemR23(Cmklr1) signaling in DE-DM cell interactions in normal tooth development. Here we present, for the first time, tissue-specific expression patterns of Chemerin and ChemR23 in mouse tooth development. We show that Chemerin is expressed in cultured DE progenitor cells, while ChemR23 is expressed in cultured DM cells. Moreover, we demonstrate that ribosomal protein S6 (rS6) and Akt, downstream targets of Chemerin/ChemR23 signaling, are phosphorylated in response to Chemerin/ChemR23 signaling in vitro and are expressed in mouse tooth development. Together, these results suggest roles for Chemerin/ChemR23-mediated DE-DM cell signaling during tooth morphogenesis. PMID:23053848

  2. ChromPlot for MicroChemLab

    2001-12-19

    The software entitled "ChromPlot for MicroChemLab" is used to collect, display, and save data from the Sandia National Laboratories chemical analysis system dubbed MicroChemLab. Sensor data is streamed from a MicroChemLab unit into a computer thru RS-232 in a manner that is not amenable to plotting. Also, there is no direct way to start and stop the unit as is. This software rearranges the data into something that can be easily plotted in real-time thenmore » save the data into a text file. In addition, this software provides the users a means to start and stop the hardware. This software was written specifically for MicroChemLab. MicroChemLab data is delivered at 6- 7 pts/sec/channel in a two-channel system for 1-2 min. This code is written around that premise. It is written for Pentium or higher machines running Windows 9x/Me/NT/2000/XP. This software was not developed under the BMS CRADA; it is software we use in the lab for our own testing. Bristol Meyers Squibb (BMS) will use this software for testing an online process monitor based on MicroChemLab. They have not indicated their interest in marketing our device or the software.« less

  3. Synthetic high-resolution near-IR spectra of the Sun for planetary data reductions made from ATMOS/Spacelab-3 and Atlas-3 data

    NASA Astrophysics Data System (ADS)

    Seo, Haingja; Kim, Sang J.; Hwang, Sungwon; Jung, Aeran; Kim, Ji Hyun; Kim, Joo Hyeon; Kim, Kap-Sung; Lee, Jinny; Jang, Minhwan

    2007-12-01

    We have constructed synthetic solar spectra for the 2302-4800 cm -1 (2.08-4.34 μm) range, a spectral range where planetary objects mainly emit reflected sunlight, using ATMOS (Atmospheric Trace Molecule Spectroscopy)/Spacelab-3 and Atlas-3 spectra, of which resolution is 0.01 cm -1. We adopted Voigt line profiles for the modeling of line shapes based on an atlas of line identifications compiled by Geller [Geller, M., 1992. Key to Identification of Solar Features. A High-Resolution Atlas of the Infrared Spectrum of the Sun and the Earth Atmosphere from Space. NASA Reference Publ. 1224, vol. III. NASA, Washington, DC, pp. 1-22], who derived solar line positions and intensities from contaminated high-resolution solar spectra obtained by ATMOS/Spacelab-3. Because the ATMOS spectra in these wavelength ranges are compromised by absorption lines of molecules existing in Earth's high-altitude atmosphere and in the compartment of the spacecraft, the direct use of these high-resolution solar spectra has been inconvenient for the data reductions of planetary spectra. We compared the synthetic solar spectra with the ATMOS spectra, and obtained satisfactory fits for the majority of the solar lines with the exception of abnormal lines, which do not fit with Voigt line profiles. From the model fits, we were able to determine Voigt line parameters for the majority of solar lines; and we made a list of the abnormal lines. We also constructed telluric-line-free solar spectra by manually eliminating telluric lines from the ATMOS spectra and filling the gaps with adjacent continua. These synthetic solar spectra will be useful to eliminate solar continua from spectra of planetary objects to extract their own intrinsic spectral features.

  4. AEGIS Automated Targeting for the MSL ChemCam Instrument

    NASA Astrophysics Data System (ADS)

    Estlin, T.; Anderson, R. C.; Blaney, D. L.; Bornstein, B.; Burl, M. C.; Castano, R.; Gaines, D.; Judd, M.; Thompson, D. R.; Wiens, R. C.

    2013-12-01

    The Autonomous Exploration for Gathering Increased Science (AEGIS) system enables automated science data collection by a planetary rover. AEGIS has been in use on the Mars Exploration Rover (MER) mission Opportunity rover since 2010 to provide onboard targeting of the MER Panoramic Camera based on scientist-specified objectives. AEGIS is now being applied for use with the Mars Science Laboratory (MSL) mission ChemCam spectrometer. ChemCam uses a Laser Induced Breakdown Spectrometer (LIBS) to analyze the elemental composition of rocks and soil from up to seven meters away. ChemCam's tightly-focused laser beam (350-550 um) enables targeting of very fine-scale terrain features. AEGIS is being applied in two ways to help ChemCam collect valuable science data. The first application is to enable automated targeting of ChemCam during or after or in the middle of long drives. The majority of ChemCam measurements are collected by allowing the science team to select specific targets in rover images. However this requires the rover to stay in the same area while images are downlinked, analyzed for targets, and new commands uplinked. The only data that can be acquired without this communication cycle is via blind targeting, where measurements are often of soil patches vs. instead of more valuable targets such as rocks with specific properties. AEGIS is being applied to automatically analyze images onboard and select targets for ChemCam analysis. This approach allows the rover to autonomously select and sequence targeted measurements in an opportunistic fashion at different points along the rover's drive path. Rock targets can be prioritized for measurement based on various geologically relevant features, including size, shape and albedo. A second application is to enable intelligent pointing refinement of ChemCam when acquiring data of small targets, such as veins or concretions that are only a few millimeters wide. Due to backlash and other pointing challenges, it can often

  5. PubChem BioAssay: 2014 update

    PubMed Central

    Wang, Yanli; Suzek, Tugba; Zhang, Jian; Wang, Jiyao; He, Siqian; Cheng, Tiejun; Shoemaker, Benjamin A.; Gindulyte, Asta; Bryant, Stephen H.

    2014-01-01

    PubChem’s BioAssay database (http://pubchem.ncbi.nlm.nih.gov) is a public repository for archiving biological tests of small molecules generated through high-throughput screening experiments, medicinal chemistry studies, chemical biology research and drug discovery programs. In addition, the BioAssay database contains data from high-throughput RNA interference screening aimed at identifying critical genes responsible for a biological process or disease condition. The mission of PubChem is to serve the community by providing free and easy access to all deposited data. To this end, PubChem BioAssay is integrated into the National Center for Biotechnology Information retrieval system, making them searchable by Entrez queries and cross-linked to other biomedical information archived at National Center for Biotechnology Information. Moreover, PubChem BioAssay provides web-based and programmatic tools allowing users to search, access and analyze bioassay test results and metadata. In this work, we provide an update for the PubChem BioAssay resource, such as information content growth, new developments supporting data integration and search, and the recently deployed PubChem Upload to streamline chemical structure and bioassay submissions. PMID:24198245

  6. Detection of Zn with ChemCam on Mars

    NASA Astrophysics Data System (ADS)

    Lasue, J.; Clegg, S. M.; Forni, O.; Cousin, A.; Wiens, R. C.; Lanza, N.; Mangold, N.; Berger, J.; Blaney, D.; Fabre, C.; Gasnault, O.; Johnson, J.; LeDeit, L.; Le Mouélic, S.; Maurice, S.; M. S. L. Science Team

    2015-10-01

    C h e m C a m i s a L a s e r- I n d u c e d B r e a k d o w n Spectroscopy (LIBS) instrument on-board the NASA Curiosity rover currently exploring Mars. ChemCam can analyze the chemical composition of geological samples without preparation and at a distance by detecting the laser induced atomic emission lines from elements present [1, 2]. ChemCam is sensitive to most chemical elements. In addition to the major elements, ChemCam can be used to detect and quantify a set of minor and trace elements such as Li, Sr, Ba, and Rb using univariate and multivariate regression techniques [3]. Mn has also been detected and quantified with ChemCam at high concentrations indicating that highly oxidizing conditions must have occurred on the surface of Mars [4]. We report here the detection of high Zn content targets with ChemCam at the Kimberley location at Gale Crater that are linked to high-Mn concentrations.

  7. New Particle Formation Events During 2013 in Hada Al Sham, Saudi-Arabia

    NASA Astrophysics Data System (ADS)

    Neitola, K.; Hyvärinen, A.; Lihavainen, H.; Alghamdi, M.; Hussein, T.; Khodeir, M.; Shehata, A.; Laaksonen, A. J.; Kulmala, M. T.

    2014-12-01

    clear growth, S is clear shrinkage, G + S is both growth and shrinkage and unclear is not clear in either way.ReferencesM. Dal Maso, et al. (2005). Bor. Env. Res., 10, 323-336.M. Kulmala, et al. (2006). Atmos. Chem. Phys., 6, 787-793. M. Kulmala, et al. (2013). Science, 336, 943-946.

  8. EarthChem: Next Developments to Meet New Demands (Invited)

    NASA Astrophysics Data System (ADS)

    Lehnert, K. A.; Walker, D.; Block, K. A.; Ash, J. M.; Chan, C.

    2009-12-01

    EarthChem is a community-driven effort to facilitate the discovery, access, and preservation of geochemical data to support research and enable new and better science. After its first 4 years of development, EarthChem has established itself as a leading community resource that offers to its users a range of data services comprising: the EarthChem Portal as a central access point to geochemical data in federated databases with tools for data discovery, data access, and data analysis; the Geochemical Resource Library that serves as a repository for user-submitted data and features an online submission tool and a searchable metadata catalog; topical data collections such as the Deep Lithosphere Dataset that are developed and maintained by EarthChem; and GEOCHRON, a system for easy population and access of geochronology and thermochronology data. Growing demands for user-based data contributions, long-term data archiving, interoperability, and expanded data coverage will be addressed in EarthChem’s next development phase, during which EarthChem will enhance its information technology infrastructure, create new digital content, expand partnerships, and continue to promote the implementation of more open and standardized data reporting in geochemistry. Large emphasis will be placed on the development of services that help investigators to organize and manage their data in a way that submission of the data and metadata to EarthChem becomes effortless, seamless, and comprehensive, and that also facilitates the publication of data. The new EarthChem Repository will provide data storage and stewardship for the widest range of geochemical data sets and data collections, with tools for data submission and a data publication service that will allow users to obtain Digital Object Identifier for Scientific Primary Data (STD-DOI) to make their submitted data citable as publications. These applications are expected to ensure more efficient and timely growth of the data

  9. Pressure sounding of the middle atmosphere from ATMOS solar occultation measurements of atmospheric CO(2) absorption lines.

    PubMed

    Abrams, M C; Gunson, M R; Lowes, L L; Rinsland, C P; Zander, R

    1996-06-01

    A method for retrieving the atmospheric pressure corresponding to the tangent point of an infrared spectrum recorded in the solar occultation mode is described and applied to measurements made by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier-transform spectrometer. Tangent pressure values are inferred from measurements of isolated CO(2) lines with temperature-insensitive strengths by measuring the slant-column CO(2) amount and by adjusting the viewing geometry until the calculated column matches the observed column. Tangent pressures are determined with a spectroscopic precision of l%-3%, corresponding to a tangent-point height precision of 70-210 m. The total uncertainty is limited primarily by the quality of the spectra and ranges between 4% and 6% (280-420 m) for spectra with signal-to-noise ratios of 300:1 and between 4% and 10% for spectra with signal-to-noise ratios of 100:1. The retrieval of atmospheric pressure increases the accuracy of the retrieved-gas concentrations by minimizing the effect of systematic errors introduced by climatological pressure data, ephemeris parameters, and the uncertainties in instrumental pointing. PMID:21085429

  10. ATMOS/ATLAS-3 Measurements of Stratospheric Chlorine and Reactive Nitrogen Partitioning Inside and Outside the November 1994 Antarctic Vortex

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Salawitch, R. J.; Michelsen, H. A.; Zander, R.; Newchurch, M. J.; Abbas, M. M.; Abrams, M. C.; Manney, G. L.; Chang, A. Y.; Irion, F. W.; Goldman, A.; Mahieu, E.

    1996-01-01

    Partitioning between HCl and ClONO2 and among the main components of the reactive nitrogen family (NO, NO2, HNO3, ClONO2, N2O5, and HO2NO2) has been studied inside and outside the Antarctic stratospheric vortex based on ATMOS profiles measured at sunrise during the 3-12 November 1994 ATLAS-3 Shuttle mission. Elevated mixing ratios of HCl in the lower stratosphere with a peak of approximately 2.9 ppbv (10(exp -9) parts per volume) were measured inside the vortex near 500 K potential temperature (approximately 19 km). Maximum ClONO2 mixing ratios of approximately 1.2, approximately 1.4, and approximately 0.9 ppbv near 700 K (approximately 25 km) were measured inside, at the edge, and outside the vortex, respectively. Model calculations reproduce the higher levels of HCl and NO(x) (NO + NO2) inside the lower stratospheric vortex both driven by photochemical processes initiated by low O3. The high HCl at low O3 results from chemical production of HC1 via the reaction of enhanced Cl with CH4, limited production of ClONO2, and the descent of inorganic chlorine from higher altitudes.

  11. Atmos/Atlas 3 Infrared Profile Measurements of Trace Gases in The November 1994 Tropical and Subtropical Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Wang, P.-H.; Arduini, R. F.; Baum, B. A.; Minnis, P.; Minnis, P.; Goldman, A.; Abrams, M. C.; Zander, R.; Mahieu, E.; Mahieu, E.; Salawitch, R. J.; Michelsen, H. A.; Irion, F. W.; Newchurch, M. J.

    1998-01-01

    Vertical mixing ratio profiles of four relatively long-lives gases, HCN, C2H2, CO, and C2H6, have been retrieved from 0.01/cm resolution infrared solar occultation spectra recorded between latitudes of 5.3degN and 31.4degN. The observations were obtained by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the Atmospheric Laboratory for Applications and Science (ATLAS) 3 shuttle flight, 3-12 November 1994. Elevated mixing ratios below the tropopause were measured for these gases during several of the occultations. The positive correlations obtained between the simultaneously measured mixing ratios suggest that the enhancements are likely the result of surface emissions, most likely biomass burning and/or urban industrial activities, followed by common injection via deep convective transport of the gases to the upper troposphere. The elevated levels of HCN may account for at least part of the "missing NO," in the upper troposphere. Comparisons of the observations with values measured during a recent aircraft campaign are presented.

  12. Middle and upper atmosphere pressure-temperature profiles and the abundances of CO2 and CO in the upper atmosphere from ATMOS/Spacelab 3 observations

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Zander, R.; Lopez-Puertas, M.

    1992-01-01

    An improved method for retrieving pressure-temperature profiles is described and is used to retrieve profiles of the kinetic-temperature and atmospheric-pressure profiles between 20 and 116 km altitudes and the CO2 and CO volume-mixing ratios between 70 and 116 km, using the IR occultation spectra recorded by the Spacelab 3 atmospheric trace molecular spectroscopy (ATMOS) Fourier transform spectrometer between April 29 and May 6, 1985. Profiles are derived for six ATMOS occultations. The CO2 and CO volume-mixing profiles are compared with previous observations and model predictions. Evidence is found for vibrational non-LTE by analyzing the lines of the (nu-2 + nu-3 - nu-2) (C-12)(O-16) band. Results are used for deriving (C-12)(O-16) (010) vibrational temperatures, which are compared with the retrieved kinetic temperatures and the predictions of non-LTE effects by recent models.

  13. ChemCom Has Students Hooked on Chemistry.

    ERIC Educational Resources Information Center

    Lyon, Betsy

    1997-01-01

    Discusses a year-long course of study called Chemistry in the Community, or ChemCom, developed by the American Chemical Society (ACS) to improve chemistry studies in high schools and to relate chemistry to the real world of students. Students spend half the time in the laboratory with more discussion on nuclear, organic, and biochemistry than that…

  14. BioCom? Is that Like ChemCom?

    ERIC Educational Resources Information Center

    Leonard, William H.; And Others

    1996-01-01

    Describes the philosophy, development, content structure, and general instructional strategy of BioCom, an introductory biology curriculum for the heterogeneously mixed high school science classroom. Discusses recent recommendations by national commissions and science education research and similarities and differences between BioCom and ChemCom.…

  15. AutoClickChem: Click Chemistry in Silico

    PubMed Central

    Durrant, Jacob D.; McCammon, J. Andrew

    2012-01-01

    Academic researchers and many in industry often lack the financial resources available to scientists working in “big pharma.” High costs include those associated with high-throughput screening and chemical synthesis. In order to address these challenges, many researchers have in part turned to alternate methodologies. Virtual screening, for example, often substitutes for high-throughput screening, and click chemistry ensures that chemical synthesis is fast, cheap, and comparatively easy. Though both in silico screening and click chemistry seek to make drug discovery more feasible, it is not yet routine to couple these two methodologies. We here present a novel computer algorithm, called AutoClickChem, capable of performing many click-chemistry reactions in silico. AutoClickChem can be used to produce large combinatorial libraries of compound models for use in virtual screens. As the compounds of these libraries are constructed according to the reactions of click chemistry, they can be easily synthesized for subsequent testing in biochemical assays. Additionally, in silico modeling of click-chemistry products may prove useful in rational drug design and drug optimization. AutoClickChem is based on the pymolecule toolbox, a framework that may facilitate the development of future python-based programs that require the manipulation of molecular models. Both the pymolecule toolbox and AutoClickChem are released under the GNU General Public License version 3 and are available for download from http://autoclickchem.ucsd.edu. PMID:22438795

  16. Application of distance correction to ChemCam laser-induced breakdown spectroscopy measurements

    NASA Astrophysics Data System (ADS)

    Mezzacappa, A.; Melikechi, N.; Cousin, A.; Wiens, R. C.; Lasue, J.; Clegg, S. M.; Tokar, R.; Bender, S.; Lanza, N. L.; Maurice, S.; Berger, G.; Forni, O.; Gasnault, O.; Dyar, M. D.; Boucher, T.; Lewin, E.; Fabre, C.

    2016-06-01

    Laser-induced breakdown spectroscopy (LIBS) provides chemical information from atomic, ionic, and molecular emissions from which geochemical composition can be deciphered. Analysis of LIBS spectra in cases where targets are observed at different distances, as is the case for the ChemCam instrument on the Mars rover Curiosity, which performs analyses at distances between 2 and 7.4 m is not a simple task. In our previous work we showed that spectral distance correction based on a proxy spectroscopic standard created from first-shot dust observations on Mars targets ameliorates the distance bias in multivariate-based elemental-composition predictions of laboratory data. In this work, we correct an expanded set of neutral and ionic spectral emissions for distance bias in the ChemCam data set. By using and testing different selection criteria to generate multiple proxy standards, we find a correction that minimizes the difference in spectral intensity measured at two different distances and increases spectral reproducibility. When the quantitative performance of distance correction is assessed, there is improvement for SiO2, Al2O3, CaO, FeOT, Na2O, K2O, that is, for most of the major rock forming elements, and for the total major-element weight percent predicted. However, for MgO the method does not provide improvements while for TiO2, it yields inconsistent results. In addition, we have observed that many emission lines do not behave consistently with distance, evidenced from laboratory analogue measurements and ChemCam data. This limits the effectiveness of the method.

  17. Response to ``Comment on `Slow Debye-type peak observed in the dielectric response of polyalcohols' '' [J. Chem. Phys. 134, 037101 (2011)

    NASA Astrophysics Data System (ADS)

    Bergman, R.; Jansson, H.; Swenson, J.

    2011-01-01

    In our recent article [R. Bergman et al., J. Chem. Phys. 132, 044504 (2010)] we investigated some polyalcohols, i.e., glycerol, xylitol, and sorbitol by dielectric spectroscopy. In the study, a low-frequency peak of Debye character that normally is hidden by the large low-frequency dispersion due to conductivity was revealed by analyzing the real part of the permittivity and by using a thin Teflon film to suppress the low-frequency dispersion. We agree with the comment by Paluch et al. [J. Chem. Phys. 134, 037101 (2011)] that the Teflon film setup will indeed create a peak due to the dc conductivity. However, due to the fact that the location of the peak was almost identical in measurement with and without Teflon, we unfortunately mainly showed the data measured with Teflon, despite that it could also be observed in the real part of the permittivity without using the Teflon setup, as shown in our original article [R. Bergman et al., J. Chem. Phys. 132, 044504 (2010)]. Here, we show that the low-frequency peak of Debye character can also be observed by subtracting the dc conductivity. Furthermore, we show that the modulus representation used in Paluch et al. [J. Chem. Phys. 134, 037101 (2011).] is also not suitable for detecting processes hidden by the conductivity.

  18. Comment on "Frequency-domain stimulated and spontaneous light emission signals at molecular junctions" [J. Chem. Phys. 141, 074107 (2014)

    NASA Astrophysics Data System (ADS)

    Galperin, Michael; Ratner, Mark A.; Nitzan, Abraham

    2015-04-01

    We discuss the derivation of the optical response in molecular junctions presented by U. Harbola et al. [J. Chem. Phys. 141, 074107 (2014)], which questions some terms in the theory of Raman scattering in molecular junctions developed in our earlier publications. We show that the terms considered in our theory represent the correct contribution to calculated Raman scattering and are in fact identical to those considered by Harbola et al. We also indicate drawbacks of the presented approach in treating the quantum transport part of the problem.

  19. ChemCam Passive Reflectance Spectroscopy at Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Johnson, J. R.; Bell, J. F.; Cloutis, E.; Bender, S.; Blaney, D. L.; Ehlmann, B. L.; Gasnault, O.; Kinch, K. M.; Le Mouelic, S.; Rice, M. S.; Wiens, R. C.; DeFlores, L.; Team, M.

    2013-12-01

    The Laser-Induced Breakdown Spectrometer (LIBS) portion of the ChemCam instrument on the Mars Science Laboratory Curiosity rover uses 3 dispersive spectrometers to cover the ultraviolet (240-342 nm), visible (382-469 nm) and visible/near-infrared (474-906 nm) spectral regions at high spectral (<0.5nm) and spatial (0.65mrad) resolution. In active LIBS mode, light emitted from a laser-generated plasma is dispersed onto these spectrometers and used to detect elemental emission lines. Typical observations include 3 msec-exposure 'dark' spectra (acquired with the LIBS laser off) used to remove the background signal from the LIBS measurement. Similar 'passive' observations of the ChemCam calibration target holder can be made at similar times of day and at identical exposure times (to minimize variations from dark current). Because this target exhibits ~95% flat reflectance in the ~400-900 nm region, radiance spectra ratios (surface/calibration target) can be normalized to known calibration target lab spectra to produce relative reflectance spectra (400-900 nm) with an estimated accuracy of 10-20%. Initial results replicated the known spectral shape and overall reflectance values of the ChemCam calibration targets and green color chip on the Mastcam calibration target. Dust contamination was evident, although dust on the ChemCam calibration targets is minimized by their tilted placement on the rover deck. All ChemCam targets that were sunlit during LIBS acquisition (~80% of all measurements) provide 'dark' spectra for which relative reflectance spectra can be obtained. Owing to the dusty nature of the Gale landing sites, passive spectra observed to date exhibit spectral shapes indicative of ferric phases, similar to spectra of palagonitic soils. Most spectra are bracketed in reflectance by typical 'bright' and 'dark' spectra from the OMEGA and CRISM orbital spectrometers. Preliminary Mastcam reflectance spectra are similar, providing additional confidence regarding the

  20. ChemCalc: a building block for tomorrow's chemical infrastructure.

    PubMed

    Patiny, Luc; Borel, Alain

    2013-05-24

    Web services, as an aspect of cloud computing, are becoming an important part of the general IT infrastructure, and scientific computing is no exception to this trend. We propose a simple approach to develop chemical Web services, through which servers could expose the essential data manipulation functionality that students and researchers need for chemical calculations. These services return their results as JSON (JavaScript Object Notation) objects, which facilitates their use for Web applications. The ChemCalc project http://www.chemcalc.org demonstrates this approach: we present three Web services related with mass spectrometry, namely isotopic distribution simulation, peptide fragmentation simulation, and molecular formula determination. We also developed a complete Web application based on these three Web services, taking advantage of modern HTML5 and JavaScript libraries (ChemDoodle and jQuery). PMID:23480664

  1. ChemCam rock laser for Mars Science Laboratory "Curiosity"

    ScienceCinema

    Wiens, Roger

    2014-08-12

    Los Alamos has a long history of space-related instruments, tied primarily to its role in defense-related treaty verification. Space-based detectors have helped determine the differences between signals from lightning bolts and potential nuclear explosions. LANL-developed gamma-ray detection instruments first revealed the existence of what we now know as gamma-ray bursts, an exciting area of astrophysical research. And the use of LANL instruments on varied space missions continues with such products as the ChemCam rock laser for NASA, shown here. The Engineering Model of the ChemCam Mars Science Laboratory rover instrument arrived at NASA's Jet Propulsion Laboratory on February 6, 2008. The Flight Model was shipped in August, 2010 for installation on the rover at JPL. ChemCam will use imaging and laser-induced breakdown spectroscopy (LIBS) to determine rock and soil compositions on Mars, up to 9 meters from the rover. The engineering model is being integrated into the rover test bed for the development and testing of the rover software. The actual flight model components were concurrently assembled at Los Alamos and in Toulouse, France. The Mars Science Laboratory is scheduled to launch in 2011. Animations courtesy of JPL/NASA.

  2. ChemCam Rock Laser for the Mars Science Laboratory

    ScienceCinema

    LANL

    2009-09-01

    Los Alamos has a long history of space-related instr... Los Alamos has a long history of space-related instruments, tied primarily to its role in defense-related treaty verification. Space-based detectors have helped determine the differences between signals from lightning bolts and potential nuclear explosions. LANL-developed gamma-ray detection instruments first revealed the existence of what we now know as gamma-ray bursts, an exciting area of astrophysical research. And the use of LANL instruments on varied space missions continues with such products as the ChemCam rock laser for NASA, shown here. The Engineering Model of the ChemCam Mars Science Laboratory rover instrument arrived at NASA's Jet Propulsion Laboratory on February 6, 2008. ChemCam will use imaging and laser-induced breakdown spectroscopy (LIBS) to determine rock and soil compositions on Mars, up to 9 meters from the rover. The engineering model is being integrated into the rover test bed for the development and testing of the rover software. The actual flight model components are concurrently being assembled at Los Alamos and in Toulouse, France, and will be delivered to JPL in July. The Mars Science Laboratory is scheduled to launch in 2009. Animations courtesy of JPL/NASA.

  3. CHEM-Based Self-Deploying Spacecraft Radar Antennas

    NASA Technical Reports Server (NTRS)

    Sokolowski, Witold; Huang, John; Ghaffarian, Reza

    2004-01-01

    A document proposes self-deploying spacecraft radar antennas based on cold hibernated elastic memory (CHEM) structures. Described in a number of prior NASA Tech Briefs articles, the CHEM concept is one of utilizing open-cell shape-memory-polymer (SMP) foams to make lightweight structures that can be compressed for storage and can later be expanded, then rigidified for use. A CHEM-based antenna according to the proposal would comprise three layers of microstrip patches and transmission lines interspersed with two flat layers of SMP foam, which would serve as both dielectric spacers and as means of deployment. The SMP foam layers would be fabricated at full size at a temperature below the SMP glass-transition temperature (Tg). The layers would be assembled into a unitary structure, which, at temperature above Tg, would be compacted to much smaller thickness, then rolled up for storage. Next, the structure would be cooled to below Tg and kept there during launch. Upon reaching the assigned position in outer space, the structure would be heated above Tg to make it rebound to its original size and shape. The structure as thus deployed would then be rigidified by natural cooling to below Tg

  4. ChemCam Rock Laser for the Mars Science Laboratory

    SciTech Connect

    LANL

    2008-03-24

    Los Alamos has a long history of space-related instr... Los Alamos has a long history of space-related instruments, tied primarily to its role in defense-related treaty verification. Space-based detectors have helped determine the differences between signals from lightning bolts and potential nuclear explosions. LANL-developed gamma-ray detection instruments first revealed the existence of what we now know as gamma-ray bursts, an exciting area of astrophysical research. And the use of LANL instruments on varied space missions continues with such products as the ChemCam rock laser for NASA, shown here. The Engineering Model of the ChemCam Mars Science Laboratory rover instrument arrived at NASA's Jet Propulsion Laboratory on February 6, 2008. ChemCam will use imaging and laser-induced breakdown spectroscopy (LIBS) to determine rock and soil compositions on Mars, up to 9 meters from the rover. The engineering model is being integrated into the rover test bed for the development and testing of the rover software. The actual flight model components are concurrently being assembled at Los Alamos and in Toulouse, France, and will be delivered to JPL in July. The Mars Science Laboratory is scheduled to launch in 2009. Animations courtesy of JPL/NASA.

  5. ChemCam rock laser for Mars Science Laboratory "Curiosity"

    SciTech Connect

    Wiens, Roger

    2010-09-03

    Los Alamos has a long history of space-related instruments, tied primarily to its role in defense-related treaty verification. Space-based detectors have helped determine the differences between signals from lightning bolts and potential nuclear explosions. LANL-developed gamma-ray detection instruments first revealed the existence of what we now know as gamma-ray bursts, an exciting area of astrophysical research. And the use of LANL instruments on varied space missions continues with such products as the ChemCam rock laser for NASA, shown here. The Engineering Model of the ChemCam Mars Science Laboratory rover instrument arrived at NASA's Jet Propulsion Laboratory on February 6, 2008. The Flight Model was shipped in August, 2010 for installation on the rover at JPL. ChemCam will use imaging and laser-induced breakdown spectroscopy (LIBS) to determine rock and soil compositions on Mars, up to 9 meters from the rover. The engineering model is being integrated into the rover test bed for the development and testing of the rover software. The actual flight model components were concurrently assembled at Los Alamos and in Toulouse, France. The Mars Science Laboratory is scheduled to launch in 2011. Animations courtesy of JPL/NASA.

  6. ChemKits: A Teacher-Training and Instrument-Sharing Project.

    ERIC Educational Resources Information Center

    Mitchell, Mike; Shubert, David; Herman, Carolyn

    1999-01-01

    Describes the ChemKits initiative devised by private colleges in Kansas to help high school science teachers meet their needs for laboratory equipment. Discusses conclusions from three years of running the ChemKits teacher-education program. (WRM)

  7. The Potassic Sedimentary Rocks in Gale Crater, Mars, as Seen by ChemCam Onboard Curiosity.

    USGS Publications Warehouse

    Le Deit, Laetitia; Mangold, Nicolas; Forni, Olivier; Cousin, Agnes; Lasue, Jeremie; Schröder, Susanne; Wiens, Roger C.; Sumner, Dawn Y.; Fabre, Cecile; Stack, Katherine M.; Anderson, Ryan; Blaney, Diana L.; Clegg, Samuel M.; Dromart, Gilles; Fisk, Martin; Gasnault, Olivier; Grotzinger, John P.; Gupta, Sanjeev; Lanza, Nina; Le Mouélic, Stephane; Maurice, Sylvestre; McLennan, Scott M.; Meslin, Pierre-Yves; Nachon, Marion; Newsom, Horton E.; Payre, Valerie; Rapin, William; Rice, Melissa; Sautter, Violaine; Treiman, Alan H.

    2016-01-01

    The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters-thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system (Grotzinger et al., 2015). From ChemCam LIBS chemical analyses, this suite of sedimentary rocks has an overall mean K2O abundance that is more than five times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations reveals that the mean K2O abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e. mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.

  8. Dust modeling over Saudi Arabia using WRF-Chem: March 2009 severe dust case

    NASA Astrophysics Data System (ADS)

    Zhang, Yongxin; Liu, Yubao; Kucera, Paul A.; Alharbi, Badr H.; Pan, Linlin; Ghulam, Ayman

    2015-10-01

    This paper documents the performance of the fully coupled WRF-Chem model at 21.6 km and 7.2 km resolution over Saudi Arabia in simulating a severe dust storm event that occurred in March 2009. The comparisons between the model simulations and the observed AOD at the Solar Village AERONET site and the MODIS measurements show that WRF-Chem satisfactorily resolves the arrival, evolution and spatial distributions of the dust storm over Saudi Arabia especially for the fine domain at 7.2 km resolution. The model simulated surface meteorological variables at Riyadh Airport, Hafr Al-Batin Airport, Dammam Airport and Gassim Airport follow the observations in terms of magnitude and temporal evolution although model biases such as deficiencies in simulating the amplitude of diurnal cycles are noted. Higher resolution and shorter initialization time improve the model performance in aerosol optical depth but for surface variables shorter initialization time improves correlation while higher horizontal resolution improves mean biases to some extent. The simulated dust plume is mainly confined between the surface and the 5-km height, with the peak concentrations located in the lowest 500 m. The vertical extent of the dust plume shows gradual decreases during the simulation period when averaged over the entire fine domain and an area centered around Solar Village, and also varies in accordance with the development and decay of the boundary layer.

  9. Engaging Organic Chemistry Students Using ChemDraw for iPad

    ERIC Educational Resources Information Center

    Morsch, Layne A.; Lewis, Michael

    2015-01-01

    Drawing structures, mechanisms, and syntheses is a vital part of success in organic chemistry courses. ChemDraw for iPad has been used to increase classroom experiences in the preparation of high quality chemical drawings. The embedded Flick-to-Share allows for simple, real-time exchange of ChemDraw documents. ChemDraw for iPad also allows…

  10. 75 FR 57478 - Accreditation and Approval of Chem Coast, Inc., as a Commercial Gauger and Laboratory

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-21

    ... SECURITY U.S. Customs and Border Protection Accreditation and Approval of Chem Coast, Inc., as a Commercial...: Notice of accreditation and approval of Chem Coast, Inc., as a commercial gauger and laboratory. SUMMARY: Notice is hereby given that, pursuant to 19 CFR 151.12 and 19 CFR 151.13, Chem Coast, Inc., 11820 North...

  11. In-situ small-angle X-ray scattering study of the precipitation behavior in a Fe-25 at.%Co-9 at.%Mo alloy

    SciTech Connect

    Zickler, Gerald A. Eidenberger, Elisabeth; Leitner, Harald; Stergar, Erich; Clemens, Helmut; Staron, Peter; Lippmann, Thomas; Schreyer, Andreas

    2008-12-15

    Fe-Co-Mo alloys show extraordinary mechanical properties which make them potential candidates for various high-performance applications. In the present study, for the first time, the precipitation behavior in a Fe-25 at.%Co-9 at.%Mo alloy was studied by small-angle X-ray scattering using high-energy synchrotron radiation. The specimens were isothermally aged in an in-situ furnace. The small-angle X-ray scattering patterns showed scaling behavior and were evaluated by employing a model function from the literature. This approach provides information about the characteristic length scale and the volume fraction of the precipitates in the alloy.

  12. Formation Conditions of Basalts at Gale Crater, Mars from ChemCam Analyses

    NASA Astrophysics Data System (ADS)

    Filiberto, J.; Bridges, J.; Dasgupta, R.; Edwards, P.; Schwenzer, S. P.; Wiens, R. C.

    2015-12-01

    Surface igneous rocks shed light onto the chemistry, tectonic, and thermal state of planetary interiors. For the purpose of comparative planetology, therefore, it is critical to fully utilize the compositional diversity of igneous rocks for different terrestrial planets. For Mars, igneous float rocks and conglomerate clasts at Gale Crater, as analyzed by ChemCam [1] using a new calibration [2], have a larger range in chemistry than have been analyzed at any other landing site or within the Martian meteorite collection [3, 4]. These rocks may reflect different conditions of melting within the Martian interior than any previously analyzed basalts. Here we present new formation conditions for basaltic and trachybasalt/dioritic rocks at Gale Crater from ChemCam analyses following previous procedures [5, 6]. We then compare these estimates of basalt formation with previous estimates for rocks from the Noachian (Gusev Crater, Meridiani Planum, and a clast in the NWA 7034 meteorite [5, 6]), Hesperian (surface volcanics [7]), and Amazonian (surface volcanics and shergottites [7-8]), to calculate an average mantle potential temperature for different Martian epochs and investigate how the interior of Mars has changed through time. Finally, we will compare Martian mantle potential temperatures with petrologic estimate of cooling for the Earth. Our calculated estimate for the mantle potential temperature (TP) of rocks at Gale Crater is 1450 ± 45 °C which is within error of previous estimates for Noachian aged rocks [5, 6]. The TP estimates for the Hesperian and Amazonian, based on orbital analyses of the crust [7], are lower in temperature than the estimates for the Noachian. Our results are consistent with simple convective cooling of the Martian interior. [1] Wiens R. et al. (2012) Space Sci Rev 170. 167-227. [2] Anderson R. et al. (2015) LPSC. Abstract #7031. [3] Schmidt M.E. et al. (2014) JGRP 2013JE004481. [4] Sautter V. et al. (2014) JGRP 2013JE004472. [5] Filiberto J

  13. Comment on "Using quaternions to calculate RMSD" [J. Comp. Chem. 25, 1849 (2004)].

    PubMed

    Kneller, G R

    2005-11-30

    Coutsias et al. have recently published a method to find the optimal rotational superposition of two molecular structures, which is based on a representation of rotations by quaternions (J. Comp. Chem. 25(15), 1849 (2004)). The method, which has been suggested by other authors before, is compared to the one by Kabsch, where the elements of the rotation matrix are directly used as variables of the optimization problem. The statement that the two methods are equivalent is misleading in the sense that the Kabsch method may yield an improper optimal rotation, which must be explicitly checked for, whereas the quaternion method does not mix proper and improper rotations. Nevertheless, both types of solutions can be considered by solving the same eigenvector problem. The relation between the two types of solutions is briefly discussed and bounds for the eigenvalues are given. PMID:16175580

  14. Molecular recognition of chem/biowarfare agents using micromechanical sensors

    NASA Astrophysics Data System (ADS)

    Ji, H.-F.; Yan, X.; Lu, Y.; Du, H.; Thundat, T.

    2006-05-01

    Recent terrorists events have shown that an urgent and widespread need exists for development of novel sensors for chemical and biowarfare agents. The advent of inexpensive, mass-produced microcantilever sensors, promises to bring about a revolution in detection of terrorists threats. Extremely sensitive chem/biosensors can be developed using microcantilever platform. Both frequency and bending of microcantilevers can be used to detect the chemical and biological species in air or solution. The specificity is achieved by immobilizing chemically-specific receptors the cantilever. This short report will give an overview of chemical/biological warfare agents sensor recently developed based on microcantilevers.

  15. EOS CHEM: A Mission to Study Ozone and Climate

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark

    1998-01-01

    The Earth's stratosphere contains the ozone layer, which shields us from the Sun@ harmful ultraviolet (UV) radiation. Ozone is destroyed through chemical reactions involving natural and man-made nitrogen, hydrogen, bromine, and chlorine compounds. The release of chlorofluoro-carbons CFCs) has caused a dramatic decrease in the protective stratospheric ozone layer during the last two decades. Detection of stratospheric ozone depletion led to regulation and phase-out of CFC production worldwide. As a result, man-made chlorine levels in the atmosphere are slowly beginning to decrease. CHEM will be able to determine whether the stratospheric ozone layer is now recovering, as predicted by scientific models.

  16. Evaluation of Meso-NH and WRF/CHEM simulated gas and aerosol chemistry over Europe based on hourly observations

    NASA Astrophysics Data System (ADS)

    Berger, A.; Barbet, C.; Leriche, M.; Deguillaume, L.; Mari, C.; Chaumerliac, N.; Bègue, N.; Tulet, P.; Gazen, D.; Escobar, J.

    2016-07-01

    Gas chemistry and aerosol chemistry of 10 km-resolution mesoscale models Meso-NH and WRF/CHEM were evaluated on three cases over Europe. These one-day duration cases were selected from Freney et al. (2011) and occurred on contrasted meteorological conditions and at different seasons: a cyclonic circulation with a well-marked frontal zone on winter, an anti-cyclonic situation with local storm precipitations on summer and a cold front in the northwest of Europe associated to a convergence of air masses over eastern Europe and conflicting air masses over Spain and France on autumn. To assess the performance of the two models, surface hourly databases from observation stations over Europe were used, together with airborne measurements. For both models, the meteorological fields were in good agreement with the measurements for the three days. Winds presented the largest normalised mean bias integrated over all European stations for both models. Daily gas chemistry was reproduced with normalised mean biases between - 14 and 11%, a level of accuracy that is acceptable for policy support. The two models' performances were degraded during night-time quite likely due to the constant primary species emissions. The PM2.5 bulk mass concentration was overestimated by Meso-NH over Europe and slightly underestimated by WRF/CHEM. The absence of wet deposition in the models partly explains the local discrepancies with the observations. More locally, the systematic low mixing ratio of volatile organic compounds in the gas phase simulated by WRF/CHEM at three stations was correlated with the underestimation of OM (organic matter) mass in the aerosol phase. Moreover, this mass of OM was mainly composed of anthropogenic POAs (primary organic aerosols) in WRF/CHEM, suggesting a missing source for SOAs (secondary organic aerosols) mass in WRF/CHEM aerosol parameterisation. The contribution of OM was well simulated by Meso-NH, with a higher contribution for the summer case. For Meso

  17. Seasonal Variations of Water Vapor in the Lower Stratosphere Inferred from ATMOS/ATLAS-3 Measurements of H2O and CH4

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Michelsen, H. A.; Gunson, M. R.; Abrams, M. C.; Newchurch, M. J.; Salawitch, R. J.; Chang, A. Y.; Goldman, A.; Irion, F. W.; Manney, G. L.; Moyer, E. J.; Nagaraju, R.; Rinsland, C. P.; Stiller, G. P.; Zander, R.

    1996-01-01

    Stratospheric measurements of H2O and CH4 by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer on the ATLAS-3 shuttle flight in November 1994 have been examined to investigate the altitude and geographic variability of H2O and the quantity H = (H2O + 2CH4) in the tropics and at mid-latitudes (8 to 49 deg N) in the northern hemisphere. The measurements indicate an average value of 7.24 plus or minus 0.44 ppmv for H between altitudes of about 18 to 35 km, corresponding to an annual average water vapor mixing ratio of 3.85 plus or minus 0.29 ppmv entering the stratosphere. The H2O vertical distribution in the tropics exhibits a wave-like structure in the 16- to 25-km altitude range, suggestive of seasonal variations in the water vapor transported from the troposphere to the stratosphere. The hygropause appears to be nearly coincident with the tropopause at the time of observations. This is consistent with the phase of the seasonal cycle of H2O in the lower stratosphere, since the ATMOS observations were made in November when the H2O content of air injected into the stratosphere from the troposphere is decreasing from its seasonal peak in July - August.

  18. On the Assessment and Uncertainty of Atmospheric Trace Gas Burden Measurements with High Resolution Infrared Solar Occultation Spectra from Space by the ATMOS Experiment

    NASA Technical Reports Server (NTRS)

    Abrams, M. C.; Chang, A. Y.; Gunson, M. R.; Abbas, M. M.; Goldman, A.; Irion, F. W.; Michelsen, H. A.; Newchurch, M. J.; Rinsland, C. P.; Stiller, G. P.; Zander, R.

    1996-01-01

    The Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument is a high resolution Fourier transform spectrometer that measures atmospheric composition from low Earth orbit with infrared solar occultation sounding in the limb geometry. Following an initial flight in 1985, ATMOS participated in the Atmospheric Laboratory for Applications and Science (ATLAS) 1, 2, and 3 Space Shuttle missions in 1992, 1993, and 1994 yielding a total of 440 occultation measurements over a nine year period. The suite of more than thirty atmospheric trace gases profiled includes CO2, O3, N2O, CH4, H2O, NO, NO2, HNO3, HCl, HF, ClONO2, CCl3F, CCl2F2, CHF2Cl, and N2O5. The analysis method has been revised throughout the mission years culminating in the 'version 2' data set. The spectroscopic error analysis is described in the context of supporting the precision estimates reported with the profiles; in addition, systematic uncertainties assessed from the quality of the spectroscopic database are described and tabulated for comparisons with other experiments.

  19. Seasonal Variations of Water Vapor in the Lower Stratosphere Inferred from ATMOS/ATLAS-3 Measurements of H2O and CH4

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Michelsen, H. A.; Gunson, M. R.; Abrams, M. C.; Newchurch, M. J.; Salawitch, R. J.; Chang, A. Y.; Goldman, A.; Irion, F. W.; Manney, G. L.; Moyer, E. J.; Nagaraju, R.; Rinsland, C. P.; Stiller, G. P.; Zander, R.

    1996-01-01

    Stratospheric measurements of H2O and CH4 by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer on the ATLAS-3 shuttle flight in November 1994 have been examined to investigate the altitude and geographic variability of H2O and the quantity H = (H2O + 2CH4) in the tropics and at mid-latitudes (8 to 49 deg N) in the northern hemisphere. The measurements indicate an average value of 7.24 +/- 0.44 ppmv for H between altitudes of about 18 to 35 km, corresponding to an annual average water vapor mixing ratio of 3.85 +/- 0.29 ppmv entering the stratosphere. The H2O vertical distribution in the tropics exhibits a wave-like structure in the 16- to 25-km altitude range, suggestive of seasonal variations in the water vapor transported from the troposphere to the stratosphere. The hygropause appears to be nearly coincident with the tropopause at the time of observations. This is consistent with the phase of the seasonal cycle of H2O in the lower stratosphere, since the ATMOS observations were made in November when the H2O content of air injected into the stratosphere from the troposphere is decreasing from its seasonal peak in July-August.

  20. ATMOS Measurements of H2O + 2CH4 and Total Reactive Nitrogen in the November 1994 Antarctic Stratosphere: Dehydration and Denitrification in the Vortex

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Salawitch, R. J.; Newchurch, M. J.; Zander, R.; Abbas, M. M.; Abrams, M. C.; Manney, G. L.; Michelsen, H. A.; Chang, A. Y.; Goldman, A.

    1996-01-01

    Simultaneous stratospheric volume mixing ratios (VMR's) measured inside and outside the Antarctic vortex by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument in November 1994 reveal previously unobserved features in the distributions of total reactive nitrogen (NO(y)) and total hydrogen (H2O + 2CH4). Maximum removal of NO(y) due to sedimentation of polar stratospheric clouds (PSC's) inside the vortex occurred at a potential temperature (Theta) of 500-525 K (approximately 20 km), where values were 5 times smaller than measurements outside. Maximum loss of H2O + 2CH4 due to PSC's occurred in the vortex at 425-450 K, approximately 3 km lower than the peak NO(y) loss. At that level, H2O + 2CH4 VMR's inside the vortex were approximately 70% of corresponding values outside. The Antarctic and April 1993 Arctic measurements by ATMOS show no significant differences in H2O + 2CH4 VMR's outside the vortices in the two hemispheres. Elevated NO(y) VMRs were measured inside the vortex near 700 K. Recent model calculations indicate that this feature results from downward transport of elevated NO(y) produced in the thermosphere and mesosphere.

  1. Implementing marine organic aerosols into the GEOS-Chem model

    DOE PAGESBeta

    Gantt, B.; Johnson, M. S.; Crippa, M.; Prévôt, A. S. H.; Meskhidze, N.

    2014-09-09

    Marine organic aerosols (MOA) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem model. The implemented emission scheme improved the large underprediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from -79% when using the default settings to -12% when marine organic aerosols are added). Model predictions were also in goodmore » agreement (correlation coefficient of 0.62 and normalized mean bias of -36%) with hourly surface concentrations of MOA observed during the summertime at an inland site near Paris, France. Our study shows that MOA have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having > 10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly-emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.« less

  2. Implementing marine organic aerosols into the GEOS-Chem model

    DOE PAGESBeta

    Gantt, B.; Johnson, M. S.; Crippa, M.; Prévôt, A. S. H.; Meskhidze, N.

    2015-03-17

    Marine-sourced organic aerosols (MOAs) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem (Global Earth Observing System Chemistry) model. The implemented emission scheme improved the large underprediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from -79% when using the default settings to -12% when marine organic aerosols are added). Modelmore » predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of -36%) with hourly surface concentrations of MOAs observed during the summertime at an inland site near Paris, France. Our study shows that MOAs have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having >10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.« less

  3. Curiosity ChemCam Finds High-Silica Mars Rocks

    SciTech Connect

    Frydenvang, Jens

    2015-12-17

    A team of scientists, including one from Los Alamos National Laboratory, has found much higher concentrations of silica at some sites the Curiosity rover has investigated in the past seven months than anywhere else it has visited since landing on Mars 40 months ago. The first discovery was as Curiosity approached the area “Marias Pass,” where a lower geological unit contacts an overlying one. ChemCam, the rover’s laser-firing instrument for checking rock composition from a distance, detected bountiful silica in some targets the rover passed along the way to the contact zone. The ChemCam instrument was developed at Los Alamos in partnership with the French IRAP laboratory in Toulouse and the French Space Agency. “The high silica was a surprise,” said Jens Frydenvang of Los Alamos National Laboratory and the University of Copenhagen, also a Curiosity science team member. “While we’re still working with multiple hypotheses on how the silica got so enriched, these hypotheses all require considerable water activity, and on Earth high silica deposits are often associated with environments that provide excellent support for microbial life. Because of this, the science team agreed to make a rare backtrack to investigate it more.”

  4. Implementing marine organic aerosols into the GEOS-Chem model

    NASA Astrophysics Data System (ADS)

    Gantt, B.; Johnson, M. S.; Crippa, M.; Prévôt, A. S. H.; Meskhidze, N.

    2014-09-01

    Marine organic aerosols (MOA) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem model. The implemented emission scheme improved the large underprediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from -79% when using the default settings to -12% when marine organic aerosols are added). Model predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of -36%) with hourly surface concentrations of MOA observed during the summertime at an inland site near Paris, France. Our study shows that MOA have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having > 10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly-emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.

  5. Implementing marine organic aerosols into the GEOS-Chem model

    NASA Astrophysics Data System (ADS)

    Gantt, B.; Johnson, M. S.; Crippa, M.; Prévôt, A. S. H.; Meskhidze, N.

    2015-03-01

    Marine-sourced organic aerosols (MOAs) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem (Global Earth Observing System Chemistry) model. The implemented emission scheme improved the large underprediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from -79% when using the default settings to -12% when marine organic aerosols are added). Model predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of -36%) with hourly surface concentrations of MOAs observed during the summertime at an inland site near Paris, France. Our study shows that MOAs have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having >10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.

  6. ChemBrowser: a flexible framework for mining chemical documents.

    PubMed

    Wu, Xian; Zhang, Li; Chen, Ying; Rhodes, James; Griffin, Thomas D; Boyer, Stephen K; Alba, Alfredo; Cai, Keke

    2010-01-01

    The ability to extract chemical and biological entities and relations from text documents automatically has great value to biochemical research and development activities. The growing maturity of text mining and artificial intelligence technologies shows promise in enabling such automatic chemical entity extraction capabilities (called "Chemical Annotation" in this paper). Many techniques have been reported in the literature, ranging from dictionary and rule-based techniques to machine learning approaches. In practice, we found that no single technique works well in all cases. A combinatorial approach that allows one to quickly compose different annotation techniques together for a given situation is most effective. In this paper, we describe the key challenges we face in real-world chemical annotation scenarios. We then present a solution called ChemBrowser which has a flexible framework for chemical annotation. ChemBrowser includes a suite of customizable processing units that might be utilized in a chemical annotator, a high-level language that describes the composition of various processing units that would form a chemical annotator, and an execution engine that translates the composition language to an actual annotator that can generate annotation results for a given set of documents. We demonstrate the impact of this approach by tailoring an annotator for extracting chemical names from patent documents and show how this annotator can be easily modified with simple configuration alone. PMID:20865486

  7. Comment on "Fast determination of the optimal rotational matrix for macromolecular superpositions" [J. Comp. Chem. 31, 1561 (2010)].

    PubMed

    Kneller, Gerald R

    2011-01-15

    Recently Liu et al. published a fast algorithm to solve the eigenvector problem arising in the quaternion-based method for the rotational superposition of molecular structures (J Comput Chem 2010, 31, 1561.). In this Comment, it is shown that the construction of the 4 × 4 matrix to be diagonalized—and not the diagonalization itself—represents the dominating part of the computational effort for the quaternion-based solution of the rotational superposition problem if molecules with more than about 100 atoms are considered. PMID:20662082

  8. Development and application of the WRFPLUS-Chem online chemistry adjoint and WRFDA-Chem assimilation system

    NASA Astrophysics Data System (ADS)

    Guerrette, J. J.; Henze, D. K.

    2015-02-01

    Here we present the online meteorology and chemistry adjoint and tangent linear model, WRFPLUS-Chem, which incorporates modules to treat boundary layer mixing, emission, aging, dry deposition, and advection of black carbon aerosol. We also develop land surface and surface layer adjoints to account for coupling between radiation and vertical mixing. Model performance is verified against finite difference derivative approximations. A second order checkpointing scheme is created to reduce computational costs and enable simulations longer than six hours. The adjoint is coupled to WRFDA-Chem, in order to conduct a sensitivity study of anthropogenic and biomass burning sources throughout California during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign. A cost function weighting scheme was devised to increase adjoint sensitivity robustness in future inverse modeling studies. Results of the sensitivity study show that, for this domain and time period, anthropogenic emissions are over predicted, while wildfire emissions are under predicted. We consider the diurnal variation in emission sensitivities to determine at what time sources should be scaled up or down. Also, adjoint sensitivities for two choices of land surface model indicate that emission inversion results would be sensitive to forward model configuration. The tools described here are the first step in conducting four-dimensional variational data assimilation in a coupled meteorology-chemistry model, which will potentially provide new constraints on aerosol precursor emissions and their distributions. Such analyses will be invaluable to assessments of particulate matter health and climate impacts.

  9. ChemTok: A New Rule Based Tokenizer for Chemical Named Entity Recognition.

    PubMed

    Akkasi, Abbas; Varoğlu, Ekrem; Dimililer, Nazife

    2016-01-01

    Named Entity Recognition (NER) from text constitutes the first step in many text mining applications. The most important preliminary step for NER systems using machine learning approaches is tokenization where raw text is segmented into tokens. This study proposes an enhanced rule based tokenizer, ChemTok, which utilizes rules extracted mainly from the train data set. The main novelty of ChemTok is the use of the extracted rules in order to merge the tokens split in the previous steps, thus producing longer and more discriminative tokens. ChemTok is compared to the tokenization methods utilized by ChemSpot and tmChem. Support Vector Machines and Conditional Random Fields are employed as the learning algorithms. The experimental results show that the classifiers trained on the output of ChemTok outperforms all classifiers trained on the output of the other two tokenizers in terms of classification performance, and the number of incorrectly segmented entities. PMID:26942193

  10. ChemTok: A New Rule Based Tokenizer for Chemical Named Entity Recognition

    PubMed Central

    Akkasi, Abbas; Varoğlu, Ekrem; Dimililer, Nazife

    2016-01-01

    Named Entity Recognition (NER) from text constitutes the first step in many text mining applications. The most important preliminary step for NER systems using machine learning approaches is tokenization where raw text is segmented into tokens. This study proposes an enhanced rule based tokenizer, ChemTok, which utilizes rules extracted mainly from the train data set. The main novelty of ChemTok is the use of the extracted rules in order to merge the tokens split in the previous steps, thus producing longer and more discriminative tokens. ChemTok is compared to the tokenization methods utilized by ChemSpot and tmChem. Support Vector Machines and Conditional Random Fields are employed as the learning algorithms. The experimental results show that the classifiers trained on the output of ChemTok outperforms all classifiers trained on the output of the other two tokenizers in terms of classification performance, and the number of incorrectly segmented entities. PMID:26942193

  11. Triumphs and Tribulations of WRF-Chem Development and Use

    SciTech Connect

    Gustafson, William I.; Fast, Jerome D.; Easter, Richard C.; Ghan, Steven J.

    2005-06-27

    In order to address scientific questions related to aerosol chemistry and meteorological-aerosol-radiation-cloud feedbacks at the urban to regional scale, scientists at the Pacific Northwest National Laboratory (PNNL) have made substantial contributions to the chemistry version of the Weather Research and Forecasting model (WRF-Chem) during the past one and a half years. These contributions include an additional gas-phase chemistry mechanism, a sectional aerosol module, an additional photolysis module, feedbacks between aerosols and radiation, and extending the nesting capability of WRF to include the chemistry scalars. During the development process, a number of limitations in WRF have been identified that complicate adding all the desired chemistry capabilities as originally planned. These issues will be discussed along with changes that have been made to help mitigate some of them. Mechanisms currently in development will also be discussed including a secondary organic aerosol (SOA) mechanism for the sectional aerosol module, aqueous chemistry, and the aerosol indirect effect.

  12. ChemTechLinks: Alliances for Chemical Technician Education

    NASA Astrophysics Data System (ADS)

    Nameroff, Tamara

    2003-09-01

    ChemTechLinks (CTL) is a project of the American Chemical Society (ACS) Educational and International Activities Division and funded by the National Science Foundation to support and advance chemistry-based technician education. The project aims to help improve technician education programs, foster academic-industry alliances, provide professional development opportunities for faculty, and increase student recruitment into chemical technology. The CTL Web site serves as an information clearinghouse and link to other ACS resources and programs, including a Web-based, Voluntary Industry Standards (VIS) database, the Chemistry Technician Program Approval Service, the College Chemistry Consultants Service, summer workshops for high school teachers and two-year college faculty that emphasize a technology-oriented curriculum, scholarships for two-year college faculty to attend ACS Short Courses, a self-study instructional guide for faculty to use in preparing for classroom instruction, and information and free recruitment materials about career opportunities in chemistry technology.

  13. Hydrogen isotope MicroChemLab FY15.

    SciTech Connect

    Robinson, David; Luo, Weifang; Stewart, Kenneth D.

    2015-09-01

    We have developed a new method to measure the composition of gaseous mixtures of any two hydrogen isotopes, as well as an inert gas component. When tritium is one of those hydrogen isotopes, there is usually some helium present, because the tritium decays to form helium at a rate of about 1% every 2 months. The usual way of measuring composition of these mixtures involves mass spectrometry, which involves bulky, energy-intensive, expensive instruments, including vacuum pumps that can quite undesirably disperse tritium. Our approach uses calorimetry of a small quantity of hydrogen-absorbing material to determine gas composition without consuming or dispersing the analytes. Our work was a proof of principle using a rather large and slow benchtop calorimeter. Incorporation of microfabricated calorimeters, such as those that have been developed in Sandia’s MicroChemLab program or that are now commercially available, would allow for faster measurements and a smaller instrument footprint.

  14. Major-Element Compositional Diversity Observed by ChemCam Along the MSL Traverse: The First Three Years

    NASA Astrophysics Data System (ADS)

    Wiens, R. C.; Mangold, N.; Maurice, S.; Blaney, D. L.; Clegg, S. M.; Gasda, P. J.; Frydenvang, J.; Gasnault, O.; Forni, O.; Cousin, A.; Lasue, J.; Lanza, N.; Anderson, R. B.; Sautter, V.; Bridges, J.; Le Deit, L.; Nachon, M.; Rapin, W.; Meslin, P. Y.; Newsom, H. E.; Clark, B. C.; Vaniman, D. T.; Bridges, N.; Herkenhoff, K. E.; Ehlmann, B. L.; Dyar, M. D.; Fisk, M. R.; Francis, R.; Leveille, R. J.; Johnson, J. R.; Melikechi, N.; Jackson, R.; Fabre, C.; Payré, V.; Grotzinger, J. P.; Vasavada, A. R.; Crisp, J. A.

    2015-12-01

    ChemCam on Curiosity has used LIBS to obtain elemental compositions of >6000 target points at distances to 7.4 m from the rover. Observations include igneous clasts, sediments, diagenetic features, and other details often not accessible by the rover arm. A major re-calibration was recently completed using >350 standards. This significantly improved the accuracies of mineral end-members including plag-feldspars, hi-Si compositions, oxide grains, Mg-rich end-members (presumably Mg saponites; not yet confirmed by CheMin), and Mg and Ca sulfates. Here we draw conclusions from the overall compositional distributions observed in Gale crater from landing until the present using the new calibration. Observations from Bradbury Rise (sols 0-53, 326-520) show a scattering of compositions toward mineral end-members from igneous clasts and pebbles transported from the crater rim. In contrast, Sheepbed mudstones (first drill location; sols 126-300) form a tight cluster close to average Mars composition. The nearby Shaler fluvial sandstone outcrop (sols 306-325)--the first outcrop of potential deltaic foreset beds--shows K enrichment. This enrichment reaches a peak of 6 wt % K2O (sol 625) in the Mt. Remarkable member of the Kimberley formation, Kimberley being a drill location flanked by foreset beds 7 km SW of Shaler. The Pahrump outcrop (sols 753-919)—first observed material of the Murray formation at Mt. Sharp's base—shows lower Mg, higher Si, and much higher Al, consistent with stronger alteration. Further along the traverse ChemCam discovered an outcrop of light-toned Murray formation rock (sols 992 on) of nearly pure SiO2+TiO2. Overall, the ChemCam database points to a very strong diversity of inputs and alteration processes within a relatively short distance within Gale. Igneous compositions: while Jake Matijevic, a float analyzed early by APXS, appeared nepheline normative, no clear nepheline has been found by ChemCam. Additionally, despite the significant number of

  15. Development and application of the WRFPLUS-Chem online chemistry adjoint and WRFDA-Chem assimilation system

    NASA Astrophysics Data System (ADS)

    Guerrette, J. J.; Henze, D. K.

    2015-06-01

    Here we present the online meteorology and chemistry adjoint and tangent linear model, WRFPLUS-Chem (Weather Research and Forecasting plus chemistry), which incorporates modules to treat boundary layer mixing, emission, aging, dry deposition, and advection of black carbon aerosol. We also develop land surface and surface layer adjoints to account for coupling between radiation and vertical mixing. Model performance is verified against finite difference derivative approximations. A second-order checkpointing scheme is created to reduce computational costs and enable simulations longer than 6 h. The adjoint is coupled to WRFDA-Chem, in order to conduct a sensitivity study of anthropogenic and biomass burning sources throughout California during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign. A cost-function weighting scheme was devised to reduce the impact of statistically insignificant residual errors in future inverse modeling studies. Results of the sensitivity study show that, for this domain and time period, anthropogenic emissions are overpredicted, while wildfire emission error signs vary spatially. We consider the diurnal variation in emission sensitivities to determine at what time sources should be scaled up or down. Also, adjoint sensitivities for two choices of land surface model (LSM) indicate that emission inversion results would be sensitive to forward model configuration. The tools described here are the first step in conducting four-dimensional variational data assimilation in a coupled meteorology-chemistry model, which will potentially provide new constraints on aerosol precursor emissions and their distributions. Such analyses will be invaluable to assessments of particulate matter health and climate impacts.

  16. Comment on ``Study of dielectric relaxations of anhydrous trehalose and maltose glasses'' [J. Chem. Phys. 134, 014508 (2011)

    NASA Astrophysics Data System (ADS)

    Kaminski, K.; Wlodarczyk, P.; Paluch, M.

    2011-10-01

    Very recently Kwon et al. [H.-J. Kwon, J.-A. Seo, H. K. Kim, and Y. H. Hwang, J. Chem. Phys. 134, 014508 (2011)] published an article on the study of dielectric relaxation in trehalose and maltose glasses. They carried out broadband dielectric measurements at very wide range of temperatures covering supercooled liquid as well as glassy state of both saccharides. It is worth to mention that authors have also applied a new method for obtaining anhydrous glasses of trehalose and maltose that enables avoiding their caramelization. Four relaxation processes were identified in dielectric spectra of both saccharides. The slower one was identified as structural relaxation process the next one, not observed by the others, was assigned as Johari-Goldstein (JG) β-relaxation, while the last two secondary modes were of the same nature as found by Kaminski et al. [K. Kaminski, E. Kaminska, P. Wlodarczyk, S. Pawlus, D. Kimla, A. Kasprzycka, M. Paluch, J. Ziolo, W. Szeja, and K. L. Ngai, J. Phys. Chem. B 112, 12816 (2008)]. In this comment we show that the authors mistakenly assigned the slowest relaxation process as structural mode of disaccharides. We have proven that this relaxation process is an effect of formation of thin layer of air or water between plate of capacitor and sample. The same effect can be observed if plates of capacitor are oxidized. Thus, we concluded that their slowest mode is connected to the dc conduction process while their β JG process is primary relaxation of trehalose and maltose.

  17. Operational forecast products and applications based on WRF/Chem

    NASA Astrophysics Data System (ADS)

    Hirtl, Marcus; Flandorfer, Claudia; Langer, Matthias; Mantovani, Simone; Olefs, Marc; Schellander-Gorgas, Theresa

    2015-04-01

    The responsibilities of the national weather service of Austria (ZAMG) include the support of the federal states and the public in questions connected to the protection of the environment in the frame of advisory and counseling services as well as expert opinions. The ZAMG conducts daily Air-Quality forecasts using the on-line coupled model WRF/Chem. The mother domain expands over Europe, North Africa and parts of Russia. The nested domain includes the alpine region and has a horizontal resolution of 4 km. Local emissions (Austria) are used in combination with European inventories (TNO and EMEP) for the simulations. The modeling system is presented and the results from the evaluation of the assimilation of pollutants using the 3D-VAR software GSI is shown. Currently observational data (PM10 and O3) from the Austrian Air-Quality network and from European stations (EEA) are assimilated into the model on an operational basis. In addition PM maps are produced using Aerosol Optical Thickness (AOT) observations from MODIS in combination with model data using machine learning techniques. The modeling system is operationally evaluated with different data sets. The emphasis of the application is on the forecast of pollutants which are compared to the hourly values (PM10, O3 and NO2) of the Austrian Air-Quality network. As the meteorological conditions are important for transport and chemical processes, some parameters like wind and precipitation are automatically evaluated (SAL diagrams, maps, …) with other models (e.g. ECMWF, AROME, …) and ground stations via web interface. The prediction of the AOT is also important for operators of solar power plants. In the past Numerical Weather Prediction (NWP) models were used to predict the AOT based on cloud forecasts at the ZAMG. These models do not consider the spatial and temporal variation of the aerosol distribution in the atmosphere with a consequent impact on the accuracy of forecasts especially during clear-sky days

  18. Comparison of Formal Operations: Students Enrolled in ChemCom versus a Traditional Chemistry Course.

    ERIC Educational Resources Information Center

    Smith, Leslie A.; Bitner, Betty L.

    The purpose of this study was to determine the influence of an STS curriculum (ChemCom) versus a traditional chemistry curriculum (GenChem) on student formal reasoning level. Cluster random sampling was used to select the sample (N=123). Gender differences in formal reasoning level were also investigated. The abbreviated GALT pretest was…

  19. Life after "ChemCom": Do They Succeed in University-Level Chemistry Courses?

    ERIC Educational Resources Information Center

    Mason, Diana

    Chemistry in the Community ("ChemCom") is a high-school level chemistry text developed by the American Chemical Society (ACS) designed for the college-bound student. The purpose of this study was to identify students enrolled in a university-level chemistry course designed for the nonscience major who had experienced the ChemCom curriculum in high…

  20. Outreach within the Bristol ChemLabS CETL (Centre for Excellence in Teaching and Learning)

    ERIC Educational Resources Information Center

    Shallcross, Dudley E.; Harrison, Tim G.; Obey, Tim M.; Croker, Steve J.; Norman, Nick C.

    2013-01-01

    This paper presents an overview of the Bristol ChemLabS project. In particular, it describes the development and impacts of the outreach project within Bristol ChemLabS, the UK's Centre for Excellence in Teaching and Learning (CETL) in practical chemistry, and its continuation beyond the funded project. The major elements of working with both…

  1. Online-coupled modeling of volcanic ash and SO2 dispersion with WRF-Chem

    NASA Astrophysics Data System (ADS)

    Stuefer, Martin; Egan, Sean; Webley, Peter; Grell, Georg; Freitas, Saulo; Pavolonis, Mike; Dehn, Jonathan

    2014-05-01

    We included a volcanic emission and plume model into the Weather Research Forecast Model with inline Chemistry (WRF-Chem). The volcanic emission model with WRF-Chem has been tested and evaluated with historic eruptions, and the volcanic application was included into the official release of WRF-Chem beginning with WRF version 3.3 in 2011. Operational volcanic WRF-Chem runs have been developed using different domains centered on main volcanoes of the Aleutian chain and Popocatépetl Volcano, Mexico. The Global Forecast System (GFS) is used for the meteorological initialization of WRF-Chem, and default eruption source parameters serve as initial source data for the runs. We report on the model setup, and the advantages to treat the volcanic ash and sulphur dioxide emissions inline within the numerical weather prediction model. In addition we outline possibilities to initialize WRF-Chem with a fully automated algorithm to retrieve volcanic ash cloud properties from satellite data. WRF-Chem runs from recent volcanic eruptions resulted in atmospheric ash loadings, which compared well with the satellite data taking into account that satellite retrieval data represent only a limited amount of the actually emitted source due to detection thresholds. In addition particle aggregative effects are not included in the WRF-Chem model to date.

  2. ChemCam Investigation of the John Klein and Cumberland Drill Tailings

    NASA Astrophysics Data System (ADS)

    Jackson, R. S.; Wiens, R. C.; Newsom, H. E.; Vaniman, D. T.; Williams, J. M.

    2014-07-01

    Geochemical investigation by MSL’s ChemCam of drill tailings taken from the Sheepbed Mudstone, comparing and contrasting the composition of the substrate and the tailings as well as elemental chemistry from ChemCam and mineralogy observed by CheMin.

  3. ChemLabBox for SnifferStars

    2002-01-24

    The software entitled "ChemLabBox for SnifferStars" is used to collect, display, and save data from the Sandia National Laboratories chemical analysis system dubbed SnifferStar. Sensor data is streamed from a SnifferStar unit into a computer thru RS-232 in a manner that is not amendable to plotting. Also, there is no direct way to start and stop the unit as is. This software rearranges the data into something that can be easily plotted in real-time thenmore » saves the data into a text fild. In addition, this software provides the users a means to start and stop the hardware. This software was written specifically for SnifferStar. SnifferStar data is delivered at a very fast rate but for a short period of time. This software is written around that premise. It is written for Pentium or higher machines running Windows 95/98/ME/NT/2000/XP. Lockheed Martin is interested in using it for testing SnifferStar units before deployment. To date they have not indicated their intent to deliver the code either in part or whole as part of their product.« less

  4. Comment on “Frequency-domain stimulated and spontaneous light emission signals at molecular junctions” [J. Chem. Phys. 141, 074107 (2014)

    SciTech Connect

    Galperin, Michael; Ratner, Mark A.; Nitzan, Abraham

    2015-04-07

    We discuss the derivation of the optical response in molecular junctions presented by U. Harbola et al. [J. Chem. Phys. 141, 074107 (2014)], which questions some terms in the theory of Raman scattering in molecular junctions developed in our earlier publications. We show that the terms considered in our theory represent the correct contribution to calculated Raman scattering and are in fact identical to those considered by Harbola et al. We also indicate drawbacks of the presented approach in treating the quantum transport part of the problem.

  5. An overview of the PubChem BioAssay resource.

    PubMed

    Wang, Yanli; Bolton, Evan; Dracheva, Svetlana; Karapetyan, Karen; Shoemaker, Benjamin A; Suzek, Tugba O; Wang, Jiyao; Xiao, Jewen; Zhang, Jian; Bryant, Stephen H

    2010-01-01

    The PubChem BioAssay database (http://pubchem.ncbi.nlm.nih.gov) is a public repository for biological activities of small molecules and small interfering RNAs (siRNAs) hosted by the US National Institutes of Health (NIH). It archives experimental descriptions of assays and biological test results and makes the information freely accessible to the public. A PubChem BioAssay data entry includes an assay description, a summary and detailed test results. Each assay record is linked to the molecular target, whenever possible, and is cross-referenced to other National Center for Biotechnology Information (NCBI) database records. 'Related BioAssays' are identified by examining the assay target relationship and activity profile of commonly tested compounds. A key goal of PubChem BioAssay is to make the biological activity information easily accessible through the NCBI information retrieval system-Entrez, and various web-based PubChem services. An integrated suite of data analysis tools are available to optimize the utility of the chemical structure and biological activity information within PubChem, enabling researchers to aggregate, compare and analyze biological test results contributed by multiple organizations. In this work, we describe the PubChem BioAssay database, including data model, bioassay deposition and utilities that PubChem provides for searching, downloading and analyzing the biological activity information contained therein. PMID:19933261

  6. ChemCam Remote Microscopic Imager (RMI) Onboard Curiosity: Results of the First Three Months on Mars

    NASA Astrophysics Data System (ADS)

    Le Mouelic, Stephane; Gasnault, Olivier; Herkenhoff, Ken; Langevin, Yves; Maurice, Sylvestre; Bridges, Nathan; Pinet, Patrick; Mangold, Nicolas; Johnson, Jeffrey; Wiens, Roger; Bell, Jim; Dromart, Gilles; MSL Science Team

    2013-04-01

    The ChemCam instrument onboard the Curiosity rover is a Laser-Induced Breakdown Spectrometer (LIBS) coupled to a Remote Micro-Imager (RMI) [1,2]. Its main objective is to remotely determine the elemental composition of soils and rocks situated at distances up to 7 meters from the rover. We focus on the imaging capability of ChemCam using the RMI and initial analysis of RMI data [3,4,5,6]. The objectives of the RMI are to provide geomorphologic context of the LIBS analyses, locate the laser pits, document the changes induced by the laser shots on the target, and study the martian rocks and soils at high resolution. It is also the main tool to check the focusing of the laser, which is directly related to the intrinsic quality of LIBS spectra. This is particularly important for targets displaying significant variations of depth within the scene, and for which the optimum focus distance might differ from one LIBS point to the other. During the first months of the surface mission, well defined holes have been generally observed on soils, whereas the laser pits were sometimes hardly detectable on some rocks. RMI coupled to the LIBS therefore provides a way to investigate the rock hardness. The first images also demonstrate that the camera by itself adds a significant scientific value to the study of rocks by revealing their fine texture and morphology. Secondary imaging products have been produced. These include mosaics, color-added images using pansharpening to merge the black and white high resolution RMI images with the colors acquired by the MastCam multispectral cameras, and 3D-shape retrieval using the z-stack technique [7]. References: [1] Maurice et al., Space Sci. Reviews, Vol 170, Issue 1-4, pp. 95-166, 2012. [2] Wiens et al., Space Science Reviews, Space Sci. Reviews, Vol 170, Issue 1-4, pp. 167-227, 2012. [3] Le Mouélic et al., LPSC XLIV, 2013. [4] Langevin et al., LPSC XLIV, 2013. [5] Bridges et al.., LPSC XLIV, 2013. [6] Cousin et al. , LPSC XLIV, 2013. [7

  7. Continuous and discontinuous precipitation in Fe-1 at.%Cr-1 at.%Mo alloy upon nitriding; crystal structure and composition of ternary nitrides

    NASA Astrophysics Data System (ADS)

    Steiner, Tobias; Ramudu Meka, Sai; Rheingans, Bastian; Bischoff, Ewald; Waldenmaier, Thomas; Yeli, Guma; Martin, Tomas L.; Bagot, Paul A. J.; Moody, Michael P.; Mittemeijer, Eric J.

    2016-05-01

    The internal nitriding response of a ternary Fe-1 at.%Cr-1 at.%Mo alloy, which serves as a model alloy for many CrMo-based steels, was investigated. The nitrides developing upon nitriding were characterised by X-ray diffraction, scanning electron microscopy, electron probe microanalysis, transmission electron microscopy and atom probe tomography. The developed nitrides were shown to be (metastable) ternary mixed nitrides, which exhibit complex morphological, compositional and structural transformations as a function of nitriding time. Analogous to nitrided binary Fe-Cr and Fe-Mo alloys, in ternary Fe-Cr-Mo alloys initially continuous precipitation of fine, coherent, cubic, NaCl-type nitride platelets, here with the composition (Cr½,Mo½)N¾, occurs, with the broad faces of the platelets parallel to the {1 0 0}α-Fe lattice planes. These nitrides undergo a discontinuous precipitation reaction upon prolonged nitriding leading to the development of lamellae of a novel, hexagonal CrMoN2 nitride along {1 1 0}α-Fe lattice planes, and of spherical cubic, NaCl-type (Cr,Mo)Nx nitride particles within the ferrite lamellae. The observed structural and compositional changes of the ternary nitrides have been attributed to the thermodynamic and kinetic constraints for the internal precipitation of (misfitting) nitrides in the ferrite matrix.

  8. High resolution infrared spectroscopy from space: A preliminary report on the results of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment on Spacelab 3

    NASA Technical Reports Server (NTRS)

    Farmer, Crofton B.; Raper, Odell F.

    1987-01-01

    The ATMOS (Atmospheric Trace Molecule Spectroscopy) experiment has the broad purpose of investigating the physical structure, chemistry, and dynamics of the upper atmosphere through the study of the distributions of the neutral minor and trace constituents and their seasonal and long-term variations. The technique used is high-resolution infrared absorption spectroscopy using the Sun as the radiation source, observing the changes in the transmission of the atmosphere as the line-of-sight from the Sun to the spacecraft penetrates the atmosphere close to the Earth's limb at sunrise and sunset. During these periods, interferograms are generated at the rate of one each second which yield, when transformed, high resolution spectra covering the 2.2 to 16 micron region of the infrared. Twenty such occultations were recorded during the Spacelab 3 flight, which have produced concentration profiles for a large number of minor and trace upper atmospheric species in both the Northern and Southern Hemispheres. Several of these species have not previously been observed in spectroscopic data. The data reduction and analysis procedures used following the flight are discussed; a number of examples of the spectra obtained are shown, and a bar graph of the species detected thus far in the analysis is given which shows the altitude ranges for which concentration profiles were retrieved.

  9. Measurements of CH4, N2O, CO, H2O and O3 in the middle atmosphere by the ATMOS experiment on Spacelab 3

    NASA Technical Reports Server (NTRS)

    Gunson, M. R.; Farmer, C. B.; Norton, R. H.; Zander, R.; Rinsland, C. P.; Shaw, J. H.; Gao, Bo-Cai

    1989-01-01

    The volume mixing ratios of five minor gases (CH4, N2O, CO, H2O, and O3) were retrieved through the middle atmosphere from the analysis of 0.01/cm resolution infrared solar occultation spectra recorded near 28 N and 48 S latitudes with the ATMOS (Atmospheric Trace Molecule Spectroscopy) instrument, flown on board Spacelab 3. The results, which constitute the first simultaneous observations of continuous profiles through the middle atmosphere for these gases, are in general agreement with reported measurements from ground, balloon and satellite-based instruments for the same seasons. In detail, the vertical profiles of these gases show the effects of the upper and middle atmospheric transport patterns dominant during the season of these observations. The profiles inferred at different longitudes around 28 N suggest a near-uniform zonal distribution of these gases. Although based on fewer observations, the sunrise occultation measurements point to a larger variability in the vertical distribution of these gases at 48 S.

  10. ChemSonde: CO2 profiles using Radiosondes

    NASA Astrophysics Data System (ADS)

    Smith, Paul D.; Freshwater, Ray; Ouyang, Bin; Jones, Rod; Harris, Neil

    2016-04-01

    Atmospheric composition measurements in the tropical tropopause layer (TTL) and upper troposphere/lower stratosphere (UTLS), are fairly sparse. They require specialised equipment, such as instrumented aircraft or large balloons, and these platforms can be expensive to run and operate intermittently, and therefore cannot provide continuous or long-term measurements. Although satellites can provide this level of coverage, they have a finite operational lifetime, are expensive to develop and launch, and encounter limits to their information retrieval; especially in the UTLS due in part to the radiative properties of clouds and the spatial gradients of the gas species encountered there, leading to errors and lower resolution vertical measurements compared to in-situ observations. The UTLS generally ia an important region of the atmosphere, being sensitive to changes in climate (through anthropogenic activity for example) which can influence the radiative, transport and chemical processing occurring there. As the interface between the stratosphere and troposphere, changes in the UTLS structure and chemical composition can effect the composition of the stratosphere (e.g. O3 and H2O) in turn changing the radiative environment, with potential feedbacks on tropospheric climate. At present, the only routine profile measurements are provided by the global ozonesonde network with a small number of ground-based lidar measurements. Again, these methods are limited by their spatial coverage and the range of species measured. Extending these existing networks by making it feasible to conduct wide-ranging composition profile measurements, would have the potential to revolutionise atmospheric measurement programmes. ChemSonde is package developed to incorporate a novel miniature optical cavity CO2 instrument launched on standard meteorological balloons (and electrochemical (EC) sensors for CO, O3, NOx).The package is suitable for use in global sonde networks, e.g. Global Climate

  11. ChemCom: A Software Program for Searching and Comparing Chemical Libraries.

    PubMed

    Saeedipour, Sirus; Tai, David; Fang, Jianwen

    2015-07-27

    An efficient chemical comparator, a computer application facilitating searching and comparing chemical libraries, is useful in drug discovery and other relevant areas. The need for an efficient and user-friendly chemical comparator prompted us to develop ChemCom (Chemical Comparator) based on Java Web Start (JavaWS) technology. ChemCom provides a user-friendly graphical interface to a number of fast algorithms including a novel algorithm termed UnionBit Tree Algorithm. It utilizes an intuitive stepwise mechanism for selecting chemical comparison parameters before starting the comparison process. UnionBit has shown approximately an 165% speedup on average compared to its closest competitive algorithm implemented in ChemCom over real data. It is approximately 11 times faster than the Open Babel FastSearch algorithm in our tests. ChemCom can be accessed free-of-charge via a user-friendly website at http://bioinformatics.org/chemcom/. PMID:26067384

  12. ChemDoodle Web Components: HTML5 toolkit for chemical graphics, interfaces, and informatics.

    PubMed

    Burger, Melanie C

    2015-01-01

    ChemDoodle Web Components (abbreviated CWC, iChemLabs, LLC) is a light-weight (~340 KB) JavaScript/HTML5 toolkit for chemical graphics, structure editing, interfaces, and informatics based on the proprietary ChemDoodle desktop software. The library uses and WebGL technologies and other HTML5 features to provide solutions for creating chemistry-related applications for the web on desktop and mobile platforms. CWC can serve a broad range of scientific disciplines including crystallography, materials science, organic and inorganic chemistry, biochemistry and chemical biology. CWC is freely available for in-house use and is open source (GPL v3) for all other uses.Graphical abstractAdd interactive 2D and 3D chemical sketchers, graphics, and spectra to websites and apps with ChemDoodle Web Components. PMID:26185528

  13. Tropospheric Emission Spectrometer (TES) for the Earth Observing System (EOS) CHEM Satellite

    NASA Technical Reports Server (NTRS)

    Beer, R.; Glavich, T.; Rider, D.

    2000-01-01

    The Tropospheric Emission Spectrometer (TES) is an imaging infrared Fourier transform spectrometer scheduled to be launched into polar sun-synchronous orbit on the Earth Observing System (EOS) CHEM satellite in December 2002.

  14. MinChem: A Prototype Petrologic Database for Hanford Site Sediments

    SciTech Connect

    Mackley, Rob D.; Last, George V.; Serkowski, John A.; Middleton, Lisa A.; Cantrell, Kirk J.

    2010-09-01

    A prototype petrologic database (MinChem) has been under continual development for several years. MinChem contains petrologic, mineralogical, and bulk-rock geochemical data for Hanford Site sediments collected over multiple decades. The database is in relational form and consists of a series of related tables modeled after the Hanford Environmental Information System HEIS (BHI 2002) structures. The HEIS-compatible tables were created in anticipation of eventual migration into HEIS, or some future form of HEIS (e.g. HEIS-GEO). There are currently a total of 13,129 results in MinChem from 521 samples collected at 381 different sampling sites. These data come from 19 different original source documents published and unpublished (e.g. letter reports) between 1976 and 2009. The data in MinChem consist of results from analytical methods such as optical and electron microscopy, x-ray diffraction, x-ray fluorescence, and electron probe microanalysis.

  15. Comment on 'The diatomic dication CuZn{sup 2+} in the gas phase' [J. Chem. Phys. 135, 034306 (2011)

    SciTech Connect

    Fiser, Jiri; Diez, Reinaldo Pis; Franzreb, Klaus; Alonso, Julio A.

    2013-02-21

    In this Comment, the density functional theory (DFT) calculations carried out by Diez et al. [J. Chem. Phys. 135, 034306 (2011)] are revised within the framework of the coupled-cluster single double triple method. These more sophisticated calculations allow us to show that the {sup 2}{Sigma}{sup +} electronic ground state of CuZn{sup 2+}, characterized as the metastable ground state by DFT calculations, is a repulsive state instead. The {sup 2}{Delta} and {sup 2}{Pi} metastable states of CuZn{sup 2+}, on the other hand, should be responsible for the formation mechanism of the dication through the near-resonant electron transfer CuZn{sup +}+ Ar{sup +}{yields} CuZn{sup 2+}+ Ar reaction.

  16. Real-time Aerosol Forecasting over North America using RAP-Chem and the GSI.

    NASA Astrophysics Data System (ADS)

    Pagowski, M.

    2015-12-01

    RAP-Chem is an implementation of WRF-Chem meteorology-chemistry model that is run daily at NOAA/ESRL over continental domain for air-quality forecasting. The chemical forecasts are combined with observations of species using three-dimensional variational data assimilation procedure implemented in the Gridpoint Statistical Interpolation (GSI). In the presentation we detail the method of the assimilation and show verification statistics of the model performance.

  17. radEq Add-On Module for CFD Solver Loci-CHEM

    NASA Technical Reports Server (NTRS)

    McCloud, Peter

    2013-01-01

    Loci-CHEM to be applied to flow velocities where surface radiation due to heating from compression and friction becomes significant. The module adds a radiation equilibrium boundary condition to the computational fluid dynamics (CFD) code to produce accurate results. The module expanded the upper limit for accurate CFD solutions of Loci-CHEM from Mach 4 to Mach 10 based on Space Shuttle Orbiter Re-Entry trajectories. Loci-CHEM already has a very promising architecture and performance, but absence of radiation equilibrium boundary condition limited the application of Loci-CHEM to below Mach 4. The immediate advantage of the add-on module is that it allows Loci-CHEM to work with supersonic flows up to Mach 10. This transformed Loci-CHEM from a rocket engine- heritage CFD code with general subsonic and low-supersonic applications, to an aeroheating code with hypersonic applications. The follow-on advantage of the module is that it is a building block for additional add-on modules that will solve for the heating generated at Mach numbers higher than 10.

  18. Comment on "Study of dielectric relaxations of anhydrous trehalose and maltose glasses" [J. Chem. Phys. 134, 014508 (2011)].

    PubMed

    Kaminski, K; Wlodarczyk, P; Paluch, M

    2011-10-28

    Very recently Kwon et al. [H.-J. Kwon, J.-A. Seo, H. K. Kim, and Y. H. Hwang, J. Chem. Phys. 134, 014508 (2011)] published an article on the study of dielectric relaxation in trehalose and maltose glasses. They carried out broadband dielectric measurements at very wide range of temperatures covering supercooled liquid as well as glassy state of both saccharides. It is worth to mention that authors have also applied a new method for obtaining anhydrous glasses of trehalose and maltose that enables avoiding their caramelization. Four relaxation processes were identified in dielectric spectra of both saccharides. The slower one was identified as structural relaxation process the next one, not observed by the others, was assigned as Johari-Goldstein (JG) β-relaxation, while the last two secondary modes were of the same nature as found by Kaminski et al. [K. Kaminski, E. Kaminska, P. Wlodarczyk, S. Pawlus, D. Kimla, A. Kasprzycka, M. Paluch, J. Ziolo, W. Szeja, and K. L. Ngai, J. Phys. Chem. B 112, 12816 (2008)]. In this comment we show that the authors mistakenly assigned the slowest relaxation process as structural mode of disaccharides. We have proven that this relaxation process is an effect of formation of thin layer of air or water between plate of capacitor and sample. The same effect can be observed if plates of capacitor are oxidized. Thus, we concluded that their slowest mode is connected to the dc conduction process while their β JG process is primary relaxation of trehalose and maltose. PMID:22047271

  19. Global Oceanic Basalt Geochemistry From EarthChem Databases

    NASA Astrophysics Data System (ADS)

    Hofmann, A. W.; Sarbas, B.; Jochum, K. P.; Stracke, A.

    2004-12-01

    metadata are inadequate or absent, and a significant fraction of the primary data and metadata contain errors, either in the original publication or in the transfer to the database. Therefore, analysis of these databases must be performed by experienced geochemists, who are best qualified to recognize erroneous or low-quality data. Even so, elimination of such erroneous or poor data frequently requires subjective judgment. Such evaluations should then produce "expert data sets", which can subsequently be used by non-experts, including non-specialist geochemists, geophysicists, and geologists. A partial expert evaluation of global MORB geochemistry has been prepared by Su [2], who gives segment-by-segment MORB averages. We are preparing an expert data set for global trace element and isotope geochemistry of ocean island basalts. On the basis of these data, we reevaluate global compatibility relationships. At this stage, these relationships are remarkably similar to those summarized by Hofmann [3], and by Sun and McDonough [4], using extremely limited data. This validates the original methodology used by these authors. At the same time, basalt suites containing geochemical anomalies can now be more clearly delineated. Thus, EarthChem databases allow us to develop a comprehensive view of global chemical differentiation of the Earth. [1] Hofmann, A.W. (2003) in Treatise on Geochemistry, ed. R.W. Carlson, Vol.2, 61-101. [2] Su,, Y.J. (2002) PhD Thesis, Columbia University, 472p. [3] Hofmann, A.W. (1988) Earth Planet. Sci. Lett. 90, 297-314. [4] Sun, S.-S. & McDonough, W.F. (1989) Geol. Soc. Spec. Publ. 42 (eds. A.D. Saunders & M.J. Norry), 313-345.

  20. Comparing MSL ChemCam Analyses to Shergottite and Terrestrial Rock Types

    NASA Astrophysics Data System (ADS)

    Bridges, J.; Edwards, P.; Dyar, M. D.; Fisk, M. R.; Schwenzer, S. P.; Forni, O.; Wiens, R. C.

    2014-12-01

    The ChemCam instrument on Mars Science Laboratory determines the elemental composition of target areas at ≤6m range, and has acquired over 145000 spectra. Here we use the individual shots and averaged targets with the PLS1 dataset on both outcrops and float rocks. Various localities were sampled, including Rocknest, Sheepbed, Shaler, Cooperstown, Darwin and Kimberley. Rocknest and Sheepbed shots have quite homogeneous, basaltic compositions with Gini factors of 0.66 and 0.67 respectively (a Gini factor of 0 indicates a completely homogeneous dataset). Shaler is similarly homogeneous with a Gini factor 0.62 but is more felsic in composition. Darwin and Kimberley both follow a basaltic mixing trend between pyroxene and alkali feldspars. They have a heterogeneous spread with factors of 0.77 and 0.74. Kimberley and Darwin are the most alkaline outcrops, and then Shaler, finally Sheepbed and Rocknest are the least alkaline. The Na2O and K2O contents are controlled by variable abundances of alkaline feldspars. Many float rocks were also analysed. They include samples with mm-sized, visible feldspar grains, which are probable phenocrysts and cumulate grains. These rocks likely come from different sources as their compositions are quite heterogeneous e.g. the Gini factor for the whole set of feldspar-rich float rocks is 0.76 (using an average composition for each target). We compare these compositions with data from the MER APXS, and from this we can see that the float rocks sampled by MSL are closer to the alkaline feldspar end of the basaltic mixing trend than the more FeO+MgO-rich MER basalts (e.g. Rieder et al. 2004 10.1126/science.1104358) The basaltic shergottite meteorites also have higher FeO+MgO contents and lower Al2O3 than the MSL rocks. When compared on Al2O3-(FeOMgO)-(Na2OK2O)-CaO and other plots, the float rocks have compositions similar to a spread between terrestrial diorite and gabbro, though some have high Na2O+K2O contents.

  1. Comparison of Laser Induced Breakdown Spectroscopy (LIBS) on Martian Meteorite NWA 7034 to ChemCam Observations at Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Gordon, S.; Newsom, H. E.; Agee, C. B.; Santos, A. R.; Clegg, S. M.; Wiens, R. C.; Lasue, J.; Sautter, V.

    2014-12-01

    The ChemCam instrument on board the Mars Science Laboratory (MSL) Curiosity rover uses laser-induced breakdown spectroscopy (LIBS) to analyze rock and soil targets on Mars from up to 7 m away. The Nd:KGW laser can shoot up to 1000 shots at one location and profile up to 1 mm depth into a rock. Identical LIBS instrumentation is located at Los Alamos National Laboratory and was used to analyze martian meteorite NWA 7034, a non-SNC basaltic breccia whose bulk composition matches the martian surface. Initial LIBS analysis of NWA 7034 included observations on two basaltic clasts in the meteorite. Electron microprobe analysis (EPMA) was performed on the two clasts for comparison with elemental compositions measured using LIBS. The two instruments give similar compositions of major oxides within the error of both techniques. EPMA analysis was also completed on three light-toned clasts and a dark-toned clast in the meteorite. The light-toned clasts have Al/Si vs. (Fe+Mg)/Si compositions ranging from felsic to mafic, and the dark-toned clast shows a mafic composition. A Sammon's map was created to compare LIBS data for NWA 7034 and ChemCam targets Stark, Crestaurum, Link, Portage, Jake_M, Mara, Thor_Lake, Coronation, Pearson, and Prebble. This nonlinear statistical mapping technique is used for clustering assessment of LIBS data in two dimensions. The map shows NWA 7034 clustering in its own location, and the closest similar ChemCam rock targets are La_Reine and Ashuamipi, which are both coarse grained targets that have a mafic component consistent with augite. The most similar ChemCam soil targets are the Crestaurum and Portage. Creation of maps with a greater number of targets will show more of the similarities between NWA 7034 and ChemCam target rocks and soils. Further analysis will compare NWA 7034 LIBS data, data from the paired meteorite NWA 7533, and a variety of ChemCam targets that are similar in morphology and texture.

  2. Stratospheric Observations of CH3D and HDO from ATMOS Infrared Solar Spectra: Enrichments of Deuterium in Methane and Implications for HD

    NASA Technical Reports Server (NTRS)

    Irion, F. W.; Moyer, E. J.; Gunson, M. R.; Rinsland, C. P.; Yung, Y. L.; Michelsen, H. A.; Salawitch, R. J.; Chang, A. Y.; Newchurch, M. J.; Abbas, M. M.; Abrams, M. C.; Zander, R.

    1996-01-01

    Stratospheric mixing ratios of CH3D from 100 mb to 17mb (approximately equals 15 to 28 km)and HDO from 100 mb to 10 mb (approximately equals 15 to 32 km) have been inferred from high resolution solar occultation infrared spectra from the Atmospheric Trace MOlecule Spectroscopy (ATMOS) Fourier-transform interferometer. The spectra, taken on board the Space Shuttle during the Spacelab 3 and ATLAS-1, -2, and -3 missions, extend in latitude from 70 deg S to 65 deg N. We find CH3D entering the stratosphere at an average mixing ratio of (9.9 +/- 0.8) x 10(exp -10) with a D/H ratio in methane (7.1 +/- 7.4)% less than that in Standard Mean Ocean Water (SMOW) (1 sigma combined precision and systematic error). In the mid to lower stratosphere, the average lifetime of CH3D is found to be (1.19 +/- 0.02) times that of CH4, resulting in an increasing D/H ratio in methane as air 'ages' and the methane mixing ratio decreases. We find an average of (1.0 +/- 0.1) molecules of stratospheric HDO are produced for each CH3D destroyed (1 sigma combined precision and systematic error), indicating that the rate of HDO production is approximately equal to the rate of CH3D destruction. Assuming negligible amounts of deuterium in species other than HDO, CH3D and HD, this limits the possible change in the stratospheric HD mixing ratio below about 10 mb to be +/- 0.1 molecules HD created per molecule CH3D destroyed.

  3. Overview of 3 years of ChemCam' chemical compositions along the Curiosity's traverse at Gale Crater.

    NASA Astrophysics Data System (ADS)

    Cousin, Agnès; Wiens, Roger; Maurice, Sylvestre; Gasnault, Olivier

    2016-04-01

    Curiosity rover has been in Gale crater for more than3 years now. It drove ~12 km from its landing point up to the Bagnold Dunes. The ChemCam instrument is widely used to assess the chemistry of rocks and soils at the submillimeter scale. As of sol 1200, ChemCam sampled >1000 targets, corresponding to >300000 laser shots, >6000 images, and many passive spectra. The Bradbury landing site, a plain located at a distal portion of the alluvial fan from Peace Vallis, exposed several float rocks presenting igneous compositions ranging from mafic up to a trachytic end-member. These observations provided an important clue concerning the diversity of early Mars magmatism that was not previously recognized. More igneous float rocks have been observed all along the traverse, being more felsic closer to the landing site, and more mafic near the cratered unit, after the Kimberley formation. The Sheepbed area is essentially composed of mudstones that show a very homogeneous composition, close to the average Martian crust, providing evidence of aqueous episodes with little alteration in this area. ChemCam showed that the bedrock host experienced other diagenetic events with Mg- and Fe-rich clays in erosion-resistant raised ridges on one hand, and calcium sulfate veins on the other hand. The nearby Shaler fluvial sandstone outcrop, the first outcrop of potential deltaic foreset beds, shows K enrichment. This enrichment is also observed at the Kimberley formation (another drill site flanked by foreset beds), located 7 km SW of Shaler, with up to 5.3 wt % at the Mount Remarkable member. Conglomerates have been analyzed in detail all along the traverse as they represent a link between the source rocks and the finer-grained sediments such as the sandstones and mudstones. They have shown an average composition that is enriched in alkalis, Al, and Si compared to the average Martian crust, with a clear enrichment in K2O in the vicinity of the Kimberley formation. Enrichment in K2O at

  4. Evaluation of the DWPF Cold Chem Dissolution Method with Tank 7 and Tank 51 Radioactive Sludge

    SciTech Connect

    Click, D.R.

    2004-03-11

    Dissolution experiments were conducted on radioactive sludge from Tank 7, before transfer of the contents of Tank 7 to Tank 51, and the subsequent sludge in Tank 51 to evaluate the effectiveness of the DWPF Cold Chem Method. The DWPF Cold Chem Method is a room temperature dissolution method (DWPF Cold Chem Method) used in the DWPF on the Slurry Receipt and Adjustment Tank (SRAT) samples in preparation for instrumental analysis. Four types of dissolutions experiments were carried out, the DWPF Cold Chem Method, hot aqua regia, sodium peroxide fusion and hot HF-HNO3. The hot HF-HNO3 digestion is modified version of the DWPF method that incorporates a heating step. The hot aqua regia and sodium peroxide fusion digestions were included as reference digestions. The resulting solutions from all the sludge digestions were analyzed by ICP-ES (Inductively Coupled Plasma Emission Spectroscopy). Visual observations and ICP-ES results were used to evaluate the effectiveness of the DWPF Cold Chem by comparison to the hot aqua regia, sodium peroxide fusion and the hot HF-HNO3 digestions. The data and experimental observations support the following conclusions: The DWPF Cold Chem Method seemed to be effective at dissolving initial species of radioactive sludge, but concurrent precipitation of insoluble mixed-metal fluoride salts was observed in both the Tank 7 and Tank 51 Cold Chem digestion solutions. Complete dissolution, by visual observation, was achieved with a modified hot HF-HNO3 digestion. This was done as an alternative to the DWPF room-temperature acid dissolution.

  5. tmChem: a high performance approach for chemical named entity recognition and normalization

    PubMed Central

    2015-01-01

    Chemical compounds and drugs are an important class of entities in biomedical research with great potential in a wide range of applications, including clinical medicine. Locating chemical named entities in the literature is a useful step in chemical text mining pipelines for identifying the chemical mentions, their properties, and their relationships as discussed in the literature. We introduce the tmChem system, a chemical named entity recognizer created by combining two independent machine learning models in an ensemble. We use the corpus released as part of the recent CHEMDNER task to develop and evaluate tmChem, achieving a micro-averaged f-measure of 0.8739 on the CEM subtask (mention-level evaluation) and 0.8745 f-measure on the CDI subtask (abstract-level evaluation). We also report a high-recall combination (0.9212 for CEM and 0.9224 for CDI). tmChem achieved the highest f-measure reported in the CHEMDNER task for the CEM subtask, and the high recall variant achieved the highest recall on both the CEM and CDI tasks. We report that tmChem is a state-of-the-art tool for chemical named entity recognition and that performance for chemical named entity recognition has now tied (or exceeded) the performance previously reported for genes and diseases. Future research should focus on tighter integration between the named entity recognition and normalization steps for improved performance. The source code and a trained model for both models of tmChem is available at: http://www.ncbi.nlm.nih.gov/CBBresearch/Lu/Demo/tmChem. The results of running tmChem (Model 2) on PubMed are available in PubTator: http://www.ncbi.nlm.nih.gov/CBBresearch/Lu/Demo/PubTator PMID:25810774

  6. Impact of resolution on aerosol radiative feedbacks with in online-coupled chemistry/climate simulations (WRF-Chem) for EURO-CORDEX compliant domains

    NASA Astrophysics Data System (ADS)

    López-Romero, Jose Maria; Baró, Rocío; Palacios-Peña, Laura; Jerez, Sonia; Jiménez-Guerrero, Pedro; Montávez, Juan Pedro

    2016-04-01

    Several studies have shown that a high spatial resolution in atmospheric model runs improves the simulation of some meteorological variables, such as precipitation, particularly extreme events and in regions with complex orography [1]. However, increasing model spatial resolution makes the computational time rise exponentially. Hence, very high resolution experiments on large domains can hamper the execution of climatic runs. This problem shoots up when using online-coupled chemistry climate models, making a careful evaluation of improvements versus costs mandatory. Under this umbrella, the objective of this work is to investigate the sensitivity of aerosol radiative feedbacks from online-coupled chemistry regional model simulations to the spatial resolution. For that, the WRF-Chem [2] model is used for a case study to simulate the episode occurring between July 25th and August 15th of 2010. It is characterized by a high loading of atmospheric aerosol particles coming mainly from wildfires over large European regions (Russia, Iberian Peninsula). Three spatial resolutions are used defined for Euro-Cordex compliant domains [3]: 0.44°, 0.22° and 0.11°. Anthropogenic emissions come from TNO databases [4]. The analysis focuses on air quality variables (mainly PM10, PM2.5), meteorological variables (temperature, radiation) and other aerosol optical properties (aerosol optical depth). The CPU time ratio for the different domains is 1 (0.44°), 4(0.22°) and 28(0.11°) (normalized times). Comparison among simulations and observations are analyzed. Preliminary results show the difficulty to justify the much larger computational cost of high-resolution experiments when comparing with observations from a meteorological point of view, despite the finer spatio-temporal detail of the obtained pollutant fields. [1] Prein, A. F. (2014, December). Precipitation in the EURO-CORDEX 0.11° and 0.44° simulations: high resolution, high benefits?. In AGU Fall Meeting Abstracts (Vol

  7. Chemo-stratigraphy in the Murray Formation Using ChemCam

    NASA Astrophysics Data System (ADS)

    Blaney, D. L.; Anderson, R. B.; Bridges, N.; Bridges, J.; Calef, F. J., III; Clegg, S. M.; Le Deit, L.; Fisk, M. R.; Forni, O.; Gasnault, O.; Kah, L. C.; Kronyak, R. E.; Lanza, N.; Lasue, J.; Mangold, N.; Maurice, S.; Milliken, R.; Ming, D. W.; Nachon, M.; Newsom, H. E.; Rapin, W.; Stack, K.; Sumner, D. Y.; Wiens, R. C.

    2015-12-01

    Curiosity has completed a detailed chemo-stratigraphy analysis at the Pahrump exposure of the Murray formation. In total >570 chemical measurements and supporting remote micro images to classify texturally were collected. Chemical trends with both stratigraphic position and with texture were evaluated. From these data emerges a complex aqueous history where sediments have interacted with fluids with variable chemistry in distinct episodes. The ChemCam data collected at the nearby "Garden City" (GC) vein complex provides constraints on the chemical evolution of the Pahrump. GC is thought be stratigraphically above the Pahrump outcrop. Fluids producing the veins likely also migrated through the Pahrump sediments. Multiple episodes of fluids are evident at GC, forming distinct Ca sulfate, F-rich, enhanced MgO, and FeO-rich veins. These different fluid chemistries could be the result of distinct fluids migrating through the section from a distance with a pre-established chemical signature, fluids locally evolved from water rock interactions, or both. Texturally rocks have been classified into two distinct categories: fine grained or as cross-bedded sandstones. The sandstones have significantly lower SiO2, Al2O3, and K2O and higher FeO, and CaO. Fine grained rocks have further been sub-classified as resistant and recessive with other textural features such as laminations and pits noted.The strongest chemical trend in the fine-grained sandstones shows enhancements in MgO and FeO in erosion-resistant materials compared to fine grained recessive units, suggesting that increased abundance of Mg- and/or iron-rich cements may provide additional strength. The MgO and FeO variations with texture are independent of stratigraphic locations (e.g resistant material at both the bottom and top of the outcrop both are enhanced in MgO and FeO). The presence of the GC MgO and FeO rich veins provides additional evidence for fluids rich in these elements were present in the outcrop. Other

  8. ChemBank: a small-molecule screening and cheminformatics resource database

    PubMed Central

    Seiler, Kathleen Petri; George, Gregory A.; Happ, Mary Pat; Bodycombe, Nicole E.; Carrinski, Hyman A.; Norton, Stephanie; Brudz, Steve; Sullivan, John P.; Muhlich, Jeremy; Serrano, Martin; Ferraiolo, Paul; Tolliday, Nicola J.; Schreiber, Stuart L.; Clemons, Paul A.

    2008-01-01

    ChemBank (http://chembank.broad.harvard.edu/) is a public, web-based informatics environment developed through a collaboration between the Chemical Biology Program and Platform at the Broad Institute of Harvard and MIT. This knowledge environment includes freely available data derived from small molecules and small-molecule screens and resources for studying these data. ChemBank is unique among small-molecule databases in its dedication to the storage of raw screening data, its rigorous definition of screening experiments in terms of statistical hypothesis testing, and its metadata-based organization of screening experiments into projects involving collections of related assays. ChemBank stores an increasingly varied set of measurements derived from cells and other biological assay systems treated with small molecules. Analysis tools are available and are continuously being developed that allow the relationships between small molecules, cell measurements, and cell states to be studied. Currently, ChemBank stores information on hundreds of thousands of small molecules and hundreds of biomedically relevant assays that have been performed at the Broad Institute by collaborators from the worldwide research community. The goal of ChemBank is to provide life scientists unfettered access to biomedically relevant data and tools heretofore available primarily in the private sector. PMID:17947324

  9. The ChemCam Instrument Suite on the Mars Science Laboratory (MSL) Rover: Science Objectives and Mast Unit Description

    NASA Astrophysics Data System (ADS)

    Maurice, S.; Wiens, R. C.; Saccoccio, M.; Barraclough, B.; Gasnault, O.; Forni, O.; Mangold, N.; Baratoux, D.; Bender, S.; Berger, G.; Bernardin, J.; Berthé, M.; Bridges, N.; Blaney, D.; Bouyé, M.; Caïs, P.; Clark, B.; Clegg, S.; Cousin, A.; Cremers, D.; Cros, A.; DeFlores, L.; Derycke, C.; Dingler, B.; Dromart, G.; Dubois, B.; Dupieux, M.; Durand, E.; d'Uston, L.; Fabre, C.; Faure, B.; Gaboriaud, A.; Gharsa, T.; Herkenhoff, K.; Kan, E.; Kirkland, L.; Kouach, D.; Lacour, J.-L.; Langevin, Y.; Lasue, J.; Le Mouélic, S.; Lescure, M.; Lewin, E.; Limonadi, D.; Manhès, G.; Mauchien, P.; McKay, C.; Meslin, P.-Y.; Michel, Y.; Miller, E.; Newsom, H. E.; Orttner, G.; Paillet, A.; Parès, L.; Parot, Y.; Pérez, R.; Pinet, P.; Poitrasson, F.; Quertier, B.; Sallé, B.; Sotin, C.; Sautter, V.; Séran, H.; Simmonds, J. J.; Sirven, J.-B.; Stiglich, R.; Striebig, N.; Thocaven, J.-J.; Toplis, M. J.; Vaniman, D.

    2012-09-01

    ChemCam is a remote sensing instrument suite on board the "Curiosity" rover (NASA) that uses Laser-Induced Breakdown Spectroscopy (LIBS) to provide the elemental composition of soils and rocks at the surface of Mars from a distance of 1.3 to 7 m, and a telescopic imager to return high resolution context and micro-images at distances greater than 1.16 m. We describe five analytical capabilities: rock classification, quantitative composition, depth profiling, context imaging, and passive spectroscopy. They serve as a toolbox to address most of the science questions at Gale crater. ChemCam consists of a Mast-Unit (laser, telescope, camera, and electronics) and a Body-Unit (spectrometers, digital processing unit, and optical demultiplexer), which are connected by an optical fiber and an electrical interface. We then report on the development, integration, and testing of the Mast-Unit, and summarize some key characteristics of ChemCam. This confirmed that nominal or better than nominal performances were achieved for critical parameters, in particular power density (>1 GW/cm2). The analysis spot diameter varies from 350 μm at 2 m to 550 μm at 7 m distance. For remote imaging, the camera field of view is 20 mrad for 1024×1024 pixels. Field tests demonstrated that the resolution (˜90 μrad) made it possible to identify laser shots on a wide variety of images. This is sufficient for visualizing laser shot pits and textures of rocks and soils. An auto-exposure capability optimizes the dynamical range of the images. Dedicated hardware and software focus the telescope, with precision that is appropriate for the LIBS and imaging depths-of-field. The light emitted by the plasma is collected and sent to the Body-Unit via a 6 m optical fiber. The companion to this paper (Wiens et al. this issue) reports on the development of the Body-Unit, on the analysis of the emitted light, and on the good match between instrument performance and science specifications.

  10. Interactions between volatile organic compounds and reactive halogen in the tropical marine atmosphere using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Badia, Alba; Reeves, Claire E.; Baker, Alex; Volkamer, Rainer; von Glasow, Roland

    2016-04-01

    Halogen species (chlorine, bromine and iodine) are known to play an important role in the chemistry and oxidizing capacity of the troposphere, particularly in the marine boundary layer (MBL). Reactive halogens cause ozone (O3) destruction, change the HOx and NOX partitioning, affect the oxidation of volatile organic compounds (VOCs) and mercury, reduce the lifetime of methane, and take part in new particle formation. Numerical models predicted that reactive halogen compounds account for 30% of O3 destruction in the MBL and 5-20% globally. There are indications that the chemistry of reactive halogens and oxygenated VOCs (OVOCs) in the tropics are inter-related. Moreover, the presence of aldehydes, such as glyoxal (CHOCHO), has a potential impact on radical cycling and secondary organic aerosol (SOA) formation in the MBL and free troposphere (FT). Model calculations suggest aldehydes to be an important sink for bromine atoms and hence competition for their reaction with O3 forming BrO and so illustrating a link between the cycles of halogens and OVOCs in the marine atmosphere. The main objective of this contribution is to investigate the atmospheric chemistry in the tropical East Pacific with a focus on reactive halogens and OVOCs and their links using the latest version of the Weather Research and Forecasting (WRF) model coupled with Chemistry (WRF-Chem) and field data from the TORERO campaign. WRF-Chem is a highly flexible community model for atmospheric research where aerosol-radiation-cloud feedback processes are taken into account. Our current reaction mechanism in WRF-Chem is based on the MOZART mechanism and has been extended to include bromine, chlorine and iodine chemistry. The MOZART mechanism includes detailed gas-phase chemistry of CHOCHO formation as well as state-of-the-science pathways to form SOA. Oceanic emissions of aldehydes, including CHOCHO, and of organic halogens based on measurements from the TORERO campaign have been added into the model. Sea

  11. The ChemCam Instrument Suite on the Mars Science Laboratory (MSL) Rover: Science Objectives and Mast Unit Description

    USGS Publications Warehouse

    Maurice, S.; Wiens, R.C.; Saccoccio, M.; Barraclough, B.; Gasnault, O.; Forni, O.; Mangold, N.; Baratoux, D.; Bender, S.; Berger, G.; Bernardin, J.; Berthé, M.; Bridges, N.; Blaney, D.; Bouyé, M.; Caïs, P.; Clark, B.; Clegg, S.; Cousin, A.; Cremers, D.; Cros, A.; DeFlores, L.; Derycke, C.; Dingler, B.; Dromart, G.; Dubois, B.; Dupieux, M.; Durand, E.; d'Uston, L.; Fabre, C.; Faure, B.; Gaboriaud, A.; Gharsa, T.; Herkenhoff, K.; Kan, E.; Kirkland, L.; Kouach, D.; Lacour, J.-L.; Langevin, Y.; Lasue, J.; Le Mouélic, S.; Lescure, M.; Lewin, E.; Limonadi, D.; Manhès, G.; Mauchien, P.; McKay, C.; Meslin, P.-Y.; Michel, Y.; Miller, E.; Newsom, Horton E.; Orttner, G.; Paillet, A.; Parès, L.; Parot, Y.; Pérez, R.; Pinet, P.; Poitrasson, F.; Quertier, B.; Sallé, B.; Sotin, C.; Sautter, V.; Séran, H.; Simmonds, J.J.; Sirven, J.-B.; Stiglich, R.; Striebig, N.; Thocaven, J.-J.; Toplis, M.J.; Vaniman, D.

    2012-01-01

    ChemCam is a remote sensing instrument suite on board the "Curiosity" rover (NASA) that uses Laser-Induced Breakdown Spectroscopy (LIBS) to provide the elemental composition of soils and rocks at the surface of Mars from a distance of 1.3 to 7 m, and a telescopic imager to return high resolution context and micro-images at distances greater than 1.16 m. We describe five analytical capabilities: rock classification, quantitative composition, depth profiling, context imaging, and passive spectroscopy. They serve as a toolbox to address most of the science questions at Gale crater. ChemCam consists of a Mast-Unit (laser, telescope, camera, and electronics) and a Body-Unit (spectrometers, digital processing unit, and optical demultiplexer), which are connected by an optical fiber and an electrical interface. We then report on the development, integration, and testing of the Mast-Unit, and summarize some key characteristics of ChemCam. This confirmed that nominal or better than nominal performances were achieved for critical parameters, in particular power density (>1 GW/cm2). The analysis spot diameter varies from 350 μm at 2 m to 550 μm at 7 m distance. For remote imaging, the camera field of view is 20 mrad for 1024×1024 pixels. Field tests demonstrated that the resolution (˜90 μrad) made it possible to identify laser shots on a wide variety of images. This is sufficient for visualizing laser shot pits and textures of rocks and soils. An auto-exposure capability optimizes the dynamical range of the images. Dedicated hardware and software focus the telescope, with precision that is appropriate for the LIBS and imaging depths-of-field. The light emitted by the plasma is collected and sent to the Body-Unit via a 6 m optical fiber. The companion to this paper (Wiens et al. this issue) reports on the development of the Body-Unit, on the analysis of the emitted light, and on the good match between instrument performance and science specifications.

  12. Spatio-temporal variability of aerosols over East China inferred by merged visibility-GEOS-Chem aerosol optical depth

    NASA Astrophysics Data System (ADS)

    Lin, Jintai; Li, Jing

    2016-05-01

    Long-term visibility measurements offer useful information for aerosol and climate change studies. Recently, a new technique to converting visibility measurements to aerosol optical depth (AOD) has been developed on a station-to-station basis (Lin et al., 2014). However, factors such as human observation differences and local meteorological conditions often impair the spatial consistency of the visibility converted AOD dataset. Here we further adopt AOD spatial information from a chemical transport model GEOS-Chem, and merge visibility inferred and modeled early-afternoon AOD over East China on a 0.667° long. × 0.5° lat. grid for 2005-2012. Comparisons with MODIS/Aqua retrieved AOD and subsequent spectral decomposition analyses show that the merged dataset successfully corrects the low bias in the model while preserving its spatial pattern, resulting in very good agreement with MODIS in both magnitude and spatio-temporal variability. The low bias is reduced from 0.10 in GEOS-Chem AOD to 0.04 in the merged data averaged over East China, and the correlation in the seasonal and interannual variability between MODIS and merged AOD is well above 0.75 for most regions. Comparisons between the merged and AERONET data also show an overall small bias and high correlation. The merged dataset reveals four major pollution hot spots in China, including the North China Plain, the Yangtze River Delta, the Pearl River Delta and the Sichuan Basin, consistent with previous works. AOD peaks in spring-summer over the North China Plain and Yangtze River Delta and in spring over the Pearl River Delta, with no distinct seasonal cycle over the Sichuan Basin. The merged AOD has the largest difference from MODIS over the Sichuan Basin. We also discuss possible benefits of visibility based AOD data that correct the sampling bias in MODIS retrievals related to cloud-free sampling and misclassified heavy haze conditions.

  13. Spatio-temporal variability of aerosols over East China inferred by merged visibility-GEOS-Chem aerosol optical depth

    NASA Astrophysics Data System (ADS)

    Lin, Jintai; Li, Jing

    2016-05-01

    Long-term visibility measurements offer useful information for aerosol and climate change studies. Recently, a new technique to converting visibility measurements to aerosol optical depth (AOD) has been developed on a station-to-station basis (Lin et al., 2014). However, factors such as human observation differences and local meteorological conditions often impair the spatial consistency of the visibility converted AOD dataset. Here we further adopt AOD spatial information from a chemical transport model GEOS-Chem, and merge visibility inferred and modeled early-afternoon AOD over East China on a 0.667° long. × 0.5° lat. grid for 2005-2012. Comparisons with MODIS/Aqua retrieved AOD and subsequent spectral decomposition analyses show that the merged dataset successfully corrects the low bias in the model while preserving its spatial pattern, resulting in very good agreement with MODIS in both magnitude and spatio-temporal variability. The low bias is reduced from 0.10 in GEOS-Chem AOD to 0.04 in the merged data averaged over East China, and the correlation in the seasonal and interannual variability between MODIS and merged AOD is well above 0.75 for most regions. Comparisons between the merged and AERONET data also show an overall small bias and high correlation. The merged dataset reveals four major pollution hot spots in China, including the North China Plain, the Yangtze River Delta, the Pearl River Delta and the Sichuan Basin, consistent with previous works. AOD peaks in spring-summer over the North China Plain and Yangtze River Delta and in spring over the Pearl River Delta, with no distinct seasonal cycle over the Sichuan Basin. The merged AOD has the largest difference from MODIS over the Sichuan Basin. We also discuss possible benefits of visibility based AOD data that correct the sampling bias in MODIS retrievals related to cloud-free sampling and misclassified heavy haze conditions.

  14. Soil Diversity and Hydration as Observed by ChemCam at Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Meslin, P.-Y.; Gasnault, O.; Forni, O.; Schröder, S.; Cousin, A.; Berger, G.; Clegg, S. M.; Lasue, J.; Maurice, S.; Sautter, V.; Le Mouélic, S.; Wiens, R. C.; Fabre, C.; Goetz, W.; Bish, D.; Mangold, N.; Ehlmann, B.; Lanza, N.; Harri, A.-M.; Anderson, R.; Rampe, E.; McConnochie, T. H.; Pinet, P.; Blaney, D.; Léveillé, R.; Archer, D.; Barraclough, B.; Bender, S.; Blake, D.; Blank, J. G.; Bridges, N.; Clark, B. C.; DeFlores, L.; Delapp, D.; Dromart, G.; Dyar, M. D.; Fisk, M.; Gondet, B.; Grotzinger, J.; Herkenhoff, K.; Johnson, J.; Lacour, J.-L.; Langevin, Y.; Leshin, L.; Lewin, E.; Madsen, M. B.; Melikechi, N.; Mezzacappa, A.; Mischna, M. A.; Moores, J. E.; Newsom, H.; Ollila, A.; Perez, R.; Renno, N.; Sirven, J.-B.; Tokar, R.; de la Torre, M.; d'Uston, L.; Vaniman, D.; Yingst, A.; Kemppinen, Osku; Minitti, Michelle; Cremers, David; Bell, James F.; Edgar, Lauren; Farmer, Jack; Godber, Austin; Wadhwa, Meenakshi; Wellington, Danika; McEwan, Ian; Newman, Claire; Richardson, Mark; Charpentier, Antoine; Peret, Laurent; King, Penelope; Weigle, Gerald; Schmidt, Mariek; Li, Shuai; Milliken, Ralph; Robertson, Kevin; Sun, Vivian; Baker, Michael; Edwards, Christopher; Farley, Kenneth; Griffes, Jennifer; Miller, Hayden; Newcombe, Megan; Pilorget, Cedric; Rice, Melissa; Siebach, Kirsten; Stack, Katie; Stolper, Edward; Brunet, Claude; Hipkin, Victoria; Marchand, Geneviève; Sánchez, Pablo Sobrón; Favot, Laurent; Cody, George; Steele, Andrew; Flückiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Israël, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Pérez, René; Saccoccio, Muriel; Yana, Charles; Armiens-Aparicio, Carlos; Rodríguez, Javier Caride; Blázquez, Isaías Carrasco; Gómez, Felipe Gómez; Gómez-Elvira, Javier; Hettrich, Sebastian; Malvitte, Alain Lepinette; Jiménez, Mercedes Marín; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F. Javier; Jurado, Antonio Molina; Mora-Sotomayor, Luis; Caro, Guillermo Muñoz; López, Sara Navarro; Peinado-González, Verónica; Pla-García, Jorge; Manfredi, José Antonio Rodriguez; Romeral-Planelló, Julio José; Fuentes, Sara Alejandra Sans; Martinez, Eduardo Sebastian; Redondo, Josefina Torres; Urqui-O'Callaghan, Roser; Mier, María-Paz Zorzano; Chipera, Steve; Mauchien, Patrick; Manning, Heidi; Fairén, Alberto; Hayes, Alexander; Joseph, Jonathan; Squyres, Steven; Sullivan, Robert; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; DeMarines, Julia; Grinspoon, David; Reitz, Günther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Haukka, Harri; Kahanpää, Henrik; Kauhanen, Janne; Kemppinen, Osku; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Wray, James; Wilhelm, Mary Beth; Poitrasson, Franck; Patel, Kiran; Gorevan, Stephen; Indyk, Stephen; Paulsen, Gale; Gupta, Sanjeev; Schieber, Juergen; Geffroy, Claude; Baratoux, David; Cros, Alain; Lee, Qiu-Mei; Pallier, Etienne; Parot, Yann; Toplis, Mike; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Sutter, Brad; Cabane, Michel; Coscia, David; Israël, Guy; Szopa, Cyril; Robert, François; Nachon, Marion; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; François, Pascaline; Raulin, François; Teinturier, Samuel; Cameron, James; Dingler, Robert; Jackson, Ryan Steele; Johnstone, Stephen; Little, Cynthia; Nelson, Tony; Williams, Richard B.; Jones, Andrea; Kirkland, Laurel; Treiman, Allan; Baker, Burt; Cantor, Bruce; Caplinger, Michael; Davis, Scott; Duston, Brian; Edgett, Kenneth; Fay, Donald; Hardgrove, Craig; Harker, David; Herrera, Paul; Jensen, Elsa; Kennedy, Megan R.; Krezoski, Gillian; Krysak, Daniel; Lipkaman, Leslie; Malin, Michael; McCartney, Elaina; McNair, Sean; Nixon, Brian; Posiolova, Liliya; Ravine, Michael; Salamon, Andrew; Saper, Lee; Stoiber, Kevin; Supulver, Kimberley; Van Beek, Jason; Van Beek, Tessa; Zimdar, Robert; French, Katherine Louise; Iagnemma, Karl; Miller, Kristen; Summons, Roger; Goesmann, Fred; Hviid, Stubbe; Johnson, Micah; Lefavor, Matthew; Lyness, Eric; Breves, Elly; Fassett, Caleb; Bristow, Thomas; DesMarais, David; Edwards, Laurence; Haberle, Robert; Hoehler, Tori; Hollingsworth, Jeff; Kahre, Melinda; Keely, Leslie; McKay, Christopher; Wilhelm, Mary Beth; Bleacher, Lora; Brinckerhoff, William; Choi, David; Conrad, Pamela; Dworkin, Jason P.; Eigenbrode, Jennifer; Floyd, Melissa; Freissinet, Caroline; Garvin, James; Glavin, Daniel; Harpold, Daniel; Jones, Andrea; Mahaffy, Paul; Martin, David K.; McAdam, Amy; Pavlov, Alexander; Raaen, Eric; Smith, Michael D.; Stern, Jennifer; Tan, Florence; Trainer, Melissa; Meyer, Michael; Posner, Arik; Voytek, Mary; Anderson, Robert C.; Aubrey, Andrew; Beegle, Luther W.; Behar, Alberto; Brinza, David; Calef, Fred; Christensen, Lance; Crisp, Joy A.; Feldman, Jason; Feldman, Sabrina; Flesch, Gregory; Hurowitz, Joel; Jun, Insoo; Keymeulen, Didier; Maki, Justin; Morookian, John Michael; Parker, Timothy; Pavri, Betina; Schoppers, Marcel; Sengstacken, Aaron; Simmonds, John J.; Spanovich, Nicole; Vasavada, Ashwin R.; Webster, Christopher R.; Yen, Albert; Cucinotta, Francis; Jones, John H.; Ming, Douglas; Morris, Richard V.; Niles, Paul; Nolan, Thomas; Radziemski, Leon; Berman, Daniel; Dobrea, Eldar Noe; Williams, Rebecca M. E.; Lewis, Kevin; Cleghorn, Timothy; Huntress, Wesley; Manhès, Gérard; Hudgins, Judy; Olson, Timothy; Stewart, Noel; Sarrazin, Philippe; Grant, John; Vicenzi, Edward; Wilson, Sharon A.; Bullock, Mark; Ehresmann, Bent; Hamilton, Victoria; Hassler, Donald; Peterson, Joseph; Rafkin, Scot; Zeitlin, Cary; Fedosov, Fedor; Golovin, Dmitry; Karpushkina, Natalya; Kozyrev, Alexander; Litvak, Maxim; Malakhov, Alexey; Mitrofanov, Igor; Mokrousov, Maxim; Nikiforov, Sergey; Prokhorov, Vasily; Sanin, Anton; Tretyakov, Vladislav; Varenikov, Alexey; Vostrukhin, Andrey; Kuzmin, Ruslan; Wolff, Michael; McLennan, Scott; Botta, Oliver; Drake, Darrell; Bean, Keri; Lemmon, Mark; Schwenzer, Susanne P.; Lee, Ella Mae; Sucharski, Robert; Hernández, Miguel Ángel de Pablo; Ávalos, Juan José Blanco; Ramos, Miguel; Kim, Myung-Hee; Malespin, Charles; Plante, Ianik; Muller, Jan-Peter; Navarro-González, Rafael; Ewing, Ryan; Boynton, William; Downs, Robert; Fitzgibbon, Mike; Harshman, Karl; Morrison, Shaunna; Dietrich, William; Kortmann, Onno; Palucis, Marisa; Sumner, Dawn Y.; Williams, Amy; Lugmair, Günter; Wilson, Michael A.; Rubin, David; Jakosky, Bruce; Balic-Zunic, Tonci; Frydenvang, Jens; Jensen, Jaqueline Kløvgaard; Kinch, Kjartan; Koefoed, Asmus; Stipp, Susan Louise Svane; Boyd, Nick; Campbell, John L.; Gellert, Ralf; Perrett, Glynis; Pradler, Irina; VanBommel, Scott; Jacob, Samantha; Owen, Tobias; Rowland, Scott; Atlaskin, Evgeny; Savijärvi, Hannu; Boehm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Guo, Jingnan; Köhler, Jan; García, César Martín; Mueller-Mellin, Reinhold; Wimmer-Schweingruber, Robert; Bridges, John C.; Benna, Mehdi; Franz, Heather; Bower, Hannah; Brunner, Anna; Blau, Hannah; Boucher, Thomas; Carmosino, Marco; Atreya, Sushil; Elliott, Harvey; Halleaux, Douglas; Rennó, Nilton; Wong, Michael; Pepin, Robert; Elliott, Beverley; Spray, John; Thompson, Lucy; Gordon, Suzanne; Williams, Joshua; Vasconcelos, Paulo; Bentz, Jennifer; Nealson, Kenneth; Popa, Radu; Kah, Linda C.; Moersch, Jeffrey; Tate, Christopher; Day, Mackenzie; Kocurek, Gary; Hallet, Bernard; Sletten, Ronald; Francis, Raymond; McCullough, Emily; Cloutis, Ed; ten Kate, Inge Loes; Kuzmin, Ruslan; Arvidson, Raymond; Fraeman, Abigail; Scholes, Daniel; Slavney, Susan; Stein, Thomas; Ward, Jennifer; Berger, Jeffrey

    2013-09-01

    The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in composition to the martian dust. It possesses a ubiquitous hydrogen signature in ChemCam spectra, corresponding to the hydration of the amorphous phases found in the soil by the CheMin instrument. This hydration likely accounts for an important fraction of the global hydration of the surface seen by previous orbital measurements. ChemCam analyses did not reveal any significant exchange of water vapor between the regolith and the atmosphere. These observations provide constraints on the nature of the amorphous phases and their hydration.

  15. MTCI/ThermoChem steam reforming process for solid fuels for combined cycle power generation

    SciTech Connect

    Mansour, M.N.; Voelker, G.; Dural-Swamy, K.

    1995-12-31

    Manufacturing and Technology Conversion International, Inc. (MTCI) has developed a novel technology to convert solid fuels including biomass, coal, municipal solid waste (MSW) and wastewater sludges into usable syngas by steam reforming in an indirectly heated, fluid-bed reactor. MTCI has licensed and patented the technology to ThermoChem, Inc. Both MTCI and ThermoChem have built two modular commercial-scale demonstration units: one for recycle paper mill rejects (similar to refuse-derived fuel [RDF]), and another for chemical recovery of black liquor. ThermoChem has entered into an agreement with Ajinkyatara Cooperative Sugar Factory, India, for building a 10 MW combined cycle power generation facility based on bagasse and agro-residue gasification.

  16. Soil diversity and hydration as observed by ChemCam at Gale crater, Mars

    USGS Publications Warehouse

    Meslin, P.-Y.; Gasnault, O.; Forni, O.; Schroder, S.; Cousin, A.; Berger, G.; Clegg, S.M.; Lasue, J.; Maurice, S.; Sautter, V.; Le Mouélic, S.; Wiens, R.C.; Fabre, C.; Goetz, W.; Bish, D.L.; Mangold, N.; Ehlmann, B.; Lanza, N.; Harri, A.-M.; Anderson, Ryan Bradley; Rampe, E.; McConnochie, T.H.; Pinet, P.; Blaney, D.; Leveille; Archer, D.; Barraclough, B.; Bender, S.; Blake, D.; Blank, J.G.; Bridges, N.; Clark, B. C.; DeFlores, L.; Delapp, D.; Dromart, G.; Dyar, M.D.; Fisk, M. R.; Gondet, B.; Grotzinger, J.; Herkenhoff, K.; Johnson, J.; Lacour, J.-L.; Langevin, Y.; Leshin, L.; Lewin, E.; Madsen, M.B.; Melikechi, N.; Mezzacappa, Alissa; Mischna, M.A.; Moores, J.E.; Newsom, H.; Ollila, A.; Perez; Renno, N.; Sirven, J.B.; Tokar, R.; de la Torre, M.; d'Uston, L.; Vaniman, D.; Yingst, A.

    2013-01-01

    The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in composition to the martian dust. It possesses a ubiquitous hydrogen signature in ChemCam spectra, corresponding to the hydration of the amorphous phases found in the soil by the CheMin instrument. This hydration likely accounts for an important fraction of the global hydration of the surface seen by previous orbital measurements. ChemCam analyses did not reveal any significant exchange of water vapor between the regolith and the atmosphere. These observations provide constraints on the nature of the amorphous phases and their hydration.

  17. Soil diversity and hydration as observed by ChemCam at Gale crater, Mars.

    PubMed

    Meslin, P-Y; Gasnault, O; Forni, O; Schröder, S; Cousin, A; Berger, G; Clegg, S M; Lasue, J; Maurice, S; Sautter, V; Le Mouélic, S; Wiens, R C; Fabre, C; Goetz, W; Bish, D; Mangold, N; Ehlmann, B; Lanza, N; Harri, A-M; Anderson, R; Rampe, E; McConnochie, T H; Pinet, P; Blaney, D; Léveillé, R; Archer, D; Barraclough, B; Bender, S; Blake, D; Blank, J G; Bridges, N; Clark, B C; DeFlores, L; Delapp, D; Dromart, G; Dyar, M D; Fisk, M; Gondet, B; Grotzinger, J; Herkenhoff, K; Johnson, J; Lacour, J-L; Langevin, Y; Leshin, L; Lewin, E; Madsen, M B; Melikechi, N; Mezzacappa, A; Mischna, M A; Moores, J E; Newsom, H; Ollila, A; Perez, R; Renno, N; Sirven, J-B; Tokar, R; de la Torre, M; d'Uston, L; Vaniman, D; Yingst, A

    2013-09-27

    The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in composition to the martian dust. It possesses a ubiquitous hydrogen signature in ChemCam spectra, corresponding to the hydration of the amorphous phases found in the soil by the CheMin instrument. This hydration likely accounts for an important fraction of the global hydration of the surface seen by previous orbital measurements. ChemCam analyses did not reveal any significant exchange of water vapor between the regolith and the atmosphere. These observations provide constraints on the nature of the amorphous phases and their hydration. PMID:24072924

  18. ChemCam on MSL 2009: first laser induced breakdown spectrometer for space science

    SciTech Connect

    Wiens, Roger C

    2008-01-01

    ChemCam is one of the 10 instrument suites on the Mars Science Laboratory, a martian rover being built by Jet Propulsion Laboratory, for the next NASA mission to Mars (MSL 2009). ChemCam is an instrument package consisting of two remote sensing instruments: a Laser-Induced Breakdown Spectrometer (LIBS) and a Remote Micro-Imager (RMI). LIBS provides elemental compositions of rocks and soils, while the RMI places the LIBS analyses in their geomorphologic context. Both instruments rely on an autofocus capability to precisely focus on the chosen target, located at distances from the rover comprised between 1 and 9 m for LIBS, and 2 m and infinity for RMI. ChemCam will help determine which samples, within the vicinity of the MSL rover, are of sufficient interest to use the contact and in-situ instruments for further characterization. It will provide valuable analyses of samples that are inaccessible to contact and in-situ instruments, and of a much larger number of samples than can be done with this kind of instrument. ChemCam also has a capability to provide passive spectroscopy data of rocks and soils on Mars. ChemCam hardware consists of a Mast Unit (MU), provided by France, and a Body Unit (BU) built and tested in the USA. The Flight Model of the MU is assembled, tested and now available in the USA, while the BU is currently being assembled and tested. Both will be connected by the end of year '08 for end-to-end functional and performance tests, before delivery to JPL and assembly on the MSL rover. Launch is scheduled for October 09. After describing the concept of ChemCam, this presentation focuses on its French part, Mast Unit. The results presented show that Mast Unit is able to generate a plasma and collect its light, over the full applicable ranges of distances and temperatures on Mars.

  19. Calcium Sulfate Characterized by ChemCam/Curiosity at Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Nachon, M.; Clegg, S. N.; Mangold, N.; Schroeder, S.; Kah, L. C.; Dromart, G.; Ollila, A.; Johnson, J. R.; Oehler, D. Z.; Bridges, J. C.; LeMouelic, S.; Forni, O.; Wiens, R. C.; Rapin, W.; Anderson, R. B.; Blaney, D. L.; Bell, J. F. , III; Clark, B.; Cousin, A.; Dyar, M. D.; Ehlmann, B.; Fabre, C.; Gasnault, O.; Grotzinger, J.; Lasue, J.; Lewin, E.; Leveille, R.; McLennan, S.; Maurice, S.; Meslin, P.-Y.; Rice, M.; Squyres, S. W.; Stack, K.; Sumner, D. Y.; Vaniman, D.; Wellington, D.

    2014-01-01

    Onboard the Mars Science Laboratory (MSL) Curiosity rover, the ChemCam instrument consists of :(1) a Laser-Induced Breakdown Spectrometer (LIBS) for elemental analysis of the targets [1;2] and (2) a Remote Micro Imager (RMI), for the imaging context of laser analysis [3]. Within the Gale crater, Curiosity traveled from Bradbury Landing through the Rocknest region and into Yellowknife Bay (YB). In the latter, abundant light-toned fracture-fill material were seen [4;5]. ChemCam analysis demonstrate that those fracture fills consist of calcium sulfates [6].

  20. Calibrating the ChemCam LIBS for carbonate minerals on Mars

    SciTech Connect

    Wiens, Roger C; Clegg, Samuel M; Ollila, Ann M; Barefield, James E; Lanza, Nina; Newsom, Horton E

    2009-01-01

    The ChemCam instrument suite on board the NASA Mars Science Laboratory (MSL) rover includes the first LIBS instrument for extraterrestrial applications. Here we examine carbonate minerals in a simulated martian environment using the LIDS technique in order to better understand the in situ signature of these materials on Mars. Both chemical composition and rock type are determined using multivariate analysis (MVA) techniques. Composition is confirmed using scanning electron microscopy (SEM) techniques. Our initial results suggest that ChemCam can recognize and differentiate between carbonate materials on Mars.

  1. Calibrating the ChemCam LIBS for Carbonate Minerals on Mars

    DOE R&D Accomplishments Database

    Wiens, Roger C.; Clegg, Samuel M.; Ollila, Ann M.; Barefield, James E.; Lanza, Nina; Newsom, Horton E.

    2009-01-01

    The ChemCam instrument suite on board the NASA Mars Science Laboratory (MSL) rover includes the first LIBS instrument for extraterrestrial applications. Here we examine carbonate minerals in a simulated martian environment using the LIDS technique in order to better understand the in situ signature of these materials on Mars. Both chemical composition and rock type are determined using multivariate analysis (MVA) techniques. Composition is confirmed using scanning electron microscopy (SEM) techniques. Our initial results suggest that ChemCam can recognize and differentiate between carbonate materials on Mars.

  2. EarthChem: International Collaboration for Solid Earth Geochemistry in Geoinformatics

    NASA Astrophysics Data System (ADS)

    Walker, J. D.; Lehnert, K. A.; Hofmann, A. W.; Sarbas, B.; Carlson, R. W.

    2005-12-01

    The current on-line information systems for igneous rock geochemistry - PetDB, GEOROC, and NAVDAT - convincingly demonstrate the value of rigorous scientific data management of geochemical data for research and education. The next generation of hypothesis formulation and testing can be vastly facilitated by enhancing these electronic resources through integration of available datasets, expansion of data coverage in location, time, and tectonic setting, timely updates with new data, and through intuitive and efficient access and data analysis tools for the broader geosciences community. PetDB, GEOROC, and NAVDAT have therefore formed the EarthChem consortium (www.earthchem.org) as a international collaborative effort to address these needs and serve the larger earth science community by facilitating the compilation, communication, serving, and visualization of geochemical data, and their integration with other geological, geochronological, geophysical, and geodetic information to maximize their scientific application. We report on the status of and future plans for EarthChem activities. EarthChem's development plan includes: (1) expanding the functionality of the web portal to become a `one-stop shop for geochemical data' with search capability across databases, standardized and integrated data output, generally applicable tools for data quality assessment, and data analysis/visualization including plotting methods and an information-rich map interface; and (2) expanding data holdings by generating new datasets as identified and prioritized through community outreach, and facilitating data contributions from the community by offering web-based data submission capability and technical assistance for design, implementation, and population of new databases and their integration with all EarthChem data holdings. Such federated databases and datasets will retain their identity within the EarthChem system. We also plan on working with publishers to ease the assimilation

  3. Calibrating the ChemCam laser-induced breakdown spectroscopy instrument for carbonate minerals on Mars

    SciTech Connect

    Lanza, Nina L.; Wiens, Roger C.; Clegg, Samuel M.; Ollila, Ann M.; Humphries, Seth D.; Newsom, Horton E.; Barefield, James E.

    2010-05-01

    The ChemCam instrument suite onboard the NASA Mars Science Laboratory rover includes the first laser-induced breakdown spectroscopy (LIBS) instrument for extraterrestrial applications. Here we examine carbonate minerals in a simulated martian environment to better understand the LIBS signature of these materials on Mars. Both chemical composition and rock type are determined using multivariate analysis techniques. Composition is confirmed using scanning electron microscopy. Our results show that ChemCam can recognize and differentiate between different types of carbonate materials on Mars.

  4. Comment on ``Unified explanation of the anomalous dynamic properties of highly asymmetric polymer blends'' [J. Chem. Phys. 138, 054903 (2013)

    NASA Astrophysics Data System (ADS)

    Colmenero, J.

    2013-05-01

    In a recent paper by Ngai and Capaccioli ["Unified explanation of the anomalous dynamic properties of highly asymmetric polymer blends," J. Chem. Phys. 138, 054903 (2013), 10.1063/1.4789585] the authors claimed that the so-called coupling model (CM) provides a unified explanation of all dynamical anomalies that have been reported for dynamically asymmetric blends over last ten years. Approximately half of the paper is devoted to chain-dynamic properties involving un-entangled polymers. According to the authors, the application of the CM to these results is based on the existence of a crossover at a time tc ≈ 1-2 ns of the magnitudes describing chain-dynamics. Ngai and Capaccioli claimed that the existence of such a crossover is supported by the neutron scattering and MD-simulation results, corresponding to the blend poly(methyl methacrylate)/poly(ethylene oxide), by Niedzwiedz et al. [Phys. Rev. Lett. 98, 168301 (2007), 10.1103/PhysRevLett.98.168301] and Brodeck et al. [Macromolecules 43, 3036 (2010), 10.1021/ma902820a], respectively. Being one of the authors of these two papers, I will demonstrate here that there is no evidence supporting such a crossover in the data reported in these papers.

  5. Compositions of Sub-Millimeter-Size Clasts seen by ChemCam in Martian Soils at Gale : A Window Into the Production processes of Soils

    NASA Astrophysics Data System (ADS)

    Cousin, A.; Meslin, P.; Forni, O.; Rapin, W.; Tokar, R. L.; Fabre, C.; Wiens, R. C.; Gasnault, O.; Ollila, A.; Maurice, S.; Lasue, J.; Sautter, V.; Clegg, S. M.; Le Mouélic, S.; Dromart, G.; Mangold, N.; Berger, G.; Team, M.

    2013-12-01

    Curiosity landed the August 6, 2012 in Gale Crater, Mars. With its 80 kg payload, this rover possesses unique analytical capabilities to investigate the chemistry and mineralogy of the Martian soil. In particular, the ChemCam laser-induced breakdown spectroscopy (LIBS) instrument allows shallow (mm to cm) soil depth profile analysis, thanks to shot-to-shot spectra acquisition (usually 30 laser shots are performed, but many more can be done). This instrument gives for the first time a good opportunity to carry out large numbers of analyses on soil chemistry and its homogeneity at fine spatial scales (from 360 to 550 μm [Maurice et al, 2012]). This study is focused on the geochemical diversity observed between different soil separates, in particular between fine sand and coarse sand particles, whose mobility and geographical origin are likely to be different. Previous missions have shown that the soils have a uniform composition planet-wide [Yen et al., 2005]. Analyses performed by the APXS and by ChemCam in an aeolian sand shadow and in its vicinity extend this result to the fine-grained soils encountered in Gale Crater [Blake et al., 2013; Meslin et al., 2013]. However, ChemCam has sampled more than 170 soils during the first 250 sols, and has revealed the presence of three kinds of soils in Gale: i) mm-sized grains of felsic composition, usually encountered in the hummocky unit, ii) mafic, fine-grained soils found at Rocknest and throughout the rover traverse, and iii) soils with an intermediate composition, possibly as a result of mechanical mixing between the two former categories, or possibly chemically distinct [Meslin et al, 2013]. To follow up with this analysis, the composition of coarse sand grains was investigated using the spectra acquired shot by shot. Independent Component Analysis (ICA) [Forni et al., 2013] shows that there are two principal groups of clasts. Spectral analysis confirms that a first group is enriched in Na, Si, Ca and Al, whereas the

  6. MicroChemLab, A Novel Approach for Handheld Chemical Sensing

    NASA Astrophysics Data System (ADS)

    Lewis, Patrick

    2003-03-01

    In 1996, Sandia National Laboratories began development of a chemical sensing platform based on microfabricated components. The goal of the project was to develop a handheld system for the detection of chemical warfare (CW) agent vapors in air. The components developed for this project are analogous to devices used in analytical laboratories. The benefit of microfabrication is that the resulting components are small and require little power to operate. The key elements of MicroChemLab are a sample collector - preconcentrator, a GC column and a surface acoustic wave (SAW) array detector. The preconcentrator is a thermally isolated silicon nitride membrane with a resistive heater patterned on one side and a sorptive sol gel film deposited on the other. Since the membrane has a very small mass, the resistive heater can ballistically elevate the temperature of the sorptive film to 200° C in approximately 10 ms. The sol gel film collects target compounds efficiently, but rejects volatile industrial solvents like alcohols, ketones, etc. The GC column is a one-meter high aspect ratio spiral channel etched in silicon with an anodically bonded pyrex lid completing the channel. A heater patterned on the silicon allows the column to be temperature ramped. Analytes injected from the preconcentrator are separated in this stage. The SAW array detector contains 3 delay lines used for sensing and 1 reference delay line. Each delay line is driven by an application specific integrated circuit (ASIC) at 500 MHz. Instead of counting frequency, additional ASICs incorporate a phase comparator that delivers a DC signal proportional to the amount of phase change. The three sensing elements of the detector provide a pattern that is indicative of the class of compound detected i.e. nerve agents or blister agents. Combined, these components provide a selective and sensitive handheld solution for the detection of chemical warfare agents. We will present lab data showing the performance of

  7. Igneous composition vaiations determined by ChemCam along Curiosity's traverse from Bradbury to Rocknest area at Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Sautter, Violaine; MSL Science Team

    2013-04-01

    Since landing in Gale Crater (-4.59, 137,44°) the rover Curiosity, has driven during the first 90 sols, 420 meter east descending ∼ 20m from the Bradbury Landing site towards Glenelg. From sols 13 on, the ChemCam instrument suite performed compositional and imaging analyses of rocks and soils along the route. Each Chem- Cam LIBS observations covers a spot between 350 and 550 μm dia thus individual observations generally do not represent the whole rock composition but rather represent individual grains or a mixture thereof. Most of observations consist of a linear 5-point raster or a 3 x 3 grid. All major elements were regularly reported together with minor and trace elements. During the traverse, two distinct zones have been characterized: Zone I, from sol 0 to sol 47 (i.e. 280 meter traverse), belongs to the Humocky terrains supposed to be a part of the alluvial fan below Peace Vallis, which descends from the crater rim to the Northwest. It is defined by abundant gravels and igneous float rocks and isolated conglomerate outcrops. Rock textures indicate a high ratio of intrusive over extrusive: plutonic rocks vary from homogenous grain size either coarse (1-3mm grains Mara) or fine grained (less than 300 m Coronation) to variable grain size within a given rock (Jake-M). Some contain abundant laths of whitish minerals. ChemCam analyses are Si-rich (up to 60% wt.% or more) together with high Al (more than 15%) and high alkali (Na > K) in a range expected for alkali feldspar compositions. The lowest Si content correlates with low Al and high Fe consistent with ferromagnesian composition. The highest Si content (Stark a white vesicular rock) could indicate the presence of quartz. Clasts analyzed in one conglomerate (Link) had a range of compositions dominated by feldspathic material consistent with loose pebbles in the area and igneous porphyroblast. Beyond Anton soil (sol48), Curiosity entered zone II, transitional to a more distal unit with respect to the fan

  8. ChemSource SourceBook, Version 2.0: Volume 1.

    ERIC Educational Resources Information Center

    Orna, Mary Virginia, Ed.; And Others

    ChemSource is designed as a strategy to help preservice and inservice high school chemistry teachers promote student learning more effectively. Its major premise is that well-designed laboratory investigations are an important avenue for cultivating student interest, engagement, and meaningful learning in chemistry. The SourceBook component of…

  9. a Spectroscopy Based P-Chem Lab, Including a Detailed Text and Lab Manual

    NASA Astrophysics Data System (ADS)

    Muenter, John

    2015-06-01

    Rochester's second semester physical chemistry lab course is based on spectroscopy experiments and follows a full semester of quantum mechanics lectures. The laboratory course is fully separate from the traditional physical chemistry course and has its own lectures. The lab course is constructed to achieve three major goals: provide a detailed knowledge of the instrumentation that acquires data, establish a good understanding of how that data is analyzed, and give students a familiarity with spectroscopic techniques and quantum mechanical models. Instrumentation is emphasized by using common components to construct different experiments. Microwave, modulation and detection components are used for both OCS pure rotation and ESR experiments. Optical components, a monochromator, and PMT detectors are used in a HeNe laser induced fluorescence experiment on I2 {(J. Chem. Ed. 73, 576 (1996)) and a photoluminescence experiment on pyrene {(J. Chem. Ed. 73, 580 (1996)). OCS is studied in both the microwave and infrared regions, and the C=S stretching vibration is identified through microwave intensity measurements. Lecture notes and laboratory instructions are combined in an exhaustive text of more than 400 pages, containing 325 figures, 285 equations and numerous MathCad data analysis programs. This text can be downloaded as a 10 Mbyte pdf file at chem.rochester.edu/˜muenter/CHEM232Manual.

  10. ChemSource SourceBook, Version 2.0: Volume 2.

    ERIC Educational Resources Information Center

    Orna, Mary Virginia, Ed.; And Others

    ChemSource is designed as a strategy to help preservice and inservice high school chemistry teachers promote student learning more effectively. Its major premise is that well-designed laboratory investigations are an important avenue for cultivating student interest, engagement, and meaningful learning in chemistry. The SourceBook component of…

  11. Chemistry Provision for Primary Pupils: The Experiences of 10 Years of Bristol ChemLabs Outreach

    ERIC Educational Resources Information Center

    Harrison, Timothy G.; Shallcross, Dudley E.

    2016-01-01

    Bristol ChemLabS, the UK's Centre for Excellence in Teaching and Learning in practical chemistry, delivers numerous outreach activity days per year for thousands of primary school pupils annually. These mainly comprise demonstration assemblies and hands on workshops for pupils in the main. The activities support the UK's Key Stage 2 science…

  12. Introduction to the Spring 2014 ConfChem on the Flipped Classroom

    ERIC Educational Resources Information Center

    Luker, Chris; Muzyka, Jennifer; Belford, Robert

    2015-01-01

    Students' active engagement is one of the most critical challenges to any successful learning environment. The blending of active engagement along with rich, meaningful content is necessary for chemical educators to re-examine the purpose of the chemistry classroom. The Spring 2014 ConfChem conference, Flipped Classroom, was held from May 9 to…

  13. The Virtual ChemLab Project: A Realistic and Sophisticated Simulation of Inorganic Qualitative Analysis

    ERIC Educational Resources Information Center

    Woodfield, Brian F.; Catlin, Heidi R.; Waddoups, Gregory L.; Moore, Melissa S.; Swan, Richard; Bodily, Greg; Allen, Rob

    2004-01-01

    Virtual ChemLab project is an instructional laboratory involved in providing a practical experience by connecting the theory and laboratory practicals, teaching laboratory techniques and teaching the cognitive processes. This lab provides the students with the freedom to explore, repeat the procedures again, focuses on the underlying principles of…

  14. ConfChem Conference on Flipped Classroom: Using a Blog to Flip a Classroom

    ERIC Educational Resources Information Center

    Haile, January D.

    2015-01-01

    This communication summarizes one of the invited papers to the Flipped Classroom ACS Division of Chemical Education Committee on Computers in Chemical Education online ConfChem held from May 18 to June 24, 2014. Just in Time Teaching is a technique in which students read the material before class and respond to a few questions. In a first-year…

  15. Industrial capability to chem-mill aluminum alloy 2219 in T-37 and T-87

    NASA Technical Reports Server (NTRS)

    Milewski, C., Jr.; Chen, K. C. S.

    1979-01-01

    Procedures and chemical baths were developed for chem-milling aluminum alloy 2219. Using a series of sample etchings, it was found that good etching results could be obtained by using 'white plastic for porcelain repair (toluol, xylol, and petroleum distillates)' on top of cellosolve acetate as resist coatings and ferric chloride as on etchant.

  16. The ChemViz Project: Using a Supercomputer To Illustrate Abstract Concepts in Chemistry.

    ERIC Educational Resources Information Center

    Beckwith, E. Kenneth; Nelson, Christopher

    1998-01-01

    Describes the Chemistry Visualization (ChemViz) Project, a Web venture maintained by the University of Illinois National Center for Supercomputing Applications (NCSA) that enables high school students to use computational chemistry as a technique for understanding abstract concepts. Discusses the evolution of computational chemistry and provides a…

  17. ChemSource SourceBook, Version 2.0: Volume 3.

    ERIC Educational Resources Information Center

    Orna, Mary Virginia, Ed.; And Others

    ChemSource is designed as a strategy to help preservice and inservice high school chemistry teachers promote student learning more effectively. Its major premise is that well-designed laboratory investigations are an important avenue for cultivating student interest, engagement, and meaningful learning in chemistry. The SourceBook component of…

  18. ChemSource SourceBook, Version 2.0: Volume 4.

    ERIC Educational Resources Information Center

    Orna, Mary Virginia, Ed.; And Others

    ChemSource is designed as a strategy to help preservice and inservice high school chemistry teachers promote student learning more effectively. Its major premise is that well-designed laboratory investigations are an important avenue for cultivating student interest, engagement, and meaningful learning in chemistry. The SourceBook component of…

  19. WebChem Viewer: a tool for the easy dissemination of chemical and structural data sets

    PubMed Central

    2014-01-01

    Background Sharing sets of chemical data (e.g., chemical properties, docking scores, etc.) among collaborators with diverse skill sets is a common task in computer-aided drug design and medicinal chemistry. The ability to associate this data with images of the relevant molecular structures greatly facilitates scientific communication. There is a need for a simple, free, open-source program that can automatically export aggregated reports of entire chemical data sets to files viewable on any computer, regardless of the operating system and without requiring the installation of additional software. Results We here present a program called WebChem Viewer that automatically generates these types of highly portable reports. Furthermore, in designing WebChem Viewer we have also created a useful online web application for remotely generating molecular structures from SMILES strings. We encourage the direct use of this online application as well as its incorporation into other software packages. Conclusions With these features, WebChem Viewer enables interdisciplinary collaborations that require the sharing and visualization of small molecule structures and associated sets of heterogeneous chemical data. The program is released under the FreeBSD license and can be downloaded from http://nbcr.ucsd.edu/WebChemViewer. The associated web application (called “Smiley2png 1.0”) can be accessed through freely available web services provided by the National Biomedical Computation Resource at http://nbcr.ucsd.edu. PMID:24886360

  20. An investigation of methods for injecting emissions from boreal wildfires using WRF-Chem during ARCTAS

    NASA Astrophysics Data System (ADS)

    Sessions, W. R.; Fuelberg, H. E.; Kahn, R. A.; Winker, D. M.

    2010-11-01

    The Weather Research and Forecasting Model (WRF) is considered a "next generation" mesoscale meteorology model. The inclusion of a chemistry module (WRF-Chem) allows transport simulations of chemical and aerosol species such as those observed during NASA's Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) in 2008. The ARCTAS summer deployment phase during June and July coincided with large boreal wildfires in Saskatchewan and Eastern Russia. One of the most important aspects of simulating wildfire plume transport is the height at which emissions are injected. WRF-Chem contains an integrated one-dimensional plume rise model to determine the appropriate injection layer. The plume rise model accounts for thermal buoyancy associated with fires and the local atmospheric stability. This study compares results from the plume model against those of two more traditional injection methods: Injecting within the planetary boundary layer, and in a layer 3-5 km above ground level. Fire locations are satellite derived from the GOES Wildfire Automated Biomass Burning Algorithm (WF_ABBA) and the MODIS thermal hotspot detection. Two methods for preprocessing these fire data are compared: The prep_chem_sources method included with WRF-Chem, and the Naval Research Laboratory's Fire Locating and Monitoring of Burning Emissions (FLAMBE). Results from the simulations are compared with satellite-derived products from the AIRS, MISR and CALIOP sensors. Results show that the FLAMBE pre-processor produces more realistic injection heights than does prep_chem_sources. The plume rise model using FLAMBE provides the best agreement with satellite-observed injection heights. Conversely, when the planetary boundary layer or the 3-5 km AGL layer were filled with emissions, the resulting injection heights exhibit less agreement with observed plume heights. Results indicate that differences in injection heights produce different transport pathways. These

  1. Transport Simulations of Carbon Monoxide and Aerosols from Boreal Wildfires during ARCTAS using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Sessions, W.; Fuelberg, H. E.; Winker, D. M.; Chu, A. D.; Kahn, R. A.

    2009-12-01

    The Weather Research and Forecasting Model (WRF) was developed by the National Center for Atmospheric Research as the next generation of mesoscale meteorology model. The inclusion of a chemistry module (WRF-Chem) allows transport simulations of chemical and aerosol species such as those observed during NASA’s Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) during 2008. The ARCTAS summer deployment phase during June and July coincided with large boreal wildfires in Saskatchewan and Eastern Russia. We identified fires using the GOES Wildfire Automated Biomass Burning Algorithm (WF_ABBA) and thermal hotspot detections from MODIS sensors onboard the Aqua and Terra satellites. The fires on both continents produced plumes large enough to affect the atmospheric chemical composition of downwind population centers as well as the Arctic. Atmospheric steering currents vary greatly with altitude, making plume injection height one of the most important aspects of accurately modeling the transport of burning emissions. WRF-Chem integrates a one-dimensional plume model at grid cells containing fires to explicitly resolve the upper and lower limits of injection height. The early July fires provide multiple cases to satellite remotely sense the horizontal and vertical evolution of carbon monoxide (AIRS/MISR) and aerosols (CALIPSO) downwind of the fires. Lidar and in situ measurements from the NASA DC-8 and B-200 aircraft permit further validation of results from WRF-Chem. Using these various data sources, this paper will evaluate the ability of WRF-Chem to properly model the biomass injection heights and the downwind transport of fire plumes. Model-derived plume characteristics also will be compared with those observed by the satellites and in situ data. Finally, forecast sensitivities to varying WRF-Chem grid resolutions and plume rise mechanics will be presented.

  2. WRF/Chem-MADRID: Incorporation of an Improved Aerosol Module into WRF/Chem and Its Initial Application to the TexAQS2000 Episode

    SciTech Connect

    Zhang, Yang; Pan, Ying; Wang, K.; Fast, Jerome D.; Grell, G. A.

    2010-09-17

    The Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (MADRID) with three improved gas/particle mass transfer approaches (i.e., bulk equilibrium (EQUI), hybrid (HYBR), and kinetic (KINE)) has been incorporated into the Weather Research and Forecast/Chemistry Model (WRF/Chem) (referred to as WRF/Chem-MADRID) and evaluated with a 5-day episode from the 2000 Texas Air Quality Study (TexAQS2000). WRF/Chem-MADRID demonstrates an overall good skill in simulating surface/aloft meteorological parameters and chemical concentrations, tropospheric O3 residuals, and aerosol optical depths. The discrepancies can be attributed to inaccuracies in meteorological predictions (e.g., overprediction in mid-day boundary layer height), inaccurate total emissions or their hourly variations (e.g., HCHO, olefins, other inorganic aerosols), and uncertainties in initial and boundary conditions for some species (e.g., other inorganic aerosols and O3) at surface and aloft. Major differences in the results among the three gas/particle mass transfer approaches occur over coastal areas, where EQUI predicts higher PM2.5 than HYBR and KINE due to improperly redistributing condensed nitrate from chloride depletion process to fine PM mode. The net direct, semi-direct, and indirect effects of PM2.5 decreased domain wide shortwave radiation by 11.2-14.4 W m-2 (or 4.1-5.6%), decreased near-surface temperature by 0.06-0.14 °C (or 0.2-0.4%), led to 125 to 796 cm-3 cloud condensation nuclei at a supersaturation of 0.1%, produced cloud droplet numbers as high as 2064 cm-3, and reduced domain wide mean precipitation by 0.22-0.59 mm day-1.

  3. Calcium Sulfate Vein Observations at Yellowknife Bay using ChemCam on the Curiosity Rover

    NASA Astrophysics Data System (ADS)

    Clegg, S. M.; Mangold, N.; Nachon, M.; Le Mouelic, S.; Ollila, A.; Vaniman, D. T.; Kah, L. C.; Dromart, G.; Bridges, J.; Rice, M. S.; Wellington, D. F.; Bell, J. F.; Anderson, R. B.; Clark, B. C.; Cousin, A.; Forni, O.; Lasue, J.; Schröder, S.; Meslin, P.; Dyar, M. D.; Blaney, D. L.; Maurice, S.; Wiens, R. C.; Team, M.

    2013-12-01

    The Mars Science Laboratory Curiosity rover completed its traverse from the Bradbury landing site into Yellowknife Bay (YKB) on sol 125, where it spent ~175 sols. The YKB region is characterized as a fluvio-lacustrine depositional environment. The entire Curiosity payload was used to thoroughly investigate parts of YKB from which significant geochemical observations were made, including the identification of anhydrite and hydrated calcium sulfate. The Curiosity ChemCam package consists of a remote Laser-Induced Breakdown Spectrometer (LIBS) and a Remote Micro-Imager (RMI). LIBS is essentially an elemental analysis micro-probe capable of 300 - 550 μm spatial resolution from 1.5 - 7.0 m standoff distance from the Curiosity mast. The RMI records context images that have a resolution of 40 μrad, which corresponds to 120 μm at 3 meters. The ChemCam instrument recorded many calcium rich geochemical features as it descended ~18 m into YKB. Many light-toned veins became apparent with the ChemCam RMI and Mastcam once Curiosity entered YKB. The ChemCam LIBS instrument is uniquely capable of distinctly probing the elemental composition of these vein structures separately from the host rock. LIBS demonstrated that the white vein material was dominated by CaSO4, while the host rock had relatively low SO3 compositions. The ChemCam instrument can also qualitatively detect H, presumably due to H2O, in many samples. While some of these veins contained no H signature beyond the ubiquitous small amount of H on rock surfaces and in soils, some of the veins contained various amounts of H as a function of depth indicating that some of the samples were either bassanite or gypsum. Mastcam spectral hydration surveys detect evidence of hydration that is consistent with (but not a unique indicator of) the presence of gypsum in some, but not all, of the veins. The CheMin X-ray diffraction instrument identified both anhydrite and bassanite in the matrix of a mudstone unit but did not detect

  4. Diagenetic Features Analyzed by ChemCam/Curiosity at Pahrump Hills, Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Nachon, M.; Mangold, N.; Cousin, A.; Forni, O.; Anderson, R. B.; Blank, J. G.; Calef, F.; Clegg, S.; Fabre, C.; Fisk, M.; Gasnault, O.; Kah, L. C.; Kronyak, R.; Lasue, J.; Meslin, P.-Y.; Le Mouelic, S.; Maurice, S.; Oehler, D. Z.; Payre, V.; Rapin, W.; Sumner, D.; Stack, K.; Schroeder, S.; Wiens, R. C.

    2015-01-01

    Onboard the Mars Science Laboratory (MSL) Curiosity rover, the ChemCam instrument consists of : (1) a Laser-Induced Breakdown Spectrometer (LIBS) for elemental analysis of targets and (2) a Remote Micro Imager (RMI), which provides imaging context for the LIBS. The LIBS/ChemCam performs analysis typically of spot sizes 350-550 micrometers in diameter, up to 7 meters from the rover. Within Gale crater, Curiosity traveled from Bradbury Landing toward the base of Mount Sharp, reaching Pahrump Hills outcrop circa sol 750. This region, as seen from orbit, represents the first exposures of lower Mount Sharp. In this abstract we focus on two types of features present within the Pahrump Hills outcrop: concretion features and light-toned veins.

  5. Managing the computational chemistry big data problem: the ioChem-BD platform.

    PubMed

    Álvarez-Moreno, M; de Graaf, C; López, N; Maseras, F; Poblet, J M; Bo, C

    2015-01-26

    We present the ioChem-BD platform ( www.iochem-bd.org ) as a multiheaded tool aimed to manage large volumes of quantum chemistry results from a diverse group of already common simulation packages. The platform has an extensible structure. The key modules managing the main tasks are to (i) upload of output files from common computational chemistry packages, (ii) extract meaningful data from the results, and (iii) generate output summaries in user-friendly formats. A heavy use of the Chemical Mark-up Language (CML) is made in the intermediate files used by ioChem-BD. From them and using XSL techniques, we manipulate and transform such chemical data sets to fulfill researchers' needs in the form of HTML5 reports, supporting information, and other research media. PMID:25469626

  6. Comment on ``Hydrophobic effects on partial molar volume'' [J. Chem. Phys. 122, 094509 (2005)

    NASA Astrophysics Data System (ADS)

    Graziano, Giuseppe

    2005-10-01

    It is pointed out that the results obtained by Imai and Hirata [ J. Chem. Phys.122, 094509 (2005)] for the partial molar volume of benzene in a detailed model of water and in a hypothetical nonpolar water model should be interpreted with care. By turning off the electrostatic interactions among water molecules, keeping fixed the molar volume and so the liquid number density, in order to produce the hypothetical nonpolar water without H bonds, the size of water molecules increases from about 2.8 to about 3.2Å. This fact is due to the bunching-up effect of H bonds. The consequences of this fact are clarified by means of calculations performed using the analytical expression of the partial molar volume derived by Lee [J. Phys. Chem.87, 112 (1983)] from the scaled particle theory equation of state for hard-sphere mixtures.

  7. Characterising Brazilian biomass burning emissions using WRF-Chem with MOSAIC sectional aerosol

    NASA Astrophysics Data System (ADS)

    Archer-Nicholls, S.; Lowe, D.; Darbyshire, E.; Morgan, W. T.; Bela, M. M.; Pereira, G.; Trembath, J.; Kaiser, J. W.; Longo, K. M.; Freitas, S. R.; Coe, H.; McFiggans, G.

    2015-03-01

    The South American Biomass Burning Analysis (SAMBBA) field campaign took detailed in situ flight measurements of aerosol during the 2012 dry season to characterise biomass burning aerosol and improve understanding of its impacts on weather and climate. Developments have been made to the Weather Research and Forecast model with chemistry (WRF-Chem) model to improve the representation of biomass burning aerosol in the region, by coupling a sectional aerosol scheme to the plume-rise parameterisation. Brazilian Biomass Burning Emissions Model (3BEM) fire emissions are used, prepared using PREP-CHEM-SRC, and mapped to CBM-Z and MOSAIC species. Model results have been evaluated against remote sensing products, AERONET sites, and four case studies of flight measurements from the SAMBBA campaign. WRF-Chem predicted layers of elevated aerosol loadings (5-20 μg sm-3) of particulate organic matter at high altitude (6-8 km) over tropical forest regions, while flight measurements showed a sharp decrease above 2-4 km altitude. This difference was attributed to the plume-rise parameterisation overestimating injection height. The 3BEM emissions product was modified using estimates of active fire size and burned area for the 2012 fire season, which reduced the fire size. The enhancement factor for fire emissions was increased from 1.3 to 5 to retain reasonable aerosol optical depths (AODs). The smaller fire size lowered the injection height of the emissions, but WRF-Chem still showed elevated aerosol loadings between 4-5 km altitude. Over eastern cerrado (savannah-like) regions, both modelled and measured aerosol loadings decreased above approximately 4 km altitude. Compared with MODIS satellite data and AERONET sites, WRF-Chem represented AOD magnitude well (between 0.3-1.5) over western tropical forest fire regions in the first half of the campaign, but tended to over-predict them in the second half, when precipitation was more significant. Over eastern cerrado regions, WRF-Chem

  8. The semantics of Chemical Markup Language (CML) for computational chemistry : CompChem

    PubMed Central

    2012-01-01

    This paper introduces a subdomain chemistry format for storing computational chemistry data called CompChem. It has been developed based on the design, concepts and methodologies of Chemical Markup Language (CML) by adding computational chemistry semantics on top of the CML Schema. The format allows a wide range of ab initio quantum chemistry calculations of individual molecules to be stored. These calculations include, for example, single point energy calculation, molecular geometry optimization, and vibrational frequency analysis. The paper also describes the supporting infrastructure, such as processing software, dictionaries, validation tools and database repositories. In addition, some of the challenges and difficulties in developing common computational chemistry dictionaries are discussed. The uses of CompChem are illustrated by two practical applications. PMID:22870956

  9. ChemCam for Mars Science Laboratory rover, undergoing pre-flight testing

    ScienceCinema

    None

    2014-08-12

    Los Alamos National Laboratory and partners developed a laser instrument, ChemCam, that will ride on the elevated mast of the Mars Science Laboratory rover Curiosity. The system allows Curiosity to "zap" rocks from a distance, reading their chemical composition through spectroscopic analysis. In this video, laboratory shaker-table testing of the instrument ensures that all of its components are solidly attached and resistant to damage from the rigors of launch, travel and landing.

  10. ChemCam for Mars Science Laboratory rover, undergoing pre-flight testing

    SciTech Connect

    2011-10-20

    Los Alamos National Laboratory and partners developed a laser instrument, ChemCam, that will ride on the elevated mast of the Mars Science Laboratory rover Curiosity. The system allows Curiosity to "zap" rocks from a distance, reading their chemical composition through spectroscopic analysis. In this video, laboratory shaker-table testing of the instrument ensures that all of its components are solidly attached and resistant to damage from the rigors of launch, travel and landing.

  11. HIV Structural Database using Chem BLAST for all classes of AIDS inhibitors

    National Institute of Standards and Technology Data Gateway

    SRD 155 HIV Structural Database using Chem BLAST for all classes of AIDS inhibitors (Web, free access)   The HIV structural database (HIVSDB) is a comprehensive collection of the structures of HIV protease, both of unliganded enzyme and of its inhibitor complexes. It contains abstracts and crystallographic data such as inhibitor and protein coordinates for 248 data sets, of which only 141 are from the Protein Data Bank (PDB).

  12. Mixed waste treatment using the ChemChar thermolytic detoxification technique

    SciTech Connect

    Kuchynka, D.

    1995-10-01

    The diversity of mixed waste matrices contained at Department of Energy sites that require treatment preclude a single, universal treatment technology capable of handling sludges, solids, heterogeneous debris, aqueous and organic liquids and soils. This report describes the ChemChar thermolytic detoxification process. The process is a thermal, chemically reductive technology that converts the organic portion of mixed wastes to a synthesis gas, while simultaneously absorbing volatile inorganics on a carbon-based char.

  13. WRF/Chem-MADRID: Incorporation of an aerosol module into WRF/Chem and its initial application to the TexAQS2000 episode

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Pan, Ying; Wang, Kai; Fast, Jerome D.; Grell, Georg A.

    2010-09-01

    The Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (MADRID) with three improved gas/particle mass transfer approaches (i.e., bulk equilibrium (EQUI), hybrid (HYBR), and kinetic (KINE)) has been incorporated into the Weather Research and Forecast/Chemistry Model (WRF/Chem) (referred to as WRF/Chem-MADRID) and evaluated with a 5-day episode from the 2000 Texas Air Quality Study (TexAQS2000). WRF/Chem-MADRID demonstrates an overall good skill in simulating surface/aloft meteorological parameters and chemical concentrations of O3 and PM2.5, tropospheric O3 residuals, and aerosol optical depths. The discrepancies can be attributed to inaccuracies in meteorological predictions (e.g., overprediction in mid-day boundary layer height), sensitivity to meteorological schemes used (e.g., boundary layer and land-surface schemes), inaccurate total emissions or their hourly variations (e.g., HCHO, olefins, other inorganic aerosols) or uncounted wildfire emissions, uncertainties in initial and boundary conditions for some species (e.g., other inorganic aerosols, CO, and O3) at surface and aloft, and some missing/inactivated model treatments for this application (e.g., chlorine chemistry and secondary organic aerosol formation). Major differences in the results among the three gas/particle mass transfer approaches occur over coastal areas, where EQUI predicts higher PM2.5 than HYBR and KINE due to improperly redistributing condensed nitrate from chloride depletion process to fine PM mode. The net direct, semi-direct, and indirect effects of PM2.5 decrease domainwide shortwave radiation by 11.2-14.4 W m-2 (or 4.1-5.6%) and near-surface temperature by 0.06-0.14°C (or 0.2-0.4%), lead to 125 to 796 cm-3 cloud condensation nuclei at a supersaturation of 0.1%, produce cloud droplet numbers as high as 2064 cm-3, and reduce domainwide mean precipitation by 0.22-0.59 mm day-1.

  14. Effectiveness analysis of ACOS-Xco2 bias correction method with GEOS-Chem model results

    NASA Astrophysics Data System (ADS)

    Liu, Da; Lei, Liping; Liu, Min; Guo, Lijie; Wang, Qian; Bie, Nian

    2015-08-01

    Satellite observations and model simulations are of two important data sources to study atmospheric carbon dioxide concentration. For analyzing and evaluating the bias correction method of ACOS dry-air column averaged CO2 (Xco2) product, the GEOS-Chem Xco2 simulations are selected according to observing time and locations of the ACOS product. The GEOS-Chem simulations of CO2 profiles are transformed to Xco2 data by convolving with satellite averaging kernels and pressure weighting functions. The GEOS-Chem Xco2 data are then compared with both bias uncorrected and bias corrected satellite retrievals of ACOS. The comparisons show that the bias uncorrected ACOS retrievals are on average 1.12ppm higher than the model Xco2 data, while the corrected ACOS retrievals are only on average 0.06ppm lower than the model Xco2 data. By assuming consistency between model Xco2 simulations and true atmospheric Xco2, this study indicates that the bias can be obvious decreased through the bias correction method, and the correction is effective and necessary for satellite Xco2 retrievals.

  15. ChemProt-3.0: a global chemical biology diseases mapping

    PubMed Central

    Kringelum, Jens; Kjaerulff, Sonny Kim; Brunak, Søren; Lund, Ole; Oprea, Tudor I.; Taboureau, Olivier

    2016-01-01

    ChemProt is a publicly available compilation of chemical-protein-disease annotation resources that enables the study of systems pharmacology for a small molecule across multiple layers of complexity from molecular to clinical levels. In this third version, ChemProt has been updated to more than 1.7 million compounds with 7.8 million bioactivity measurements for 19 504 proteins. Here, we report the implementation of global pharmacological heatmap, supporting a user-friendly navigation of chemogenomics space. This facilitates the visualization and selection of chemicals that share similar structural properties. In addition, the user has the possibility to search by compound, target, pathway, disease and clinical effect. Genetic variations associated to target proteins were integrated, making it possible to plan pharmacogenetic studies and to suggest human response variability to drug. Finally, Quantitative Structure–Activity Relationship models for 850 proteins having sufficient data were implemented, enabling secondary pharmacological profiling predictions from molecular structure. Database URL: http://potentia.cbs.dtu.dk/ChemProt/ PMID:26876982

  16. ChemMine tools: an online service for analyzing and clustering small molecules

    PubMed Central

    Backman, Tyler W. H.; Cao, Yiqun; Girke, Thomas

    2011-01-01

    ChemMine Tools is an online service for small molecule data analysis. It provides a web interface to a set of cheminformatics and data mining tools that are useful for various analysis routines performed in chemical genomics and drug discovery. The service also offers programmable access options via the R library ChemmineR. The primary functionalities of ChemMine Tools fall into five major application areas: data visualization, structure comparisons, similarity searching, compound clustering and prediction of chemical properties. First, users can upload compound data sets to the online Compound Workbench. Numerous utilities are provided for compound viewing, structure drawing and format interconversion. Second, pairwise structural similarities among compounds can be quantified. Third, interfaces to ultra-fast structure similarity search algorithms are available to efficiently mine the chemical space in the public domain. These include fingerprint and embedding/indexing algorithms. Fourth, the service includes a Clustering Toolbox that integrates cheminformatic algorithms with data mining utilities to enable systematic structure and activity based analyses of custom compound sets. Fifth, physicochemical property descriptors of custom compound sets can be calculated. These descriptors are important for assessing the bioactivity profile of compounds in silico and quantitative structure—activity relationship (QSAR) analyses. ChemMine Tools is available at: http://chemmine.ucr.edu. PMID:21576229

  17. Benchmarking Ligand-Based Virtual High-Throughput Screening with the PubChem Database

    PubMed Central

    Butkiewicz, Mariusz; Lowe, Edward W.; Mueller, Ralf; Mendenhall, Jeffrey L.; Teixeira, Pedro L.; Weaver, C. David; Meiler, Jens

    2013-01-01

    With the rapidly increasing availability of High-Throughput Screening (HTS) data in the public domain, such as the PubChem database, methods for ligand-based computer-aided drug discovery (LB-CADD) have the potential to accelerate and reduce the cost of probe development and drug discovery efforts in academia. We assemble nine data sets from realistic HTS campaigns representing major families of drug target proteins for benchmarking LB-CADD methods. Each data set is public domain through PubChem and carefully collated through confirmation screens validating active compounds. These data sets provide the foundation for benchmarking a new cheminformatics framework BCL::ChemInfo, which is freely available for non-commercial use. Quantitative structure activity relationship (QSAR) models are built using Artificial Neural Networks (ANNs), Support Vector Machines (SVMs), Decision Trees (DTs), and Kohonen networks (KNs). Problem-specific descriptor optimization protocols are assessed including Sequential Feature Forward Selection (SFFS) and various information content measures. Measures of predictive power and confidence are evaluated through cross-validation, and a consensus prediction scheme is tested that combines orthogonal machine learning algorithms into a single predictor. Enrichments ranging from 15 to 101 for a TPR cutoff of 25% are observed. PMID:23299552

  18. Effective fragment potential method in Q-CHEM: a guide for users and developers.

    PubMed

    Ghosh, Debashree; Kosenkov, Dmytro; Vanovschi, Vitalii; Flick, Joanna; Kaliman, Ilya; Shao, Yihan; Gilbert, Andrew T B; Krylov, Anna I; Slipchenko, Lyudmila V

    2013-05-01

    A detailed description of the implementation of the effective fragment potential (EFP) method in the Q-CHEM electronic structure package is presented. The Q-CHEM implementation interfaces EFP with standard quantum mechanical (QM) methods such as Hartree-Fock, density functional theory, perturbation theory, and coupled-cluster methods, as well as with methods for electronically excited and open-shell species, for example, configuration interaction, time-dependent density functional theory, and equation-of-motion coupled-cluster models. In addition to the QM/EFP functionality, a "fragment-only" feature is also available (when the system is described by effective fragments only). To aid further developments of the EFP methodology, a detailed description of the C++ classes and EFP module's workflow is presented. The EFP input structure and EFP job options are described. To assist setting up and performing EFP calculations, a collection of Perl service scripts is provided. The precomputed EFP parameters for standard fragments such as common solvents are stored in Q-CHEM's auxiliary library; they can be easily invoked, similar to specifying standard basis sets. The instructions for generating user-defined EFP parameters are given. Fragments positions can be specified by their center of mass coordinates and Euler angles. The interface with the IQMOL and WEBMO software is also described. PMID:23319180

  19. Optimizing global CO concentrations and emissions based on DART/CAM-CHEM

    NASA Astrophysics Data System (ADS)

    Gaubert, B.; Arellano, A. F.; Barre, J.; Worden, H. M.; Emmons, L. K.; Wiedinmyer, C.; Anderson, J. L.; Deeter, M. N.; Mizzi, A. P.; Edwards, D. P.

    2014-12-01

    Atmospheric Carbon Monoxide (CO) is an important trace gas in tropospheric chemistry through its impact on the oxidizing capacity of the troposphere, as precursor of ozone, and as a good tracer of combustion from both anthropogenic sources and wildfires. We will investigate the potential of the assimilation of TERRA/MOPITT observations to constrain the regional to global CO budget using DART (Data assimilation Research Testbed) together with the global Community Atmospheric Model (CAM-Chem). DART/CAM-Chem is based on an ensemble adjustment Kalman filter (EAKF) framework which facilitates statistical estimation of error correlations between chemical states (CO and related species) and parameters (including sources) in the model using the ensemble statistics derived from dynamical and chemical perturbations in the model. Here, we estimate CO emissions within DART/CAM-Chem using a state augmentation approach where CO emissions are added to the CO state vector being analyzed. We compare these optimized emissions to estimates derived from a traditional Bayesian synthesis inversion using the CO analyses (assimilated CO states) as observational constraints. The spatio-temporal distribution of CO and other chemical species will be compared to profile measurements from aircraft and other satellite instruments (e.g., INTEX-B, ARCTAS).

  20. A CNES remote operations center for the MSL ChemCam instrument

    SciTech Connect

    Wiens, Roger C; Lafaille, Vivian; Lorgny, Eric; Baroukh, Julien; Gaboriaud, Alain; Saccoccio, Muriel; Perez, Rene; Gasnault, Olivier

    2010-01-01

    For the first time, a CNES remote operations center in Toulouse will be involved in the tactical operations of a Martian rover in order to operate the ChemCam science instrument in the framework of the NASA MSL (Mars Science Laboratory) mission in 2012. CNES/CESR and LANL have developed and delivered to JPL the ChemCam (Chemistry Camera) instrument located on the top of mast and in the body of the rover. This instrument incorporates a Laser-Induced Breakdown Spectrometer (LIBS) and a Remote Micro-Imager (RMI) for determining elemental compositions of rock targets or soil samples at remote distances from the rover (2-7 m). An agreement has been achieved for operating ChemCam, alternatively, from Toulouse (FR) and Los Alamos (NM, USA), through the JPL ground data system in Pasadena (CA, USA) for a complete Martian year (2 years on Earth). After a brief overview of the MSL mission, this paper presents the instrument, the mission operational system and JPL organization requirements for the scientific investigators (PI and Co-Is). This paper emphasizes innovations applied on the ground segment components and on the operational approach to satisfy the requirements and constraints due to these shared and distributed operations over the world.

  1. Health assessment for Thermo Chem, Inc. , Muskegon, Michigan, Region 5. CERCLIS No. MID044567162. Preliminary report

    SciTech Connect

    Not Available

    1988-11-28

    Thermo-Chem, Inc. is listed on the National Priorities List. The Thermo-Chem, Inc. site is located in Muskegon County, Michigan. Thermo-Chem, Inc. was involved in solvent reprocessing and liquid-waste disposal, beginning operations in 1969 and continuing until August 1980. The company received paint waste, antifreeze waste, and spent halogenated and nonhalogenated solvents. A soil-gas and soil-sampling survey detected: trichloroethene (TCE), 24,000 ppb; tetrachloroethene (PCE), 400,000 ppb; 1,1,1-trichloroethane, 16,000 ppb; 1,2-dichloroethylene, 4,500 ppb; toluene, 92,000 ppb; ethyl benzene, 450,000 ppb; and xylene, 2,100,000 ppb. The following contaminants and their respective concentrations in ppb were detected in the monitoring wells in 1986 as part of the hydrogeologic investigation: TCE, 67,000; PCE, 54,000; 1,1,1-trichloroethane, 26,000; 1,2-dichloroethene, 7,200; toluene, 100,000; ethyl benzene, 2,000; benzene, 5,000; methylene chloride, 1,800 and xylene, 17,000. No contamination has been detected in nearby residential wells. The site is of potential public health concern because of the risk to human health that could result from possible exposure to hazardous substances at levels that may result in adverse health effects over time. Human exposure to several organic contaminants may occur via contact with soil, surface water, or ground water contamination.

  2. ChemScreener: A Distributed Computing Tool for Scaffold based Virtual Screening.

    PubMed

    Karthikeyan, Muthukumarasamy; Pandit, Deepak; Vyas, Renu

    2015-01-01

    In this work we present ChemScreener, a Java-based application to perform virtual library generation combined with virtual screening in a platform-independent distributed computing environment. ChemScreener comprises a scaffold identifier, a distinct scaffold extractor, an interactive virtual library generator as well as a virtual screening module for subsequently selecting putative bioactive molecules. The virtual libraries are annotated with chemophore-, pharmacophore- and toxicophore-based information for compound prioritization. The hits selected can then be further processed using QSAR, docking and other in silico approaches which can all be interfaced within the ChemScreener framework. As a sample application, in this work scaffold selectivity, diversity, connectivity and promiscuity towards six important therapeutic classes have been studied. In order to illustrate the computational power of the application, 55 scaffolds extracted from 161 anti-psychotic compounds were enumerated to produce a virtual library comprising 118 million compounds (17 GB) and annotated with chemophore, pharmacophore and toxicophore based features in a single step which would be non-trivial to perform with many standard software tools today on libraries of this size. PMID:26138574

  3. CHEM-PATH-TRACKER: An automated tool to analyze chemical motifs in molecular structures.

    PubMed

    Ribeiro, João V; Cerqueira, N M F S A; Fernandes, Pedro A; Ramos, Maria J

    2014-07-01

    In this article, we propose a method for locating functionally relevant chemical motifs in protein structures. The chemical motifs can be a small group of residues or structure protein fragments with highly conserved properties that have important biological functions. However, the detection of chemical motifs is rather difficult because they often consist of a set of amino acid residues separated by long, variable regions, and they only come together to form a functional group when the protein is folded into its three-dimensional structure. Furthermore, the assemblage of these residues is often dependent on non-covalent interactions among the constituent amino acids that are difficult to detect or visualize. To simplify the analysis of these chemical motifs and give access to a generalized use for all users, we developed chem-path-tracker. This software is a VMD plug-in that allows the user to highlight and reveal potential chemical motifs requiring only a few selections. The analysis is based on atoms/residues pair distances applying a modified version of Dijkstra's algorithm, and it makes possible to monitor the distances of a large pathway, even during a molecular dynamics simulation. This tool turned out to be very useful, fast, and user-friendly in the performed tests. The chem-path-tracker package is distributed as an independent platform and can be found at http://www.fc.up.pt/PortoBioComp/database/doku.php?id=chem-path-tracker. PMID:24775806

  4. ChemProt-3.0: a global chemical biology diseases mapping.

    PubMed

    Kringelum, Jens; Kjaerulff, Sonny Kim; Brunak, Søren; Lund, Ole; Oprea, Tudor I; Taboureau, Olivier

    2016-01-01

    ChemProt is a publicly available compilation of chemical-protein-disease annotation resources that enables the study of systems pharmacology for a small molecule across multiple layers of complexity from molecular to clinical levels. In this third version, ChemProt has been updated to more than 1.7 million compounds with 7.8 million bioactivity measurements for 19,504 proteins. Here, we report the implementation of global pharmacological heatmap, supporting a user-friendly navigation of chemogenomics space. This facilitates the visualization and selection of chemicals that share similar structural properties. In addition, the user has the possibility to search by compound, target, pathway, disease and clinical effect. Genetic variations associated to target proteins were integrated, making it possible to plan pharmacogenetic studies and to suggest human response variability to drug. Finally, Quantitative Structure-Activity Relationship models for 850 proteins having sufficient data were implemented, enabling secondary pharmacological profiling predictions from molecular structure. Database URL: http://potentia.cbs.dtu.dk/ChemProt/. PMID:26876982

  5. Investigation of variation of precipitation by the cloud seeding using WRF-CHEM model

    NASA Astrophysics Data System (ADS)

    Chae, S.; Lee, K.; Lee, C.; Ahn, K.; Choi, Y.

    2012-12-01

    Resent observational and numerical studies demonstrate a significant effect of aerosols on the amount of precipitation and its spatial distribution. Airborne cloud seeding experiments using the AgI particles have been carried out in Korea. The Weather Research Forecast model coupled with chemistry mechanism and aerosol modules (WRF-CHEM) is used to investigate the effects of the airborne cloud seeding on precipitation. The sensitivity tests (EXP 1, 2, and 3) of the WRF-CHEM were performed on the airborne cloud seeding experiments. EXP 1 is a control run from the original WRF model which has no aerosol effect. EXP 2 and EXP 3 are the WRF-CHEM simulations coupled with RADM2/MADE-SORGAM modules and CBMZ/MOSAIC modules, respectively. The AgI seeding was considered as an emission of primary PM2.5 in the simulations. The unspeciated primary PM2.5 are of 10000 μg/(m2s) at 0.5 km about the ground level to simulate the cloud seeding in both cases. The results of sensitivity experiments with the chemistry mechanism and aerosol schemes showed that for the six hours after the seeding, the accumulated amounts of precipitation increased about 14% for EXP 2 and 45% for EXP3, compared to EXP 1. Also, the simulations showed that the seeding brought initial precipitation time forward aerosol by 10 minutes.

  6. Development of a Uniform Classification Tool for Peridotites Through the use of Geochemical Data From the EarthChem Deep Lithosphere Dataset

    NASA Astrophysics Data System (ADS)

    Block, K. A.; Stern, R. J.; Bavoso, M. T.; Lehnert, K. A.

    2008-12-01

    Geochemical data management projects such as PetDB, GEOROC, SedDB, and EarthChem provide access to disciplinary solid earth data widely used for domain research. The complexity of geochemical data often poses challenges to cross-disciplinary researchers who need simple tools to bridge gaps in specialized domain knowledge. Geophysical measurements collected through EarthScope require correlation with mantle xenolith geochemical and physical sample characteristics derived from modal mineralogy and rock classification. For many samples from the literature, information relevant for properly classifying a rock is often incomplete, incorrect, or altogether missing. However, major oxide data are commonly reported for deep crustal and mantle xenoliths and provide a viable means for classification, similar to the TAS (Total Alkali Silica) classification used for igneous rocks. In partnership with EarthScope researchers, an analogous approach for the classification of peridotites is being developed based on SiO2-CaO-Al2O3-MgO (SCAM) whole rock data and mineral composition obtained from analyses served and archived in the EarthChem Deep Lithosphere Dataset. We present a comparison of results of peridotite classifications based on the bulk chemical classification and observed and calculated modal data as well as a visualization scheme that can be implemented as a database query tool to facilitate the acquisition of data based on a uniform classification scheme.

  7. ODM2 (Observation Data Model): The EarthChem Use Case

    NASA Astrophysics Data System (ADS)

    Lehnert, Kerstin; Song, Lulin; Hsu, Leslie; Horsburgh, Jeffrey S.; Aufdenkampe, Anthony K.; Mayorga, Emilio; Tarboton, David; Zaslavsky, Ilya

    2014-05-01

    PetDB is an online data system that was created in the late 1990's to serve online a synthesis of published geochemical and petrological data of igneous and metamorphic rocks. PetDB has today reached a volume of 2.5 million analytical values for nearly 70,000 rock samples. PetDB's data model (Lehnert et al., G-Cubed 2000) was designed to store sample-based observational data generated by the analysis of rocks, together with a wide range of metadata documenting provenance of the samples, analytical procedures, data quality, and data source. Attempts to store additional types of geochemical data such as time-series data of seafloor hydrothermal springs and volcanic gases, depth-series data for marine sediments and soils, and mineral or mineral inclusion data revealed the limitations of the schema: the inability to properly record sample hierarchies (for example, a garnet that is included in a diamond that is included in a xenolith that is included in a kimberlite rock sample), inability to properly store time-series data, inability to accommodate classification schemes other than rock lithologies, deficiencies of identifying and documenting datasets that are not part of publications. In order to overcome these deficiencies, PetDB has been developing a new data schema using the ODM2 information model (ODM=Observation Data Model). The development of ODM2 is a collaborative project that leverages the experience of several existing information representations, including PetDB and EarthChem, and the CUAHSI HIS Observations Data Model (ODM), as well as the general specification for encoding observational data called Observations and Measurements (O&M) to develop a uniform information model that seamlessly manages spatially discrete, feature-based earth observations from environmental samples and sample fractions as well as in-situ sensors, and to test its initial implementation in a variety of user scenarios. The O&M model, adopted as an international standard by the Open

  8. An investigation of methods for injecting emissions from boreal wildfires using WRF-Chem during ARCTAS

    NASA Astrophysics Data System (ADS)

    Sessions, W. R.; Fuelberg, H. E.; Kahn, R. A.; Winker, D. M.

    2011-06-01

    The Weather Research and Forecasting Model (WRF) is considered a "next generation" mesoscale meteorology model. The inclusion of a chemistry module (WRF-Chem) allows transport simulations of chemical and aerosol species such as those observed during NASA's Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) in 2008. The ARCTAS summer deployment phase during June and July coincided with large boreal wildfires in Saskatchewan and Eastern Russia. One of the most important aspects of simulating wildfire plume transport is the height at which emissions are injected. WRF-Chem contains an integrated one-dimensional plume rise model to determine the appropriate injection layer. The plume rise model accounts for thermal buoyancy associated with fires and local atmospheric stability. This paper describes a case study of a 10 day period during the Spring phase of ARCTAS. It compares results from the plume model against those of two more traditional injection methods: Injecting within the planetary boundary layer, and in a layer 3-5 km above ground level. Fire locations are satellite derived from the GOES Wildfire Automated Biomass Burning Algorithm (WF_ABBA) and the MODIS thermal hotspot detection. Two methods for preprocessing these fire data are compared: The prep_chem_sources method included with WRF-Chem, and the Naval Research Laboratory's Fire Locating and Monitoring of Burning Emissions (FLAMBE). Results from the simulations are compared with satellite-derived products from the AIRS, MISR and CALIOP sensors. When FLAMBE provides input to the 1-D plume rise model, the resulting injection heights exhibit the best agreement with satellite-observed injection heights. The FLAMBE-derived heights are more realistic than those utilizing prep_chem_sources. Conversely, when the planetary boundary layer or the 3-5 km a.g.l. layer were filled with emissions, the resulting injection heights exhibit less agreement with observed plume heights

  9. Impact of improved soil climatology and intialization on WRF-chem dust simulations over West Asia

    NASA Astrophysics Data System (ADS)

    Omid Nabavi, Seyed; Haimberger, Leopold; Samimi, Cyrus

    2016-04-01

    Meteorological forecast models such as WRF-chem are designed to forecast not only standard atmospheric parameters but also aerosol, particularly mineral dust concentrations. It has therefore become an important tool for the prediction of dust storms in West Asia where dust storms have the considerable impact on living conditions. However, verification of forecasts against satellite data indicates only moderate skill in prediction of such events. Earlier studies have already indicated that the erosion factor, land use classification, soil moisture, and temperature initializations play a critical role in the accuracy of WRF-chem dust simulations. In the standard setting the erosion factor and land use classification are based on topographic variations and post-processed images of the advanced very high-resolution radiometer (AVHRR) during the period April 1992-March 1993. Furthermore, WRF-chem is normally initialized by the soil moisture and temperature of Final Analysis (FNL) model on 1.0x1.0 degree grids. In this study, we have changed boundary initial conditions so that they better represent current changing environmental conditions. To do so, land use (only bare soil class) and the erosion factor were both modified using information from MODIS deep blue AOD (Aerosol Optical Depth). In this method, bare soils are where the relative frequency of dust occurrence (deep blue AOD > 0.5) is more than one-third of a given month. Subsequently, the erosion factor, limited within the bare soil class, is determined by the monthly frequency of dust occurrence ranging from 0.3 to 1. It is worth to mention, that 50 percent of calculated erosion factor is afterward assigned to sand class while silt and clay classes each gain 25 percent of it. Soil moisture and temperature from the Global Land Data Assimilation System (GLDAS) were utilized to provide these initializations in higher resolution of 0.25 degree than in the standard setting. Modified and control simulations were

  10. EarthChem and SESAR: Data Resources and Interoperability for EarthScope Cyberinfrastructure

    NASA Astrophysics Data System (ADS)

    Lehnert, K. A.; Walker, D.; Block, K.; Vinay, S.; Ash, J.

    2008-12-01

    Data management within the EarthScope Cyberinfrastructure needs to pursue two goals in order to advance and maximize the broad scientific application and impact of the large volumes of observational data acquired by EarthScope facilities: (a) to provide access to all data acquired by EarthScope facilities, and to promote their use by broad audiences, and (b) to facilitate discovery of, access to, and integration of multi-disciplinary data sets that complement EarthScope data in support of EarthScope science. EarthChem and SESAR, the System for Earth Sample Registration, are two projects within the Geoinformatics for Geochemistry program that offer resources for EarthScope CI. EarthChem operates a data portal that currently provides access to >13 million analytical values for >600,000 samples, more than half of which are from North America, including data from the USGS and all data from the NAVDAT database, a web-accessible repository for age, chemical and isotopic data from Mesozoic and younger igneous rocks in western North America. The new EarthChem GEOCHRON database will house data collected in association with GeoEarthScope, storing and serving geochronological data submitted by participating facilities. The EarthChem Deep Lithosphere Dataset is a compilation of petrological data for mantle xenoliths, initiated in collaboration with GeoFrame to complement geophysical endeavors within EarthScope science. The EarthChem Geochemical Resource Library provides a home for geochemical and petrological data products and data sets. Parts of the digital data in EarthScope CI refer to physical samples such as drill cores, igneous rocks, or water and gas samples, collected, for example, by SAFOD or by EarthScope science projects and acquired through lab-based analysis. Management of sample-based data requires the use of global unique identifiers for samples, so that distributed data for individual samples generated in different labs and published in different papers can be

  11. Comment on: ``The hindered rotor density-of-states interpolation function'' [J. Chem. Phys. 106, 6675 (1997)] and ``The hindered rotor density- of-states'' [J. Chem. Phys. 108, 2314 (1998)

    NASA Astrophysics Data System (ADS)

    McClurg, Richard B.

    1999-10-01

    There has been some confusion regarding the various approximations for the hindered rotor partition function and its associated thermodynamic functions and density of states. This comment seeks to clarify the situation by comparing and contrasting the various functions, particularly with regard to the consistent use of reference energies. Only the tabular data of Pitzer and Gwinn [J. Chem. Phys. 10, 428 (1942)] and our analytic function [J. Chem. Phys. 106, 6675 (1997)] have consistent reference energies. The main contribution of our publication is the set of simple, asymptotically correct expressions for the thermodynamic functions. There are similar, but different approximations to the density of states given by Knyazev and co-workers [J. Phys. Chem. A 102, 3916 (1998)] and by me [J. Chem. Phys. 108, 1748 (1998)].

  12. Reply to comment by Ben-Zvi, A., D. Rosenfeld and A. Givati on the paper: Levin, Z., N. Halfon and P. Alpert, “Reassessment of rain experiments and operations in Israel including synoptic considerations,” Atmos. Res. 97, 513-525. DOI: 10.1016/j.atmosres.2010.06.011

    NASA Astrophysics Data System (ADS)

    Levin, Zev; Halfon, Noam; Alpert, Pinhas

    2011-03-01

    Levin et al. (2010; hereafter LHA) (Levin, Z., Halfon, N., Alpert, P., 2010. Reassessment of rain experiments and operations in Israel including synoptic considerations. Atmos. Res. 97, 513-525. DOI:10.1016/j.atmosres.2010.06.011.), reanalyzed the results of the operational seeding in northern Israel between 1975 and 2007 and the preceding Israel 2 cloud seeding experiment (1969-1975) and concluded that there is no net increase in precipitation over the target areas. Our analysis revealed that a synoptic bias during Israel 2 is one of the reasons for the apparent positive effect of seeding in the northern target area and the negative effect in the southern area both of which disappeared in the following experiment in the south (Israel 3; 1975-1995) and the operational seeding in the north. Ben-Zvi et al. (2010;hereafter BRG) criticized our paper primarily on the ground that we did not consider the positive results of Israel 1 experiment (1960-1967). It should be noted that in Israel 1 different seeding lines were used from those in both Israel 2 and the operational period. In addition, its raw data is not accessible anymore for reanalysis. Furthermore, Israel 2 had been designed as a confirmatory cross-over experiment to Israel 1 and failed to reproduce its promising results with double ratio (DR) of ~ 1.00, namely, zero rainfall enhancements. The same DR values were also found in Israel 3 and in the operational seeding. Therefore, because of the differences in the two experiments, the lack of access to the raw data and the disappointing results of the confirmatory experiment, we decided to concentrate our analysis on the more recent seeding activities. The attempt by BRG to explain the reduction of the DR to ~ 1.00 in the operational seeding period by the suppression due to pollution have been disproved by Alpert et al. (2008, 2009) and also fail to explain the sharp decline of the target/control ratio right at the beginning of the operational seeding period when

  13. Science-Technology-Society (STS) and ChemCom Courses versus College Chemistry Courses: Is There a Mismatch?

    ERIC Educational Resources Information Center

    Sanger, Michael J.; Greenbowe, Thomas J.

    1996-01-01

    This opinion paper discusses several issues surrounding questions of ChemCom and STS courses taken by science majors. Explores the basis for a potential mismatch students having an STS-based course may experience. Discusses objectivism and constructivism. (MKR)

  14. Comment on: ``Disentangling density and temperature effects in the viscous slowing down of glass forming liquids'' [J. Chem. Phys. 120, 6135 (2004)

    NASA Astrophysics Data System (ADS)

    Roland, C. M.; Casalini, R.

    2004-12-01

    Recently, Tarjus et al. [G. Tarjus, D. Kivelson, S. Mossa, and C. Alba-Simionesco, J. Chem. Phys. 120, 6135 (2004)] concluded from a review of data for a variety of glass formers that the supercooled dynamics are almost invariably dominated by temperature T, rather than by density ρ. By including additional published data into such a compilation, we show that for van der Waals molecular liquids, the dynamics near Tg are in fact governed as much by density as by temperature. Moreover, relaxation times measured at various temperatures and pressures can be superimposed by plotting as a function ργ/T. This scaling form can arise from an assumed inverse power law for the intermolecular repulsive potential, with γ a material constant.

  15. Science-Technology-Society (STS) and ChemCom Courses Versus College Chemistry Courses: Is There a Mismatch?

    NASA Astrophysics Data System (ADS)

    Sanger, Michael J.; Greenbowe, Thomas J.

    1996-06-01

    This opinion paper poses questions for the chemical education community to consider about the nature of college chemistry courses and the expected student prerequisites. It also explores the basis for a potential mismatch that may exist for students enrolled in a traditional college chemistry course who have had Science-Technology-Society (STS) or ChemCom courses as their only prior high school chemistry courses. Even though ChemCom and STS courses are not designed to prepare students for traditional college chemistry courses for science and engineering majors, there has been an increase in the number of ChemCom and STS students enrolling in these courses. As background, the general teaching approach of ChemCom and STS courses is discussed in terms of the behaviorist, cognitive, and constructivist learning theories. This article addresses the advantages and disadvantages of high school chemistry courses based on ChemCom and reviews the chemical education research comparing the effectiveness of ChemCom courses to traditional high school chemistry courses. The authors concluded that more research comparing the effect of these instructional methods on both traditional and alternative assessments is warranted.

  16. Modeling of Lightning-Related Plumes into the Chemistry and Transport GEOS-Chem Global Model: Impact on the Upper Tropospheric Chemistry.

    NASA Astrophysics Data System (ADS)

    Gressent, A.

    2014-12-01

    This work is dedicated to the study of the lightning-related plumes in terms of origin, quantification of the plumes trace gas, and impact on the budget of ozone in particular in the upper troposphere (critical region regarding the greenhouse effect). Recently, Gressent et al., 2014, demonstrated that the majority (74%) of large scale plumes (>300km) from lightning emissions (LNOx) is related to warm conveyor belts and extra-tropical cyclones originating from North America and entering the intercontinental pathway between North America and Europe, leading to a negative (positive) west to east NOy (O3) zonal gradient with -0.4 (+18) ppb difference during spring and -0.6 (+14) ppb difference in summer. In order to better constraint lightning emissions impact in global models, a plume parameterization has been implemented in the 3D chemistry and transport GEOS-Chem global model (Harvard University). Such parameterization was successfully developed for aircraft exhausts application (Cariolle et al., 2009). It allows reproducing sub-grid processes related to lightning NOx chemistry and the chemical evolution during transport in the atmosphere. The issue is here based on the evaluation of parameters such as the plume lifetime and the effective reaction rate constant within the plume. The Dynamically Simple Model of Atmospheric Chemical Complexity (DSMACC) is used to determine such critical values and to better understand the chemical interactions between NOx and O3 species within the undiluted fraction of the plume. Additionally high-resolved simulations of the French meso-scale Meso-NH model are applied over specific case studies of thunderstorms in order to consider the dynamical conditions necessary to represent the plume dilution to the background atmosphere. Finally, sensitivity tests are carried out with the GEOS-Chem model to evaluate the impact of this plume-in-grid model on the ozone and nitrogen species budget.

  17. Hydrogen in soils and dust as observed in ChemCam spectra at Gale Crater, Mars.

    NASA Astrophysics Data System (ADS)

    Schröder, Susanne; Meslin, Pierre-Yves; Cousin, Agnès; Ollila, Ann; Maurice, Sylvestre; Gasnault, Olivier; Ehlmann, Bethany; Dyar, Darby; Lasue, Jérémie; Mangold, Nicolas; Forni, Olivier; Wiens, Roger; MSL Science Team

    2013-04-01

    The NASA Mars Science Laboratory (MSL) rover Curiosity includes the ChemCam instrument to provide elemental analysis of soils and rocks, with the first Laser-Induced Breakdown Spectroscopy (LIBS) instrument ever used on a planetary mission. It is combined with a Remote Micro-Imager (RMI), enabling pre- and post-LIBS context images of the target. For LIBS, radiation from a high power laser (Nd:KGW with 1067 nm, 8 - 14 mJ on the target) is focused onto the sample where material is ablated and a luminous plasma is produced. Information on the elemental composition is obtained from relaxation of excited atoms and ions due to specific transitions coming along with characteristic spectral lines. Moreover, bremsstrahlung and recombination from unbound states result in a continuous spectrum superimposed upon the characteristic emission. At the edge of the visible to NIR wavelength range, where the most intense hydrogen peak (Hα at 656.5 nm) is found, this continuous emission can prevent the detection of less intense emission lines and has to be carefully taken into account. In ChemCam data, the H emission feature is usually overlapped by a C peak at 658.0 nm that is present with almost constant intensity in all the LIBS data due to the CO2-dominated atmosphere on Mars. To investigate variations of the H signal, univariate analysis was used to compare the abundance of each element to the area of these peaks. In this study, the H emission signal in LIBS spectra of martian soils and dust on rocks is investigated. The focus will be on ChemCam data taken on Sol 74 of a fine-grained soil named Crestaurum, where spectra were obtained as usual during day and for comparison additionally during early martian day before dawn. Intense H lines were observed in the spectra, slightly decreasing in intensity with shot number and featuring enhanced values for some single shot spectra The H signal remains more intense than the nonvarying C peak for the daytime data as well as for the pre

  18. Igneous mineralogy at Bradbury Rise: The first ChemCam campaign at Gale crater

    NASA Astrophysics Data System (ADS)

    Sautter, V.; Fabre, C.; Forni, O.; Toplis, M. J.; Cousin, A.; Ollila, A. M.; Meslin, P. Y.; Maurice, S.; Wiens, R. C.; Baratoux, D.; Mangold, N.; Le Mouélic, S.; Gasnault, O.; Berger, G.; Lasue, J.; Anderson, R. A.; Lewin, E.; Schmidt, M.; Dyar, D.; Ehlmann, B. L.; Bridges, J.; Clark, B.; Pinet, P.

    2014-01-01

    and compositional analyses using Chemistry Camera (ChemCam) remote microimager and laser-induced breakdown spectroscopy (LIBS) have been performed on five float rocks and coarse gravels along the first 100 m of the Curiosity traverse at Bradbury Rise. ChemCam, the first LIBS instrument sent to another planet, offers the opportunity to assess mineralogic diversity at grain-size scales (~ 100 µm) and, from this, lithologic diversity. Depth profiling indicates that targets are relatively free of surface coatings. One type of igneous rock is volcanic and includes both aphanitic (Coronation) and porphyritic (Mara) samples. The porphyritic sample shows dark grains that are likely pyroxene megacrysts in a fine-grained mesostasis containing andesine needles. Both types have magnesium-poor basaltic compositions and in this respect are similar to the evolved Jake Matijevic rock analyzed further along the Curiosity traverse both with Alpha-Particle X-ray Spectrometer and ChemCam instruments. The second rock type encountered is a coarse-grained intrusive rock (Thor Lake) showing equigranular texture with millimeter size crystals of feldspars and Fe-Ti oxides. Such a rock is not unique at Gale as the surrounding coarse gravels (such as Beaulieu) and the conglomerate Link are dominated by feldspathic (andesine-bytownite) clasts. Finally, alkali feldspar compositions associated with a silica polymorph have been analyzed in fractured filling material of Preble rock and in Stark, a putative pumice or an impact melt. These observations document magmatic diversity at Gale and describe the first fragments of feldspar-rich lithologies (possibly an anorthosite) that may be ancient crust transported from the crater rim and now forming float rocks, coarse gravel, or conglomerate clasts.

  19. Incorporation of a Chemical Equilibrium Equation of State into LOCI-Chem

    NASA Technical Reports Server (NTRS)

    Cox, Carey F.

    2005-01-01

    Renewed interest in development of advanced high-speed transport, reentry vehicles and propulsion systems has led to a resurgence of research into high speed aerodynamics. As this flow regime is typically dominated by hot reacting gaseous flow, efficient models for the characteristic chemical activity are necessary for accurate and cost effective analysis and design of aerodynamic vehicles that transit this regime. The LOCI-Chem code recently developed by Ed Luke at Mississippi State University for NASA/MSFC and used by NASA/MSFC and SSC represents an important step in providing an accurate, efficient computational tool for the simulation of reacting flows through the use of finite-rate kinetics [3]. Finite rate chemistry however, requires the solution of an additional N-1 species mass conservation equations with source terms involving reaction kinetics that are not fully understood. In the equilibrium limit, where the reaction rates approach infinity, these equations become very stiff. Through the use of the assumption of local chemical equilibrium the set of governing equations is reduced back to the usual gas dynamic equations, and thus requires less computation, while still allowing for the inclusion of reacting flow phenomenology. The incorporation of a chemical equilibrium equation of state module into the LOCI-Chem code was the primary objective of the current research. The major goals of the project were: (1) the development of a chemical equilibrium composition solver, and (2) the incorporation of chemical equilibrium solver into LOCI-Chem. Due to time and resource constraints, code optimization was not considered unless it was important to the proper functioning of the code.

  20. New Development of the Online Integrated Climate-Chemistry model framwork (RegCM-CHEM4)

    NASA Astrophysics Data System (ADS)

    Zakey, A. S.; Shalaby, A. K.; Solmon, F.; Giorgi, F.; Tawfik, A. B.; Steiner, A. L.; Baklanov, A.

    2012-04-01

    The RegCM-CHEM4 is a new online integrated climate-chemistry model based on the regional climate model (RegCM4). The RegCM4 developed at the Abdus Salam International Centre for Theoretical Physics (ICTP), is a hydrostatic, sigma coordinate model. Tropospheric gas-phase chemistry is integrated into the climate model using the condensed version of the Carbon Bond Mechanism CBM-Z with lumped species that represent broad categories of organics based on carbon bond structure. The computationally rapid radical balance method RBM is coupled as a chemical solver to the gas-phase mechanism. Photolysis rates are determined as a function of meteorological and chemical inputs and interpolated from an array of pre-determined values based on the Tropospheric Ultraviolet-Visible Model (TUV) with cloud cover corrections. Cloud optical depths and cloud altitudes from RegCM-CHEM4 are used in the photolysis calculations, thereby directly coupling the photolysis rates and chemical reactions to meteorological conditions at each model time step. In this study, we evaluate the model over Europe for two different time scales: (1) an event-based analysis of the ozone episode associated with the heat wave of August 2003 and (2) a climatological analysis of a six-year simulation (2000-2005). For the episode analysis, model simulations show a good agreement with the European Monitoring and Evaluation Program (EMEP) observations of hourly ozone over different regions in Europe and capture ozone concentrations during and after the summer 2003 heat wave event. Analysis of the full six years of simulation indicates that the coupled chemistry-climate model can reproduce the seasonal cycle of ozone, with an overestimation of ozone in the non-event years of 5-15 ppb depending on the geographic region. Overall, the ozone and ozone precursor evaluation shows the feasibility of using RegCM-CHEM4 for decadal-length simulations of chemistry-climate interactions.

  1. Evaluation of a regional assimilation system coupled with the WRF-chem model

    NASA Astrophysics Data System (ADS)

    Liu, Yan-an; Gao, Wei; Huang, Hung-lung; Strabala, Kathleen; Liu, Chaoshun; Shi, Runhe

    2013-09-01

    Air quality has become a social issue that is causing great concern to humankind across the globe, but particularly in developing countries. Even though the Weather Research and Forecasting with Chemistry (WRF-Chem) model has been applied in many regions, the resolution for inputting meteorology field analysis still impacts the accuracy of forecast. This article describes the application of the CIMSS Regional Assimilation System (CRAS) in East China, and its capability to assimilate the direct broadcast (DB) satellite data for obtaining more detailed meteorological information, including cloud top pressure (CTP) and total precipitation water (TPW) from MODIS. Performance evaluation of CRAS is based on qualitative and quantitative analyses. Compared with data collected from ERA-Interim, Radiosonde, and the Tropical Rainfall Measuring Mission (TRMM) precipitation measurements using bias and Root Mean Square Error (RMSE), CRAS has a systematic error due to the impact of topography and other factors; however, the forecast accuracy of all elements in the model center area is higher at various levels. The bias computed with Radiosonde reveals that the temperature and geopotential height of CRAS are better than ERA-Interim at first guess. Moreover, the location of the 24 h accumulated precipitation forecast are highly consistent with the TRMM retrieval precipitation, which means that the performance of CRAS is excellent. In summation, the newly built Vtable can realize the function of inputting the meteorology field from CRAS output into WRF, which couples the CRAS with WRF-Chem. Therefore, this study not only provides for forecast accuracy of CRAS, but also increases the capability of running the WRF-Chem model at higher resolutions in the future.

  2. Toward Regional Fossil Fuel CO2 Emissions Verification Using WRF-CHEM

    NASA Astrophysics Data System (ADS)

    Delle Monache, L.; Kosoviæ, B.; Cameron-Smith, P.; Bergmann, D.; Grant, K.; Guilderson, T.

    2008-12-01

    As efforts to reduce emissions of green house gases take shape it is becoming obvious that an essential component of a viable solution will involve emission verification. While detailed inventories of green house gas sources will represent important component of the solution additional verification methodologies will be necessary to reduce uncertainties in emission estimates especially for distributed sources and CO2 offsets. We developed tools for solving inverse dispersion problem for distributed emissions of green house gases. For that purpose we combine probabilistic inverse methodology based on Bayesian inversion with stochastic sampling and weather forecasting and air quality model WRF-CHEM. We demonstrate estimation of CO2 emissions associated with fossil fuel burning in California over two one-week periods in 2006. We use WRF- CHEM in tracer simulation mode to solve forward dispersion problem for emissions over eleven air basins. We first use direct inversion approach to determine optimal location for a limited number of CO2 - C14 isotope sensors. We then use Bayesian inference with stochastic sampling to determine probability distributions for emissions from California air basins. Moreover, we vary the number of sensors and frequency of measurements to study their effect on the accuracy and uncertainty level of the emission estimation. Finally, to take into account uncertainties associated with forward modeling, we combine Bayesian inference and stochastic sampling with ensemble modeling. The ensemble is created by running WRF-CHEM with different initial and boundary conditions as well as different boundary layer and surface model options. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory (LLNL) under Contract DE-AC52-07NA27344 (LLNL-ABS-406901-DRAFT). The project 07-ERD- 064 was funded by the Laboratory Directed Research and Development Program at LLNL.

  3. Evaluating WRF-Chem aerosol indirect effects in Southeast Pacific marine stratocumulus during VOCALS-REx

    SciTech Connect

    Saide, Pablo; Spak, S. N.; Carmichael, Gregory; Mena-Carrasco, M. A.; Yang, Qing; Howell, S. G.; Leon, Dolislager; Snider, Jefferson R.; Bandy, Alan R.; Collett, Jeffrey L.; Benedict, K. B.; de Szoeke, S.; Hawkins, Lisa; Allen, Grant; Crawford, I.; Crosier, J.; Springston, S. R.

    2012-03-30

    We evaluate a regional-scale simulation with the WRF-Chem model for the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx), which sampled the Southeast Pacific's persistent stratocumulus deck. Evaluation of VOCALS-REx ship-based and aircraft observations focuses on analyzing how aerosol loading affects marine boundary layer (MBL) dynamics and cloud microphysics. We compare local time series and campaign averaged longitudinal gradients, and highlight differences in model simulations with (W) and without wet (NW) deposition processes. The higher aerosol loadings in the NW case produce considerable changes in MBL dynamics and cloud microphysics, in accordance with the established conceptual model of aerosol indirect effects. These include increase in cloud albedo, increase in MBL and cloud heights, drizzle suppression, increase in liquid water content, and increase in cloud lifetime. Moreover, better statistical representation of aerosol mass and number concentration improves model fidelity in reproducing observed spatial and temporal variability in cloud properties, including top and base height, droplet concentration, water content, rain rate, optical depth (COD) and liquid water path (LWP). Together, these help to quantify confidence in WRF-Chem's modeled aerosol-cloud interactions, while identifying structural and parametric uncertainties including: irreversibility in rain wet removal; overestimation of marine DMS and sea salt emissions and accelerated aqueous sulfate conversion. Our findings suggest that WRF-Chem simulates marine cloud-aerosol interactions at a level sufficient for applications in forecasting weather and air quality and studying aerosol climate forcing, including the reliability required for policy analysis and geo-engineering applications.

  4. Evaluating WRF-Chem aerosol indirect effects in Southeast Pacific marine stratocumulus during VOCALS-REx

    SciTech Connect

    Saide P. E.; Springston S.; Spak, S. N.; Carmichael, G. R.; Mena-Carrasco, M. A.; Yang, Q.; Howell, S.; Leon, D. C.; Snider, J. R.; Bandy, A. R.; Collett, J. L.; Benedict, K. B.; de Szoeke, S. P.; Hawkins, L. N.; Allen, G.; Crawford, I.; Crosier, J.

    2012-03-29

    We evaluate a regional-scale simulation with the WRF-Chem model for the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx), which sampled the Southeast Pacific's persistent stratocumulus deck. Evaluation of VOCALS-REx ship-based and three aircraft observations focuses on analyzing how aerosol loading affects marine boundary layer (MBL) dynamics and cloud microphysics. We compare local time series and campaign-averaged longitudinal gradients, and highlight differences in model simulations with (W) and without (NW) wet deposition processes. The higher aerosol loadings in the NW case produce considerable changes in MBL dynamics and cloud microphysics, in accordance with the established conceptual model of aerosol indirect effects. These include increase in cloud albedo, increase in MBL and cloud heights, drizzle suppression, increase in liquid water content, and increase in cloud lifetime. Moreover, better statistical representation of aerosol mass and number concentration improves model fidelity in reproducing observed spatial and temporal variability in cloud properties, including top and base height, droplet concentration, water content, rain rate, optical depth (COD) and liquid water path (LWP). Together, these help to quantify confidence in WRF-Chem's modeled aerosol-cloud interactions, especially in the activation parameterization, while identifying structural and parametric uncertainties including: irreversibility in rain wet removal; overestimation of marine DMS and sea salt emissions, and accelerated aqueous sulfate conversion. Our findings suggest that WRF-Chem simulates marine cloud-aerosol interactions at a level sufficient for applications in forecasting weather and air quality and studying aerosol climate forcing, and may do so with the reliability required for policy analysis.

  5. Regional Modeling of Dust Mass Balance and Radiative Forcing over East Asia using WRF-Chem

    SciTech Connect

    Chen, Siyu; Zhao, Chun; Qian, Yun; Leung, Lai-Yung R.; Huang, J.; Huang, Zhongwei; Bi, Jianrong; Zhang, Wu; Shi, Jinsen; Yang, Lei; Li, Deshuai; Li, Jinxin

    2014-12-01

    The Weather Research and Forecasting model with Chemistry (WRF-Chem) is used to investigate the seasonal and annual variations of mineral dust over East Asia during 2007-2011, with a focus on the dust mass balance and radiative forcing. A variety of measurements from in-stu and satellite observations have been used to evaluate simulation results. Generally, WRF-Chem reproduces not only the column variability but also the vertical profile and size distribution of mineral dust over and near the dust source regions of East Asia. We investigate the dust lifecycle and the factors that control the seasonal and spatial variations of dust mass balance and radiative forcing over the seven sub-regions of East Asia, i.e. source regions, the Tibetan Plateau, Northern China, Southern China, the ocean outflow region, and Korea-Japan regions. Results show that, over the source regions, transport and dry deposition are the two dominant sinks. Transport contributes to ~30% of the dust sink over the source regions. Dust results in a surface cooling of up to -14 and -10 W m-2, atmospheric warming of up to 20 and 15 W m-2, and TOA cooling of -5 and -8 W m-2 over the two major dust source regions of East Asia, respectively. Over the Tibetan Plateau, transport is the dominant source with a peak in summer. Over identified outflow regions, maximum dust mass loading in spring is contributed by the transport. Dry and wet depositions are the comparably dominant sinks, but wet deposition is larger than dry deposition over the Korea-Japan region, particularly in spring (70% versus 30%). The WRF-Chem simulations can generally capture the measured features of dust aerosols and its radaitve properties and dust mass balance over East Asia, which provides confidence for use in further investigation of dust impact on climate over East Asia.

  6. Chemical Response of CESM/CAM-Chem to MOPITT CO Ensemble-based Chemical Data Assimilation

    NASA Astrophysics Data System (ADS)

    Gaubert, B.; Arellano, A. F.; Barré, J.; Worden, H. M.; Emmons, L. K.; Tilmes, S.; Buchholz, R. R.; Wiedinmyer, C.; Vitt, F.; Anderson, J. L.; Deeter, M. N.; Edwards, D. P.

    2015-12-01

    Carbon Monoxide is a key component in tropospheric chemistry. It plays an important role by affecting the oxidative capacity through its reaction with OH and being a precursor of tropospheric ozone. One year of multispectral retrievals of CO partial columns obtained from the MOPITT instrument have been assimilated into the Community Atmosphere Model with Chemistry (CAM-Chem). The assimilation is carried out using an Ensemble Adjustment Kalman Filter algorithm within the Data Assimilation Research Testbed (DART) package. Two assimilation experiments have been performed: 1) assimilation of meteorological observations and 2) joint assimilation of meteorological observations and MOPITT CO. We first evaluate the assimilation performance by investigating skill scores and other statistics for the two experiments, and comparing to independent CO datasets such as surface (WDCGG), aircraft (MOZAIC-IAGOS), and FTS (NDACC). Our results clearly demonstrate an overall improvement for spatio-temporal magnitude and variability in representing CO abundance in CAM-Chem. We then investigate the response of CAM-Chem to changes in CO fields (via CO assimilation) focusing mainly on the oxidative capacity (i.e., OH distribution, methane lifetime) and CO chemical production and loss (i.e., regional to global budget). This is carried out by analyzing the mean 6-hourly forecast adjustments as reflected between the two experiments. We show that changes in CO directly impact OH abundance, with subsequent non-linear responses in CO chemical production (CO from methane and VOCs) and CO loss. This is clearly evident in NOx-limited regions (e.g., Southern Hemisphere, remote sites). Such analysis has direct implications on the consistencies in inverse modeling estimates of CO sources through improved representation of chemical response (including full chemistry) in atmospheric chemistry models and through multi-species constraints.

  7. Sensitivity of Urbanization Impact over China by Using WRF/Chem

    NASA Astrophysics Data System (ADS)

    Yu, M.; Carmichael, G.

    2012-12-01

    Urbanization in China is an inevitable process coming along with economic development and population boost, which brings two impacts on air quality modeling. One is land-cover change and the other one is the additional stream of anthropogenic heat. In this study, we employed Weather Research Forecasting -Chemistry (WRF-Chem) to evaluate the sensitivity of meteorology and ozone concentrations in response to urbanization, by two cases, Jing-Jin-Ji (JJJ, indicating Beijing-Tianjin-Hebei) and Yangtze River Delta (YRD) areas. The first impact was achieved by updating the default land-cover data in WRF/Chem. Preliminary results showed an increase in 2-m temperature and PBL heights, and a decrease in wind-speed and dew points. For ozone concentrations, after updating land-cover data there was a corresponding rise in the surface level. The maximum increase was as much as 20 ppb for JJJ and 14 ppb for YRD area. The second impact was evaluated by adding anthropogenic heat stream into simulations. This heat stream was developed by considering both urban expansion and peak value at city centers. Test results showed a comparative 2-m temperature increase when compared to the first impact. While for PBL heights and dew points, the difference is negligible. Ozone concentrations within surface layer were also enhanced. The maximum increase was 7 ppb for JJJ area. Taking urbanization into consideration is a significant improvement for air quality modeling over China. After including both 1st and 2nd impact into WRF/Chem, the mean error was reduced by 35.6% for urban locations. One of our ongoing studies is focusing on further improvement of updating more recent land-cover data and anthropogenic heat. Ozone difference after including 1st impact Temporal plots for PKU(urban location)

  8. Evaluating WRF-Chem aerosol indirect effects in Southeast Pacific marine stratocumulus during VOCALS-REx

    NASA Astrophysics Data System (ADS)

    Saide, P. E.; Spak, S. N.; Carmichael, G. R.; Mena-Carrasco, M. A.; Howell, S.; Leon, D. C.; Snider, J. R.; Bandy, A. R.; Collett, J. L.; Benedict, K. B.; de Szoeke, S. P.; Hawkins, L. N.; Allen, G.; Crawford, I.; Crosier, J.; Springston, S. R.

    2011-11-01

    We evaluate a regional-scale simulation with the WRF-Chem model for the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx), which sampled the Southeast Pacific's persistent stratocumulus deck. Evaluation of VOCALS-REx ship-based and aircraft observations focuses on analyzing how aerosol loading affects marine boundary layer (MBL) dynamics and cloud microphysics. We compare local time series and campaign-averaged longitudinal gradients, and highlight differences in model simulations with (W) and without wet (NW) deposition processes. The higher aerosol loadings in the NW case produce considerable changes in MBL dynamics and cloud microphysics, in accordance with the established conceptual model of aerosol indirect effects. These include increase in cloud albedo, increase in MBL and cloud heights, drizzle suppression, increase in liquid water content, and increase in cloud lifetime. Moreover, better statistical representation of aerosol mass and number concentration improves model fidelity in reproducing observed spatial and temporal variability in cloud properties, including top and base height, droplet concentration, water content, rain rate, optical depth (COD) and liquid water path (LWP). Together, these help to quantify confidence in WRF-Chem's modeled aerosol-cloud interactions, while identifying structural and parametric uncertainties including: irreversibility in rain wet removal; overestimation of marine DMS and sea salt emissions and accelerated aqueous sulfate conversion. Our findings suggest that WRF-Chem simulates marine cloud-aerosol interactions at a level sufficient for applications in forecasting weather and air quality and studying aerosol climate forcing, including the reliability required for policy analysis and geo-engineering applications.

  9. Effects on Student Achievement in General Chemistry Following Participation in an Online Preparatory Course. ChemPrep, a Voluntary, Self-Paced, Online Introduction to Chemistry

    NASA Astrophysics Data System (ADS)

    Botch, Beatrice; Day, Roberta; Vining, William; Stewart, Barbara; Rath, Kenneth; Peterfreund, Alan; Hart, David

    2007-03-01

    ChemPrep was developed to be a stand-alone preparatory short-course to help students succeed in general chemistry. It is Web-based and delivered using the OWL system. Students reported that the ChemPrep materials (short information pages, parameterized questions with detailed feedback, tutorials, and answers to questions through the OWL message system) permitted them to work independently without the need for textbook or lecture. On average, students who completed ChemPrep had higher grades in the subsequent GenChem, Nursing, and Honors chemistry courses, with a greater percentage achieving a grade of C- or higher. Participation in ChemPrep was voluntary, and more women than men responded. Students in the Honors course enrolled in ChemPrep in higher percentages than students in GenChem and Nursing. SAT and departmental math placement exam scores were used as proxy measures of prior achievement and ability. Based on these, Honors chemistry ChemPrep users were on par with their peers but performed better in the course than non-users. In GenChem and Nursing chemistry courses, ChemPrep helped students of high prior achievement and ability perform better than their achievement scores would predict. Weaker or less motivated students did not respond to the voluntary offerings of ChemPrep in the same numbers as stronger or more motivated students, and we are seeking alternate ways to reach this population.

  10. Comment on ``Quasirelativistic theory equivalent to fully relativistic theory'' [J. Chem. Phys. 123, 241102 (2005)

    NASA Astrophysics Data System (ADS)

    Filatov, Michael

    2006-09-01

    The connection between the exact quasirelativistic approach developed in the title reference [W. Kutzelnigg and W. Liu, J. Chem. Phys. 123, 241102 (2005)] and the method of elimination of the small component in matrix form developed previously by Dyall is explicitly worked out. An equation that links Hermitian and non-Hermitian formulations of the exact quasirelativistic theory is derived. Besides establishing a kinship between the existing formulations, the proposed equation can be employed for the derivation of new formulations of the exact quasirelativistic theory.

  11. A highly sensitive, integrable, multimode, interferometric, evanescent-wave chem/bio sensor

    NASA Astrophysics Data System (ADS)

    Lillie, Jeffrey J.

    A fully integrated optical chem/bio sensor complete with integrated source, chemically sensitive waveguide, detector arrays, and associated signal processing electronics on a Si-CMOS chip is a challenging, but highly desirable goal. An evanescent-wave multimode interferometric sensing element is a sensitive method for sensing, which is easily integrated on Si-CMOS. This work is concerned with the design, analysis, and demonstration of a planar multimode interferometric chem/bio sensor that is compatible with the fabrication constraints of Si-CMOS. A 4000-micron-long interferometric that can be adapted for different agents by a particular sensing layer has been fabricated on silicon using silicon dioxide and silicon oxynitride. Hexaflouro-isopropanol substituted polynorbornene is the sensing layer. This sensor has also been fabricated on a Si-CMOS circuit with embedded photodetectors. A sensor on silicon was demonstrated with a minimum detectable index change of 2.0x10 -6 using an accurate gas delivery system and a custom hermetic waveguide test chamber. A modal pattern analysis strategy has also been developed to extract the optimal SNR from the measured modal patterns. An understanding of the noise processes and spatial bandwidth effects has enabled an experimentally-based prediction of the index sensitivity of a fully integrated multimode chem/bio sensor on Si-CMOS at 9.2x10-7. Theoretically, the sensitivity enhancement of high over low index sensing layers and transverse-magnetic over transverse electric modes is described. Also, the sensitivity enhancement of higher-order-transverse modes has been quantified. The wide-angle beam propagation method has been used to simulate the sensor. This simulation showed the relation between the modal pattern repetition period and sensor sensitivity. Further, the modal coupling properties of the multimode y-junction have been described. A second multimode y-junction has been designed to change the modal excitation under the

  12. Torsional Angle Driver (TorAD) System for HyperChem/Excel

    NASA Astrophysics Data System (ADS)

    Starkey, Ronald

    1999-02-01

    The torsional angle driver system for HyperChem/Excel is a package of several Excel spreadsheets and macro programs to be used with HyperChem to obtain and plot information, such as total energy, for the conformations that result from a 360° rotation about a torsional angle system in a molecule. The TorAD system also includes several HyperChem scripts to facilitate its use. TorAD was developed for use in the undergraduate organic chemistry laboratory. The results obtained with TorAD could be obtained manually with HyperChem, but it would take considerable time and would not be instructive to the students. Use of the TorAD system allows students to spend their time on the more important aspect of conformation analysisinterpretation of results. The Excel spreadsheet/macro programs in TorAD include:

    · Tor_xl_a and tor_xl obtain and plot the total energy at 5° torsional-angle intervals. The calculation method, the torsional-angle restraint, and the structure to be used at each angle can be set by the user. The advanced version, tor_xl_a, which requires HyperChem 4.5 or later, also allows torsional-angle structures to be saved for later recall as individual structures or, using a HyperChem script, in a movie format. It also provides a rapid scan of the 360° rotation where only single-point calculations, rather than geometry optimizations, are performed. The tor_xl system will perform routine tasks in a manner suitable for most instructional settings. · Tor_Comp performs molecular mechanics optimizations at 5° intervals and obtains and plots four energy parameters (total, torsional, nonbonded, and bond [bend plus stretch] energy) as a function of torsional angle. The calculation method and the restraint can be specified. · TorDipol produces a plot of the total energy and the calculated dipole moment at 5° steps of the torsional angle. The default calculation is the semi-empirical AM

  13. ChemCam passive reflectance spectroscopy of surface materials at the Curiosity landing site, Mars

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey R.; Bell, J. F.; Bender, S.; Blaney, D.; Cloutis, E.; DeFlores, L.; Ehlmann, B.; Gasnault, O.; Gondet, B.; Kinch, K.; Lemmon, M.; Le Mouélic, S.; Maurice, S.; Rice, M.; Wiens, R. C.

    2015-03-01

    The spectrometers on the Mars Science Laboratory (MSL) ChemCam instrument were used in passive mode to record visible/near-infrared (400-840 nm) radiance from the martian surface. Using the onboard ChemCam calibration targets' housing as a reflectance standard, we developed methods to collect, calibrate, and reduce radiance observations to relative reflectance. Such measurements accurately reproduce the known reflectance spectra of other calibration targets on the rover, and represent the highest spatial resolution (0.65 mrad) and spectral sampling (<1 nm) visible/near-infrared reflectance spectra from a landed platform on Mars. Relative reflectance spectra of surface rocks and soils match those from orbital observations and multispectral data from the MSL Mastcam camera. Preliminary analyses of the band depths, spectral slopes, and reflectance ratios of the more than 2000 spectra taken during the first year of MSL operations demonstrate at least six spectral classes of materials distinguished by variations in ferrous and ferric components. Initial comparisons of ChemCam spectra to laboratory spectra of minerals and Mars analog materials demonstrate similarities with palagonitic soils and indications of orthopyroxene in some dark rocks. Magnesium-rich "raised ridges" tend to exhibit distinct near-infrared slopes. The ferric absorption downturn typically found for martian materials at <600 nm is greatly subdued in brushed rocks and drill tailings, consistent with their more ferrous nature. Calcium-sulfate veins exhibit the highest relative reflectances observed, but are still relatively red owing to the effects of residual dust. Such dust is overall less prominent on rocks sampled within the "blast zone" immediately surrounding the landing site. These samples were likely affected by the landing thrusters, which partially removed the ubiquitous dust coatings. Increased dust coatings on the calibration targets during the first year of the mission were documented by

  14. ChemCam First Discovery of High Silica Sediments in Gale Crater

    NASA Astrophysics Data System (ADS)

    Frydenvang, J.; Gasda, P. J.; Wiens, R. C.; Newsom, H. E.; Bridges, J.; Gasnault, O.; Maurice, S.; Forni, O.; Mangold, N.; Cousin, A.; Payré, V.; Anderson, R. B.; Mitrofanov, I. G.; Jun, I.; Rice, M. S.; Milliken, R.; Edwards, P.; Vaniman, D. T.; Morris, R. V.; Blake, D. F.; Gellert, R.; Thompson, L. M.; Clark, B. C.; Hurowitz, J.; Sumner, D. Y.; Ehlmann, B. L.; Fraeman, A.; Kinch, K. M.; Madsen, M. B.; Calef, F.; Grotzinger, J. P.; Vasavada, A. R.

    2015-12-01

    On sol 991, The Curiosity rover ascended a steep slope to Marias Pass in Gale Crater. Close to the top, ChemCam analyzed the rock target Elk from an apparent bright unit. Utilizing the new elemental calibration implemented for ChemCam in the summer of 2015, four of five points on Elk were measured to contain 76-82 wt% SiO2 and >3 wt% TiO2, whereas the last point showed elevated CaSO4. The Elk target is identified to be part of the Murray formation, and hence related to the Pahrump area mudstones that were subjected to intensive studies by the Curiosity rover team over the sols 758-948. While the Murray formation west of Elk did show elevated SiO2 (~65 wt%) compared to the Pahrump area, no targets with similarly high SiO2 wt% as Elk were observed, thus prompting - together with detection of anomalously high DAN H signals in the same area - the Curiosity rover to return to the Elk target area for additional analyses. This return led to numerous additional high Si observations (targets Pistol, Mary, Shepard, Dublin Gulch and Frog) that all corroborated the initial high Si observation at Elk. Additionally, the Alpha Particle X-ray Spectrometer (APXS) analyzed the target Lamoose and found SiO2 content in excess of 72 wt% and moderately elevated TiO2. Considering the difference in footprint (1.7 cm for APXS vs ~400μm for ChemCam) and the fact that the target couldn't be brushed, this is considered a good corroboration of the very high Si observed with ChemCam. These targets suggest that the Elk-area targets represent an end-member of the Murray formation, but there are multiple working hypotheses for the origin of the high SiO2 and TiO2 in these: 1. primary precipitates from the water column of a lake, 2. a post-depositional leaching/weathering front and 3. a hydrothermal silica precipitate.

  15. Application of the Loci-Based CFD Code Chem at MSFC: Preliminary Results

    NASA Technical Reports Server (NTRS)

    West, Jeff S.; Rothermel, Jeff

    2002-01-01

    Contents include the following: 1. Objectives. Concentrate on determining the qualitative accuracy, performance and robustness of the Chen code. 2. What is the Loci-Chem CFD code? Density-based, finite volume, generalized unstructured grid, Navier-Stokes solver. The algorithm was implemented using the Loci framework, which allows implementation issues such as parallel processing to be handled transparently to the coding of the CFD algorithm. 3. Application to Bifurcating Duct problem. Flow splits from single duct to two ducts. 4. Application to single element injector. 5. Application to PSU RBCC rig. 6. 90 degree elbow benchmark problem. 7. Future work.

  16. Estimates of black carbon emissions in the western United States using the GEOS-Chem adjoint model

    NASA Astrophysics Data System (ADS)

    Mao, Y. H.; Li, Q. B.; Henze, D. K.; Jiang, Z.; Jones, D. B. A.; Kopacz, M.; He, C.; Qi, L.; Gao, M.; Hao, W.-M.; Liou, K.-N.

    2015-07-01

    We estimate black carbon (BC) emissions in the western United States for July-September 2006 by inverting surface BC concentrations from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network using a global chemical transport model (GEOS-Chem) and its adjoint. Our best estimate of the BC emissions is 49.9 Gg at 2° × 2.5° (a factor of 2.1 increase) and 47.3 Gg at 0.5° × 0.667° (1.9 times increase). Model results now capture the observed major fire episodes with substantial bias reductions ( 35 % at 2° × 2.5° and 15 % at 0.5° × 0.667°). The emissions are 20-50 % larger than those from our earlier analytical inversions (Mao et al., 2014). The discrepancy is especially drastic in the partitioning of anthropogenic versus biomass burning emissions. The August biomass burning BC emissions are 4.6-6.5 Gg and anthropogenic BC emissions 8.6-12.8 Gg, varying with the model resolution, error specifications, and subsets of observations used. On average both anthropogenic and biomass burning emissions in the adjoint inversions increase 2-fold relative to the respective {a priori} emissions, in distinct contrast to the halving of the anthropogenic and tripling of the biomass burning emissions in the analytical inversions. We attribute these discrepancies to the inability of the adjoint inversion system, with limited spatiotemporal coverage of the IMPROVE observations, to effectively distinguish collocated anthropogenic and biomass burning emissions on model grid scales. This calls for concurrent measurements of other tracers of biomass burning and fossil fuel combustion (e.g., carbon monoxide and carbon isotopes). We find that the adjoint inversion system as is has sufficient information content to constrain the total emissions of BC on the model grid scales.

  17. Nanoplatforms for Detection, Remediation and Protection Against Chem-Bio Warfare

    NASA Astrophysics Data System (ADS)

    Denkbaş, E. B.; Bayram, C.; Kavaz, D.; Çirak, T.; Demirbilek, M.

    Chemical and biological substances have been used as warfare agents by terrorists by varying degree of sophistication. It is critical that these agents be detected in real-time with high level of sensitively, specificity, and accuracy. Many different types of techniques and systems have been developed to detect these agents. But there are some limitations in these conventional techniques and systems. Limitations include the collection, handling and sampling procedures, detection limits, sample transfer, expensive equipment, personnel training, and detection materials. Due to the unique properties such as quantum effect, very high surface/volume ratio, enhanced surface reactivity, conductivity, electrical and magnetic properties of the nanomaterials offer great opportunity to develop very fast, sensitive, accurate and cost effective detection techniques and systems to detect chemical and biological (chem.-bio) warfare agents. Furthermore, surface modification of the materials is very easy and effective way to get functional or smart surfaces to be used as nano-biosensor platform. In that respect many different types of nanomaterials have been developed and used for the detection, remediation and protection, such as gold and silver nanoparticles, quantum dots, Nano chips and arrays, fluorescent polymeric and magnetic nanoparticles, fiber optic and cantilever based nanobiosensors, nanofibrillar nanostructures etc. This study summarizes preparation and characterization of nanotechnology based approaches for the detection of and remediation and protection against chem.-bio warfare agents.

  18. Recent Highlights of ChemCam’s exploration of Gale Crater

    NASA Astrophysics Data System (ADS)

    Blaney, Diana L.; Wiens, Roger C.; Maurice, Sylvestre; Anderson, Ryan; Clegg, Samuel; Le Deit, Laetitia; Forni, Olivier; Gasnault, Olivier; Johnson, Jeffry R.; Lanza, Nina; Lasue, Jeremie A.; Mangold, Nicholas; Nachon, Marion; Newsom, Horton; Pilleri , Agnes; Sautter, Violaine

    2014-11-01

    ChemCam has been exploring Gale Crater and documenting the chemistry along our traverse to Mount Sharp. More than 160,000 LIBS spectra and 2,000 images have been returned to Earth from locations along the 9 km route. Key discoveries documented by ChemCam along the traverse since leaving the Yellow Knife Bay drilling location include: 1) abundant alkali feldspar present in conglomerates and float rocks; 2) MnO present at up to several wt. % in specific coatings and in the Kimberly outcrop; its presence suggests highly oxidized fluids existed during emplacement; 3) fluorine present in key lithologies; the associated chemistry indicates the occurrence of fluor-apatites in igneous rocks and micas in conglomerates; 4) Cap rocks showing a wide range of compositions that span the compositions of outcrops seen at previous locations (e.g. “Shaler”, “Point Lake”) 5) a pair of iron meteorites, “Lebanon” and “Littleton”, 6) Chlorine-bearing soils in “Hidden Valley” and corresponding light toned outcrops and 7) an assessment of coatings in Gale that indicate alteration rates are generally slower than rates of aeolian abrasion. The talk will also include discussion of most recent results and their implications for fluvial processes at Gale.

  19. Statistical Downscaling of WRF-Chem Model: An Air Quality Analysis over Bogota, Colombia

    NASA Astrophysics Data System (ADS)

    Kumar, Anikender; Rojas, Nestor

    2015-04-01

    Statistical downscaling is a technique that is used to extract high-resolution information from regional scale variables produced by coarse resolution models such as Chemical Transport Models (CTMs). The fully coupled WRF-Chem (Weather Research and Forecasting with Chemistry) model is used to simulate air quality over Bogota. Bogota is a tropical Andean megacity located over a high-altitude plateau in the middle of very complex terrain. The WRF-Chem model was adopted for simulating the hourly ozone concentrations. The computational domains were chosen of 120x120x32, 121x121x32 and 121x121x32 grid points with horizontal resolutions of 27, 9 and 3 km respectively. The model was initialized with real boundary conditions using NCAR-NCEP's Final Analysis (FNL) and a 1ox1o (~111 km x 111 km) resolution. Boundary conditions were updated every 6 hours using reanalysis data. The emission rates were obtained from global inventories, namely the REanalysis of the TROpospheric (RETRO) chemical composition and the Emission Database for Global Atmospheric Research (EDGAR). Multiple linear regression and artificial neural network techniques are used to downscale the model output at each monitoring stations. The results confirm that the statistically downscaled outputs reduce simulated errors by up to 25%. This study provides a general overview of statistical downscaling of chemical transport models and can constitute a reference for future air quality modeling exercises over Bogota and other Colombian cities.

  20. Using Combustion Tracers to Estimate Surface Black Carbon Distributions in WRF-Chem

    NASA Astrophysics Data System (ADS)

    Raman, A.; Arellano, A. F.

    2015-12-01

    Black Carbon (BC) emissions significantly affect the global and regional climate, air quality, and human health. However, BC observations are currently limited in space and time; leading to considerable uncertainties in the estimates of BC distribution from regional and global models. Here, we investigate the usefulness of carbon monoxide (CO) in quantifying BC across continental United States (CONUS). We use high resolution EPA AQS observations of CO and IMPROVE BC to estimate BC/CO ratios. We model the BC and CO distribution using the community Weather Research and Forecasting model with Chemistry (WRF-Chem). We configured WRF-Chem using MOZART chemistry, NEI 2005, MEGAN, and FINNv1.5 for anthropogenic, biogenic and fire emissions, respectively. In this work, we address the following three key questions: 1) What are the discrepancies in the estimates of BC and CO distributions across CONUS during summer and winter periods?, 2) How do BC/CO ratios change for different spatial and temporal regimes?, 3) Can we get better estimates of BC from WRF-Chem if we use BC/CO ratios along with optimizing CO concentrations? We compare ratios derived from the model and observations and develop characteristic ratios for several geographical and temporal regimes. We use an independent set of measurements of BC and CO to evaluate these ratios. Finally, we use a Bayesian synthesis inversion to optimize CO from WRF-Chem using regionally tagged CO tracers. We multiply the characteristic ratios we derived with the optimized CO to obtain BC distributions. Our initial results suggest that the maximum ratios of BC versus CO occur in the western US during the summer (average: 4 ng/m3/ppbv) and in the southeast during the winter (average: 5 ng/m3/ppbv). However, we find that these relationships vary in space and time and are highly dependent on fuel usage and meteorology. We find that optimizing CO using EPA-AQS provides improvements in BC but only over areas where BC/CO ratios are close

  1. Inclusion of biomass burning in WRF-Chem: Impact of wildfires on weather forecasts

    SciTech Connect

    Grell, G. A.; Freitas, Saulo; Stuefer, Martin; Fast, Jerome D.

    2011-06-06

    A plume rise algorithm for wildfires was included in WRF-Chem, and applied to look at the impact of intense wildfires during the 2004 Alaska wildfire season on weather forecasts using model resolutions of 10km and 2km. Biomass burning emissions were estimated using a biomass burning emissions model. In addition, a 1-D, time-dependent cloud model was used online in WRF-Chem to estimate injection heights as well as the final emission rates. It was shown that with the inclusion of the intense wildfires of the 2004 fire season in the model simulations, the interaction of the aerosols with the atmospheric radiation led to significant modifications of vertical profiles of temperature and moisture in cloud-free areas. On the other hand, when clouds were present, the high concentrations of fine aerosol (PM2.5) and the resulting large numbers of Cloud Condensation Nuclei (CCN) had a strong impact on clouds and microphysics, with decreased precipitation coverage and precipitation amounts during the first 12 hours of the integration, but significantly stronger storms during the afternoon hours.

  2. Pro- and Anti-Inflammatory Role of ChemR23 Signaling in Pollutant-Induced Inflammatory Lung Responses.

    PubMed

    Provoost, Sharen; De Grove, Katrien C; Fraser, Graeme L; Lannoy, Vincent J; Tournoy, Kurt G; Brusselle, Guy G; Maes, Tania; Joos, Guy F

    2016-02-15

    Inhalation of traffic-related particulate matter (e.g., diesel exhaust particles [DEPs]) is associated with acute inflammatory responses in the lung, and it promotes the development and aggravation of allergic airway diseases. We previously demonstrated that exposure to DEP was associated with increased recruitment and maturation of monocytes and conventional dendritic cells (DCs), resulting in TH2 polarization. Monocytes and immature DCs express the G-protein coupled receptor chemR23, which binds the chemoattractant chemerin. Using chemR23 knockout (KO) and corresponding wild-type (WT) mice, we determined the role of chemR23 signaling in response to acute exposure to DEPs and in response to DEP-enhanced house dust mite (HDM)-induced allergic airway inflammation. Exposure to DEP alone, as well as combined exposure to DEP plus HDM, elevated the levels of chemerin in the bronchoalveolar lavage fluid of WT mice. In response to acute exposure to DEPs, monocytes and monocyte-derived DCs accumulated in the lungs of WT mice, but this response was significantly attenuated in chemR23 KO mice. Concomitant exposure to DEP plus HDM resulted in allergic airway inflammation with increased eosinophilia, goblet cell metaplasia, and TH2 cytokine production in WT mice, which was further enhanced in chemR23 KO mice. In conclusion, we demonstrated an opposing role for chemR23 signaling depending on the context of DEP-induced inflammation. The chemR23 axis showed proinflammatory properties in a model of DEP-induced acute lung inflammation, in contrast to anti-inflammatory effects in a model of DEP-enhanced allergic airway inflammation. PMID:26773141

  3. PUG-SOAP and PUG-REST: web services for programmatic access to chemical information in PubChem.

    PubMed

    Kim, Sunghwan; Thiessen, Paul A; Bolton, Evan E; Bryant, Stephen H

    2015-07-01

    PubChem (http://pubchem.ncbi.nlm.nih.gov) is a public repository for information on chemical substances and their biological activities, developed and maintained by the US National Institutes of Health (NIH). PubChem contains more than 180 million depositor-provided chemical substance descriptions, 60 million unique chemical structures and 225 million bioactivity assay results, covering more than 9000 unique protein target sequences. As an information resource for the chemical biology research community, it routinely receives more than 1 million requests per day from an estimated more than 1 million unique users per month. Programmatic access to this vast amount of data is provided by several different systems, including the US National Center for Biotechnology Information (NCBI)'s Entrez Utilities (E-Utilities or E-Utils) and the PubChem Power User Gateway (PUG)-a common gateway interface (CGI) that exchanges data through eXtended Markup Language (XML). Further simplifying programmatic access, PubChem provides two additional general purpose web services: PUG-SOAP, which uses the simple object access protocol (SOAP) and PUG-REST, which is a Representational State Transfer (REST)-style interface. These interfaces can be harnessed in combination to access the data contained in PubChem, which is integrated with the more than thirty databases available within the NCBI Entrez system. PMID:25934803

  4. PUG-SOAP and PUG-REST: web services for programmatic access to chemical information in PubChem

    PubMed Central

    Kim, Sunghwan; Thiessen, Paul A.; Bolton, Evan E.; Bryant, Stephen H.

    2015-01-01

    PubChem (http://pubchem.ncbi.nlm.nih.gov) is a public repository for information on chemical substances and their biological activities, developed and maintained by the US National Institutes of Health (NIH). PubChem contains more than 180 million depositor-provided chemical substance descriptions, 60 million unique chemical structures and 225 million bioactivity assay results, covering more than 9000 unique protein target sequences. As an information resource for the chemical biology research community, it routinely receives more than 1 million requests per day from an estimated more than 1 million unique users per month. Programmatic access to this vast amount of data is provided by several different systems, including the US National Center for Biotechnology Information (NCBI)'s Entrez Utilities (E-Utilities or E-Utils) and the PubChem Power User Gateway (PUG)—a common gateway interface (CGI) that exchanges data through eXtended Markup Language (XML). Further simplifying programmatic access, PubChem provides two additional general purpose web services: PUG-SOAP, which uses the simple object access protocol (SOAP) and PUG-REST, which is a Representational State Transfer (REST)-style interface. These interfaces can be harnessed in combination to access the data contained in PubChem, which is integrated with the more than thirty databases available within the NCBI Entrez system. PMID:25934803

  5. Calibration of the MSL/ChemCam/LIBS Remote Sensing Composition Instrument

    NASA Technical Reports Server (NTRS)

    Wiens, R. C.; Maurice S.; Bender, S.; Barraclough, B. L.; Cousin, A.; Forni, O.; Ollila, A.; Newsom, H.; Vaniman, D.; Clegg, S.; Lasue, J. A.; Blaney, D.; DeFlores, L.; Morris, R. V.

    2011-01-01

    The ChemCam instrument suite on board the 2011 Mars Science Laboratory (MSL) Rover, Curiosity, will provide remote-sensing composition information for rock and soil samples within seven meters of the rover using a laser-induced breakdown spectroscopy (LIBS) system, and will provide context imaging with a resolution of 0.10 mradians using the remote micro-imager (RMI) camera. The high resolution is needed to image the small analysis footprint of the LIBS system, at 0.2-0.6 mm diameter. This fine scale analytical capability will enable remote probing of stratigraphic layers or other small features the size of "blueberries" or smaller. ChemCam is intended for rapid survey analyses within 7 m of the rover, with each measurement taking less than 6 minutes. Repeated laser pulses remove dust coatings and provide depth profiles through weathering layers, allowing detailed investigation of rock varnish features as well as analysis of the underlying pristine rock composition. The LIBS technique uses brief laser pulses greater than 10 MW/square mm to ablate and electrically excite material from the sample of interest. The plasma emits photons with wavelengths characteristic of the elements present in the material, permitting detection and quantification of nearly all elements, including the light elements H, Li, Be, B, C, N, O. ChemCam LIBS projects 14 mJ of 1067 nm photons on target and covers a spectral range of 240-850 nm with resolutions between 0.15 and 0.60 nm FWHM. The Nd:KGW laser is passively cooled and is tuned to provide maximum power output from -10 to 0 C, though it can operate at 20% degraded energy output at room temperature. Preliminary calibrations were carried out on the flight model (FM) in 2008. However, the detectors were replaced in 2009, and final calibrations occurred in April-June, 2010. This presentation describes the LIBS calibration and characterization procedures and results, and details plans for final analyses during rover system thermal testing

  6. Evaluation and comparison of O3 forecasts of ALARO-CAMx and WRF-Chem

    NASA Astrophysics Data System (ADS)

    Flandorfer, Claudia; Hirtl, Marcus

    2015-04-01

    ZAMG runs two models for Air-Quality forecasts operationally: ALARO-CAMx and WRF-Chem. ALARO-CAMx is a combination of the meteorological model ALARO and the photochemical dispersion model CAMx and is operated at ZAMG by order of the regional governments since 2005. The emphasis of this modeling system is on predicting ozone peaks in the north-east Austrian flatlands. Two modeling domains are used with the highest resolution (5 km) in the alpine region. Various extensions with external data sources have been conducted in the past to improve the daily forecasts of the model, e.g. data assimilation of O3- and PM10 observations from the Austrian measurement network (with optimum interpolation technique); MACC-II boundary conditions; combination of high resolved emission inventories for Austria with TNO and EMEP data. The biogenic emissions are provided by the SMOKE model. The model runs 2 times per day for a period of 48 hours. The second model which is operational is the on-line coupled model WRF-Chem. Meteorology is simulated simultaneously with the emission, turbulent mixing, transport, transformation, and fate of trace gases and aerosols. 2 domains are used for the simulations. The mother domain covers Europe with a resolution of 12 km. The inner domain includes the alpine region with a horizontal resolution of 4km. 45 model levels are used in the vertical. The model runs 2 times per day for a period of 72 hours and is initialized with ECMWF forecasts. The evaluation of both models is conducted for summer 2014 with the main focus on the forecasts of ozone. The measurements of the Air-Quality stations are compared with the punctual forecasts at the sites of the stations and with the area forecasts for every province of Austria. Beside the evaluation a comparison of the forecasts of ALARO-CAMx and WRF-Chem is done. The summer 2014 was the coldest and the dullest in the last 9 years. Due to this only two exceedances of the information threshold were measured (June

  7. Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model.

    PubMed

    Wang, Long; Wang, Shuxiao; Zhang, Lei; Wang, Yuxuan; Zhang, Yanxu; Nielsen, Chris; McElroy, Michael B; Hao, Jiming

    2014-07-01

    China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35-50% of THg concentration and 50-70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China. PMID:24768744

  8. Assessments of Potential Rock Coatings at Rocknest, Gale Crater with ChemCam

    NASA Technical Reports Server (NTRS)

    Blaney, D. L.; Anderson, R.; Berger, G.; Bridges, J.; Bridges, N.; Clark, B.; Clegg, S.; Ehlman, B.; Goetz, W.; King, P.; Lanza, N.; Mangold, N.; Meslin, P.-Y.; Newsom, H.

    2013-01-01

    Many locations on Mars have low color contrast between the rocks and soils due to the rocks being "dusty"--basically having a surface that is spectrally similar to Martian soil. In general this has been interpreted as soil and/or dust clinging to the rock though either mechanical or electrostic processes. However, given the apparent mobility of thin films of water forming cemented soils on Mars and at Gale Crater, the possibility exists that some of these "dusty" surfaces may actually be coatings formed by thin films of water locally mobilizing soil/air fall material at the rock interface. This type of coating was observed by Spirit during an investigation of the rock Mazatzal which showed enhanced salts above "normal soil" and an enhancement of nano phase iron oxide that was 10 micronmeters thick. We decided to use ChemCam to investigate the possibility of similar rock coatings forming at the Rocknest site at Gale Crater.

  9. Aerosol impact on seasonal prediction using FIM-Chem-iHYCOM coupled model

    NASA Astrophysics Data System (ADS)

    sun, shan; Grell, Georg; Bleck, Rainer

    2016-04-01

    A coupled model consisting of the weather model FIM and the ocean model iHYCOM, both operating on an icosahedral horizontal grid, is being developed for subseasonal to seasonal prediction. Initial results indicate that the model skill is comparable to that of the operational model CFSv2 used by NCEP. In addition, an online atmospheric chemistry module is coupled to FIM. The purpose of onging experiments with the FIM-Chem-iHYCOM combination is to investigate the aerosol impact on the atmospheric and oceanic circulation at the seasonal scale. We compare the model sensitivity with various chemistry emissions, including aerosols, fire and anthropogenic emissions. Additional emphasis of this work is on the effect of aerosols on cloudiness and precipitation, either directly or indirectly through changes in SST. To isolate the latter effect, we conduct parallel experiments with observed SST.

  10. Application of iChemExplorer in pharmaceutical pH stress testing.

    PubMed

    Qiu, Fenghe; Du, Lily; Soman, Ashish; Jankovsky, Corinne; Li, Chan

    2013-03-25

    pH stress testing is an integral part of pharmaceutical stress testing and is a regulatory requirement for validating a stability indicating analytical method and elucidating degradation products and degradation pathways. This paper reports the results of an evaluation of iChemExplorer (ICE) for drug substance and drug product pH stress testing in comparison with the conventional (manual) approach. ICE is a simple and inexpensive technology, and through real case studies it was demonstrated that ICE is an efficient and "fit-for-purpose" alternative in conducting pharmaceutical pH stress testing. In addition, when using a non-isothermal ICE protocol, it is feasible to estimate the pH degradation kinetics (e.g., E(a)) using the ICE software. PMID:23339989

  11. The PubChemQC project: A large chemical database from the first principle calculations

    NASA Astrophysics Data System (ADS)

    Maho, Nakata

    2015-12-01

    In this research, we have been constructing a large database of molecules by ab initio calculations. Currently, we have over 1.53 million entries of 6-31G* B3LYP optimized geometries and ten excited states by 6-31+G* TDDFT calculations. To calculate molecules, we only refer the InChI (International Chemical Identifier) representation of chemical formula by the International Union of Pure and Applied Chemistry (IUPAC), thus, no reference to experimental data. These results are open to public at http://pubchemqc.riken.jp/. The molecular data have been taken from the PubChem Project (http://pubchem.ncbi.nlm.nih.gov/) which is one of the largest in the world (approximately 63 million molecules are listed) and free (public domain) database. Our final goal is, using these data, to develop a molecular search engine or molecular expert system to find molecules which have desired properties.

  12. A New WRF-Chem Treatment for Studying Regional Scale Impacts of Cloud-Aerosol Interactions in Parameterized Cumuli

    SciTech Connect

    Berg, Larry K.; Shrivastava, ManishKumar B.; Easter, Richard C.; Fast, Jerome D.; Chapman, Elaine G.; Liu, Ying

    2015-01-01

    A new treatment of cloud-aerosol interactions within parameterized shallow and deep convection has been implemented in WRF-Chem that can be used to better understand the aerosol lifecycle over regional to synoptic scales. The modifications to the model to represent cloud-aerosol interactions include treatment of the cloud dropletnumber mixing ratio; key cloud microphysical and macrophysical parameters (including the updraft fractional area, updraft and downdraft mass fluxes, and entrainment) averaged over the population of shallow clouds, or a single deep convective cloud; and vertical transport, activation/resuspension, aqueous chemistry, and wet removal of aerosol and trace gases in warm clouds. Thesechanges have been implemented in both the WRF-Chem chemistry packages as well as the Kain-Fritsch cumulus parameterization that has been modified to better represent shallow convective clouds. Preliminary testing of the modified WRF-Chem has been completed using observations from the Cumulus Humilis Aerosol Processing Study (CHAPS) as well as a high-resolution simulation that does not include parameterized convection. The simulation results are used to investigate the impact of cloud-aerosol interactions on the regional scale transport of black carbon (BC), organic aerosol (OA), and sulfate aerosol. Based on the simulations presented here, changes in the column integrated BC can be as large as -50% when cloud-aerosol interactions are considered (due largely to wet removal), or as large as +35% for sulfate in non-precipitating conditions due to the sulfate production in the parameterized clouds. The modifications to WRF-Chem version 3.2.1 are found to account for changes in the cloud drop number concentration (CDNC) and changes in the chemical composition of cloud-drop residuals in a way that is consistent with observations collected during CHAPS. Efforts are currently underway to port the changes described here to WRF-Chem version 3.5, and it is anticipated that they

  13. Viral vectors for gene modification of plants as chem/bio sensors.

    SciTech Connect

    Manginell, Monica; Harper, Jason C.; Arango, Dulce C.; Brozik, Susan Marie; Dolan, Patricia L.

    2006-11-01

    Chemical or biological sensors that are specific, sensitive, and robust allowing intelligence gathering for verification of nuclear non-proliferation treaty compliance and detouring production of weapons of mass destruction are sorely needed. Although much progress has been made in the area of biosensors, improvements in sensor lifetime, robustness, and device packaging are required before these devices become widely used. Current chemical and biological detection and identification techniques require less-than-covert sample collection followed by transport to a laboratory for analysis. In addition to being expensive and time consuming, results can often be inconclusive due to compromised sample integrity during collection and transport. We report here a demonstration of a plant based sensor technology which utilizes mature and seedling plants as chemical sensors. One can envision genetically modifying native plants at a site of interest that can report the presence of specific toxins or chemicals. In this one year project we used a developed inducible expression system to show the feasibility of plant sensors. The vector was designed as a safe, non-infectious vector which could be used to invade, replicate, and introduce foreign genes into mature host plants that then allow the plant to sense chem/bio agents. The genes introduced through the vector included a reporter gene that encodes for green fluorescent protein (GFP) and a gene that encodes for a mammalian receptor that recognizes a chemical agent. Specifically, GFP was induced by the presence of 17-{beta}-Estradiol (estrogen). Detection of fluorescence indicated the presence of the target chemical agent. Since the sensor is a plant, costly device packaging development or manufacturing of the sensor were not required. Additionally, the biological recognition and reporting elements are maintained in a living, natural environment and therefore do not suffer from lifetime disadvantages typical of most biosensing

  14. Mixed Waste Treatment Using the ChemChar Thermolytic Detoxification Technique

    SciTech Connect

    Kuchynka, D.J.

    1997-01-01

    This R and D program addresses the treatment of mixed waste employing the ChemChar Thermolytic Detoxification process. Surrogate mixed waste streams will be treated in a four inch diameter, continuous feed, adiabatic reactor with the goal of meeting all regulatory treatment levels for the contaminants in the surrogates with the concomitant production of contaminant free by-products. Successful completion of this program will show that organic contaminants in mixed waste surrogates will be converted to a clean, energy rich synthesis gas capable of being used, without further processing, for power or heat generation. The inorganic components in the surrogates will be found to be adsorbed on a macroporous coal char activated carbon substrate which is mixed with the waste prior to treatment. These contaminants include radioactive metal surrogate species, RCRA hazardous metals and any acid gases formed during the treatment process. The program has three main tasks that will be performed to meet the above objectives. The first task is the design and construction of the four inch reactor at Mirage Systems in Sunnyvale, CA. The second task is production and procurement of the activated carbon char employed in the ChemChartest runs and identification of two surrogate mixed wastes. The last task is testing and operation of the reactor on char/surrogate waste mixtures to be performed at the University of Missouri. The deliverables for the project are a Design Review Report, Operational Test Plan, Topical Report and Final Report. This report contains only the results of the design and construction carbon production-surrogate waste identification tasks.Treatment of the surrogate mixed wastes has just begun and will not be reported in this version of the Final Report. The latter will be reported in the final version of the Final Report.

  15. Aerosol Radiative Forcing over North India during Pre-Monsoon Season using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Misra, A.; Kumar, K.; Michael, M.; Tripathi, S. N.

    2013-12-01

    Study of aerosols is important for a fair understanding of the Earth climate system. This requires knowledge of the physical, chemical, optical, and morphological properties of aerosols. Aerosol radiative forcing provides information on the effect of aerosols on the Earth radiation budget. Radiative forcing estimates using model data provide an opportunity to examine the contribution of individual aerosol species to overall radiative forcing. We have used Weather Research and Forecast with Online Chemistry (WRF-Chem) derived aerosol concentration data to compute aerosol radiative forcing over north India during pre-monsoon season of 2008, 2009, and 2010. WRF-Chem derived mass concentrations are converted to number concentrations using standard procedure. Optical Properties of Aerosol and Cloud (OPAC) software package is used to compute extinction and scattering coefficients, and asymmetry parameter. Computations are performed at different altitudes and the obtained values are integrated to get the column optical properties. Santa Barbara Discrete Ordinate Radiative Transfer (SBDART) model is used to calculate the radiative forcing at surface and top-of-atmosphere. Higher values of aerosol radiative forcing are observed over desert region in western Indian state of Rajasthan, and Punjab of Pakistan. Contribution of individual aerosol species to atmospheric radiative forcing is also assessed. Dust radiative forcing is high over western India. Radiative forcing due to BC and water-soluble (WASO) aerosols are higher over north-west Indian states of Punjab and Haryana, and the Indo-Gangetic Basin. A pool of high WASO optical depth and radiative forcing is observed over the Indo-Bangladesh border. The findings of aerosol optical depth and radiative forcing are consistent with the geography and prevailing aerosol climatology of various regions. Heating rate profiles due to total aerosols and only due to BC have been evaluated at selected stations in north India. They show

  16. Analysis of modified MYJ and YSU boundary layer schemes in WRF-Chem with respect to simulated boundary layer heights and pollutant concentrations

    NASA Astrophysics Data System (ADS)

    Forkel, Renate; Foreman, Richard; Emeis, Stefan

    2014-05-01

    To improve the performance of boundary layer schemes currently applied within WRF-Chem (Grell et al., 2005), the Mellor-Yamada-Janjic (MYJ) model (Mellor and Yamada 1982) and the Yonsei University (YSU) PBL scheme (Hong et al. 2006) have been updated using data from a 100 m high offshore measurement tower called FINO1. The turbulence intensity in the Mellor-Yamada-Janjic model has been enhanced as described in Foreman and Emeis (2012). An alternative to the exchange coefficient for stable stratification in the YSU scheme is described in Foreman et al. (2014). These modifications to the two schemes have been applied and are compared with the existing schemes. For example, the updated MYJ scheme results in an improved representation of the turbulent kinetic energy throughout the boundary layer as compared with the measurements at FINO1. The modified MYJ and YSU schemes, which have been originally developed for wind energy applications, have been implemented into version 3.5 of the WRF model. Simulations with WRF-Chem were carried out for Europe and the region of Augsburg in order to evaluate the effect of the modified PBL schemes on simulated PBL heights, gas phase pollutant and aerosol concentrations. Foreman, R.J. and S. Emeis, 2012. A method for increasing the turbulent kinetic energy in the Mellor-Yamada-Janjic boundary layer parametrization. Boundary Layer Meteorology 145:329-349. Foreman, R.J. S. Emeis and B. Canadillas, 2014. Stable boundary layer parametrization without eddy viscosity or turbulent kinetic energy equation approaches. Submitted to Boundary Layer Meteorology 2014. Grell, G. A., Peckham, S. E., Schmitz, R., McKeen, S. A., Frost, G., Skamarock,W. C., and Eder, B., 2005. Fully Coupled Online Chemistry within the WRF Model. Atmospheric Environment 39, 6957-6975. Hong S, Noh Y, Dudhia J 2006. Nonlocal boundary layer vertical diffusion in a medium-range forecast model. Mon Wea Rev 124:2322-2339. Mellor GL, Yamada T 1982. Development of a turbulence

  17. ALS - resources

    MedlinePlus

    Resources - ALS ... The following organizations are good resources for information on amyotrophic lateral sclerosis : Muscular Dystrophy Association -- mda.org/disease/amyotrophic-lateral-sclerosis National Amyotrophic Lateral Sclerosis (ALS) Registry -- ...

  18. ALS Association

    MedlinePlus

    ... ALS. Find Out How Our Mission Leading the fight to treat and cure ALS through global research ... you participate, advocate, and donate, you advance the fight to find the cure and lead us toward ...

  19. ChemEd Bridges: Building Bridges between Two-Year College Chemistry Faculty and the National Chemical Education Community

    ERIC Educational Resources Information Center

    Ungar, Harry; Brown, David R.

    2010-01-01

    ChemEd Bridges is an NSF-funded project that provides career and professional development opportunities for chemistry faculty members who teach at two-year colleges (2YCs). We broaden the interests and the horizons of these faculty members by building bridges between them and the broader community of chemical educators. In particular, we have…

  20. ChemVoyage: A Web-Based, Simulated Learning Environment with Scaffolding and Linking Visualization to Conceptualization

    ERIC Educational Resources Information Center

    McRae, Christopher; Karuso, Peter; Liu, Fei

    2012-01-01

    The Web is now a standard tool for information access and dissemination in higher education. The prospect of Web-based, simulated learning platforms and technologies, however, remains underexplored. We have developed a Web-based tutorial program (ChemVoyage) for a third-year organic chemistry class on the topic of pericyclic reactions to…

  1. Evaluating the Effectiveness of the Open-Access ChemWiki Resource as a Replacement for Traditional General Chemistry Textbooks

    ERIC Educational Resources Information Center

    Allen, Gregory; Guzman-Alvarez, Alberto; Smith, Amy; Gamage, Alan; Molinaro, Marco; Larsen, Delmar S.

    2015-01-01

    Open educational resources (OERs) provide a potential alternative to costly textbooks and can allow content to be edited and adapted to a variety of classroom environments. At the University of California, Davis, the OER "ChemWiki" project, as part of the greater STEMWiki Hyperlibrary, was developed to supplant traditional post-secondary…

  2. The "Virtual ChemLab" Project: A Realistic and Sophisticated Simulation of Organic Synthesis and Organic Qualitative Analysis

    ERIC Educational Resources Information Center

    Woodfield, Brian F.; Andrus, Merritt B.; Waddoups, Gregory L.; Moore, Melissa S.; Swan, Richard; Allen, Rob; Bodily, Greg; Andersen, Tricia; Miller, Jordan; Simmons, Bryon; Stanger, Richard

    2005-01-01

    A set of sophisticated and realistic laboratory simulations is created for use in freshman- and sophomore-level chemistry classes and laboratories called 'Virtual ChemLab'. A detailed assessment of student responses is provided and the simulation's pedagogical utility is described using the organic simulation.

  3. Chemistry Outreach Project to High Schools Using a Mobile Chemistry Laboratory, ChemKits, and Teacher Workshops

    ERIC Educational Resources Information Center

    Long, Gary L.; Bailey, Carol A.; Bunn, Barbara B.; Slebodnick, Carla; Johnson, Michael R.; Derozier, Shad

    2012-01-01

    The Chemistry Outreach Program (ChOP) of Virginia Tech was a university-based outreach program that addressed the needs of high school chemistry classes in underfunded rural and inner-city school districts. The primary features of ChOP were a mobile chemistry laboratory (MCL), a shipping-based outreach program (ChemKits), and teacher workshops.…

  4. Rotational Analysis of FTIR Spectra from Cigarette Smoke: An Application of Chem Spec II Software in the Undergraduate Laboratory

    ERIC Educational Resources Information Center

    Ford, Alan R.; Burns, William A.; Reeve, Scott W.

    2004-01-01

    A version of the classic gas phase infrared experiment was developed for students at Arkansas State University based on the shortcomings of the rotationally resolved infrared experiment. Chem Spec II is a noncommercial Windows-based software package developed to aid in the potentially complicated problem of assigning quantum numbers to observed…

  5. Interpreting aerosol lifetimes using the GEOS-Chem model and constraints from radionuclide measurements

    NASA Astrophysics Data System (ADS)

    Croft, B.; Pierce, J. R.; Martin, R. V.

    2013-12-01

    Aerosol removal processes control global aerosol abundance, but the rate of that removal remains uncertain. A recent study of aerosol-bound radionuclide measurements after the Fukushima Dai-Ichi nuclear power plant accident documents 137Cs removal (e-folding) times of 10.0 to 13.9 days, suggesting that mean aerosol lifetimes in the range of 3-7 days in global models might be too short by a factor of two. In this study, we attribute this discrepancy to differences between the e-folding and mean aerosol lifetimes. We implement a~simulation of 137Cs and 133Xe into the GEOS-Chem chemical transport model and examine the removal rates for the Fukushima case. We find a~general consistency between modelled and measured e-folding times. The simulated 137Cs global burden e-folding time is about 14 days. However, the simulated mean lifetime of aerosol-bound 137Cs over a 6 month post-accident period is only 1.8 days. We find that the mean lifetime depends strongly on the removal rates in the first few days after emissions, before the aerosols leave the boundary layer and are transported to altitudes and latitudes where lifetimes with respect to wet removal are longer by a few orders of magnitude. We present sensitivity simulations that demonstrate the influence of differences in altitude and location of the radionuclides on the mean lifetime. Global mean lifetimes are shown to strongly depend on the altitude of injection. The global mean 137Cs lifetime is more than one order of magnitude greater for the injection at 7 km than into the boundary layer above the Fukushima site. Instantaneous removal rates are slower during the first few days after the emissions for a free tropospheric vs. boundary layer injection and this strongly controls the mean lifetimes. Global mean aerosol lifetimes for the GEOS-Chem model are 3-6 days, which is longer than for the 137Cs injected at the Fukushima site (likely due to precipitation shortly after Fukushima emissions), but about the same as the

  6. Interpreting aerosol lifetimes using the GEOS-Chem model and constraints from radionuclide measurements

    NASA Astrophysics Data System (ADS)

    Croft, B.; Pierce, J. R.; Martin, R. V.

    2014-04-01

    Aerosol removal processes control global aerosol abundance, but the rate of that removal remains uncertain. A recent study of aerosol-bound radionuclide measurements after the Fukushima Daiichi nuclear power plant accident documents 137Cs removal (e-folding) times of 10.0-13.9 days, suggesting that mean aerosol lifetimes in the range of 3-7 days in global models might be too short by a factor of two. In this study, we attribute this discrepancy to differences between the e-folding and mean aerosol lifetimes. We implement a simulation of 137Cs and 133Xe into the GEOS-Chem chemical transport model and examine the removal rates for the Fukushima case. We find a general consistency between modelled and measured e-folding times. The simulated 137Cs global burden e-folding time is about 14 days. However, the simulated mean lifetime of aerosol-bound 137Cs over a 6-month post-accident period is only 1.8 days. We find that the mean lifetime depends strongly on the removal rates in the first few days after emissions, before the aerosols leave the boundary layer and are transported to altitudes and latitudes where lifetimes with respect to wet removal are longer by a few orders of magnitude. We present sensitivity simulations that demonstrate the influence of differences in altitude and location of the radionuclides on the mean lifetime. Global mean lifetimes are shown to strongly depend on the altitude of injection. The global mean 137Cs lifetime is more than one order of magnitude greater for the injection at 7 km than into the boundary layer above the Fukushima site. Instantaneous removal rates are slower during the first few days after the emissions for a free tropospheric versus boundary layer injection and this strongly controls the mean lifetimes. Global mean aerosol lifetimes for the GEOS-Chem model are 3-6 days, which is longer than that for the 137Cs injected at the Fukushima site (likely due to precipitation shortly after Fukushima emissions), but similar to the

  7. Evaluation of WRF-CHEM Model: A case study of Air Pollution Episode in Istanbul Metropolitan

    NASA Astrophysics Data System (ADS)

    Aydınöz, Esra; Gürer, Kemal; Toros, Hüseyin

    2014-05-01

    Istanbul is the largest city in Europe with a population of about 14 million and nearly 3.2 million registered vehicles. Considering that the city is at the junction of major transportation routes on both land and sea, emissions from all motor vehicles operating in the city and those that are in transit is the major source of pollution. The natural gas is used as the major heat source and the impact of other heating sources on the pollution episodes is not clearly known. During 19-29 December 2013 İstanbul metropolitan area experienced a severe PM10 episode with average episode concentration of 127µgm-3 . The episode was associated with a high pressure system with center pressure of 1030 mb residing over Balkans and north of Black Sea and thereby influencing Istanbul. We carried out simulations using the Weather Research and Forecasting model with Chemistry (WRF-CHEM) v3.5 to examine the meteorological conditions and to produce estimates of PM10 over Istanbul for 17-31 December 2013. The three nested domains was setup using 18, 6 and 2 km horizontal grid spacing with (90x90), (115x115) and (130x130) grid points in 1st, 2nd and 3rd domains, respectively. The each domain was run using one way nesting option after preparing the results from the mother domain as an input to subsequent inner domain. 34 vertical levels were used with the lowest layer depth of 15 m above the surface and extending to 15 km at the model top. The model was configured using the model options after many tests to find optimal model parameters and was initialized using global emissions data available publicly. The local emissions database is still in works and is not available to use in the model instead of global data. The estimated PM10 concentrations were compared against the observed conditions. This work shows the first attempt of using WRF-CHEM in Turkey to estimate the pollutant concentrations instead of using other air pollution models such as WRF/CMAQ combination. At the time of

  8. Iodine's impact on tropospheric oxidants: a global model study in GEOS-Chem

    NASA Astrophysics Data System (ADS)

    Sherwen, T.; Evans, M. J.; Carpenter, L. J.; Andrews, S. J.; Lidster, R. T.; Dix, B.; Koenig, T. K.; Sinreich, R.; Ortega, I.; Volkamer, R.; Saiz-Lopez, A.; Prados-Roman, C.; Mahajan, A. S.; Ordóñez, C.

    2016-02-01

    We present a global simulation of tropospheric iodine chemistry within the GEOS-Chem chemical transport model. This includes organic and inorganic iodine sources, standard gas-phase iodine chemistry, and simplified higher iodine oxide (I2OX, X = 2, 3, 4) chemistry, photolysis, deposition, and parametrized heterogeneous reactions. In comparisons with recent iodine oxide (IO) observations, the simulation shows an average bias of ˜ +90 % with available surface observations in the marine boundary layer (outside of polar regions), and of ˜ +73 % within the free troposphere (350 hPa < p < 900 hPa) over the eastern Pacific. Iodine emissions (3.8 Tg yr-1) are overwhelmingly dominated by the inorganic ocean source, with 76 % of this emission from hypoiodous acid (HOI). HOI is also found to be the dominant iodine species in terms of global tropospheric IY burden (contributing up to 70 %). The iodine chemistry leads to a significant global tropospheric O3 burden decrease (9.0 %) compared to standard GEOS-Chem (v9-2). The iodine-driven OX loss rate1 (748 Tg OX yr-1) is due to photolysis of HOI (78 %), photolysis of OIO (21 %), and reaction between IO and BrO (1 %). Increases in global mean OH concentrations (1.8 %) by increased conversion of hydroperoxy radicals exceeds the decrease in OH primary production from the reduced O3 concentration. We perform sensitivity studies on a range of parameters and conclude that the simulation is sensitive to choices in parametrization of heterogeneous uptake, ocean surface iodide, and I2OX (X = 2, 3, 4) photolysis. The new iodine chemistry combines with previously implemented bromine chemistry to yield a total bromine- and iodine-driven tropospheric O3 burden decrease of 14.4 % compared to a simulation without iodine and bromine chemistry in the model, and a small increase in OH (1.8 %). This is a significant impact and so halogen chemistry needs to be considered in both climate and air quality models. 1 Here OX is defined as O3 + NO2 + 2

  9. ChemCam results from the Shaler outcrop in Gale crater, Mars

    USGS Publications Warehouse

    Anderson, Ryan B.; Bridges, J.C.; Williams, A.; Edgar, L.; Ollila, A.; Williams, J.; Nachon, Marion; Mangold, N.; Fisk, M.; Schieber, J.; Gupta, S.; Dromart, G.; Wiens, R.; Le Mouélic, Stéphane; Forni, O.; Lanza, N.; Mezzacappa, Alissa; Sautter, V.; Blaney, D.; Clark, B.; Clegg, S.; Gasnault, O.; Lasue, J.; Léveillé, Richard; Lewin, E.; Lewis, K.W.; Maurice, S.; Newsom, H.; Schwenzer, S.P.; Vaniman, D.

    2015-01-01

    The ChemCam campaign at the fluvial sedimentary outcrop “Shaler” resulted in observations of 28 non-soil targets, 26 of which included active laser induced breakdown spectroscopy (LIBS), and all of which included Remote Micro-Imager (RMI) images. The Shaler outcrop can be divided into seven facies based on grain size, texture, color, resistance to erosion, and sedimentary structures. The ChemCam observations cover Facies 3 through 7. For all targets, the majority of the grains were below the limit of the RMI resolution, but many targets had a portion of resolvable grains coarser than ∼0.5 mm. The Shaler facies show significant scatter in LIBS spectra and compositions from point to point, but several key compositional trends are apparent, most notably in the average K2O content of the observed facies. Facies 3 is lower in K2O than the other facies and is similar in composition to the “snake,” a clastic dike that occurs lower in the Yellowknife Bay stratigraphic section. Facies 7 is enriched in K2O relative to the other facies and shows some compositional and textural similarities to float rocks near Yellowknife Bay. The remaining facies (4, 5, and 6) are similar in composition to the Sheepbed and Gillespie Lake members, although the Shaler facies have slightly elevated K2O and FeOT. Several analysis points within Shaler suggest the presence of feldspars, though these points have excess FeOT which suggests the presence of Fe oxide cement or inclusions. The majority of LIBS analyses have compositions which indicate that they are mixtures of pyroxene and feldspar. The Shaler feldspathic compositions are more alkaline than typical feldspars from shergottites, suggesting an alkaline basaltic source region, particularly for the K2O-enriched Facies 7. Apart from possible iron-oxide cement, there is little evidence for chemical alteration at Shaler, although calcium-sulfate veins comparable to those observed lower in the stratigraphic section are present. The

  10. Constraints on Eurasian ship NOx emissions using OMI NO2 observations and GEOS-Chem

    NASA Astrophysics Data System (ADS)

    Vinken, Geert C. M.; Boersma, Folkert; van Donkelaar, Aaron; Zhang, Lin

    2013-04-01

    Ships emit large quantities of nitrogen oxides (NOx = NO + NO2), important precursors for ozone (O3) and particulate matter formation. Ships burn low-grade marine heavy fuel due to the limited regulations that exist for the maritime sector in international waters. Previous studies showed that global ship NOx emission inventories amount to 3.0-10.4 Tg N per year (15-30% of total NOx emissions), with most emissions close to land and affecting air quality in densely populated coastal regions. Bottom-up inventories depend on the extrapolation of a relatively small number of measurements that are often unable to capture annual emission changes and can suffer from large uncertainties. Satellites provide long-term, high-resolution retrievals that can be used to improve emission estimates. In this study we provide top-down constraints on ship NOx emissions in major European ship routes, using observed NO2 columns from the Ozone Monitoring Instrument (OMI) and NO2 columns simulated with the nested (0.5°×0.67°) version of the GEOS-Chem chemistry transport model. We use a plume-in-grid treatment of ship NOx emissions to account for in-plume chemistry in our model. We ensure consistency between the retrievals and model simulations by using the high-resolution GEOS-Chem NO2 profiles as a priori. We find evidence that ship emissions in the Mediterranean Sea are geographically misplaced by up to 150 km and biased high by a factor of 4 as compared to the most recent (EMEP) ship emission inventory. Better agreement is found over the shipping lane between Spain and the English Channel. We extend our approach and also provide constraints for major ship routes in the Red Sea and Indian Ocean. Using the full benefit of the long-term retrieval record of OMI, we present a new Eurasian ship emission inventory for the years 2005 to 2010, based on the EMEP and AMVER-ICOADS inventories, and top-down constraints from the satellite retrievals. Our work shows that satellite retrievals can

  11. ChemCam results from the Shaler outcrop in Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Anderson, Ryan; Bridges, J. C.; Williams, A.; Edgar, L.; Ollila, A.; Williams, J.; Nachon, M.; Mangold, N.; Fisk, M.; Schieber, J.; Gupta, S.; Dromart, G.; Wiens, R.; Le Mouélic, S.; Forni, O.; Lanza, N.; Mezzacappa, A.; Sautter, V.; Blaney, D.; Clark, B.; Clegg, S.; Gasnault, O.; Lasue, J.; Léveillé, R.; Lewin, E.; Lewis, K. W.; Maurice, S.; Newsom, H.; Schwenzer, S. P.; Vaniman, D.

    2015-03-01

    The ChemCam campaign at the fluvial sedimentary outcrop "Shaler" resulted in observations of 28 non-soil targets, 26 of which included active laser induced breakdown spectroscopy (LIBS), and all of which included Remote Micro-Imager (RMI) images. The Shaler outcrop can be divided into seven facies based on grain size, texture, color, resistance to erosion, and sedimentary structures. The ChemCam observations cover Facies 3 through 7. For all targets, the majority of the grains were below the limit of the RMI resolution, but many targets had a portion of resolvable grains coarser than ∼0.5 mm. The Shaler facies show significant scatter in LIBS spectra and compositions from point to point, but several key compositional trends are apparent, most notably in the average K2O content of the observed facies. Facies 3 is lower in K2O than the other facies and is similar in composition to the "snake," a clastic dike that occurs lower in the Yellowknife Bay stratigraphic section. Facies 7 is enriched in K2O relative to the other facies and shows some compositional and textural similarities to float rocks near Yellowknife Bay. The remaining facies (4, 5, and 6) are similar in composition to the Sheepbed and Gillespie Lake members, although the Shaler facies have slightly elevated K2O and FeOT. Several analysis points within Shaler suggest the presence of feldspars, though these points have excess FeOT which suggests the presence of Fe oxide cement or inclusions. The majority of LIBS analyses have compositions which indicate that they are mixtures of pyroxene and feldspar. The Shaler feldspathic compositions are more alkaline than typical feldspars from shergottites, suggesting an alkaline basaltic source region, particularly for the K2O-enriched Facies 7. Apart from possible iron-oxide cement, there is little evidence for chemical alteration at Shaler, although calcium-sulfate veins comparable to those observed lower in the stratigraphic section are present. The differing

  12. WRF-Chem model sensitivity to chemical mechanisms choice in reconstructing aerosol optical properties

    NASA Astrophysics Data System (ADS)

    Balzarini, A.; Pirovano, G.; Honzak, L.; Žabkar, R.; Curci, G.; Forkel, R.; Hirtl, M.; San José, R.; Tuccella, P.; Grell, G. A.

    2015-08-01

    In the framework of the AQMEII initiative WRF-Chem has been applied over Europe adopting two chemical configurations for the calendar year 2010. The first one employed the RADM2 gas-phase chemistry and MADE/SORGAM aerosol module, while the second one implemented the CBM-Z gaseous parameterization and MOSAIC aerosol chemistry. Configurations shared the same domain, meteorological setups and input data. The Comparison demonstrated that CBM-Z has a more efficient ozone-NO titration than RADM2 in regions with sufficiently high levels of NOx and VOCs. At the same time, CBM-Z is found to have a more effective NO2 + OH reaction. The parameterization of the relative humidity of deliquescence point has a strong impact on HNO3 and NO3 concentrations over Europe, particularly over the sea. The MADE approach showed to be more efficient than MOSAIC. Differently, particulate sulfate and SO2 ground concentrations proved to be more influenced by the heterogeneous SO2 cloud oxidation. PM10 and PM2.5 have shown similar results for MOSAIC and MADE/SORGAM, even though some differences were found in the dust and sea salt size partitioning between modes and bins. Indeed, in MADE the sea salt was distributed only in the coarse fraction, while the dust emissions were distributed mainly in the fine fraction. Finally, different chemical mechanisms give different Aerosol Optical Depths (AOD). WRF-Chem is found to under predict the AODs in both configurations because of the misrepresentation of the dust coarse particle, as shown by the analysis of the relationship between the Angström exponent and the AOD bias. Differently, when the AOD is dominated by fine particles, the differences in model performance are more evident, with MADE/SORGAM generally performing better than MOSAIC. Indeed the higher availability of both sulfate and nitrate has a significant influence on reconstruction of the AOD estimations. This paper shows the great importance of chemical mechanisms in both gaseous and

  13. Development by Genetic Immunization of Monovalent Antibodies (Nanobodies) Behaving as Antagonists of the Human ChemR23 Receptor.

    PubMed

    Peyrassol, Xavier; Laeremans, Toon; Gouwy, Mieke; Lahura, Vannessa; Debulpaep, Maja; Van Damme, Jo; Steyaert, Jan; Parmentier, Marc; Langer, Ingrid

    2016-03-15

    The generation of Abs that recognize the native conformation of G protein-coupled receptors can be a challenging task because, like most multimembrane-spanning proteins, they are extremely difficult to purify as native protein. By combining genetic immunization, phage display, and biopanning, we identified two functional monovalent Abs (nanobodies) targeting ChemR23. The two nanobodies (CA4910 and CA5183) were highly specific for the human receptor and bind ChemR23 with moderate affinity. Binding studies also showed that they share a common binding site that overlaps with that of chemerin, the natural ligand of ChemR23. Consistent with these results, we found that the nanobodies were able to antagonize chemerin-induced intracellular calcium increase. The inhibition was partial when chemerin was used as agonist and complete when the chemerin(149-157) nonapeptide was used as agonist. Engineering of a bivalent CA4910 nanobody resulted in a relatively modest increase in affinity but a marked enhancement of efficacy as an antagonist of chemerin induced intracellular calcium mobilization and a much higher potency against the chemerin(149-157) nonapeptide-induced response. We also demonstrated that the fluorescently labeled nanobodies detect ChemR23 on the surface of human primary cell populations as efficiently as a reference mouse mAb and that the bivalent CA4910 nanobody behaves as an efficient antagonist of chemerin-induced chemotaxis of human primary cells. Thus, these nanobodies constitute new tools to study the role of the chemerin/ChemR23 system in physiological and pathological conditions. PMID:26864035

  14. Effects on Student Achievement in General Chemistry following Participation in an Online Preparatory Course: ChemPrep, a Voluntary, Self-Paced, Online Introduction to Chemistry

    ERIC Educational Resources Information Center

    Botch, Beatrice; Day, Roberta; Vining, William; Stewart, Barbara; Rath, Kenneth; Peterfreund, Alan; Hart, David

    2007-01-01

    ChemPrep was developed to be a stand-alone preparatory short-course to help students succeed in general chemistry. It is Web-based and delivered using the OWL system. Students reported that the ChemPrep materials (short information pages, parameterized questions with detailed feedback, tutorials, and answers to questions through the OWL message…

  15. The Virtual ChemLab Project: A Realistic and Sophisticated Simulation of Inorganic Qualitative Analysis

    NASA Astrophysics Data System (ADS)

    Woodfield, Brian F.; Catlin, Heidi R.; Waddoups, Gregory L.; Moore, Melissa S.; Swan, Richard; Allen, Rob; Bodily, Greg

    2004-11-01

    We have created a set of sophisticated and realistic laboratory simulations for use in freshman- and sophomore-level chemistry classes and laboratories called Virtual ChemLab. We have completed simulations for Inorganic Qualitative Analysis, Organic Synthesis and Organic Qualitative Analysis, Experiments in Quantum Chemistry, Gas Properties, Titration Experiments, and Calorimetric and Thermochemical Experiments. The purpose of our simulations is to reinforce concepts taught in the classroom, provide an environment for creative learning, and emphasize the thinking behind instructional laboratory experiments. We have used the inorganic simulation extensively with thousands of students in our department at Brigham Young University. We have learned from our evaluation that: (i) students enjoy using these simulations and find them to be an asset in learning effective problem-solving strategies, (ii) students like the fact that they can both reproduce experimental procedures and explore various topics in ways they choose, and (iii) students naturally divide themselves into two groups: creative learners, who excel in an open-ended environment of virtual laboratories, and structured learners, who struggle in this same environment. In this article, we describe the Inorganic Qualitative Analysis simulation; we also share specific evaluation findings from using the inorganic simulation in classroom and laboratory settings.

  16. AMPTE/CCE CHEM observations of the energetic ion population at geosynchronous altitudes

    NASA Technical Reports Server (NTRS)

    Daglis, Ioannis A.; Sarris, Emmanuel T.; Wilken, Berend

    1993-01-01

    The paper presents results of a statistical study of average characteristics of the energetic ion population at geosynchronous altitudes, using energetic-ion (1-300 keV/e) measurements from the CHEM spectrometer aboard the AMPTE Charge Composition Explorer between January 1985 and June 1987. Data were sorted into four MLT groups and two extreme geomagnetic activity levels ('very quiet' for AE less than 30 nT and 'very active' for AE greater than 700 nT). A clear quiet-time dayside feature found in the measurements was a dip in H(+) and He(2+) spectra, at 6.6 keV/e in the prenoon sector and at 3.5 keV/e in the postnoon sector. During active times, the ion fluxes increased (except for He(+)), and the O(+) contribution to the total energy density increased dramatically. The pitch angle distributions were normal during quiet times and isotropic or field-aligned during active times.

  17. Modeling Transport in Gas Chromatography Columns for the Micro-ChemLab

    SciTech Connect

    ADKINS,DOUGLAS R.; FRYE-MASON,GREGORY CHARLES; HUDSON,MARY L.; KOTTENSTETTE,RICHARD; MATZKE,CAROLYN M.; SALINGER,ANDREW G.; SHADID,JOHN N.; WONG, CHUNGNIN CHANN

    1999-09-01

    The gas chromatography (GC) column is a critical component in the microsystem for chemical detection ({mu}ChemLab{trademark}) being developed at Sandia. The goal is to etch a meter-long GC column onto a 1-cm{sup 2} silicon chip while maintaining good chromatographic performance. Our design strategy is to use a modeling and simulation approach. We have developed an analytical tool that models the transport and surface interaction process to achieve an optimized design of the GC column. This analytical tool has a flow module and a separation module. The flow module considers both the compressibility and slip flow effects that may significantly influence the gas transport in a long and narrow column. The separation module models analyte transport and physico-chemical interaction with the coated surface in the GC column. It predicts the column efficiency and performance. Results of our analysis will be presented in this paper. In addition to the analytical tool, we have also developed a time-dependent adsorption/desorption model and incorporated this model into a computational fluid dynamics (CFD) code to simulate analyte transport and separation process in GC columns. CFD simulations can capture the complex three-dimensional flow and transport dynamics, whereas the analytical tool cannot. Different column geometries have been studied, and results will be presented in this paper. Overall we have demonstrated that the modeling and simulation approach can guide the design of the GC column and will reduce the number of iterations in the device development.

  18. Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

    NASA Astrophysics Data System (ADS)

    Shao, Yihan; Gan, Zhengting; Epifanovsky, Evgeny; Gilbert, Andrew T. B.; Wormit, Michael; Kussmann, Joerg; Lange, Adrian W.; Behn, Andrew; Deng, Jia; Feng, Xintian; Ghosh, Debashree; Goldey, Matthew; Horn, Paul R.; Jacobson, Leif D.; Kaliman, Ilya; Khaliullin, Rustam Z.; Kuś, Tomasz; Landau, Arie; Liu, Jie; Proynov, Emil I.; Rhee, Young Min; Richard, Ryan M.; Rohrdanz, Mary A.; Steele, Ryan P.; Sundstrom, Eric J.; Woodcock, H. Lee, III; Zimmerman, Paul M.; Zuev, Dmitry; Albrecht, Ben; Alguire, Ethan; Austin, Brian; Beran, Gregory J. O.; Bernard, Yves A.; Berquist, Eric; Brandhorst, Kai; Bravaya, Ksenia B.; Brown, Shawn T.; Casanova, David; Chang, Chun-Min; Chen, Yunqing; Chien, Siu Hung; Closser, Kristina D.; Crittenden, Deborah L.; Diedenhofen, Michael; DiStasio, Robert A., Jr.; Do, Hainam; Dutoi, Anthony D.; Edgar, Richard G.; Fatehi, Shervin; Fusti-Molnar, Laszlo; Ghysels, An; Golubeva-Zadorozhnaya, Anna; Gomes, Joseph; Hanson-Heine, Magnus W. D.; Harbach, Philipp H. P.; Hauser, Andreas W.; Hohenstein, Edward G.; Holden, Zachary C.; Jagau, Thomas-C.; Ji, Hyunjun; Kaduk, Benjamin; Khistyaev, Kirill; Kim, Jaehoon; Kim, Jihan; King, Rollin A.; Klunzinger, Phil; Kosenkov, Dmytro; Kowalczyk, Tim; Krauter, Caroline M.; Lao, Ka Un; Laurent, Adèle D.; Lawler, Keith V.; Levchenko, Sergey V.; Lin, Ching Yeh; Liu, Fenglai; Livshits, Ester; Lochan, Rohini C.; Luenser, Arne; Manohar, Prashant; Manzer, Samuel F.; Mao, Shan-Ping; Mardirossian, Narbe; Marenich, Aleksandr V.; Maurer, Simon A.; Mayhall, Nicholas J.; Neuscamman, Eric; Oana, C. Melania; Olivares-Amaya, Roberto; O'Neill, Darragh P.; Parkhill, John A.; Perrine, Trilisa M.; Peverati, Roberto; Prociuk, Alexander; Rehn, Dirk R.; Rosta, Edina; Russ, Nicholas J.; Sharada, Shaama M.; Sharma, Sandeep; Small, David W.; Sodt, Alexander; Stein, Tamar; Stück, David; Su, Yu-Chuan; Thom, Alex J. W.; Tsuchimochi, Takashi; Vanovschi, Vitalii; Vogt, Leslie; Vydrov, Oleg; Wang, Tao; Watson, Mark A.; Wenzel, Jan; White, Alec; Williams, Christopher F.; Yang, Jun; Yeganeh, Sina; Yost, Shane R.; You, Zhi-Qiang; Zhang, Igor Ying; Zhang, Xing; Zhao, Yan; Brooks, Bernard R.; Chan, Garnet K. L.; Chipman, Daniel M.; Cramer, Christopher J.; Goddard, William A., III; Gordon, Mark S.; Hehre, Warren J.; Klamt, Andreas; Schaefer, Henry F., III; Schmidt, Michael W.; Sherrill, C. David; Truhlar, Donald G.; Warshel, Arieh; Xu, Xin; Aspuru-Guzik, Alán; Baer, Roi; Bell, Alexis T.; Besley, Nicholas A.; Chai, Jeng-Da; Dreuw, Andreas; Dunietz, Barry D.; Furlani, Thomas R.; Gwaltney, Steven R.; Hsu, Chao-Ping; Jung, Yousung; Kong, Jing; Lambrecht, Daniel S.; Liang, WanZhen; Ochsenfeld, Christian; Rassolov, Vitaly A.; Slipchenko, Lyudmila V.; Subotnik, Joseph E.; Van Voorhis, Troy; Herbert, John M.; Krylov, Anna I.; Gill, Peter M. W.; Head-Gordon, Martin

    2015-01-01

    A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.

  19. Investigating the Effect of Soot Emissions on Precipitation over Western CONUS Using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Tseng, H. L. R.; Liou, K. N.; Gu, Y.; Wu, L.; Fovell, R. G.

    2014-12-01

    The current Exceptional Drought (US Drought Monitor) over the Western Continental United States (CONUS) warrants an in-depth investigation of possible causes of decreased precipitation. Soot, a mixture of black carbon and organic carbon, can increase in its hygroscopicity by two-fold (at relative humidity of 80%) when coated with sulfuric acid, rendering smaller, although quantitatively more, cloud particles. This has the potential to exacerbate the aridity in the western states. In this study, we examined the role of soot and its possible effect on reducing precipitation west of and over the Rocky Mountains from an online and coupled meteorological and chemical perspective. In particular, we utilized the Weather Research and Forecasting-Chemistry (WRF-Chem) model at the horizontal resolution of 30 km, employing the Fu-Liou-Gu plane-parallel radiation scheme and a three dimensional parametrization over mountainous areas to account for direct and indirect feedback of soot and cloud particles, including ice crystals, to understand precipitation patterns based on simulation results. Identifying factors that can mediate drought severity will improve hydrological prediction, and subsequent resource usage and allocation.

  20. CAM-chem: description and evaluation of interactive atmospheric chemistry in the Community Earth System Model

    SciTech Connect

    Lamarque, J.-F.; Emmons, L.; Hess, Peter; Kinnison, Douglas E.; Tilmes, S.; Vitt, Francis; Heald, C. L.; Holland, Elisabeth A.; Lauritzen, P. H.; Neu, J.; Orlando, J. J.; Rasch, Philip J.; Tyndall, G. S.

    2012-03-27

    We discuss and evaluate the representation of atmospheric chemistry in the global Community Atmosphere Model (CAM) version 4, the atmospheric component of the Community Earth System Model (CESM). We present a variety of configurations for the representation of tropospheric and stratospheric chemistry, wet removal, and online and offline meteorology. Results from simulations illustrating these configurations are compared with surface, aircraft and satellite observations. Major biases include a negative bias in the high-latitude CO distribution, a positive bias in upper-tropospheric/lower-stratospheric ozone, and a positive bias in summertime surface ozone (over the United States and Europe). The tropospheric net chemical ozone production varies significantly between configurations, partly related to variations in stratosphere-troposphere exchange. Aerosol optical depth tends to be underestimated over most regions, while comparison with aerosol surface measurements over the United States indicate reasonable results for sulfate, especially in the online simulation. Other aerosol species exhibit significant biases. Overall, the model-data comparison indicates that the offline simulation driven by GEOS5 meteorological analyses provides the best simulation, possibly due in part to the increased vertical resolution (52 levels instead of 26 for online dynamics). The CAM-chem code as described in this paper, along with all the necessary datasets needed to perform the simulations described here, are available for download at www.cesm.ucar.edu.

  1. Identification of "Known Unknowns" Utilizing Accurate Mass Data and ChemSpider

    NASA Astrophysics Data System (ADS)

    Little, James L.; Williams, Antony J.; Pshenichnov, Alexey; Tkachenko, Valery

    2012-01-01

    In many cases, an unknown to an investigator is actually known in the chemical literature, a reference database, or an internet resource. We refer to these types of compounds as "known unknowns." ChemSpider is a very valuable internet database of known compounds useful in the identification of these types of compounds in commercial, environmental, forensic, and natural product samples. The database contains over 26 million entries from hundreds of data sources and is provided as a free resource to the community. Accurate mass mass spectrometry data is used to query the database by either elemental composition or a monoisotopic mass. Searching by elemental composition is the preferred approach. However, it is often difficult to determine a unique elemental composition for compounds with molecular weights greater than 600 Da. In these cases, searching by the monoisotopic mass is advantageous. In either case, the search results are refined by sorting the number of references associated with each compound in descending order. This raises the most useful candidates to the top of the list for further evaluation. These approaches were shown to be successful in identifying "known unknowns" noted in our laboratory and for compounds of interest to others.

  2. Preliminary performance assessment of biotoxin detection for UWS applications using a MicroChemLab device.

    SciTech Connect

    VanderNoot, Victoria A.; Haroldsen, Brent L.; Renzi, Ronald F.; Shokair, Isaac R.

    2010-03-01

    In a multiyear research agreement with Tenix Investments Pty. Ltd., Sandia has been developing field deployable technologies for detection of biotoxins in water supply systems. The unattended water sensor or UWS employs microfluidic chip based gel electrophoresis for monitoring biological analytes in a small integrated sensor platform. This instrument collects, prepares, and analyzes water samples in an automated manner. Sample analysis is done using the {mu}ChemLab{trademark} analysis module. This report uses analysis results of two datasets collected using the UWS to estimate performance of the device. The first dataset is made up of samples containing ricin at varying concentrations and is used for assessing instrument response and detection probability. The second dataset is comprised of analyses of water samples collected at a water utility which are used to assess the false positive probability. The analyses of the two sets are used to estimate the Receiver Operating Characteristic or ROC curves for the device at one set of operational and detection algorithm parameters. For these parameters and based on a statistical estimate, the ricin probability of detection is about 0.9 at a concentration of 5 nM for a false positive probability of 1 x 10{sup -6}.

  3. ChemScan—an on-line ultraviolet spectral process analyzer

    NASA Astrophysics Data System (ADS)

    Beemster, Bernard J.; Schlager, Kenneth J.

    1996-03-01

    ChemScan is a product line of ultraviolet, on-line process analyzers that grew out of a NASA SBIR program targeted at on-line monitoring of plant nutrient solutions as part of the NASA CELSS program. The original goal for NASA was to provide on-line measurement of all the hydroponic plant nutrients necessary to develop and maintain a plant growth facility in space. Two different spectrometric techniques were applied to provide on-line measurements of all plant nutrients. One technology, ultraviolet absorption spectrometry, provided on-line measurements of nitrate, iron, and some of the transition metal nutrients. This technology not only demonstrated a capability to meet these CELSS needs but has now been incorporated into a family of commercial analytical instruments used for environmental process monitoring and control applications. A second technology, Liquid Atomic Emission Spectrometry (LAES), also originated in this same NASA SBIR, is still at an earlier stage of development and is expected to reach the market in the next 18-24 months.

  4. Background error statistics for aerosol variables from WRF/Chem predictions in Southern California

    NASA Astrophysics Data System (ADS)

    Zang, Zengliang; Hao, Zilong; Pan, Xiaobin; Li, Zhijin; Chen, Dan; Zhang, Li; Li, Qinbin

    2015-05-01

    Background error covariance (BEC) is crucial in data assimilation. This paper addresses the multivariate BEC associated with black carbon, organic carbon, nitrates, sulfates, and other constituents of aerosol species. These aerosol species are modeled and predicted using the Model for Simulating Aerosol Interactions and Chemistry scheme (MOSAIC) in the Weather Research and Forecasting/Chemistry (WRF/Chem) model at a resolution of 4 km in Southern California. The BEC is estimated from the differences between the 36-hour and 12-hour forecasts using the NMC method. The results indicated that the maximum background error standard deviation is associated with nitrate and is larger than that of black carbon, organic carbon, and sulfate. The horizontal and vertical scale of the correlation of nitrate is much smaller than that of other species. A significant cross-correlation is found between the species of black carbon and organic carbon. The cross-correlations between nitrate and other variables are relatively smaller and exhibit a relatively smaller length scale. Single observation data assimilation experiments are performed to illustrate the effect of the BEC on analysis increments.

  5. Recent advancements in the gas-phase MicroChemLab

    NASA Astrophysics Data System (ADS)

    Manginell, Ronald P.; Lewis, Patrick R.; Adkins, Douglas R.; Kottenstette, Richard J.; Wheeler, David; Sokolowski, Sara; Trudell, Dan; Byrnes, Joy; Okandan, Murat; Bauer, Joseph M.; Manley, Robert G.

    2004-12-01

    Sandia's hand-held MicroChemLabTM system uses a micromachined preconcentrator (PC), a gas chromatography channel (GC) and a quartz surface acoustic wave array (SAW) detector for sensitive/selective detection of gas-phase chemical analytes. Requisite system size, performance, power budget and time response mandate microfabrication of the key analytical system components. In the fielded system hybrid integration has been employed, permitting optimization of the individual components. Recent improvements in the hybrid-integrated system, using plastic, metal or silicon/glass manifolds, is described, as is system performance against semivolatile compounds and toxic industrial chemicals. The design and performance of a new three-dimensional micropreconcentrator is also introduced. To further reduce system dead volume, eliminate unheated transfer lines and simplify assembly, there is an effort to monolithically integrate the silicon PC and GC with a suitable silicon-based detector, such as a magnetically-actuated flexural plate wave sensor (magFPW) or a magnetically-actuated pivot plate resonator (PPR).

  6. Visible and Near-Infrared (VNIR) Spectroscopy of Altered Basalts with Application to the ChemCam Library for Mars Science Laboratory

    NASA Astrophysics Data System (ADS)

    Hadnott, B.; Ehlmann, B. L.

    2012-12-01

    The discovery of Fe, Mg, and Al clays on Mars using VNIR spectroscopy from orbit indicates past low temperature/pressure hydrothermal and weathering environments. Laboratory analysis of Mars-analog rocks from these settings on Earth was used to build the ChemCam sample library for Mars Science Laboratory, permitting for more accurate compositional analysis of Martian samples, improved linkages between VNIR's mineralogic and ChemCam's elemental data, and improved recognition of different environmental settings for aqueous alteration. VNIR spectroscopy was used to analyze 4 suites of altered basaltic rocks—one from San Carlos, AZ and three from various locations in Iceland. Continuum shape and absorption features were found to vary, depending on the environment and extent of alteration. Relatively unaltered rocks had electronic absorptions related to ferrous iron. The strength of the 1.9- μm (μm = microns) H2O absorption correlated with the degree of aqueous alteration. Samples with strong 1.9- μm absorptions often exhibited absorption bands at 1.4, 2.2, and 2.3 μm indicating the presence of clay minerals and/or features at 0.5-0.8 μm indicative of ferric iron oxides. Diagnostic absorption features and continuum slopes have been used to identify a representative subset of rocks from each suite for further analysis for the ChemCam library. Noteworthy spectral features for all suites included variation of absorption bands from 2.0-2.5 μm. Most samples contained an absorption band near 2.21 μm, indicating the presence of Si-OH or Al-OH; a 2.3 μm band is also present in some samples, indicating the presence of Mg-OH and Fe-OH, with subtle shifts between 2.29 and 2.35 μm indicating the major cation and constituent phase (e.g. amorphous phase, smectite or chlorite). Overall continuum slope correlated with the degree of alteration. Flat slopes contained weak 1.9 μm bands (little alteration) and sometimes ferrous iron absorptions of primary minerals. Negative

  7. Development of a grid-independent GEOS-Chem chemical transport model (v9-02) as an atmospheric chemistry module for Earth system models

    NASA Astrophysics Data System (ADS)

    Long, M. S.; Yantosca, R.; Nielsen, J. E.; Keller, C. A.; da Silva, A.; Sulprizio, M. P.; Pawson, S.; Jacob, D. J.

    2015-03-01

    The GEOS-Chem global chemical transport model (CTM), used by a large atmospheric chemistry research community, has been re-engineered to also serve as an atmospheric chemistry module for Earth system models (ESMs). This was done using an Earth System Modeling Framework (ESMF) interface that operates independently of the GEOS-Chem scientific code, permitting the exact same GEOS-Chem code to be used as an ESM module or as a stand-alone CTM. In this manner, the continual stream of updates contributed by the CTM user community is automatically passed on to the ESM module, which remains state of science and referenced to the latest version of the standard GEOS-Chem CTM. A major step in this re-engineering was to make GEOS-Chem grid independent, i.e., capable of using any geophysical grid specified at run time. GEOS-Chem data sockets were also created for communication between modules and with external ESM code. The grid-independent, ESMF-compatible GEOS-Chem is now the standard version of the GEOS-Chem CTM. It has been implemented as an atmospheric chemistry module into the NASA GEOS-5 ESM. The coupled GEOS-5-GEOS-Chem system was tested for scalability and performance with a tropospheric oxidant-aerosol simulation (120 coupled species, 66 transported tracers) using 48-240 cores and message-passing interface (MPI) distributed-memory parallelization. Numerical experiments demonstrate that the GEOS-Chem chemistry module scales efficiently for the number of cores tested, with no degradation as the number of cores increases. Although inclusion of atmospheric chemistry in ESMs is computationally expensive, the excellent scalability of the chemistry module means that the relative cost goes down with increasing number of cores in a massively parallel environment.

  8. Operational on-line coupled chemical weather forecasts for Europe with WRF/Chem

    NASA Astrophysics Data System (ADS)

    Hirtl, Marcus; Mantovani, Simone; Krüger, Bernd C.; Flandorfer, Claudia; Langer, Matthias

    2014-05-01

    Air quality is a key element for the well-being and quality of life of European citizens. Air pollution measurements and modeling tools are essential for the assessment of air quality according to EU legislation. The responsibilities of ZAMG as the national weather service of Austria include the support of the federal states and the public in questions connected to the protection of the environment in the frame of advisory and counseling services as well as expert opinions. ZAMG conducts daily Air-Quality forecasts using the on-line coupled model WRF/Chem. Meteorology is simulated simultaneously with the emissions, turbulent mixing, transport, transformation, and fate of trace gases and aerosols. The emphasis of the application is on predicting pollutants over Austria. Two domains are used for the simulations: the mother domain covers Europe with a resolution of 12 km, the inner domain includes the alpine region with a horizontal resolution of 4 km; 45 model levels are used in the vertical direction. The model runs 2 times per day for a period of 72 hours and is initialized with ECMWF forecasts. On-line coupled models allow considering two-way interactions between different atmospheric processes including chemistry (both gases and aerosols), clouds, radiation, boundary layer, emissions, meteorology and climate. In the operational set-up direct-, indirect and semi-direct effects between meteorology and air chemistry are enabled. The model is running on the HPCF (High Performance Computing Facility) of the ZAMG. In the current set-up 1248 CPUs are used. As the simulations need a big amount of computing resources, a method to safe I/O-time was implemented. Every MPI task writes all its output into the shared memory filesystem of the compute nodes. Once the WRF/Chem integration is finished, all split NetCDF-files are merged and saved on the global file system. The merge-routine is based on parallel-NetCDF. With this method the model runs about 30% faster on the SGI

  9. Atmospheric pressure plasma for decontamination of chem/bio warfare agents

    SciTech Connect

    Hermann, H.W.; Selwyn, G.S.; Henins, I.; Park, J.

    1999-07-01

    The Atmospheric Pressure Plasma Jet (APPJ) is a unique, capacitively-coupled rf, nonthermal, uniform discharge operating at atmospheric pressure with a high flow of He/O{sub 2} feedgas. The APPJ generates highly reactive atomic and metastable species of oxygen and directs them onto a contaminated surface at high velocity. This may provide a much needed method of decontamination of CBW agents which, unlike traditional decon methods, is dry and nondestructive to sensitive equipment. The reactive effluent of the APPJ at 175 C has been shown to kill Bacillus globigii spores, a surrogate for Anthrax, with a D value (time to reduce viability by a factor of 10) of 4.5 sec at a standoff distance of 0.5 cm. This is 10 times faster than hot gas at the same temperature and requires 80% less energy input to achieve the same level of kill. This D value is also an order of magnitude better than achieved by other nonthermal plasma discharges, and unlike these other discharges, the APPJ provides a downstream process which can be applied to all accessible surfaces with no need for the contaminated object to fit within a chamber. Through active cooling of the electrodes, the authors have also achieved a D value of 15 sec at an effluent temperature of just 75 C, making the decontamination of personnel a definite possibility. The APPJ has also been shown to oxidize surrogates of the CW agents, Mustard and VX, and a collaborative effort is now proceeding with the actual agents at the Edgewood Chem/Bio Center (ECBC, formerly ERDEC). Efforts are now being directed towards reducing the consumption of He and increasing the working stand-off distance.

  10. Performance of WRF-Chem over Indian region: Comparison with measurements

    NASA Astrophysics Data System (ADS)

    Govardhan, Gaurav; Nanjundiah, Ravi S.; Satheesh, S. K.; Krishnamoorthy, K.; Kotamarthi, V. R.

    2015-06-01

    The aerosol mass concentrations over several Indian regions have been simulated using the online chemistry transport model, WRF-Chem, for two distinct seasons of 2011, representing the pre-monsoon (May) and post-monsoon (October) periods during the Indo-US joint experiment `Ganges Valley Aerosol Experiment (GVAX)'. The simulated values were compared with concurrent measurements. It is found that the model systematically underestimates near-surface BC mass concentrations as well as columnar Aerosol Optical Depths (AODs) from the measurements. Examining this in the light of the model-simulated meteorological parameters, we notice the model overestimates both planetary boundary layer height (PBLH) and surface wind speeds, leading to deeper mixing and dispersion and hence lower surface concentrations of aerosols. Shortcoming in simulating rainfall pattern also has an impact through the scavenging effect. It also appears that the columnar AODs are influenced by the unrealistic emission scenarios in the model. Comparison with vertical profiles of BC obtained from aircraft-based measurements also shows a systematic underestimation by the model at all levels. It is seen that concentration of other aerosols, viz., dust and sea-salt are closely linked with meteorological conditions prevailing over the region. Dust is higher during pre-monsoon periods due to the prevalence of north-westerly winds that advect dust from deserts of west Asia into the Indo-Gangetic plain. Winds and rainfall influence sea-salt concentrations. Thus, the unrealistic simulation of wind and rainfall leads to model simulated dust and sea-salt also to deviate from the real values; which together with BC also causes underperformance of the model with regard to columnar AOD. It appears that for better simulations of aerosols over Indian region, the model needs an improvement in the simulation of the meteorology.

  11. Mixed waste treatment using the ChemChar thermolytic detoxification technique

    SciTech Connect

    Kuchynka, D.

    1995-12-31

    The diversity of mixed waste matrices contained at Department of Energy sites that require treatment preclude a single, universal treatment technology capable of handling sludges, solids, heterogeneous debris, aqueous and organic liquids and soils. Versatility of the treatment technology, volume reduction and containment of the radioactive component of the mixed waste streams are three criteria to be considered when evaluating potential treatment technologies. The ChemChar thermolytic detoxification process being developed under this R and D contract is a thermal, chemically reductive technology that converts the organic portion of a mixed waste stream to an energy-rich synthesis gas while simultaneously absorbing volatile inorganic species (metals and acid gases) on a macroporous, carbon-based char. The latter is mixed with the waste stream prior to entering the reactor. Substoichiometric amounts of oxidant are fed into the top portion of the cylindrical reactor generating a thin, radial thermochemical reaction zone. This zone generates all the necessary heat to promote the highly endothermic reduction of the organic components in the waste in the lower portion of the reactor, producing, principally, hydrogen and carbon monoxide. The solid by-product is a regenerated carbon char that, depending on the inorganic loading, is capable for reuse. The in situ scrubbing of contaminants by the char within the reactor coupled with a char filter for final polishing produce an exceptionally clean synthesis gas effluent suitable for on-site generation of heat, steam or electricity. Despite the elevated temperatures in the thermochemical reaction zone, the reductive nature of the process precludes formation of nitrogen oxides and halogenated organic compound by-products.

  12. How wild is your model fire? Constraining WRF-Chem wildfire smoke simulations with satellite observations

    NASA Astrophysics Data System (ADS)

    Fischer, E. V.; Ford, B.; Lassman, W.; Pierce, J. R.; Pfister, G.; Volckens, J.; Magzamen, S.; Gan, R.

    2015-12-01

    Exposure to high concentrations of particulate matter (PM) present during acute pollution events is associated with adverse health effects. While many anthropogenic pollution sources are regulated in the United States, emissions from wildfires are difficult to characterize and control. With wildfire frequency and intensity in the western U.S. projected to increase, it is important to more precisely determine the effect that wildfire emissions have on human health, and whether improved forecasts of these air pollution events can mitigate the health risks associated with wildfires. One of the challenges associated with determining health risks associated with wildfire emissions is that the low spatial resolution of surface monitors means that surface measurements may not be representative of a population's exposure, due to steep concentration gradients. To obtain better estimates of ambient exposure levels for health studies, a chemical transport model (CTM) can be used to simulate the evolution of a wildfire plume as it travels over populated regions downwind. Improving the performance of a CTM would allow the development of a new forecasting framework that could better help decision makers estimate and potentially mitigate future health impacts. We use the Weather Research and Forecasting model with online chemistry (WRF-Chem) to simulate wildfire plume evolution. By varying the model resolution, meteorology reanalysis initial conditions, and biomass burning inventories, we are able to explore the sensitivity of model simulations to these various parameters. Satellite observations are used first to evaluate model skill, and then to constrain the model results. These data are then used to estimate population-level exposure, with the aim of better characterizing the effects that wildfire emissions have on human health.

  13. Modeling of SO2 dispersion from the 2014 Holuhraun eruption in Iceland using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Rognvaldsson, Olafur; Arnason, Gylfi; Palsson, Thorgeir; Eliasson, Jonas; Weber, Konradin; Böhlke, Christoph; Thorsteinsson, Throstur; Tirpitz, Lukas; Platt, Ulrich; Smith, Paul D.; Jones, Roderic L.

    2015-04-01

    The fissure eruption in Holuhraun in central Iceland is the country's largest lava and gas eruption since 1783 but has produced very little volcanic ash. The eruption started in late August 2014 and is still ongoing as of January 2015. The main threat from this event has been atmospheric pollution of SO2 that is carried by wind to all parts of the country and produces elevated concentrations of SO2 that have frequently violated National Air Quality Standards (NAQS) in many population centers. The Volcanic Ash Research (VAR) group in Iceland is focused on airborne measurement of ash contamination to support safe air travel, as well as various gas concentrations. In relation to the Holuhraun eruption the VAR group has organized an investigation campaign including 10 measurement flights and performed measurements of both the source emissions and the plume distribution. SO2 concentrations measured at the source showed clear potential for creating pollution events in the toxic range and contamination of surface waters. The data obtained in the measurement campaign was used for calibration of the WRF-chem model of the dispersion of SO2 and volcanic ash concentration. The model has both been run in operational forecast mode (since mid October) as well as in a dynamical downscaling mode, to estimate the dispersion and fallout of SO2 from the plume. The model results indicate that a large part of the sulphur was precipitated in the Icelandic highlands. The first melt waters during the spring thaw are likely to contain acid sulphur compounds that can be harmful for vegetation, with the highland vegetation being the most vulnerable. These results will be helpful to estimate the pollution load on farmlands and pastures of farmers.

  14. WRF-Chem Simulations of Aerosols and Anthropogenic Aerosol Radiative Forcing in East Asia

    SciTech Connect

    Gao, Yi; Zhao, Chun; Liu, Xiaohong; Zhang, Meigen; Leung, Lai-Yung R.

    2014-08-01

    This study aims to provide a first comprehensive evaluation of WRF-Chem for modeling aerosols and anthropogenic aerosol radiative forcing (RF) over East Asia. Several numerical experiments were conducted from November 2007 to December 2008. Comparison between model results and observations shows that the model can generally reproduce the observed spatial distributions of aerosol concentration, aerosol optical depth (AOD) and single scattering albedo (SSA) from measurements at different sites, including the relatively higher aerosol concentration and AOD over East China and the relatively lower AOD over Southeast Asia, Korean, and Japan. The model also depicts the seasonal variation and transport of pollutions over East Asia. Particulate matter of 10 um or less in the aerodynamic diameter (PM10), black carbon (BC), sulfate (SO42-), nitrate (NO3-) and ammonium (NH4+) concentrations are higher in spring than other seasons in Japan due to the pollutant transport from polluted area of East Asia. AOD is high over Southwest and Central China in winter, spring and autumn and over North China in summer while is low over South China in summer due to monsoon precipitation. SSA is lowest in winter and highest in summer. The model also captures the dust events at the Zhangye site in the semi-arid region of China. Anthropogenic aerosol RF is estimated to range from -5 to -20 W m-2 over land and -20 to -40 W m-2 over ocean at the top of atmosphere (TOA), 5 to 30 W m-2 in the atmosphere (ATM) and -15 to -40 W m-2 at the bottom (BOT). The warming effect of anthropogenic aerosol in ATM results from BC aerosol while the negative aerosol RF at TOA is caused by scattering aerosols such as SO4 2-, NO3 - and NH4+. Positive BC RF at TOA compensates 40~50% of the TOA cooling associated with anthropogenic aerosol.

  15. Feldspars Detected by ChemCam in Gale Crater with Implications for Future Martian Exploration

    NASA Astrophysics Data System (ADS)

    Gasda, P. J.; Carlson, E.; Wiens, R. C.; Bridges, J.; Sautter, V.; Cousin, A.; Maurice, S.; Gasnault, O.; Clegg, S. M.

    2015-12-01

    Feldspar is a common igneous mineral that can shed light on parent magma temperatures, pressures, and compositions. During the first 801 sols of the NASA Mars Science Laboratory mission, we have detected 125 possible feldspar grains using the ChemCam LIBS instrument. We analyzed spectra from successive laser shots at the same location and approximate whole rock compositions for each target. Feldspar-containing targets range from tephrite-basanite to trachyandesite. The most common feldspar type is andesine; no targets are >An60. Over 30% are anorthoclase, and ~10% have potassium contents up to Or60. Individual shot measurements in a single spot suggest some feldspars are zoned. Most of these rocks are either float or incorporated into conglomerates, and thus we do not know their provenance. Many of the samples may originate from the Gale crater walls, indicative of Southern Highland ancient crust. Some may also be flung from further away (e.g., emplaced by impact processes). Hence, these rocks may give us a general clue to the variety of evolved igneous materials on Mars. The ubiquity of feldspars at Gale suggests that they have been significantly underestimated for the Southern Highlands, if not for the whole of Mars. For example, significant abundance of andesitic feldspars in both the southern highland and northern lowlands of Mars would imply that Martian volcanism has produced a greater extent of evolved igneous materials to a greater degree than previously thought. Remote sensing instruments are insensitive to plagioclase due to dust cover, lack of exposures, or low feldspar FeO content. However, the Mars 2020 rover will be equipped with 3 new instruments, the arm-mounted SHERLOC Raman, PIXL μXRF, and the mast-mounted SuperCam combined Raman-LIBS instruments, which should help characterize Martian feldspars. Additionally, the SuperCam instrument plans to include three feldspars in its suite of 20+ onboard standards to improve feldspar chemical analysis.

  16. Comment on ``Model of saturated lithium ammonia as a single-component liquid metal'' [J. Chem. Phys. 124, 074702 (2006)

    NASA Astrophysics Data System (ADS)

    Chuev, Gennady N.; Quémerais, Pascal

    2008-01-01

    We demonstrate in this Comment that the theory of simple metals applied to the saturated Li -NH3 solution in the titled paper [U. Pinsook and S. Hannongbua, J. Chem. Phys.124, 074702 (2006)] should account for the peculiarities of the solution, namely, the high solvent polarizability and different energy scales for ion-ion and electron-electron interactions. Calculations not taking into account these peculiarities contradict the experimental phase diagram of the Li -NH3 solution.

  17. 77 FR 47427 - Accreditation and Approval of Chem Gas International LLC, as a Commercial Gauger and Laboratory

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-08

    ...Notice is hereby given that, pursuant to 19 CFR 151.12 and 19 CFR 151.13, Chem Gas International LLC, 12002 Highway 146, Dickinson, TX 77539, has been approved to gauge and accredited to test petroleum and petroleum products, organic chemicals and vegetable oils for customs purposes, in accordance with the provisions of 19 CFR 151.12 and 19 CFR 151.13. Anyone wishing to employ this entity to......

  18. Data mining PubChem using a support vector machine with the Signature molecular descriptor: classification of factor XIa inhibitors.

    PubMed

    Weis, Derick C; Visco, Donald P; Faulon, Jean-Loup

    2008-11-01

    The amount of high-throughput screening (HTS) data readily available has significantly increased because of the PubChem project (http://pubchem.ncbi.nlm.nih.gov/). There is considerable opportunity for data mining of small molecules for a variety of biological systems using cheminformatic tools and the resources available through PubChem. In this work, we trained a support vector machine (SVM) classifier using the Signature molecular descriptor on factor XIa inhibitor HTS data. The optimal number of Signatures was selected by implementing a feature selection algorithm of highly correlated clusters. Our method included an improvement that allowed clusters to work together for accuracy improvement, where previous methods have scored clusters on an individual basis. The resulting model had a 10-fold cross-validation accuracy of 89%, and additional validation was provided by two independent test sets. We applied the SVM to rapidly predict activity for approximately 12 million compounds also deposited in PubChem. Confidence in these predictions was assessed by considering the number of Signatures within the training set range for a given compound, defined as the overlap metric. To further evaluate compounds identified as active by the SVM, docking studies were performed using AutoDock. A focused database of compounds predicted to be active was obtained with several of the compounds appreciably dissimilar to those used in training the SVM. This focused database is suitable for further study. The data mining technique presented here is not specific to factor XIa inhibitors, and could be applied to other bioassays in PubChem where one is looking to expand the search for small molecules as chemical probes. PMID:18829357

  19. Classification/Quantification of non-homogeneous basalts using Multivariate Analysis for MSL/ChemCam data

    NASA Astrophysics Data System (ADS)

    Cousin, A.; Forni, O.; Sautter, V.; Fabre, C.; Gasnault, O.; Maurice, S.

    2011-10-01

    ChemCam is part of the Mars Science Laboratory (MSL) - Curiosity - rover payload, which is scheduled for launch at the end of November 2011. This instrument is the first one using Laser-Induced Breakdown Spectroscopy (LIBS) for planetary exploration. Chemcam will investigate the geochemistry of the Martian surface [1, 2] at remote distances (1 to 7 m). It is composed of two physical parts: the Body Unit, located in the core of the rover, which includes three spectrometers and their electronics, and the Mast Unit, on top of the mast, which includes the laser, the telescope, the Remote Micro Imaging (RMI) and their electronics. ChemCam performs a small-footprint measurement (0,2 to 0,6 mm in diameter) : the LIBS technique creates a plasma of ablated material in electronically excited states, and then analyses the light with its spectrometers to obtain emission spectra and therefore analyze the composition of the sample. The Flight Model underwent several calibrations before delivery, with a wide range of samples and conditions [3]. Several tools are developed to analyze the data, like the peak identification tool with its ChemCam specific table, and statistical tools to determine the elemental composition of analyzed sample using "Partial Least Square" method (PLS) [4], and also to classify rocks using the Independent Component Analysis (ICA) [5, 6, 7]. The objective of this work is to show the capability of ChemCam to classify phyric textured basalts with porphyrocrysts of variable compositions set in fine-grained mesostasis.

  20. Analysis of the WRF-Chem simulations contributing to the AQMEII-Phase II exercise with respect to aerosol impact on precipitation

    NASA Astrophysics Data System (ADS)

    Werhahn, Johannes; Balzarini, Allessandra; Baró, Roccio; Curci, Gabriele; Forkel, Renate; Hirtl, Marcus; Honzak, Luka; Jiménez-Guerrero, Pedro; Langer, Matthias; Lorenz, Christof; Pérez, Juan L.; Pirovano, Guido; San José, Roberto; Tuccella, Paolo; Žabkar, Rahela

    2014-05-01

    Simulated feedback effects between aerosol concentrations and meteorological variables and on pollutant distributions are expected to depend on model configuration and the meteorological situation. In order to quantity these effects the second phase of the AQMEII (Air Quality Model Evaluation International Initiative; http://aqmeii.jrc.ec.europa.eu/) model inter-comparison exercise focused on online coupled meteorology-chemistry models. Among others, seven of the participating groups contributed simulations with WRF-Chem (Grell et al., 2005) for Europe. According to the common simulation strategy for AQMEII phase 2, the entire year 2010 was simulated as a sequence of 2-day time slices. For better comparability, the seven groups using WRF-Chem applied the same grid spacing of 23 km and shared common processing of initial and boundary conditions as well as anthropogenic and fire emissions. The simulations differ by the chosen chemistry option, aerosol module, cloud microphysics, and by the degree of aerosol-meteorology feedback that was considered. Results from this small ensemble are analyzed with respect to the effect of the different degrees of aerosol-meteorology feedback, i.e. no aerosol feedback, direct aerosol effect, and direct plus indirect aerosol effect, on large scale precipitation. Simulated precipitation fields were compared against daily precipitation observations as given by E-OBS 25 km resolution gridded dataset from the EU-FP6 project ENSEMBLES (http://ensembles-eu.metoffice.com) and the data providers in the ECA&D project (http://www.ecad.eu). As expected, a first analysis confirms that the average impact of aerosol feedback is only very small on the considered spatial and temporal scale, i.e. due to the fact that initial meteorological conditions were taken every 3rd day from a one day non-feedback spin-up run. However, the analysis of the correlations between simulation and observations for the first and the second day indicates for some

  1. Air quality modeling for the urban Jackson, Mississippi Region using a high resolution WRF/Chem model.

    PubMed

    Yerramilli, Anjaneyulu; Dodla, Venkata B; Desamsetti, Srinivas; Challa, Srinivas V; Young, John H; Patrick, Chuck; Baham, Julius M; Hughes, Robert L; Yerramilli, Sudha; Tuluri, Francis; Hardy, Mark G; Swanier, Shelton J

    2011-06-01

    In this study, an attempt was made to simulate the air quality with reference to ozone over the Jackson (Mississippi) region using an online WRF/Chem (Weather Research and Forecasting-Chemistry) model. The WRF/Chem model has the advantages of the integration of the meteorological and chemistry modules with the same computational grid and same physical parameterizations and includes the feedback between the atmospheric chemistry and physical processes. The model was designed to have three nested domains with the inner-most domain covering the study region with a resolution of 1 km. The model was integrated for 48 hours continuously starting from 0000 UTC of 6 June 2006 and the evolution of surface ozone and other precursor pollutants were analyzed. The model simulated atmospheric flow fields and distributions of NO2 and O3 were evaluated for each of the three different time periods. The GIS based spatial distribution maps for ozone, its precursors NO, NO2, CO and HONO and the back trajectories indicate that all the mobile sources in Jackson, Ridgeland and Madison contributing significantly for their formation. The present study demonstrates the applicability of WRF/Chem model to generate quantitative information at high spatial and temporal resolution for the development of decision support systems for air quality regulatory agencies and health administrators. PMID:21776240

  2. The ChemCam Remote Micro-Imager at Gale crater: Review of the first year of operations on Mars

    NASA Astrophysics Data System (ADS)

    Le Mouélic, S.; Gasnault, O.; Herkenhoff, K. E.; Bridges, N. T.; Langevin, Y.; Mangold, N.; Maurice, S.; Wiens, R. C.; Pinet, P.; Newsom, H. E.; Deen, R. G.; Bell, J. F.; Johnson, J. R.; Rapin, W.; Barraclough, B.; Blaney, D. L.; Deflores, L.; Maki, J.; Malin, M. C.; Pérez, R.; Saccoccio, M.

    2015-03-01

    The Mars Science Laboratory rover, "Curiosity" landed near the base of a 5 km-high mound of layered material in Gale crater. Mounted on the rover mast, the ChemCam instrument is designed to remotely determine the composition of soils and rocks located a few meters from the rover, using a Laser-Induced Breakdown Spectrometer (LIBS) coupled to a Remote Micro-Imager (RMI). We provide an overview of the diverse imaging investigations that were carried out by ChemCam's RMI during the first year of operation on Mars. 1182 individual panchromatic RMI images were acquired from Sol 10 to Sol 360 to document the ChemCam LIBS measurements and to characterize soils, rocks and rover hardware. We show several types of derived imaging products, including mosaics of images taken before and after laser shots, difference images to enhance the most subtle laser pits, merges with color Mastcam-100 images, micro-topography using the Z-stack technique, and time lapse movies. The very high spatial resolution of RMI is able to resolve rock textures at sub-mm scales, which provides clues regarding the origin (igneous versus sedimentary) of rocks, and to reveal information about their diagenetic and weathering evolution. In addition to its scientific value over the range accessible by LIBS (1-7 m), we also show that RMI can also serve as a powerful long distance reconnaissance tool to characterize the landscape at distances up to several kilometers from the rover.

  3. Air Quality Modeling for the Urban Jackson, Mississippi Region Using a High Resolution WRF/Chem Model

    PubMed Central

    Yerramilli, Anjaneyulu; Dodla, Venkata B.; Desamsetti, Srinivas; Challa, Srinivas V.; Young, John H.; Patrick, Chuck; Baham, Julius M.; Hughes, Robert L.; Yerramilli, Sudha; Tuluri, Francis; Hardy, Mark G.; Swanier, Shelton J.

    2011-01-01

    In this study, an attempt was made to simulate the air quality with reference to ozone over the Jackson (Mississippi) region using an online WRF/Chem (Weather Research and Forecasting–Chemistry) model. The WRF/Chem model has the advantages of the integration of the meteorological and chemistry modules with the same computational grid and same physical parameterizations and includes the feedback between the atmospheric chemistry and physical processes. The model was designed to have three nested domains with the inner-most domain covering the study region with a resolution of 1 km. The model was integrated for 48 hours continuously starting from 0000 UTC of 6 June 2006 and the evolution of surface ozone and other precursor pollutants were analyzed. The model simulated atmospheric flow fields and distributions of NO2 and O3 were evaluated for each of the three different time periods. The GIS based spatial distribution maps for ozone, its precursors NO, NO2, CO and HONO and the back trajectories indicate that all the mobile sources in Jackson, Ridgeland and Madison contributing significantly for their formation. The present study demonstrates the applicability of WRF/Chem model to generate quantitative information at high spatial and temporal resolution for the development of decision support systems for air quality regulatory agencies and health administrators. PMID:21776240

  4. NutriChem: a systems chemical biology resource to explore the medicinal value of plant-based foods.

    PubMed

    Jensen, Kasper; Panagiotou, Gianni; Kouskoumvekaki, Irene

    2015-01-01

    There is rising evidence of an inverse association between chronic diseases and diets characterized by rich fruit and vegetable consumption. Dietary components may act directly or indirectly on the human genome and modulate multiple processes involved in disease risk and disease progression. However, there is currently no exhaustive resource on the health benefits associated to specific dietary interventions, or a resource covering the broad molecular content of food. Here we present the first release of NutriChem, available at http://cbs.dtu.dk/services/NutriChem-1.0, a database generated by text mining of 21 million MEDLINE abstracts for information that links plant-based foods with their small molecule components and human disease phenotypes. NutriChem contains text-mined data for 18478 pairs of 1772 plant-based foods and 7898 phytochemicals, and 6242 pairs of 1066 plant-based foods and 751 diseases. In addition, it includes predicted associations for 548 phytochemicals and 252 diseases. To the best of our knowledge this database is the only resource linking the chemical space of plant-based foods with human disease phenotypes and provides a foundation for understanding mechanistically the consequences of eating behaviors on health. PMID:25106869

  5. Gaseous chemistry and aerosol mechanism developments for version 3.5.1 of the online regional model, WRF-Chem

    NASA Astrophysics Data System (ADS)

    Archer-Nicholls, S.; Lowe, D.; Utembe, S.; Allan, J.; Zaveri, R. A.; Fast, J. D.; Hodnebrog, Ø.; Denier van der Gon, H.; McFiggans, G.

    2014-11-01

    We have made a number of developments to the Weather, Research and Forecasting model coupled with Chemistry (WRF-Chem), with the aim of improving model prediction of trace atmospheric gas-phase chemical and aerosol composition, and of interactions between air quality and weather. A reduced form of the Common Reactive Intermediates gas-phase chemical mechanism (CRIv2-R5) has been added, using the Kinetic Pre-Processor (KPP) interface, to enable more explicit simulation of VOC degradation. N2O5 heterogeneous chemistry has been added to the existing sectional MOSAIC aerosol module, and coupled to both the CRIv2-R5 and existing CBM-Z gas-phase schemes. Modifications have also been made to the sea-spray aerosol emission representation, allowing the inclusion of primary organic material in sea-spray aerosol. We have worked on the European domain, with a particular focus on making the model suitable for the study of nighttime chemistry and oxidation by the nitrate radical in the UK atmosphere. Driven by appropriate emissions, wind fields and chemical boundary conditions, implementation of the different developments are illustrated, using a modified version of WRF-Chem 3.4.1, in order to demonstrate the impact that these changes have in the Northwest European domain. These developments are publicly available in WRF-Chem from version 3.5.1 onwards.

  6. Modeling of the chemical composition of fine particulate matter: Development and performance assessment of EASYWRF-Chem

    NASA Astrophysics Data System (ADS)

    Mendez, M.; Lebègue, P.; Visez, N.; Fèvre-Nollet, V.; Crenn, V.; Riffault, V.; Petitprez, D.

    2016-03-01

    The European emission Adaptation SYstem for the WRF-Chem model (EASYWRF-Chem) has been developed to generate chemical information supporting the WRF-Chem requirements from any emission inventory based on the CORINAIR methodology. Using RADM2 and RACM2 mechanisms, "emission species" are converted into "model species" thanks to the SAPRC methodology for gas phase pollutant and the PM10 and PM2.5 fractions. Furthermore, by adapting US EPA PM2.5 profiles, the processing of aerosol chemical speciation profiles separates the unspeciated PM2.5 emission into five chemical families: sulfates, nitrates, elemental carbon, organic aerosol and unspeciated aerosol. The evaluation of the model has been performed by separately comparing model outcomes with (i) meteorological measurements; (ii) NO2, O3, PM10 and PM2.5 mass concentrations from the regional air quality monitoring network; (iii) hourly-resolved data from four field campaign measurements, in winter and in summer, on two sites in the French northern region. In the latter, a High Resolution - Time of Flight - Aerosol Mass Spectrometer (HR-ToF-AMS) provided non-refractory PM1 concentrations of sulfate, nitrate and ammonium ions as well as organic matter (OM), while an aethalometer provided black carbon (BC) concentrations in the PM2.5 fraction. Meteorological data (temperature, wind, relative humidity) are well simulated for all the time series data except for specific events as wind direction changes or rainfall. For particulate matter, results are presented by considering firstly the total mass concentration of PM2.5 and PM10. EASYWRF-Chem simulations overestimated the PM10 mass concentrations by + 22% and + 4% for summer and winter periods respectively, whereas for the finer PM2.5 fraction, mass concentrations were overestimated by + 20% in summer and underestimated by - 13% in winter. Simulated sulfate concentrations were underestimated and nitrate concentrations were overestimated but hourly variations were well

  7. Calibration of the Fluorine, Chlorine and Hydrogen Content of Apatites With the ChemCam LIBS Instrument

    NASA Technical Reports Server (NTRS)

    Meslin, P.-Y.; Cicutto, L.; Forni, O.; Drouet, C.; Rapin, W.; Nachon, M.; Cousin, A.; Blank, J. G.; McCubbin, F. M.; Gasnault, O.; Newsom, H.; Mangold, N.; Schroeder, S.; Sautter, V.; Maurice, S.; Wiens, R. C.

    2016-01-01

    Determining the composition of apatites is important to understand the behavior of volatiles during planetary differentiation. Apatite is an ubiquitous magmatic mineral in the SNC meteorites. It is a significant reservoir of halogens in these meteorites and has been used to estimate the halogen budget of Mars. Apatites have been identified in sandstones and pebbles at Gale crater by ChemCam, a Laser-Induced Breakdown Spectroscometer (LIBS) instrument onboard the Curiosity rover. Their presence was inferred from correlations between calcium, fluorine (using the CaF molecular band centered near 603 nm, whose detection limit is much lower that atomic or ionic lines and, in some cases, phosphorus (whose detection limit is much larger). An initial quantification of fluorine, based on fluorite (CaF2)/basalt mixtures and obtained at the LANL laboratory, indicated that the excess of F/Ca (compared to the stoichiometry of pure fluorapatites) found on Mars in some cases could be explained by the presence of fluorite. Chlorine was not detected in these targets, at least above a detection limit of 0.6 wt% estimated from. Fluorapatite was later also detected by X-ray diffraction (with CheMin) at a level of approx.1wt% in the Windjana drill sample (Kimberley area), and several points analyzed by ChemCam in this area also revealed a correlation between Ca and F. The in situ detection of F-rich, Cl-poor apatites contrasts with the Cl-rich, F-poor compositions of apatites found in basaltic shergottites and in gabbroic clasts from the martian meteorite NWA 7034, which were also found to be more Cl-rich than apatites from basalts on Earth, the Moon, or Vesta. The in situ observations could call into question one of the few possible explanations brought forward to explain the SNC results, namely that Mars may be highly depleted in fluorine. The purpose of the present study is to refine the calibration of the F, Cl, OH and P signals measured by the ChemCam LIBS instrument, initiated

  8. Sensitivity analysis of the microphysics scheme in WRF-Chem contributions to AQMEII phase 2

    NASA Astrophysics Data System (ADS)

    Baró, Rocio; Jiménez-Guerrero, Pedro; Balzarini, Alessandra; Curci, Gabriele; Forkel, Renate; Grell, Georg; Hirtl, Marcus; Honzak, Luka; Langer, Matthias; Pérez, Juan L.; Pirovano, Guido; San José, Roberto; Tuccella, Paolo; Werhahn, Johannes; Žabkar, Rahela

    2015-08-01

    The parameterization of cloud microphysics is a crucial part of fully-coupled meteorology-chemistry models, since microphysics governs the formation, growth and dissipation of hydrometeors and also aerosol cloud interactions. The main objective of this study, which is based on two simulations for Europe contributing to Phase 2 of the Air Quality Model Evaluation International Initiative (AQMEII) is to assess the sensitivity of WRF-Chem to the selection of the microphysics scheme. Two one-year simulations including aerosol cloud interactions with identical physical-chemical parameterizations except for the microphysics scheme (Morrison -MORRAT vs Lin -LINES) are compared. The study covers the difference between the simulations for two three-month periods (cold and a warm) during the year 2010, allowing thus a seasonal analysis. Overall, when comparing to observational data, no significant benefits from the selection of the microphysical schemes can be derived from the results. However, these results highlight a marked north-south pattern of differences, as well as a decisive impact of the aerosol pollution on the results. The MORRAT simulation resulted in higher cloud water mixing ratios over remote areas with low CCN concentrations, whereas the LINES simulation yields higher cloud water mixing ratios over the more polluted areas. Regarding the droplet number mixing ratio, the Morrison scheme was found to yield higher values both during winter and summer for nearly the entire model domain. As smaller and more numerous cloud droplets are more effective in scattering shortwave radiation, the downwelling shortwave radiation flux at surface was found to be up to 30 W m-2 lower for central Europe for the MORRAT simulation as compared to the simulation using the LINES simulation during wintertime. Finally, less convective precipitation is simulated over land with MORRAT during summertime, while no almost difference was found for the winter. On the other hand, non

  9. Overview of the diagenetic features analyzed by ChemCam onboard Curiosity

    NASA Astrophysics Data System (ADS)

    Mangold, N.; Forni, O.; Nachon, M.; Blaney, D. L.; Wiens, R. C.; Kah, L. C.; Kronyak, R. E.; Clegg, S. M.; Cousin, A.; Fisk, M. R.; Gasnault, O.; Grotzinger, J. P.; Lanza, N.; Lasue, J.; Le Deit, L.; Le Mouelic, S.; Maurice, S.; Meslin, P. Y.; Rapin, W.; Newsom, H. E.; Sumner, D. Y.

    2015-12-01

    The Curiosity rover has encountered a variety of sedimentary rocks with significant variations in both texture and composition. Most of the sandstones and mudstones are interpreted as having been deposited in a fluvio-lacustrine environment, as analyzed in details in the waypoints named Yellowknife Bay, Kimberley and Pahrump. All of these sediments have been crossed by diagenetic features of different composition. Light-toned Ca-sulfate veins observed initially at Yellowknife Bay were observed along the traverse, and in high density at the Pahrump location. As they appear in all sediments and show straight fractures, they correspond to late-stage diagenetic features, due to fluid circulation, with fractures probably due to hydraulic stress at depth. In contrast to light-toned veins, earlier-stage diagenetic features have shown variable composition in the three areas. At Yellowknife Bay, raised ridges display enriched Mg proportion, probably linked to Mg-clay whereas outcrops at Kimberley display fracture fills enriched in Mn and Zn. Pahrump displays a large variety of diagenetic features distinct from these previous examples. Mg-enriched concretions contain S and abundant Ni. Mg enrichments have also been observed in resistant zones along fractures and in resistant layers. Locally concretions also display high Fe, S-bearing material interpreted as Fe-sulfate, probably jarosite. A special location named Garden City at the top of the Parhump sequence displays a complex area with light-toned veins surrounded by darker veins. The latter display strong Ca signatures correlated with F, interpreted as fluorite. No C or S emissions were observed that could alternatively explain the high Ca abundance by carbonates or sulfates. The dark tone of the F-bearing minerals may be due to the presence of Fe. These specific dark veins could derive from the leaching of F-apatite, a mineral that has been observed both in the sandstones and in some of the igneous clasts analyzed by Chem

  10. WRF-Chem simulations of aerosols and anthropogenic aerosol radiative forcing in East Asia

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Zhao, Chun; Liu, Xiaohong; Zhang, Meigen; Leung, L. Ruby

    2014-08-01

    This study aims to provide a first comprehensive evaluation of WRF-Chem for modeling aerosols and anthropogenic aerosol radiative forcing (RF, including direct, semi-direct and indirect forcing) over East Asia. Several numerical experiments were conducted from November 2007 to December 2008. Comparison between model results and observations shows that the model can generally reproduce the observed spatial distributions of aerosol concentration, aerosol optical depth (AOD) and single scattering albedo (SSA) from measurements at many sites, including the relatively higher aerosol concentration and AOD over East China and the relatively lower AOD over Southeast Asia, Korea, and Japan. The model also depicts the seasonal variation and transport of pollutions over East Asia. Particulate matter of 10 μm or less in the aerodynamic diameter (PM10), black carbon (BC), sulfate (SO42-), nitrate (NO3-) and ammonium (NH4+) concentrations are higher in spring than other seasons in Japan, which indicates the possible influence of pollutant transport from polluted area of East Asia. The model underestimates SO42- and organic carbon (OC) concentrations over mainland China by about a factor of 2, while overestimates NO3- concentration in autumn along the Yangtze River. The model captures the dust events at the Zhangye site in the semi-arid region of China. AOD is high over Southwest and Central China in winter and spring and over North China in winter, spring and summer while is low over South China in summer due to monsoon precipitation. SSA is lowest in winter and highest in summer. Anthropogenic aerosol RF is estimated to range from -5 to -20 W m-2 over land and -20 to -40 W m-2 over adjacent oceans at the top of atmosphere (TOA), 5-30 W m-2 in the atmosphere (ATM) and -15 to -40 W m-2 at the bottom (BOT). The warming effect of anthropogenic aerosol in ATM results from BC aerosol while the negative aerosol RF at TOA is caused by scattering aerosols such as SO42-, NO3- and NH4

  11. Al-doping influence on crystal growth of Ni-Al alloy: Experimental testing of a theoretical model

    NASA Astrophysics Data System (ADS)

    Rong, Xi-Ming; Chen, Jun; Li, Jing-Tian; Zhuang, Jun; Ning, Xi-Jing

    2015-12-01

    Recently, a condensing potential model was developed to evaluate the crystallization ability of bulk materials [Ye X X, Ming C, Hu Y C and Ning X J 2009 J. Chem. Phys. 130 164711 and Peng K, Ming C, Ye X X, Zhang W X, Zhuang J and Ning X J 2011 Chem. Phys. Lett. 501 330], showing that the best temperature for single crystal growth is about 0.6Tm, where Tm is the melting temperature, and for Ni-Al alloy, more than 6 wt% of Al-doping will badly reduce the crystallization ability. In order to verify these predictions, we fabricated Ni-Al films with different concentrations of Al on Si substrates at room temperature by pulsed laser deposition, and post-annealed the films at 833, 933, 1033 (˜ 0.6Tm), 1133, and 1233 K in vacuum furnace, respectively. The x-ray diffraction spectra show that annealing at 0.6Tm is indeed best for larger crystal grain formation, and the film crystallization ability remarkably declines with more than 6-wt% Al doping. Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant No. 20130071110018) and the National Natural Science Foundation of China (Grant No. 11274073).

  12. Application of WRF/Chem over East Asia: Part I. Model evaluation and intercomparison with MM5/CMAQ

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Zhang, Xin; Wang, Litao; Zhang, Qiang; Duan, Fengkui; He, Kebin

    2016-01-01

    In this work, the application of the online-coupled Weather Research and Forecasting model with chemistry (WRF/Chem) version 3.3.1 is evaluated over East Asia for January, April, July, and October 2005 and compared with results from a previous application of an offline model system, i.e., the Mesoscale Model and Community Multiple Air Quality modeling system (MM5/CMAQ). The evaluation of WRF/Chem is performed using multiple observational datasets from satellites and surface networks in mainland China, Hong Kong, Taiwan, and Japan. WRF/Chem simulates well specific humidity (Q2) and downward longwave and shortwave radiation (GLW and GSW) with normalized mean biases (NMBs) within 24%, but shows moderate to large biases for temperature at 2-m (T2) (NMBs of -9.8% to 75.6%) and precipitation (NMBs of 11.4-92.7%) for some months, and wind speed at 10-m (WS10) (NMBs of 66.5-101%), for all months, indicating some limitations in the YSU planetary boundary layer scheme, the Purdue Lin cloud microphysics, and the Grell-Devenyi ensemble scheme. WRF/Chem can simulate the column abundances of gases reasonably well with NMBs within 30% for most months but moderately to significantly underpredicts the surface concentrations of major species at all sites in nearly all months with NMBs of -72% to -53.8% for CO, -99.4% to -61.7% for NOx, -84.2% to -44.5% for SO2, -63.9% to -25.2% for PM2.5, and -68.9% to 33.3% for PM10, and aerosol optical depth in all months except for October with NMBs of -38.7% to -16.2%. The model significantly overpredicts surface concentrations of O3 at most sites in nearly all months with NMBs of up to 160.3% and NO3- at the Tsinghua site in all months. Possible reasons for large underpredictions include underestimations in the anthropogenic emissions of CO, SO2, and primary aerosol, inappropriate vertical distributions of emissions of SO2 and NO2, uncertainties in upper boundary conditions (e.g., for O3 and CO), missing or inaccurate model representations (e

  13. Application of WRF/Chem over East Asia: Part II. Model improvement and sensitivity simulations

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Zhang, Xin; Wang, Kai; Zhang, Qiang; Duan, Fengkui; He, Kebin

    2016-01-01

    .5, and -64.0% to 7.2% for PM10, comparing to -84.2% to -44.5% for SO2, -88.1% to -44.0% for NO2, -11.0%-160.3% for O3, -63.9% to -25.2% for PM2.5, and -68.9%-33.3% for PM10 from the original simulation. The improved WRF/Chem is applied to estimate the impact of anthropogenic aerosols on regional climate and air quality in East Asia. Anthropogenic aerosols can increase cloud condensation nuclei, aerosol optical depth, cloud droplet number concentrations, and cloud optical depth. They can decrease surface net radiation, temperature at 2-m, wind speed at 10-m, planetary boundary layer height, and precipitation through various direct and indirect effects. These changes in turn lead to changes in chemical predictions in a variety of ways.

  14. Application of WRF/Chem-MADRID for real-time air quality forecasting over the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Chuang, Ming-Tung; Zhang, Yang; Kang, Daiwen

    2011-11-01

    A Real-Time Air Quality Forecast (RT-AQF) system that is based on a three-dimensional air quality model provides a powerful tool to forecast air quality and advise the public with proper preventive actions. In this work, a new RT-AQF system is developed based on the online-coupled Weather Research and Forecasting model with Chemistry (WRF/Chem) with the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID) (referred to as WRF/Chem-MADRID) and deployed in the southeastern U.S. during May-September, 2009. Max 1-h and 8-h average ozone (O 3) and 24-h average fine particulate matter (PM 2.5) are evaluated against surface observations from the AIRNow database in terms of spatial distribution, temporal variation, and domain-wide and region-specific discrete and categorical performance statistics. WRF/Chem-MADRID demonstrates good forecasting skill that is consistent with current RT-AQF models. The overpredictions of O 3 and underprediction of PM 2.5 are likely due to uncertainties in emissions such as those of biogenic volatile organic compounds (BVOCs) and ammonia, inaccuracies in simulated meteorological variables such as 2-m temperature, 10-m wind speed, and precipitation, and uncertainties in the boundary conditions. Sensitivity simulations show that the use of the online BVOC emissions can improve PM 2.5 forecast in areas with high BVOC emissions and adjusting lateral boundaries can improve domain-wide O 3 and PM 2.5 predictions. Several limitations and uncertainties are identified to further improve the model's forecasting skill.

  15. Simulations of the Holuhraun eruption 2014 with WRF-Chem and evaluation with satellite and ground based SO2 measurements

    NASA Astrophysics Data System (ADS)

    Hirtl, Marcus; Arnold-Arias, Delia; Flandorfer, Claudia; Maurer, Christian; Mantovani, Simone; Natali, Stefano

    2016-04-01

    Volcanic eruptions, with gas or/and particle emissions, directly influence our environment, with special significance when they either occur near inhabited regions or are transported towards them. In addition to the well-known affectation of air traffic, with large economic impacts, the ground touching plumes can lead directly to an influence of soil, water and even to a decrease of air quality. The eruption of Holuhraun in August 2014 in central Iceland is the country's largest lava and gas eruption since the Lakagígar eruption in 1783. Nevertheless, very little volcanic ash was produced. The main atmospheric threat from this event was the SO2 pollution that frequently violated the Icelandic National Air Quality Standards in many population centers. However, the SO2 affectation was not limited to Iceland but extended to mainland Europe. The on-line coupled model WRF-Chem is used to simulate the dispersion of SO2 for this event that affected the central European regions. The volcanic emissions are considered in addition to the anthropogenic and biogenic ground sources at European scale. A modified version of WRF-Chem version 4.1 is used in order to use time depending injection heights and mass fluxes which were obtained from in situ observations. WRF-Chem uses complex gas- (RADM2) and aerosol- (MADE-SORGAM) chemistry and is operated on a European domain (12 km resolution), and a nested grid covering the Alpine region (4 km resolution). The study is showing the evaluation of the model simulations with satellite and ground based measurement data of SO2. The analysis is conducted on a data management platform, which is currently developed in the frame of the ESA-funded project TAMP "Technology and Atmospheric Mission Platform": it provides comprehensive functionalities to visualize and numerically compare data from different sources (model, satellite and ground-measurements).

  16. Twelve-month, 12 km resolution North American WRF-Chem v3.4 air quality simulation: performance evaluation

    DOE PAGESBeta

    Tessum, C. W.; Hill, J. D.; Marshall, J. D.

    2015-04-07

    We present results from and evaluate the performance of a 12-month, 12 km horizontal resolution year 2005 air pollution simulation for the contiguous United States using the WRF-Chem (Weather Research and Forecasting with Chemistry) meteorology and chemical transport model (CTM). We employ the 2005 US National Emissions Inventory, the Regional Atmospheric Chemistry Mechanism (RACM), and the Modal Aerosol Dynamics Model for Europe (MADE) with a volatility basis set (VBS) secondary aerosol module. Overall, model performance is comparable to contemporary modeling efforts used for regulatory and health-effects analysis, with an annual average daytime ozone (O3) mean fractional bias (MFB) of 12%more » and an annual average fine particulate matter (PM2.5) MFB of −1%. WRF-Chem, as configured here, tends to overpredict total PM2.5 at some high concentration locations and generally overpredicts average 24 h O3 concentrations. Performance is better at predicting daytime-average and daily peak O3 concentrations, which are more relevant for regulatory and health effects analyses relative to annual average values. Predictive performance for PM2.5 subspecies is mixed: the model overpredicts particulate sulfate (MFB = 36%), underpredicts particulate nitrate (MFB = −110%) and organic carbon (MFB = −29%), and relatively accurately predicts particulate ammonium (MFB = 3%) and elemental carbon (MFB = 3%), so that the accuracy in total PM2.5 predictions is to some extent a function of offsetting over- and underpredictions of PM2.5 subspecies. Model predictive performance for PM2.5 and its subspecies is in general worse in winter and in the western US than in other seasons and regions, suggesting spatial and temporal opportunities for future WRF-Chem model development and evaluation.« less

  17. Twelve-month, 12 km resolution North American WRF-Chem v3.4 air quality simulation: performance evaluation

    DOE PAGESBeta

    Tessum, C. W.; Hill, J. D.; Marshall, J. D.

    2014-12-02

    We present results from and evaluate the performance of a 12 month, 12 km horizontal resolution air pollution simulation for the contiguous United States using the WRF-Chem (Weather Research and Forecasting with Chemistry) meteorology and chemical transport model (CTM). We employ the 2005 US National Emissions Inventory, the Regional Atmospheric Chemistry Mechanism (RACM), and the Modal Aerosol Dynamics Model for Europe (MADE) with a Volatility Basis Set (VBS) secondary aerosol module. Overall, model performance is comparable to contemporary models used for regulatory and health-effects analysis, with an annual average daytime ozone (O3) mean fractional bias (MFB) of 12% and anmore » annual average fine particulate matter (PM2.5) MFB of −1%. WRF-Chem, as configured here, tends to overpredict total PM2.5 at some high concentration locations, and generally overpredicts average 24 h O3 concentrations, with better performance at predicting average daytime and daily peak O3 concentrations. Predictive performance for PM2.5 subspecies is mixed: the model overpredicts particulate sulfate (MFB = 65%), underpredicts particulate nitrate (MFB = −110%) and organic carbon (MFB = −65%), and relatively accurately predicts particulate ammonium (MFB = 3%) and elemental carbon (MFB = 3%), so that the accuracy in total PM2.5 predictions is to some extent a function of offsetting over- and underpredictions of PM2.5 subspecies. Model predictive performance for PM2.5 and its subspecies is in general worse in winter and in the western US than in other seasons and regions, suggesting spatial and temporal opportunities for future WRF-Chem model development and evaluation.« less

  18. Simulation of the Dust Aerosol and its Climatic Effect over East Asia using WRF-Chem model

    NASA Astrophysics Data System (ADS)

    Chen, S.; Huang, J.; Zhao, C.; Qian, Y.; Ruby, L.

    2015-12-01

    WRF-Chem model is used to investigate the seasonal and inter-annual variations of mineral dust over East Asia during 2007-2011, with a focus on the dust mass balance and its direct radiative forcing and climatic impact. A variety of in-situ measurements and satellite observations have been used to evaluate the simulation results. Generally, WRF-Chem reasonably reproduces not only the column variability but also the vertical profile and size distribution of mineral dust over and near the dust source regions. In addition, the dust lifecycle and processes that control the seasonal and spatial variations of dust mass balance are investigated in seven sub-regions. Dust direct radiative forcing in a surface cooling of up to -14 and -10 W m-2, atmospheric warming of up to 9 and 2 W m-2, and TOA cooling of -5 and -8 W m-2, respectively. The ability of WRF-Chem to capture the measured features of dust optical and radiative properties and dust mass balance over East Asian provides confidence for future investigation of East Asia dust impact on regional or global climate. Over the Tibetan Plateau, dust modifies the atmospheric heating profiles and cloud properties, leading to a decrease of snowfall and hence snow coverage on the ground. These results are from a reduction of surface albedo and increased surface temperature, further accelerating snowmelt. This impact is smallest in summer, when the snow coverage is relative low. Over the East China-Korea-Japan regions, dust modifies the atmospheric heating profiles and cloud properties. Dust induces significant changes in the magnitudes and diurnal variations of surface temperature. Cloud liquid water content is also significantly impacted, as reflected in changes of cloud forcing at the top of the atmosphere (TOA) with a maximum in summer. The dust impacts on spatial distribution of precipitation and wind circulation are also investigated, showing distinct seasonality of dust impact on the regional climate over East Asia.

  19. Nonlinear mapping technique for data visualization and clustering assessment of LIBS data: application to ChemCam data.

    PubMed

    Lasue, J; Wiens, R C; Stepinski, T F; Forni, O; Clegg, S M; Maurice, S

    2011-07-01

    ChemCam is a remote laser-induced breakdown spectroscopy (LIBS) instrument that will arrive on Mars in 2012, on-board the Mars Science Laboratory Rover. The LIBS technique is crucial to accurately identify samples and quantify elemental abundances at various distances from the rover. In this study, we compare different linear and nonlinear multivariate techniques to visualize and discriminate clusters in two dimensions (2D) from the data obtained with ChemCam. We have used principal components analysis (PCA) and independent components analysis (ICA) for the linear tools and compared them with the nonlinear Sammon's map projection technique. We demonstrate that the Sammon's map gives the best 2D representation of the data set, with optimization values from 2.8% to 4.3% (0% is a perfect representation), together with an entropy value of 0.81 for the purity of the clustering analysis. The linear 2D projections result in three (ICA) and five times (PCA) more stress, and their clustering purity is more than twice higher with entropy values about 1.8. We show that the Sammon's map algorithm is faster and gives a slightly better representation of the data set if the initial conditions are taken from the ICA projection rather than the PCA projection. We conclude that the nonlinear Sammon's map projection is the best technique for combining data visualization and clustering assessment of the ChemCam LIBS data in 2D. PCA and ICA projections on more dimensions would improve on these numbers at the cost of the intuitive interpretation of the 2D projection by a human operator. PMID:21331488

  20. Twelve-month, 12 km resolution North American WRF-Chem v3.4 air quality simulation: performance evaluation

    NASA Astrophysics Data System (ADS)

    Tessum, C. W.; Hill, J. D.; Marshall, J. D.

    2015-04-01

    We present results from and evaluate the performance of a 12-month, 12 km horizontal resolution year 2005 air pollution simulation for the contiguous United States using the WRF-Chem (Weather Research and Forecasting with Chemistry) meteorology and chemical transport model (CTM). We employ the 2005 US National Emissions Inventory, the Regional Atmospheric Chemistry Mechanism (RACM), and the Modal Aerosol Dynamics Model for Europe (MADE) with a volatility basis set (VBS) secondary aerosol module. Overall, model performance is comparable to contemporary modeling efforts used for regulatory and health-effects analysis, with an annual average daytime ozone (O3) mean fractional bias (MFB) of 12% and an annual average fine particulate matter (PM2.5) MFB of -1%. WRF-Chem, as configured here, tends to overpredict total PM2.5 at some high concentration locations and generally overpredicts average 24 h O3 concentrations. Performance is better at predicting daytime-average and daily peak O3 concentrations, which are more relevant for regulatory and health effects analyses relative to annual average values. Predictive performance for PM2.5 subspecies is mixed: the model overpredicts particulate sulfate (MFB = 36%), underpredicts particulate nitrate (MFB = -110%) and organic carbon (MFB = -29%), and relatively accurately predicts particulate ammonium (MFB = 3%) and elemental carbon (MFB = 3%), so that the accuracy in total PM2.5 predictions is to some extent a function of offsetting over- and underpredictions of PM2.5 subspecies. Model predictive performance for PM2.5 and its subspecies is in general worse in winter and in the western US than in other seasons and regions, suggesting spatial and temporal opportunities for future WRF-Chem model development and evaluation.

  1. Twelve-month, 12 km resolution North American WRF-Chem v3.4 air quality simulation: performance evaluation

    NASA Astrophysics Data System (ADS)

    Tessum, C. W.; Hill, J. D.; Marshall, J. D.

    2014-12-01

    We present results from and evaluate the performance of a 12 month, 12 km horizontal resolution air pollution simulation for the contiguous United States using the WRF-Chem (Weather Research and Forecasting with Chemistry) meteorology and chemical transport model (CTM). We employ the 2005 US National Emissions Inventory, the Regional Atmospheric Chemistry Mechanism (RACM), and the Modal Aerosol Dynamics Model for Europe (MADE) with a Volatility Basis Set (VBS) secondary aerosol module. Overall, model performance is comparable to contemporary models used for regulatory and health-effects analysis, with an annual average daytime ozone (O3) mean fractional bias (MFB) of 12% and an annual average fine particulate matter (PM2.5) MFB of -1%. WRF-Chem, as configured here, tends to overpredict total PM2.5 at some high concentration locations, and generally overpredicts average 24 h O3 concentrations, with better performance at predicting average daytime and daily peak O3 concentrations. Predictive performance for PM2.5 subspecies is mixed: the model overpredicts particulate sulfate (MFB = 65%), underpredicts particulate nitrate (MFB = -110%) and organic carbon (MFB = -65%), and relatively accurately predicts particulate ammonium (MFB = 3%) and elemental carbon (MFB = 3%), so that the accuracy in total PM2.5 predictions is to some extent a function of offsetting over- and underpredictions of PM2.5 subspecies. Model predictive performance for PM2.5 and its subspecies is in general worse in winter and in the western US than in other seasons and regions, suggesting spatial and temporal opportunities for future WRF-Chem model development and evaluation.

  2. Validation of WRF/Chem model and sensitivity of chemical mechanisms to ozone simulation over megacity Delhi

    NASA Astrophysics Data System (ADS)

    Gupta, Medhavi; Mohan, Manju

    2015-12-01

    Regional Chemical transport models (CTM) are used extensively for modeling of Ozone concentration. WRF/Chem is one such CTM that includes various chemical mechanisms and is used for simulation of Ozone and other pollutant concentration at desired time step. This study focuses on the robustness of WRF/Chem simulated Ozone concentrations over a sub tropical urban airshed of megacity Delhi. Detailed analysis has been presented for the veracity of two different chemical mechanisms namely; Carbon Bond Mechanism (CBMZ) and Regional Atmospheric Chemical Model (RACM). It was observed that simulated Ozone concentrations are better predicted with CBMZ mechanism and is highly sensitive to the rate constants. The Ozone concentrations are analyzed for precursors such as Oxides of Nitrogen (NOx) and Carbon-monoxide (CO) as well as temperature considering their strong dependence on Ozone formation. A consistent positive correlation between Ozone concentration and temperature is noted whereas; NOx and CO show inverse relationship with Ozone. Further, Ozone concentration range vis-à-vis model performance is scrutinized. A poor model for low Ozone concentration levels is observed and a highly satisfactory for moderate Ozone concentration levels while satisfactory for higher Ozone levels. Despite of the limitations observed during model evaluation of Ozone predictions for low Ozone levels, it is concluded that WRF/Chem could effectively be applied for understanding its trends, tropospheric chemistry and air quality assessment for regulatory purposes at moderate Ozone concentration levels. Further, it is recommended that model implementation shall be made for policy decisions cautiously with due consideration to the magnitudes of Ozone levels present in the study domain and the performance measures in the specific concentration range.

  3. ChemCam at Gale Crater: Highlights and Discoveries from Three Years of Chemical Measurements on Mars

    NASA Astrophysics Data System (ADS)

    Blaney, Diana L.; Wiens, Roger; Maurice, Sylvestre; Gasnault, Olivier; Anderson, Ryan; Bridges, John; Bridges, Nathan; Clegg, Samuel; Clark, Benton; Ehlmann, Bethany; Dyar, Melinda D.; Fisk, Martin; Francis, Raymond; Fabre, Cecile; Forni, Olivier; Frydenvang, Jens; Johnson, Jeffery; Lanza, Nina; Leveille, Richard; Lasue, Jeremie; Le Deit, Laetitia; Mangold, Nicholas; Melikechi, Noureddine; Nachon, Marion; Newsom, Horton; Payre, Valerie; Rapin, William; Sautter, Violane; Vaniman, David; Grotzinger, John; Vasavad, Ashwin; Crisp, Joy

    2015-11-01

    ChemCam has undertaken a detailed chemical investigation of the rocks and soils at Gale crater over the last three years with over six thousand separate geochemical measurements. Recent recalibration of the ChemCam data using a new library of >350 geochemical standards has enabled increased elemental accuracies over a wider compositional range. The increased accuracy combined with ChemCam’s small spot size allows for the chemistry of mineral end members including feldspars, high silica, oxide rich grains to be identified. ChemCam has observed both sedimentary and igneous compositions. Igneous compositions are generally present in conglomerates and in float rocks. Compositions show a wide range of igneous chemistry ranging from basaltic to feldspar rich assemblages.Sedimentary rocks have a wide range of compositions reflecting both differences in chemical source regions and in depositional and diagenetic histories. The “Sheepbed” mudstones cluster around Martian average crustal compositions. The “Kimberley” outcrop showed enhanced potassium reaching concentrations up to ~6 wt% K2O. More recent observations in the Murray Formation at the base of Mt. Sharp reveal mudstones that are lower in magnesium and higher in silica and aluminum than the more basaltic mudstones previously investigated. Extremely high silica (75-85 wt%) deposits have also been identified. The high silica observations were associated with increased TiO2, While the Murray mudstones are generally low in magnesium, local enhancements in magnesium have also been noted associated with resistant facies in the outcrop. Chemical trends also indicate that iron oxide phases may also be present as cements. Sandstone facies with a mafic composition are also present. Veins in the unit also show a wide range of compositions indicating fluid chemistries rich in calcium sulfate, fluorine, magnesium and iron were present. Vein chemistry could be the result of distinct fluids migrating through from a

  4. Comment on ``Free energy simulations of single and double ion occupancy in gramicidin A'' [J. Chem. Phys. 126, 105103 (2007)

    NASA Astrophysics Data System (ADS)

    Roux, Benoît; Andersen, Olaf S.; Allen, Toby W.

    2008-06-01

    In a recent article published by Bastug and Kuyucak [J. Chem. Phys.126, 105103 (2007)] investigated the microscopic factors affecting double ion occupancy in the gramicidin channel. The analysis relied largely on the one-dimensional potential of mean force of ions along the axis of the channel (the so-called free energy profile of the ion along the channel axis), as well as on the calculation of the equilibrium association constant of the ions in the channel binding sites. It is the purpose of this communication to clarify this issue.

  5. Chem-Prep PZT 95/5 for neutron generator applications : development of laboratory-scale powder processing operations.

    SciTech Connect

    Montoya, Ted V.; Moore, Roger Howard; Spindle, Thomas Lewis Jr.

    2003-12-01

    Chemical synthesis methods are being developed as a future source of PZT 95/5 powder for neutron generator voltage bar applications. Laboratory-scale powder processes were established to produce PZT billets from these powders. The interactions between calcining temperature, sintering temperature, and pore former content were studied to identify the conditions necessary to produce PZT billets of the desired density and grain size. Several binder systems and pressing aids were evaluated for producing uniform sintered billets with low open porosity. The development of these processes supported the powder synthesis efforts and enabled comparisons between different chem-prep routes.

  6. Comment on ``Dynamics of glass-forming liquids. XIII. Microwave heating in slow motion'' [J. Chem. Phys. 130, 194509 (2009)

    NASA Astrophysics Data System (ADS)

    Johari, G. P.

    2012-07-01

    Critical reading of the dielectric method and data in the paper [W. Huang and R. Richert, J. Chem. Phys. 130, 194509 (2009)], 10.1063/1.3139519 showed that (i) the large inter-electrode area of the Teflon spacer used in the dielectric cell affected the spectral data and (ii) the measured Δɛ of propylene carbonate after making the spacer area correction is 1.8-times the known value, indicating errors from unknown sources. This puts into question their support for the dynamic heterogeneity view, and their inference on the magnitude of configurational heat capacity.

  7. Assessment of particulate accumulation climatology under inversions in Glacier Bay for the 2008 tourist season using WRF/Chem data

    NASA Astrophysics Data System (ADS)

    Pirhalla, Michael A.

    Each summer, roughly one million tourists come to Southeast Alaska aboard cruise ships to see the pristine landscape and wildlife. Tourism is an integral component in the economy for most of the towns and villages on the Alaska Panhandle. With ship emissions only modestly regulated, there have been some concerns regarding the potential environmental impacts that cruise ships have on air quality, wildlife, and visitor experience. Cruise ships travel to remote regions, and are frequently the only anthropogenic emissions source in federally protected parks, such as Glacier Bay National Park and Preserve. In the absence of winds and synoptic scale storm systems common in the Gulf of Alaska, temperature inversions frequently develop inside Glacier Bay due to radiative cooling influenced by the complex topography inside the park. Inversions act as a lid, and may trap pollutants from cruise-ship emissions depending on the meteorological conditions present. Since meteorological observations are sparse and frequently skewed to easily accessible locations, data from the Weather Research and Forecasting Model, coupled with a chemistry package (WRF/Chem), were used to examine the physical and chemical processes that are impossible to determine through direct observations. Model simulation data for 124 days during the 2008 tourist season (May 15 to September 15), including a cruise-ship emission inventory for all 225 cruise ship entries in Glacier Bay, was analyzed. Evaluation of WRF/Chem through meteorological observations reveals that the model accurately captures the synoptic conditions for most of the summer, despite problems with complex topography. WRF/Chem simulated quasi-multi-day inversion events, with strengths as high as 6.7 K (100 m)-1. Inversions were present in all grid-cell locations in Glacier Bay, with inversions occurring on average of 42% of the days during the tourist season. WRF/Chem was able to model PM 10 (particulate matter with diameter less than 10

  8. Assessing regional scale predictions of aerosols, marine stratocumulus, and their interactions during VOCALS-REx using WRF-Chem

    SciTech Connect

    Yang, Qing; Gustafson, William I.; Fast, Jerome D.; Wang, Hailong; Easter, Richard C.; Morrison, H.; Lee, Y.- N.; Chapman, Elaine G.; Spak, S. N.; Mena-Carrasco, M. A.

    2011-12-02

    In the recent chemistry version (v3.3) of the Weather Research and Forecasting (WRF-Chem) model, we have coupled the Morrison double-moment microphysics scheme with interactive aerosols so that full two-way aerosol-cloud interactions are included in simulations. We have used this new WRF-Chem functionality in a study focused on assessing predictions of aerosols, marine stratocumulus clouds, and their interactions over the Southeast Pacific using measurements from the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) and satellite retrievals. This study also serves as a detailed analysis of our WRF-Chem simulations contributed to the VOCALS model Assessment (VOCA) project. The WRF-Chem 31-day (October 15-November 16, 2008) simulation with aerosol-cloud interactions (AERO hereafter) is also compared to a simulation (MET hereafter) with fixed cloud droplet number concentrations assumed by the default in Morrison microphysics scheme with no interactive aerosols. The well-predicted aerosol properties such as number, mass composition, and optical depth lead to significant improvements in many features of the predicted stratocumulus clouds: cloud optical properties and microphysical properties such as cloud top effective radius, cloud water path, and cloud optical thickness, and cloud macrostructure such as cloud depth and cloud base height. These improvements in addition to the aerosol direct and semi-direct effects, in turn, feed back to the prediction of boundary-layer characteristics and energy budgets. Particularly, inclusion of interactive aerosols in AERO strengths temperature and humidity gradients within capping inversion layer and lowers the MBL depth by 150 m from that of the MET simulation. Mean top-of-the-atmosphere outgoing shortwave fluxes, surface latent heat, and surface downwelling longwave fluxes are in better agreement with observations in AERO, compared to the MET simulation. Nevertheless, biases in some of the simulated

  9. Anthropogenic contribution to cloud condensation nuclei and the first aerosol indirect climate effect modelled by GEOS-Chem/APM

    NASA Astrophysics Data System (ADS)

    Yu, F.

    2013-05-01

    Atmospheric particles influence climate indirectly by acting as cloud condensation nuclei (CCN) that affect cloud properties (albedo, lifetime, etc.) and precipitation. The first aerosol indirect radiative forcing (FAIRF) (i.e., cloud albedo effect) constitutes the largest uncertainty among the various radiative forcings quantified by the latest IPCC assessment report (IPCC2007). In order to confidently interpret climate change over the past century and project future change, it is essential to reduce the FAIRF uncertainty. One of the large sources of the uncertainty is the poor knowledge of the number concentrations and spatial distributions of pre-industrial and present-day aerosols. All previous and recent FAIRF studies are based on global models with simplified chemistry and aerosol microphysics, which may lead to large uncertainties in predicted aerosol properties and FAIRF values. Here, we investigate the anthropogenic contribution to CCN and associated FAIRF using a state-of-the-art global chemical transport and aerosol model (GEOS-Chem/APM) that contains a number of advanced features (including size-resolved sectional particle microphysics, online comprehensive SOx-NOx-Ox-VOCs chemistry, consideration of nitrate and secondary organic aerosols, online aerosol-cloud-radiation calculation, usage of more accurate assimilated meteorology, etc.). As far as we know, this is the first time that a global model with full chemistry and size-resolved (sectional) particle microphysics is employed to study FAIRF. Key aerosol properties predicted by GEOS-Chem/APM for the present-day case have been evaluated against a large set of land-, ship-, aircraft-, and satellite- based aerosol measurements including total particle number concentrations, CCN concentrations, AODs, and vertical profiles of extinction coefficients. The GEOS-Chem/APM model, with its advanced features and ability to reproduce observed aerosol properties (including CCN) around the globe, is expected to

  10. Al Composites

    NASA Astrophysics Data System (ADS)

    Chandanayaka, Tharaka; Azarmi, Fardad

    2014-05-01

    In the present study, cold spraying technique was used to fabricate a metal matrix composite (MMC) that consists of Ni matrix and 20 vol.% Ni3Al particles at two different particle sizes as reinforcement. This study intends to investigate the effect of reinforcement particle size on microstructural and mechanical properties of cold sprayed MMCs. Two different Ni3Al powders with nominal particle size of -45 to +5 and +45 to 100 μm were used as reinforcement in this study. Cold sprayed Ni-Ni3Al samples were subjected to the microstructural observation and characterization prior to any mechanical testing. Then, samples were tested using nano-indentation, Knoop hardness, Vickers hardness, and Resonance frequency to evaluate their mechanical properties. No significant changes were observed in microstructural characteristics due to different particle sizes. The results obtained from a variety of mechanical testings indicated that the increasing reinforcement particle size resulted in the slight reduction of mechanical properties such as elastic modulus and hardness in cold sprayed MMCs. The mechanical interlock between deposited particles defines the bonding strength in cold sprayed samples. Small size particles have a higher velocity and impact resulting in stronger interlock between deformed particles.

  11. AL Amyloidosis

    PubMed Central

    2012-01-01

    Definition of the disease AL amyloidosis results from extra-cellular deposition of fibril-forming monoclonal immunoglobulin (Ig) light chains (LC) (most commonly of lambda isotype) usually secreted by a small plasma cell clone. Most patients have evidence of isolated monoclonal gammopathy or smoldering myeloma, and the occurrence of AL amyloidosis in patients with symptomatic multiple myeloma or other B-cell lymphoproliferative disorders is unusual. The key event in the development of AL amyloidosis is the change in the secondary or tertiary structure of an abnormal monoclonal LC, which results in instable conformation. This conformational change is responsible for abnormal folding of the LC, rich in β leaves, which assemble into monomers that stack together to form amyloid fibrils. Epidemiology AL amyloidosis is the most common type of systemic amyloidois in developed countries with an estimated incidence of 9 cases/million inhabitant/year. The average age of diagnosed patients is 65 years and less than 10% of patients are under 50. Clinical description The clinical presentation is protean, because of the wide number of tissues or organs that may be affected. The most common presenting symptoms are asthenia and dyspnoea, which are poorly specific and may account for delayed diagnosis. Renal manifestations are the most frequent, affecting two thirds of patients at presentation. They are characterized by heavy proteinuria, with nephrotic syndrome and impaired renal function in half of the patients. Heart involvement, which is present at diagnosis in more than 50% of patients, leading to restrictive cardiopathy, is the most serious complication and engages prognosis. Diagnostic methods The diagnosis relies on pathological examination of an involved site showing Congo red-positive amyloid deposits, with typical apple-green birefringence under polarized light, that stain positive with an anti-LC antibody by immunohistochemistry and/or immunofluorescence. Due to the

  12. Investigating marine stratocumulus with a fully coupled cloud-aerosol scheme in a WRF/Chem Large Eddy Simulation

    NASA Astrophysics Data System (ADS)

    Kazil, J.; Wang, H.; Feingold, G.

    2009-12-01

    Drizzle in stratocumulus clouds is triggered by low concentrations of cloud condensation nuclei (CCN), and concurrently acts as a sink of CCN. The progression of this cloud-aerosol feedback may result in a transition in marine boundary layer dynamics and cloud structure; Closed cell circulation, characterized by a solid stratocumulus layer, may transition into an open cellular mode featuring low cloud fraction. Aerosol sources may balance the loss of CCN from drizzle, and delay or prevent the emergence of open cell circulation. Such sources include particle emissions from the sea surface, entrainment of aerosol from the free troposphere into the cloud deck, advection from land sources, and aerosol nucleation. In order to investigate the role of aerosol sources and processes in the transition between these two states, we have coupled in detail aerosol processes, cloud microphysics, and gas and aqueous chemistry in the WRF/Chem model. We operate WRF/Chem in Large Eddy Simulation mode. Aerosol nucleation is described with a sulfuric acid/water scheme based on laboratory measurements of the nucleation process. Here we present first results on the role of aerosol nucleation for cloud properties and drizzle formation in pristine conditions of the South-East Pacific region, and in polluted conditions.

  13. Chem2Bio2RDF: a semantic framework for linking and data mining chemogenomic and systems chemical biology data

    PubMed Central

    2010-01-01

    Background Recently there has been an explosion of new data sources about genes, proteins, genetic variations, chemical compounds, diseases and drugs. Integration of these data sources and the identification of patterns that go across them is of critical interest. Initiatives such as Bio2RDF and LODD have tackled the problem of linking biological data and drug data respectively using RDF. Thus far, the inclusion of chemogenomic and systems chemical biology information that crosses the domains of chemistry and biology has been very limited Results We have created a single repository called Chem2Bio2RDF by aggregating data from multiple chemogenomics repositories that is cross-linked into Bio2RDF and LODD. We have also created a linked-path generation tool to facilitate SPARQL query generation, and have created extended SPARQL functions to address specific chemical/biological search needs. We demonstrate the utility of Chem2Bio2RDF in investigating polypharmacology, identification of potential multiple pathway inhibitors, and the association of pathways with adverse drug reactions. Conclusions We have created a new semantic systems chemical biology resource, and have demonstrated its potential usefulness in specific examples of polypharmacology, multiple pathway inhibition and adverse drug reaction - pathway mapping. We have also demonstrated the usefulness of extending SPARQL with cheminformatics and bioinformatics functionality. PMID:20478034

  14. The potassic sedimentary rocks in Gale Crater, Mars, as seen by ChemCam on board Curiosity

    NASA Astrophysics Data System (ADS)

    Le Deit, L.; Mangold, N.; Forni, O.; Cousin, A.; Lasue, J.; Schröder, S.; Wiens, R. C.; Sumner, D.; Fabre, C.; Stack, K. M.; Anderson, R. B.; Blaney, D.; Clegg, S.; Dromart, G.; Fisk, M.; Gasnault, O.; Grotzinger, J. P.; Gupta, S.; Lanza, N.; Le Mouélic, S.; Maurice, S.; McLennan, S. M.; Meslin, P.-Y.; Nachon, M.; Newsom, H.; Payré, V.; Rapin, W.; Rice, M.; Sautter, V.; Treiman, A. H.

    2016-05-01

    The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system. From ChemCam Laser-Induced Breakdown Spectroscopy (LIBS) chemical analyses, this suite of sedimentary rocks has an overall mean K2O abundance that is more than 5 times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations reveals that the mean K2O abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e., mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater, are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.

  15. WRF-Chem Simulations of Lightning-NOx Production and Transport in Oklahoma and Colorado Thunderstorms Observed During DC3

    NASA Technical Reports Server (NTRS)

    Cummings, Kristin A.; Pickering, Kenneth E.; Barth, M.; Bela, M.; Li, Y.; Allen, D.; Bruning, E.; MacGorman, D.; Rutledge, S.; Basarab, B.; Fuchs, B.; Pollack, I.; Ryerson, T.; Carey, L.; Flocke, F.; Campos, T.; Weinheimer, A.; Diskin, G.

    2016-01-01

    The focus of this analysis is on lightning-generated nitrogen oxides (LNOx) and their distribution for two thunderstorms observed during the Deep Convective Clouds and Chemistry (DC3) field campaign in May-June 2012. The Weather Research and Forecasting Chemistry (WRF-Chem) model is used to perform cloud-resolved simulations for the May 29-30 Oklahoma severe convection, which contained one supercell, and the June 6-7 Colorado squall line. Aircraft and ground-based observations (e.g., trace gases, lightning and radar) collected during DC3 are used in comparisons against the model-simulated lightning flashes generated by the flash rate parameterization schemes (FRPSs) incorporated into the model, as well as the model-simulated LNOx predicted in the anvil outflow. Newly generated FRPSs based on DC3 radar observations and Lightning Mapping Array data are implemented in the model, along with previously developed schemes from the literature. The results of these analyses will also be compared between storms to investigate which FRPSs were most appropriate for the two types of convection and to examine the variation in the LNOx production. The simulated LNOx results from WRF-Chem will also be compared against other previously studied mid-latitude thunderstorms.

  16. Implementation and evaluation of online gas-phase chemistry within a regional climate model (RegCM-CHEM4)

    SciTech Connect

    Shalaby, A. K.; Zakey, A. S.; Tawfik, A. B.; Solmon, F.; Giorgi, Filippo; Stordal, F.; Sillman, S.; Zaveri, Rahul A.; Steiner, A. L.

    2012-05-22

    The RegCM-CHEM4 is a new online climate-chemistry model based on the International Centre for Theoretical Physics (ICTP) regional climate model (RegCM4). Tropospheric gas-phase chemistry is integrated into the climate model using the condensed version of the Carbon Bond Mechanism (CBM-Z; Zaveri and Peters, 1999) with a fast solver based on radical balances. We evaluate the model over Continental Europe for two different time scales: (1) an event-based analysis of the ozone episode associated with the heat wave of August 2003 and (2) a climatological analysis of a sixyear simulation (2000-2005). For the episode analysis, model simulations show good agreement with European Monitoring and Evaluation Program (EMEP) observations of hourly ozone over different regions in Europe and capture ozone concentrations during and after the August 2003 heat wave event. For long-term climate simulations, the model captures the seasonal cycle of ozone concentrations with some over prediction of ozone concentrations in non-heat wave summers. Overall, the ozone and ozone precursor evaluation shows the feasibility of using RegCM-CHEM4 for decadal-length simulations of chemistry-climate interactions.

  17. Evaluation of lightning-induced tropospheric ozone enhancements observed by ozone lidar and simulated by WRF/Chem

    NASA Astrophysics Data System (ADS)

    Wang, Lihua; Follette-Cook, Melanie B.; Newchurch, M. J.; Pickering, Kenneth E.; Pour-Biazar, Arastoo; Kuang, Shi; Koshak, William; Peterson, Harold

    2015-08-01

    High spatial- and temporal-resolution ozone lidar profiles, in conjunction with ozonesonde and satellite observations, are well suited to characterize short-term ozone variations due to different physical and chemical processes, such as the impact of lightning-generated NOx (LNOx) on tropospheric ozone. This work presents the hourly variation of tropospheric-ozone profiles measured by an ozone lidar at the University of Alabama in Huntsville, on July 14, 18, and 27, 2011. These ozone lidar data are compared with two WRF/Chem simulations, one with lightning NO (LNO) emissions and the other without. On July 14, 2011, the ozone lidar observed an ozone laminar structure with elevated ozone concentrations of 65∼80 ppbv below 2 km, low ozone (50∼65) ppbv between 2 and 5 km, and high ozone up to 165 ppbv between 5 and 12 km AGL. WRF/Chem simulations, in conjunction with backward trajectory analysis, suggest that lightning events occurring within upwind regions resulted in an ozone enhancement of 28 ppbv at 7.5 km AGL over Huntsville. On July 27, LNO emissions were transported to Huntsville from upwind and account for 75% of NOx and an 8.3 ppbv of ozone enhancement at ∼10 km; the model overestimates ozone between 2.5 and 5 km AGL.

  18. eL-Chem Viewer: A Freeware Package for the Analysis of Electroanalytical Data and Their Post-Acquisition Processing

    PubMed Central

    Hrbac, Jan; Halouzka, Vladimir; Trnkova, Libuse; Vacek, Jan

    2014-01-01

    In electrochemical sensing, a number of voltammetric or amperometric curves are obtained which are subsequently processed, typically by evaluating peak currents and peak potentials or wave heights and half-wave potentials, frequently after background correction. Transformations of voltammetric data can help to extract specific information, e.g., the number of transferred electrons, and can reveal aspects of the studied electrochemical system, e.g., the contribution of adsorption phenomena. In this communication, we introduce a LabView-based software package, ‘eL-Chem Viewer’, which is for the analysis of voltammetric and amperometric data, and enables their post-acquisition processing using semiderivative, semiintegral, derivative, integral and elimination procedures. The software supports the single-click transfer of peak/wave current and potential data to spreadsheet software, a feature that greatly improves productivity when constructing calibration curves, trumpet plots and performing similar tasks. eL-Chem Viewer is freeware and can be downloaded from www.lchem.cz/elchemviewer.htm. PMID:25090415

  19. Reduction and scientific analysis of data from the charge-energy-mass (CHEM) spectrometer on the AMPTE/CCE spacecraft

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.; Hamilton, D. C.; Ipavich, F. M.

    1987-01-01

    The Charge-Energy-Mass (CHEM) spectrometer instrument on the AMPTE/Charge Composition Explorer (CCE) spacecraft is designed to measure the mass and charge-state abundance of magnetospheric and magnetosheath ions between 0.3 and 315 keV/e, an energy range that includes the bulk of the ring current and the dynamically important portion of the plasma sheet population. Continuing research is being conducted using the AMPTE mission data set, and in particular, that of the CHEM spectrometer which has operated flawlessly since launch and still provides excellent quality data. The requirted routine data processing and reduction, and software develpment continues to be performed. Scientific analysis of composition data in a number of magnetospheric regions including the ring current region, near-earth plasma sheet and subsolar magnetosheath continues to be undertaken. Correlative studies using data from the sister instrument SULEICA, which determines the mass and charge states of ions in the energy range of approximately 10 to 250 keV/e on the IRM, as well as other data from the CCE and IRM spacecraft, particularly in the upstream region and plasma sheet have also been undertaken.

  20. Gaseous Chemistry and Aerosol Mechanism Developments for Version 3.5.1 of the Online Regional Model, WRF-Chem

    SciTech Connect

    Archer-Nicholls, Scott; Lowe, Douglas; Utembe, Steve; Allan, James D.; Zaveri, Rahul A.; Fast, Jerome D.; Hodnebrog, Oivind; H. Denier van der Gon; McFiggans, Gordon

    2014-11-08

    We have made a number of developments in the regional coupled model WRF-Chem, with the aim of making the model more suitable for prediction of atmospheric composition and of interactions between air quality and weather. We have worked on the European domain, with a particular focus on making the model suitable for the study of night time chemistry and oxidation by the nitrate radical in the UK atmosphere. A reduced form of the Common Reactive Intermediates gas-phase chemical mechanism (CRIv2-R5) has been implemented to enable more explicit simulation of VOC degradation. N2O5 heterogeneous chemistry has been added to the existing sectional MOSAIC aerosol module, and coupled to both the CRIv2-R5 and existing CBM-Z gas phase scheme. Modifications have also been made to the sea-spray aerosol emission representation, allowing the inclusion of primary organic material in sea-spray aerosol. Driven by appropriate emissions, wind fields and chemical boundary conditions, implementation of the different developments is illustrated in order to demonstrate the impact that these changes have in the North-West European domain. These developments are now part of the freely available WRF-Chem distribution.

  1. Incorporation of new particle formation and early growth treatments into WRF/Chem: Model improvement, evaluation, and impacts of anthropogenic aerosols over East Asia

    NASA Astrophysics Data System (ADS)

    Cai, Changjie; Zhang, Xin; Wang, Kai; Zhang, Yang; Wang, Litao; Zhang, Qiang; Duan, Fengkui; He, Kebin; Yu, Shao-Cai

    2016-01-01

    New particle formation (NPF) provides an important source of aerosol particles and cloud condensation nuclei, which may result in enhanced cloud droplet number concentration (CDNC) and cloud shortwave albedo. In this work, several nucleation parameterizations and one particle early growth parameterization are implemented into the online-coupled Weather Research and Forecasting model coupled with chemistry (WRF/Chem) to improve the model's capability in simulating NPF and early growth of ultrafine particles over East Asia. The default 8-bin over the size range of 39 nm-10 μm used in the Model for Simulating Aerosol Interactions and Chemistry aerosol module is expanded to the 12-bin over 1 nm-10 μm to explicitly track the formation and evolution of new particles. Although model biases remain in simulating H2SO4, condensation sink, growth rate, and formation rate, the evaluation of July 2008 simulation identifies a combination of three nucleation parameterizations (i.e., COMB) that can best represent the atmospheric nucleation processes in terms of both surface nucleation events and the resulting vertical distribution of ultrafine particle concentrations. COMB consists of a power law of Wang et al. (2011) based on activation theory for urban areas in planetary boundary layer (PBL), a power law of Boy et al. (2008) based on activation theory for non-urban areas in PBL, and the ion-mediated nucleation parameterization of YU10 for above PBL. The application and evaluation of the improved model with 12-bin and the COMB nucleation parameterization in East Asia during January, April, July, and October in 2001 show that the model has an overall reasonably good skill in reproducing most observed meteorological variables and surface and column chemical concentrations. Relatively large biases in simulated precipitation and wind speeds are due to inaccurate surface roughness and limitations in model treatments of cloud formation and aerosol-cloud-precipitation interactions

  2. ChemSkill Builder 2000, Version 6.1 [CD-ROM] (by James D. Spain and Harold J. Peters)

    NASA Astrophysics Data System (ADS)

    Keeney-Kennicutt, Reviewed By Wendy L.

    2000-07-01

    One of the major challenges for faculty teaching general chemistry is how to encourage students to practice solving problems. We know that for students to develop chemical intuition and problem-solving skills, they must "get their hands dirty" as they decipher and unravel problems inherent to our discipline. One tool that I've used since its release in 1996 is the ChemSkill Builder, an electronic homework package. The latest version, ChemSkill Builder (CSB) 2000, version 6.1, is an excellent, effective integration of teaching and testing most quantitative and conceptual learning objectives in an interactive way. It is inexpensive and easy to use for both students and faculty. The CSB 2000 package of personalized problem sets, specifically designed to complement most general chemistry courses, is a program on CD-ROM for PC Windows users (3.1, 95, or 98), with more than 1500 questions and a 3 1/2-in. record-management disk. There is a separate grade-management disk for the instructor. It has 24 gradable chapters, each with 5 or 6 sections, plus two new chapters that are not graded: Polymer Chemistry and an Appendix of Chemical Skills. Each section begins with a short review of the topic and many have interactive explanations. If students miss an answer, they are given a second chance for 70% credit. If they still miss, the worked-out solution is presented in detail. Students can work each section as many times as they wish to improve their scores. Periodically, the students download their data directly into a PC set up by the instructor. The data can be easily converted into an ASCII file and merged with a spreadsheet. The use of CD-ROM solves the sporadic problems associated with previous versions on 3 1/2-in. disks: software glitches, failed disks, and system incompatibilities. The quality and number of graphics and interactive exercises are much improved in this latest version. I particularly enjoyed the interactive explanations of significant figures and

  3. Top-Down Inversion of Aerosol Emissions through Adjoint Integration of Satellite Radiance and GEOS-Chem Chemical Transport Model

    NASA Astrophysics Data System (ADS)

    Xu, X.; Wang, J.; Henze, D. K.; Qu, W.; Kopacz, M.

    2012-12-01

    The knowledge of aerosol emissions from both natural and anthropogenic sources are needed to study the impacts of tropospheric aerosol on atmospheric composition, climate, and human health, but large uncertainties persist in quantifying the aerosol sources with the current bottom-up methods. This study presents a new top-down approach that spatially constrains the amount of aerosol emissions from satellite (MODIS) observed reflectance with the adjoint of a chemistry transport model (GEOS-Chem). We apply this technique with a one-month case study (April 2008) over the East Asia. The bottom-up estimated sulfate-nitrate-ammonium precursors, such as sulfur dioxide (SO2), ammonia (NH3), and nitrogen oxides (NOx), all from INTEX-B 2006 inventory, emissions of black carbon (BC), organic carbon (OC) from Bond-2007 inventory, and mineral dust simulated from DEAD dust mobilization scheme, are spatially optimized from the GEOS-Chem model and its adjoint constrained by the aerosol optical depth (AOD) that are derived from MODIS reflectance with the GEOS-Chem aerosol single scattering properties. The adjoint inverse modeling for the study period yields notable decreases in anthropogenic aerosol emissions over China: 436 Gg (33.5%) for SO2, 378 Gg (34.5%) for NH3, 319 (18.8%) for NOx, 10 Gg (9.1%) for BC, and 30 Gg (15.0%) for OC. The total amount of the mineral dust emission is reduced by 56.4% from the DEAD mobilization module which simulates dust production of 19020 Gg. Sub-regional adjustments are significant and directions of changes are spatially different. The model simulation with optimized aerosol emissions shows much better agreement with independent observations from sun-spectrophotometer observed AOD from AERONET, MISR (Multi-angle Imaging SpectroRadiometer) AOD, OMI (Ozone Monitoring Instrument) NO2 and SO2 columns, and surface aerosol concentrations measured over both anthropogenic pollution and dust source regions. Assuming the used bottom-up anthropogenic

  4. DayCent-Chem Simulations of Ecological and Biogeochemical Processes of Eight Mountain Ecosystems in the United States

    USGS Publications Warehouse

    Hartman, Melannie D.; Baron, Jill S.; Clow, David W.; Creed, Irena F.; Driscoll, Charles T.; Ewing, Holly A.; Haines, Bruce D.; Knoepp, Jennifer; Lajtha, Kate; Ojima, Dennis S.; Parton, William J.; Renfro, Jim; Robinson, R. Bruce; Van Miegroet, Helga; Weathers, Kathleen C.; Williams, Mark W.

    2009-01-01

    Atmospheric deposition of nitrogen (N) and sulfur (S) cause complex responses in ecosystems, from fertilization to forest ecosystem decline, freshwater eutrophication to acidification, loss of soil base cations, and alterations of disturbance regimes. DayCent-Chem, an ecosystem simulation model that combines ecosystem nutrient cycling and plant dynamics with aqueous geochemical equilibrium calculations, was developed to address ecosystem responses to combined atmospheric N and S deposition. It is unique among geochemically-based models in its dynamic biological cycling of N and its daily timestep for investigating ecosystem and surface water chemical response to episodic events. The model was applied to eight mountainous watersheds in the United States. The sites represent a gradient of N deposition across locales, from relatively pristine to N-saturated, and a variety of ecosystem types and climates. Overall, the model performed best in predicting stream chemistry for snowmelt-dominated sites. It was more difficult to predict daily stream chemistry for watersheds with deep soils, high amounts of atmospheric deposition, and a large degree of spatial heterogeneity. DayCent-Chem did well in representing plant and soil carbon and nitrogen pools and fluxes. Modeled stream nitrate (NO3-) and ammonium (NH4+) concentrations compared well with measurements at all sites, with few exceptions. Simulated daily stream sulfate (SO42-) concentrations compared well to measured values for sites where SO42- deposition has been low and where SO42- adsorption/desorption reactions did not seem to be important. The concentrations of base cations and silica in streams are highly dependent on the geochemistry and weathering rates of minerals in each catchment, yet these were rarely, if ever, known. Thus, DayCent-Chem could not accurately predict weathering products for some catchments. Additionally, few data were available for exchangeable soil cations or the magnitude of base cation

  5. Site sampling and treatability studies for demonstration of WasteChem's asphalt encapsulation technology under EPA's SITE program

    SciTech Connect

    Hubbard, J.; Tsadwa, S.; Wills, N.; Evans, M.

    1990-10-01

    This paper presents a sampling approach that was used to determine whether there were adequate quantities and concentrations of wastes at the Woodland Township Route 532 Site for demonstration of the asphalt encapsulation technology. This paper also presents the result of a bench-scale treatability study on wastes from this site. The preliminary sampling and analysis confirmed most of the types of organic and inorganic contaminants found at the Woodland Township Route 532 site during the remedial investigation (RI). However, the contamination levels varied over relatively short distances across the site from some contaminants. The bench-scale treatability study indicated that, when compared with concentrations in the untreated waste, WasteChem's asphalt encapsulation technology reduced semivolatile organic compound concentrations in the toxicity characteristic leaching procedure extracts of treated wastes. The study also indicated that metals concentrations in the TCLP extracts were lower in the treated wastes than the untreated wastes in some samples and higher in others.

  6. Representation of the Bi-modal Distribution of Free Tropospheric Ozone Over the Tropical Western Pacific in CAM-CHEM

    NASA Astrophysics Data System (ADS)

    Honomichl, S.; Kinnison, D. E.; Lamarque, J. F.; Saiz-Lopez, A.; Randel, W. J.; Pan, L.

    2015-12-01

    During the CONTRAST field study, in situ aircraft observations revealed a distinct bi-modal distribution of ozone mixing ratios formed by persistent layers of enhanced of ozone relative to background concentrations in the Western Tropical Pacific middle troposphere during the Northern Hemispheric winter. These enhancements may have a measureable impact on the troposphere's oxidizing capacity in the tropics, which has a direct effect on the regional climate of the western tropical Pacific Ocean and beyond. In this work, we examine the representation of the bi-modal ozone characteristics in the NCAR chemistry-climate model (CAM-CHEM). We also investigate the controlling mechanisms of the bi-modal ozone distribution combining the model and aircraft observations.

  7. Modelling of Impulsional pH Variations Using ChemFET-Based Microdevices: Application to Hydrogen Peroxide Detection

    PubMed Central

    Diallo, Abdou Karim; Djeghlaf, Lyes; Launay, Jerome; Temple-Boyer, Pierre

    2014-01-01

    This work presents the modelling of impulsional pH variations in microvolume related to water-based electrolysis and hydrogen peroxide electrochemical oxidation using an Electrochemical Field Effect Transistor (ElecFET) microdevice. This ElecFET device consists of a pH-Chemical FET (pH-ChemFET) with an integrated microelectrode around the dielectric gate area in order to trigger electrochemical reactions. Combining oxidation/reduction reactions on the microelectrode, water self-ionization and diffusion properties of associated chemical species, the model shows that the sensor response depends on the main influential parameters such as: (i) polarization parameters on the microelectrode, i.e., voltage (Vp) and time (tp); (ii) distance between the gate sensitive area and the microelectrode (d); and (iii) hydrogen peroxide concentration ([H2O2]). The model developed can predict the ElecFET response behaviour and creates new opportunities for H2O2-based enzymatic detection of biomolecules. PMID:24556666

  8. Volcanic ash transport integrated in the WRF-Chem model: a description of the application and verification results from the 2010 Eyjafjallajökull eruption.

    NASA Astrophysics Data System (ADS)

    Stuefer, Martin; Webley, Peter; Grell, Georg; Freitas, Saulo; Kim, Chang Ki; Egan, Sean

    2013-04-01

    Regional volcanic ash dispersion models are usually offline decoupled from the numerical weather prediction model. Here we describe a new functionality using an integrated modeling system that allows simulating emission, transport, and sedimentation of pollutants released during volcanic activities. A volcanic preprocessor tool has been developed to initialize the Weather Research Forecasting model with coupled Chemistry (WRF-Chem) with volcanic ash and sulphur dioxide emissions. Volcanic ash variables were added into WRF-Chem, and the model was applied to study the 2010 eruption of Eyjafjallajökull. We evaluate our results using WRF-Chem with available ash detection data from satellite and airborne sensors, and from ground based Lidar measurements made available through the AeroCom project. The volcanic ash was distributed into 10 different bins according to the particle size ranging from 2 mm to less than 3.9 μm; different particle size distributions derived from historic eruptions were tested. An umbrella shaped initial ash cloud and an empirical relationship between mass eruption rates and eruption heights were used to initialize WRF-Chem. We show WRF-Chem model verification for the Eyjafjallajökull eruptions, which occurred during the months of April and May 2010. The volcanic ash plume dispersed extensively over Europe. Comparisons with satellite remote sensing volcanic ash retrievals showed good agreement during the events, also ground-based LIDAR compared well to the model simulations. The model sensitivity analysis of the Eyjafjallajökull event showed a considerable bias of ass mass concentrations afar from the volcano depending on initial ash size and eruption rate assumptions. However the WRF-Chem model initialized with reliable eruption source parameters produced good quality forecasts, and will be tested for operational volcanic ash transport predictions.

  9. Evaluation of UTLS carbon monoxide simulations in GMI and GEOS-Chem chemical transport models using Aura MLS observations

    NASA Astrophysics Data System (ADS)

    Huang, Lei; Jiang, Jonathan H.; Murray, Lee T.; Damon, Megan R.; Su, Hui; Livesey, Nathaniel J.

    2016-05-01

    This study evaluates the distribution and variation of carbon monoxide (CO) in the upper troposphere and lower stratosphere (UTLS) during 2004-2012 as simulated by two chemical transport models, using the latest version of Aura Microwave Limb Sounder (MLS) observations. The simulated spatial distributions, temporal variations and vertical transport of CO in the UTLS region are compared with those observed by MLS. We also investigate the impact of surface emissions and deep convection on CO concentrations in the UTLS over different regions, using both model simulations and MLS observations. Global Modeling Initiative (GMI) and GEOS-Chem simulations of UTLS CO both show similar spatial distributions to observations. The global mean CO values simulated by both models agree with MLS observations at 215 and 147 hPa, but are significantly underestimated by more than 40 % at 100 hPa. In addition, the models underestimate the peak CO values by up to 70 % at 100 hPa, 60 % at 147 hPa and 40 % at 215 hPa, with GEOS-Chem generally simulating more CO at 100 hPa and less CO at 215 hPa than GMI. The seasonal distributions of CO simulated by both models are in better agreement with MLS in the Southern Hemisphere (SH) than in the Northern Hemisphere (NH), with disagreements between model and observations over enhanced CO regions such as southern Africa. The simulated vertical transport of CO shows better agreement with MLS in the tropics and the SH subtropics than the NH subtropics. We also examine regional variations in the relationships among surface CO emission, convection and UTLS CO concentrations. The two models exhibit emission-convection-CO relationships similar to those observed by MLS over the tropics and some regions with enhanced UTLS CO.

  10. The ChemCam Remote Micro-Imager on MSL: Observations From the First Year on Mars

    NASA Astrophysics Data System (ADS)

    Le Mouelic, S.; Gasnault, O.; Bridges, N. T.; Herkenhoff, K. E.; Langevin, Y.; Pinet, P. C.; Maurice, S.; Wiens, R. C.; Mangold, N.; Johnson, J. R.; Bell, J. F.; Blaney, D. L.; Barraclough, B. L.

    2013-12-01

    The Remote Microscopic Imager (RMI) portion of the ChemCam instrument on the Mars Science Laboratory 'Curiosity' rover acquires panchromatic images with a 1024x1024 pixel CCD. The main objective of the RMI is to provide geomorphologic context of the ChemCam Laser Induced Breakdown Spectroscopy (LIBS) analyses, locate the laser pits, and document the changes induced by the laser shots on the targets. Thanks to its very narrow pixel angular size of 20 microrad, RMI by itself adds a significant scientific value to the study of soils and rocks by revealing their fine texture and morphology, and can also occasionally serve as a reconnaissance tool for distant targets as the rover drives along. During the first year of operations on Mars, the RMI has been used in a variety of situations, providing more than 1000 images of rover hardware, soils and rock targets located at distances ranging from 1.2 meters up to several kilometers from the camera. Several types of products have been derived from these raw data. These include mosaics of images taken before and after the LIBS shots, difference images to identify the most subtle laser pits on hard rocks, merges with the color information acquired by the Mastcam cameras, and micro-topographic information from focal sections, also known as the z-stack technique. Further applications are also under investigation, such as night sky imaging or stereogrammetry using RMI and Mastcam 100 images. The RMI has the highest spatial resolution of the cameras on MSL's remote sensing mast, and is therefore very useful, along with Curiosity's other imaging instruments, in deciphering the history of rocks and soils at Gale crater.

  11. Representation of the Community Earth System Model (CESM1) CAM4-chem within the Chemistry-Climate Model Initiative (CCMI)

    DOE PAGESBeta

    Tilmes, Simone; Lamarque, Jean -Francois; Emmons, Louisa K.; Kinnison, Doug E.; Marsh, Dan; Garcia, Rolando R.; Smith, Anne K.; Neely, Ryan R.; Conley, Andrew; Vitt, Francis; et al

    2016-05-20

    The Community Earth System Model (CESM1) CAM4-chem has been used to perform the Chemistry Climate Model Initiative (CCMI) reference and sensitivity simulations. In this model, the Community Atmospheric Model version 4 (CAM4) is fully coupled to tropospheric and stratospheric chemistry. Details and specifics of each configuration, including new developments and improvements are described. CESM1 CAM4-chem is a low-top model that reaches up to approximately 40 km and uses a horizontal resolution of 1.9° latitude and 2.5° longitude. For the specified dynamics experiments, the model is nudged to Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis. We summarize the performance ofmore » the three reference simulations suggested by CCMI, with a focus on the last 15 years of the simulation when most observations are available. Comparisons with selected data sets are employed to demonstrate the general performance of the model. We highlight new data sets that are suited for multi-model evaluation studies. Most important improvements of the model are the treatment of stratospheric aerosols and the corresponding adjustments for radiation and optics, the updated chemistry scheme including improved polar chemistry and stratospheric dynamics and improved dry deposition rates. These updates lead to a very good representation of tropospheric ozone within 20 % of values from available observations for most regions. In particular, the trend and magnitude of surface ozone is much improved compared to earlier versions of the model. Furthermore, stratospheric column ozone of the Southern Hemisphere in winter and spring is reasonably well represented. In conclusion, all experiments still underestimate CO most significantly in Northern Hemisphere spring and show a significant underestimation of hydrocarbons based on surface observations.« less

  12. Representation of the Community Earth System Model (CESM1) CAM4-chem within the Chemistry-Climate Model Initiative (CCMI)

    NASA Astrophysics Data System (ADS)

    Tilmes, Simone; Lamarque, Jean-Francois; Emmons, Louisa K.; Kinnison, Doug E.; Marsh, Dan; Garcia, Rolando R.; Smith, Anne K.; Neely, Ryan R.; Conley, Andrew; Vitt, Francis; Martin, Maria Val; Tanimoto, Hiroshi; Simpson, Isobel; Blake, Don R.; Blake, Nicola

    2016-05-01

    The Community Earth System Model (CESM1) CAM4-chem has been used to perform the Chemistry Climate Model Initiative (CCMI) reference and sensitivity simulations. In this model, the Community Atmospheric Model version 4 (CAM4) is fully coupled to tropospheric and stratospheric chemistry. Details and specifics of each configuration, including new developments and improvements are described. CESM1 CAM4-chem is a low-top model that reaches up to approximately 40 km and uses a horizontal resolution of 1.9° latitude and 2.5° longitude. For the specified dynamics experiments, the model is nudged to Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis. We summarize the performance of the three reference simulations suggested by CCMI, with a focus on the last 15 years of the simulation when most observations are available. Comparisons with selected data sets are employed to demonstrate the general performance of the model. We highlight new data sets that are suited for multi-model evaluation studies. Most important improvements of the model are the treatment of stratospheric aerosols and the corresponding adjustments for radiation and optics, the updated chemistry scheme including improved polar chemistry and stratospheric dynamics and improved dry deposition rates. These updates lead to a very good representation of tropospheric ozone within 20 % of values from available observations for most regions. In particular, the trend and magnitude of surface ozone is much improved compared to earlier versions of the model. Furthermore, stratospheric column ozone of the Southern Hemisphere in winter and spring is reasonably well represented. All experiments still underestimate CO most significantly in Northern Hemisphere spring and show a significant underestimation of hydrocarbons based on surface observations.

  13. Towards a Comprehensive Dynamic-chemistry Assimilation for Eos-Chem: Plans and Status in NASA's Data Assimilation Office

    NASA Technical Reports Server (NTRS)

    Pawson, Steven; Lin, Shian-Jiann; Rood, Richard B.; Stajner, Ivanka; Nebuda, Sharon; Nielsen, J. Eric; Douglass, Anne R.

    2000-01-01

    In order to support the EOS-Chem project, a comprehensive assimilation package for the coupled chemical-dynamical system is being developed by the Data Assimilation Office at NASA GSFC. This involves development of a coupled chemistry/meteorology model and of data assimilation techniques for trace species and meteorology. The model is being developed using the flux-form semi-Lagrangian dynamical core of Lin and Rood, the physical parameterizations from the NCAR Community Climate Model, and atmospheric chemistry modules from the Atmospheric Chemistry and Dynamics branch at NASA GSFC. To date the following results have been obtained: (i) multi-annual simulations with the dynamics-radiation model show the credibility of the package for atmospheric simulations; (ii) initial simulations including a limited number of middle atmospheric trace gases reveal the realistic nature of transport mechanisms, although there is still a need for some improvements. Samples of these results will be shown. A meteorological assimilation system is currently being constructed using the model; this will form the basis for the proposed meteorological/chemical assimilation package. The latter part of the presentation will focus on areas targeted for development in the near and far terms, with the objective of Providing a comprehensive assimilation package for the EOS-Chem science experiment. The first stage will target ozone assimilation. The plans also encompass a reanalysis (ReSTS) for the 1991-1995 period, which includes the Mt. Pinatubo eruption and the time when a large number of UARS observations were available. One of the most challenging aspects of future developments will be to couple theoretical advances in tracer assimilation with the practical considerations of a real environment and eventually a near-real-time assimilation system.

  14. The anthropogenic contribution to atmospheric black carbon concentrations in southern Africa: a WRF-Chem modeling study

    NASA Astrophysics Data System (ADS)

    Kuik, F.; Lauer, A.; Beukes, J. P.; Van Zyl, P. G.; Josipovic, M.; Vakkari, V.; Laakso, L.; Feig, G. T.

    2015-08-01

    South Africa has one of the largest industrialized economies in Africa. Emissions of air pollutants are particularly high in the Johannesburg-Pretoria metropolitan area, the Mpumalanga Highveld and the Vaal Triangle, resulting in local air pollution. This study presents and evaluates a setup for conducting modeling experiments over southern Africa with the Weather Research and Forecasting model including chemistry and aerosols (WRF-Chem), and analyzes the contribution of anthropogenic emissions to the total black carbon (BC) concentrations from September to December 2010. The modeled BC concentrations are compared with measurements obtained at the Welgegund station situated ca. 100 km southwest of Johannesburg. An evaluation of WRF-Chem with observational data from ground-based measurement stations, radiosondes, and satellites shows that the meteorology is modeled mostly reasonably well, but precipitation amounts are widely overestimated and the onset of the wet season is modeled approximately 1 month too early in 2010. Modeled daily mean BC concentrations show a temporal correlation of 0.66 with measurements, but the total BC concentration is underestimated in the model by up to 50 %. Sensitivity studies with anthropogenic emissions of BC and co-emitted species turned off show that anthropogenic sources can contribute up to 100 % to BC concentrations in the industrialized and urban areas, and anthropogenic BC and co-emitted species together can contribute up to 60 % to PM1 levels. Particularly the co-emitted species contribute significantly to the aerosol optical depth (AOD). Furthermore, in areas of large-scale biomass-burning atmospheric heating rates are increased through absorption by BC up to an altitude of about 600hPa.

  15. Evaluation of UTLS Carbon Monoxide Simulations in GMI and GEOS-Chem Chemical Transport Models using Aura MLS Observations

    NASA Technical Reports Server (NTRS)

    Huang, Lei; Jiang, Jonathan H.; Murray, Lee T.; Damon, Megan R.; Su, Hui; Livesey, Nathaniel J.

    2016-01-01

    This study evaluates the distribution and variation of carbon monoxide (CO) in the upper troposphere and lower stratosphere (UTLS) during 2004-2012 as simulated by two chemical transport models, using the latest version of Aura Microwave Limb Sounder (MLS) observations. The simulated spatial distributions, temporal variations and vertical transport of CO in the UTLS region are compared with those observed by MLS. We also investigate the impact of surface emissions and deep convection on CO concentrations in the UTLS over different regions, using both model simulations and MLS observations. Global Modeling Initiative (GMI) and GEOS-Chem simulations of UTLS CO both show similar spatial distributions to observations. The global mean CO values simulated by both models agree with MLS observations at 215 and 147 hPa, but are significantly underestimated by more than 40% at 100 hPa. In addition, the models underestimate the peak CO values by up to 70% at 100 hPa, 60% at 147 hPa and 40% at 215 hPa, with GEOS-Chem generally simulating more CO at 100 hPa and less CO at 215 hPa than GMI. The seasonal distributions of CO simulated by both models are in better agreement with MLS in the Southern Hemisphere (SH) than in the Northern Hemisphere (NH), with disagreements between model and observations over enhanced CO regions such as southern Africa. The simulated vertical transport of CO shows better agreement with MLS in the tropics and the SH subtropics than the NH subtropics. We also examine regional variations in the relationships among surface CO emission, convection and UTLS CO concentrations. The two models exhibit emission-convection- CO relationships similar to those observed by MLS over the tropics and some regions with enhanced UTLS CO.

  16. Representation of the Community Earth System Model (CESM1) CAM4-chem within the Chemistry-Climate Model Initiative (CCMI)

    SciTech Connect

    Tilmes, Simone; Lamarque, Jean-Francois; Emmons, Louisa K.; Kinnison, Doug E.; Marsh, Dan; Garcia, Rolando R.; Smith, Anne K.; Neely, Ryan R.; Conley, Andrew; Vitt, Francis; Val Martin, Maria; Tanimoto, Hiroshi; Simpson, Isobel; Blake, Don R.; Blake, Nicola

    2016-01-01

    The Community Earth System Model (CESM1) CAM4-chem has been used to perform the Chemistry Climate Model Initiative (CCMI) reference and sensitivity simulations. In this model, the Community Atmospheric Model version 4 (CAM4) is fully coupled to tropospheric and stratospheric chemistry. Details and specifics of each configuration, including new developments and improvements are described. CESM1 CAM4-chem is a low-top model that reaches up to approximately 40 km and uses a horizontal resolution of 1.9° latitude and 2.5° longitude. For the specified dynamics experiments, the model is nudged to Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis. We summarize the performance of the three reference simulations suggested by CCMI, with a focus on the last 15 years of the simulation when most observations are available. Comparisons with selected data sets are employed to demonstrate the general performance of the model. We highlight new data sets that are suited for multi-model evaluation studies. Most important improvements of the model are the treatment of stratospheric aerosols and the corresponding adjustments for radiation and optics, the updated chemistry scheme including improved polar chemistry and stratospheric dynamics and improved dry deposition rates. These updates lead to a very good representation of tropospheric ozone within 20 % of values from available observations for most regions. In particular, the trend and magnitude of surface ozone is much improved compared to earlier versions of the model. Furthermore, stratospheric column ozone of the Southern Hemisphere in winter and spring is reasonably well represented. All experiments still underestimate CO most significantly in Northern Hemisphere spring and show a significant underestimation of hydrocarbons based on surface observations.

  17. Modeling Gas-phase Glyoxal and Associated Secondary Organic Aerosol Formation in a Megacity using WRF/Chem

    NASA Astrophysics Data System (ADS)

    Wang, K.; Hodzic, A.; Barth, M. C.; Jimenez, J. L.; Volkamer, R.; Ervens, B.; Zhang, Y.

    2011-12-01

    Organic aerosol (OA) as one of a major fine particulate matter in the atmosphere plays an important role in air pollution, human health, and climate forcing. OA is composed of directly emitted primary organic aerosol and chemically produced secondary organic aerosols (SOA). Despite much recent progress in understanding SOA formation, current air quality models cannot explain the magnitude and growth of atmospheric SOA, due to high uncertainties in sources, properties, and chemical reactions of precursors and formation pathways of SOA. Recent laboratory and modeling studies showed that glyoxal may serve as an important SOA precursor in the condensed solution of inorganic or organic aerosol particles (e.g., ammonium sulfate, fulvic acid, and amino acids). In this study, the Weather Research and Forecasting model with chemistry (WRF/Chem) is modified to account for the latest observed gas-phase yields of glyoxal from various volatile organic compounds (VOCs) and the associated SOA formation in the aqueous aerosol phase. The SOA formation in the aqueous aerosol phase is implemented using two approaches. In the first approach, two simplified parameterizations are used to represent the lumped particle-phase chemical processes under dark conditions and photochemical surface uptake. In the second approach, more detailed kinetic glyoxal reactions such as reversible glyoxal uptake, dimer formation of glyoxal, and oligomerization are treated and resolved explicitly. The updated WRF/Chem is assessed over the Mexico City and the surrounding region during March 2006 using the MILAGRO campaign data. Various observations such as organic matter from Aerodyne Aerosol Mass Spectrometer and VOCs from Proton-transfer Ion Trap Mass Spectrometry were compared. The preliminary results showed that the addition of the SOA formation from glyoxal in aqueous particles brings SOA predictions into a better agreement with field observations, in particular in presence of high relative humidity

  18. Examining natural rock varnish and weathering rinds with laser-induced breakdown spectroscopy for application to ChemCam on Mars.

    PubMed

    Lanza, Nina L; Clegg, Samuel M; Wiens, Roger C; McInroy, Rhonda E; Newsom, Horton E; Deans, Matthew D

    2012-03-01

    A laser-induced breakdown spectroscopy (LIBS) instrument is traveling to Mars as part of ChemCam on the Mars Science Laboratory rover. Martian rocks have weathered exteriors that obscure their bulk compositions. We examine weathered rocks with LIBS in a martian atmosphere to improve interpretations of ChemCam rock analyses on Mars. Profile data are analyzed using principal component analysis, and coatings and rinds are examined using scanning electron microscopy and electron probe microanalysis. Our results show that LIBS is sensitive to minor compositional changes with depth and correctly identifies rock type even if the series of laser pulses does not penetrate to unweathered material. PMID:22410929

  19. A high-resolution atlas of the infrared spectrum of the sun and the earth atmosphere from space. A compilation of ATMOS spectra of the region from 650 to 4800 cm-1 (2.3 to 16 μm). Vol. I. The sun.

    NASA Astrophysics Data System (ADS)

    Farmer, C. B.; Norton, R. H.

    1989-08-01

    During the period April 29 through May 2, 1985, the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment was operated as part of the Spacelab-3 payload of the Shuttle Challenger. The instrument, a modified Michelson interferometer covering the frequency range from 600 to 5000 cm-1 (2 to 16 μm) at a spectral resolution of 0.01 cm-1, recorded infrared spectra of the sun and of the earth's atmosphere at times close to entry into and exit from occultation by the earth's limb as seen from the Shuttle orbit of 360 km. Spectra were obtained that are free from absorptions due to constituents of the atmosphere (i.e., they are "pure solar" spectra).

  20. Role of Wet Scavenging of HOx Precursors in DC3 Oklahoma and Alabama Thunderstorms as Determined Using Aircraft Observations and Results from WRF-Chem Simulations

    NASA Astrophysics Data System (ADS)

    Bela, M. M.; Barth, M. C.; Toon, O. B.; Li, Y.; Pickering, K. E.; Cummings, K.; Allen, D. J.; O'Sullivan, D. W.; Fried, A.; Homeyer, C. R.; Morrison, H.

    2014-12-01

    In deep convective storms wet scavenging of soluble species as well as aqueous and ice chemistry affects the net transport of HOx precursors to the upper troposphere (UT), and thus impacts UT O3 production, air quality and climate. The DC3 (Deep Convective Clouds and Chemistry) field campaign took place in the central US from May-June 2012 and sampled inflow and outflow of convective storms with different dynamical and emission characteristics. This work compares wet scavenging and net transport of HOx precursors and other soluble trace gases in the DC3 May 29 Oklahoma and May 21 Alabama thunderstorms. WRF-Chem simulations at cloud resolving scales (dx=1km) are conducted with two different wet scavenging schemes. The first scheme, based on Neu and Prather (ACP, 2012), removes gases in precipitation and includes ice deposition of HNO3. However, it does not transport species dissolved in hydrometeors, and uses a constant retention fraction for soluble species during hydrometeor freezing. The second scheme, described in Barth et al. (JGR, 2001), tracks solute in individual hydrometeor classes, and includes aqueous chemistry and ice deposition of additional species. A new capability to specify the fraction of each species that is retained in ice upon hydrometeor freezing is added, and sensitivity simulations are compared with observations to determine the best estimate of the retention factor for each species. Simulated vertical distributions of trace gases of varying solubilities within the storm and immediately surrounding the storm are compared with aircraft observations in storm inflow and outflow regions. Scavenging efficiencies are calculated from the model by several flux methods and compared with scavenging efficiencies derived from observations. For the Oklahoma storm, using the Neu and Prather scheme, observed mean vertical profiles of SO2, HNO3, H2O2 and CH3OOH in outflow are better represented in the model when scavenging is included. While H2O2 is two

  1. Comment on "Simulation of Surface Ozone Pollution in the Central Gulf Coast Region Using WRF/Chem Model: Sensitivity to PBL and Land Surface Physics"

    EPA Science Inventory

    A recently published meteorology and air quality modeling study has several serious deficiencies deserving comment. The study uses the weather research and forecasting/chemistry (WRF/Chem) model to compare and evaluate boundary layer and land surface modeling options. The most se...

  2. Impact of Gas-Phase Mechanisms on Weather Research Forecasting Model with Chemistry (WRF/Chem) Predictions: Mechanism Implementation and Comparative Evaluation

    EPA Science Inventory

    Gas-phase mechanisms provide important oxidant and gaseous precursors for secondary aerosol formation. Different gas-phase mechanisms may lead to different predictions of gases, aerosols, and aerosol direct and indirect effects. In this study, WRF/Chem-MADRID simulations are cond...

  3. Note: Derivation of two-photon circular dichroism—Addendum to “Two-photon circular dichroism” [J. Chem. Phys. 62, 1006 (1975)

    SciTech Connect

    Friese, Daniel H.

    2015-09-07

    This addendum shows the detailed derivation of the fundamental equations for two-photon circular dichroism which are given in a very condensed form in the original publication [I. Tinoco, J. Chem. Phys. 62, 1006 (1975)]. In addition, some minor errors are corrected and some of the derivations in the original publication are commented.

  4. ChemEd X Data: Exposing Students to Open Scientific Data for Higher-Order Thinking and Self-Regulated Learning

    ERIC Educational Resources Information Center

    Eklund, Brandon; Prat-Resina, Xavier

    2014-01-01

    ChemEd X Data is an open web tool that collects and curates physical and chemical data of hundreds of substances. This tool allows students to navigate, select, and graphically represent data such as boiling and melting points, enthalpies of combustion, and heat capacities for hundreds of molecules. By doing so, students can independently identify…

  5. ConfChem Conference on Flipped Classroom: Reclaiming Face Time--How an Organic Chemistry Flipped Classroom Provided Access to Increased Guided Engagement

    ERIC Educational Resources Information Center

    Trogden, Bridget G.

    2015-01-01

    Students' active engagement is one of the most critical challenges to any successful learning environment. The blending of active engagement along with rich, meaningful content is necessary for chemical educators to re-examine the purpose of the chemistry classroom. The Spring 2014 ConfChem conference, Flipped Classroom, was held from May 9 to…

  6. University-School Partnerships: On the Impact on Students of Summer Schools (for School Students Aged 17-18) Run by Bristol ChemLabs

    ERIC Educational Resources Information Center

    Shaw, A. J.; Harrison, T. G.; Croker, S. J.; Medley, M.; Sellou, L.; Shallcross, K. L.; Williams, S, J.; Grayson, D. J.; Shallcross, D. E.

    2010-01-01

    Chemistry summer schools for 17-18 year old school students in the UK were run by Bristol ChemLabS, a Centre for Excellence in Teaching and Learning in Chemistry at the University of Bristol. Students attending were all studying Chemistry at post-16 level (A level in the UK) and experienced not only new practical techniques but also lectures on…

  7. Study of key factors influencing dust emission: An assessment of GEOS-Chem and DEAD simulations with observations

    NASA Astrophysics Data System (ADS)

    Bartlett, Kevin S.

    Mineral dust aerosols can impact air quality, climate change, biological cycles, tropical cyclone development and flight operations due to reduced visibility. Dust emissions are primarily limited to the extensive arid regions of the world, yet can negatively impact local to global scales, and are extremely complex to model accurately. Within this dissertation, the Dust Entrainment And Deposition (DEAD) model was adapted to run, for the first known time, using high temporal (hourly) and spatial (0.3°x0.3°) resolution data to methodically interrogate the key parameters and factors influencing global dust emissions. The dependence of dust emissions on key parameters under various conditions has been quantified and it has been shown that dust emissions within DEAD are largely determined by wind speeds, vegetation extent, soil moisture and topographic depressions. Important findings were that grid degradation from 0.3ºx0.3º to 1ºx1º, 2ºx2.5º, and 4°x5° of key meteorological, soil, and surface input parameters greatly reduced emissions approximately 13% and 29% and 64% respectively, as a result of the loss of sub grid detail within these key parameters at coarse grids. After running high resolution DEAD emissions globally for 2 years, two severe dust emission cases were chosen for an in-depth investigation of the root causes of the events and evaluation of the 2°x2.5° Goddard Earth Observing System (GEOS)-Chem and 0.3°x0.3° DEAD model capabilities to simulate the events: one over South West Asia (SWA) in June 2008 and the other over the Middle East in July 2009. The 2 year lack of rain over SWA preceding June 2008 with a 43% decrease in mean rainfall, yielded less than normal plant growth, a 28% increase in Aerosol Optical Depth (AOD), and a 24% decrease in Meteorological Aerodrome Report (METAR) observed visibility (VSBY) compared to average years. GEOS-Chem captured the observed higher AOD over SWA in June 2008. More detailed comparisons of GEOS-Chem

  8. Multiyear applications of WRF/Chem over continental U.S.: Model evaluation, variation trend, and impacts of boundary conditions

    NASA Astrophysics Data System (ADS)

    Yahya, Khairunnisa; He, Jian; Zhang, Yang

    2015-12-01

    Multiyear applications of an online-coupled meteorology-chemistry model allow an assessment of the variation trends in simulated meteorology, air quality, and their interactions to changes in emissions and meteorology, as well as the impacts of initial and boundary conditions (ICONs/BCONs) on simulated aerosol-cloud-radiation interactions over a period of time. In this work, the Weather Research and Forecasting model with Chemistry version 3.4.1 (WRF/Chem v. 3.4.1) with the 2005 Carbon Bond mechanism coupled with the Volatility Basis Set module for secondary organic aerosol formation (WRF/Chem-CB05-VBS) is applied for multiple years (2001, 2006, and 2010) over continental U.S. This work also examines the changes in simulated air quality and meteorology due to changes in emissions and meteorology and the model's capability in reproducing the observed variation trends in species concentrations from 2001 to 2010. In addition, the impacts of the chemical ICONs/BCONs on model predictions are analyzed. ICONs/BCONs are downscaled from two global models, the modified Community Earth System Model/Community Atmosphere model version 5.1 (CESM/CAM v5.1) and the Monitoring Atmospheric Composition and Climate model (MACC). The evaluation of WRF/Chem-CB05-VBS simulations with the CESM ICONs/BCONs for 2001, 2006, and 2010 shows that temperature at 2 m (T2) is underpredicted for all three years likely due to inaccuracies in soil moisture and soil temperature, resulting in biases in surface relative humidity, wind speed, and precipitation. With the exception of cloud fraction, other aerosol-cloud variables including aerosol optical depth, cloud droplet number concentration, and cloud optical thickness are underpredicted for all three years, resulting in overpredictions of radiation variables. The model performs well for O3 and particulate matter with diameter less than or equal to 2.5 (PM2.5) for all three years comparable to other studies from literature. The model is able to

  9. Assessing regional scale predictions of aerosols, marine stratocumulus, and their interactions during VOCALS-REx using WRF-Chem

    SciTech Connect

    Yang Q.; Lee Y.; Gustafson Jr., W. I.; Fast, J. D.; Wang, H.; Easter, R. C.; Morrison, H.; Chapman, E. G.; Spak, S. N.; Mena-Carrasco, M. A.

    2011-12-02

    This study assesses the ability of the recent chemistry version (v3.3) of the Weather Research and Forecasting (WRF-Chem) model to simulate boundary layer structure, aerosols, stratocumulus clouds, and energy fluxes over the Southeast Pacific Ocean. Measurements from the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) and satellite retrievals (i.e., products from the MODerate resolution Imaging Spectroradiometer (MODIS), Clouds and Earth's Radiant Energy System (CERES), and GOES-10) are used for this assessment. The Morrison double-moment microphysics scheme is newly coupled with interactive aerosols in the model. The 31-day (15 October-16 November 2008) WRF-Chem simulation with aerosol-cloud interactions (AERO hereafter) is also compared to a simulation (MET hereafter) with fixed cloud droplet number concentrations in the microphysics scheme and simplified cloud and aerosol treatments in the radiation scheme. The well-simulated aerosol quantities (aerosol number, mass composition and optical properties), and the inclusion of full aerosol-cloud couplings lead to significant improvements in many features of the simulated stratocumulus clouds: cloud optical properties and microphysical properties such as cloud top effective radius, cloud water path, and cloud optical thickness. In addition to accounting for the aerosol direct and semi-direct effects, these improvements feed back to the simulation of boundary-layer characteristics and energy budgets. Particularly, inclusion of interactive aerosols in AERO strengthens the temperature and humidity gradients within the capping inversion layer and lowers the marine boundary layer (MBL) depth by 130 m from that of the MET simulation. These differences are associated with weaker entrainment and stronger mean subsidence at the top of the MBL in AERO. Mean top-of-atmosphere outgoing shortwave fluxes, surface latent heat, and surface downwelling longwave fluxes are in better agreement with observations

  10. Application of online-coupled WRF/Chem-MADRID in East Asia: Model evaluation and climatic effects of anthropogenic aerosols

    NASA Astrophysics Data System (ADS)

    Liu, Xu-Yan; Zhang, Yang; Zhang, Qiang; He, Ke-Bin

    2016-01-01

    The online-coupled Weather Research and Forecasting model with Chemistry with the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (referred to as WRF/Chem-MADRID) is applied to simulate meteorological fields, air quality, and the direct and indirect effects of anthropogenic aerosols over East Asia in four months (January, April, July, and October) in 2008. Model evaluation against available surface and satellite measurements shows that despite some model biases, WRF/Chem-MADRID is able to reproduce reasonably well the spatial and seasonal variations of most meteorological fields and chemical concentrations. Large model biases for chemical concentrations are attributed to uncertainties in emissions and their spatial and vertical allocations, simulated meteorological fields, imperfectness of model representations of aerosol formation processes, uncertainties in the observations based on air pollution index, and the use of a coarse grid resolution. The results show that anthropogenic aerosols can reduce net shortwave flux at the surface by up to 40.5-57.2 W m-2, Temperature at 2-m by up to 0.5-0.8 °C, NO2 photolytic rates by up to 0.06-0.1 min-1 and the planetary boundary layer height by up to 83.6-130.4 m. Anthropogenic aerosols contribute to the number concentrations of aerosols by up to 6.2-8.6 × 104 cm-3 and the surface cloud concentration nuclei at a supersaturation of 0.5% by up to 1.0-1.6 × 104 cm-3. They increase the column cloud droplet number concentrations by up to 3.6-11.7 × 108 cm-2 and cloud optical thickness by up to 19.8-33.2. However, anthropogenic aerosols decrease daily precipitation in most areas by up to 3.9-18.6 mm during the 4 months. These results indicate the importance of anthropogenic aerosols in modulating regional climate changes in East Asia through aerosol direct and indirect effects, as well as the need to further improve the performance of online-coupled models.

  11. Modeling atmospheric ammonia and ammonium using a stochastic Lagrangian air quality model (STILT-Chem v0.7)

    NASA Astrophysics Data System (ADS)

    Wen, D.; Lin, J. C.; Zhang, L.; Vet, R.; Moran, M. D.

    2013-03-01

    A new chemistry module that simulates atmospheric ammonia (NH3) and ammonium (NH+4) was incorporated into a backward-in-time stochastic Lagrangian air quality model (STILT-Chem) that was originally developed to simulate the concentrations of a variety of gas-phase species at receptors. STILT-Chem simulates the transport of air parcels backward in time using ensembles of fictitious particles with stochastic motions, while accounting for emissions, deposition and chemical transformation forward in time along trajectories identified by the backward-in-time simulations. The incorporation of the new chemistry module allows the model to simulate not only gaseous species, but also multi-phase species involving NH3 and NH+4. The model was applied to simulate concentrations of NH3 and particulate NH+4 at six sites in the Canadian province of Ontario for a six-month period in 2006. The model-predicted concentrations of NH3 and particulate NH+4 were compared with observations, which show broad agreement between simulated concentrations and observations. Since the model is based on back trajectories, the influence of each major process such as emission, deposition and chemical conversion on the concentration of a modeled species at a receptor can be determined for every upstream location at each time step. This makes it possible to quantitatively investigate the upstream processes affecting receptor concentrations. The modeled results suggest that the concentrations of NH3 at those sites were significantly and frequently affected by Ohio, Iowa, Minnesota, Michigan, Wisconsin, southwestern Ontario and nearby areas. NH3 is mainly contributed by emission sources whereas particulate NH+4 is mainly contributed by the gas-to-aerosol chemical conversion of NH3. Dry deposition is the largest removal process for both NH3 and particulate NH+4. This study revealed the contrast between agricultural versus forest sites. Not only were emissions of NH3 higher, but removal mechanisms

  12. Modeling Urban Air Quality in the Berlin-Brandenburg Region: Evaluation of a WRF-Chem Setup

    NASA Astrophysics Data System (ADS)

    Kuik, F.; Churkina, G.; Butler, T. M.; Lauer, A.; Mar, K. A.

    2015-12-01

    Air pollution is the number one environmental cause of premature deaths in Europe. Despite extensive regulations, air pollution remains a challenging issue, especially in urban areas. For studying air quality in the Berlin-Brandenburg region of Germany the Weather Research and Forecasting Model with Chemistry (WRF-Chem) is set up and evaluated against meteorological and air quality observations from monitoring stations as well as from a field campaign conducted in 2014 (incl. black carbon, VOCs as well as mobile measurements of particle size distribution and particle mass). The model setup includes 3 nested domains with horizontal resolutions of 15km, 3km, and 1km, online biogenic emissions using MEGAN 2.0, and anthropogenic emissions from the TNO-MACC-II inventory. This work serves as a basis for future studies on different aspects of air pollution in the Berlin-Brandenburg region, including how heat waves affect emissions of biogenic volatile organic compounds (BVOC) from urban vegetation (summer 2006) and the impact of selected traffic measures on air quality in the Berlin-Brandenburg area (summer 2014). The model represents the meteorology as observed in the region well for both periods. An exception is the heat wave period in 2006, where the temperature simulated with 3km and 1km resolutions is biased low by around 2°C for urban built-up stations. First results of simulations with chemistry show that, on average, WRF-Chem simulates concentrations of O3 well. However, the 8 hr maxima are underestimated, and the minima are overestimated. While NOx daily means are modeled reasonably well for urban stations, they are overestimated for suburban stations. PM10 concentrations are underestimated by the model. The biases and correlation coefficients of simulated O3, NOx, and PM10 in comparison to surface observations do not show improvements for the 1km domain in comparison to the 3km domain. To improve the model performance of the 1km domain we will include an

  13. Trans-Pacific transport and evolution of aerosols: evaluation of quasi-global WRF-Chem simulation with multiple observations

    NASA Astrophysics Data System (ADS)

    Hu, Zhiyuan; Zhao, Chun; Huang, Jianping; Leung, L. Ruby; Qian, Yun; Yu, Hongbin; Huang, Lei; Kalashnikova, Olga V.

    2016-05-01

    A fully coupled meteorology-chemistry model (WRF-Chem, the Weather Research and Forecasting model coupled with chemistry) has been configured to conduct quasi-global simulation for 5 years (2010-2014) and evaluated with multiple observation data sets for the first time. The evaluation focuses on the simulation over the trans-Pacific transport region using various reanalysis and observational data sets for meteorological fields and aerosol properties. The simulation generally captures the overall spatial and seasonal variability of satellite retrieved aerosol optical depth (AOD) and absorbing AOD (AAOD) over the Pacific that is determined by the outflow of pollutants and dust and the emissions of marine aerosols. The assessment of simulated extinction Ångström exponent (EAE) indicates that the model generally reproduces the variability of aerosol size distributions as seen by satellites. In addition, the vertical profile of aerosol extinction and its seasonality over the Pacific are also well simulated. The difference between the simulation and satellite retrievals can be mainly attributed to model biases in estimating marine aerosol emissions as well as the satellite sampling and retrieval uncertainties. Compared with the surface measurements over the western USA, the model reasonably simulates the observed magnitude and seasonality of dust, sulfate, and nitrate surface concentrations, but significantly underestimates the peak surface concentrations of carbonaceous aerosol likely due to model biases in the spatial and temporal variability of biomass burning emissions and secondary organic aerosol (SOA) production. A sensitivity simulation shows that the trans-Pacific transported dust, sulfate, and nitrate can make significant contribution to surface concentrations over the rural areas of the western USA, while the peaks of carbonaceous aerosol surface concentrations are dominated by the North American emissions. Both the retrievals and simulation show small

  14. Assessing the Impacts of Wildfire Aerosols on the Diurnal Cycles of Stratocumulus Clouds over Southeast Atlantic Using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Liu, X.; Zhang, Z.

    2015-12-01

    Southern Africa is the world's largest emitter of biomass burning aerosols. The westward transport of these wildfire aerosols over the remote southeast Atlantic collocates with the Earth's major subtropical stratocumulus decks occurring in the marine boundary layer. Wildfire aerosols can significantly perturb the properties of marine stratocumulus through the microphysical effect (as CCN) and the radiative effect (as shortwave absorber); however, the relative importance of these two effects varies within 24 hours mainly due to the diurnal cycle of solar insolation. Given the fact that the strong diurnal cycles of stratocumulus are also largely controlled by the solar insolation, the wildfire aerosols are very likely to exert an additional significant effect on the diurnal cycles of stratocumulus. To prove this hypothesis, we examine the roles of wildfire aerosols in observed diurnal cycles of stratocumulus clouds using the WRF-Chem model in conjunction with satellite observations. Wildfire aerosol emissions are generated from fire radiative power detected by SEVIRI onboard Meteosat. The wildfire aerosols are treated as the internal mixture of OC, BC, and other inorganic components, and coupled with the microphysics and radiation schemes in WRF-Chem. We thoroughly compare the diurnal variations in modeled cloud properties, such as LWP and cloud fraction among 1) the case with both microphysical and radiative effects of wildfire aerosols (the reference case), 2) the case with only microphysical effect, and 3) the case with no wildfire aerosols. The differences in cloud properties are interpreted as the effects of wildfire aerosol. The wildfire aerosol, cloud, and radiation fields modeled by the reference case are validated against satellite observations, including MODIS aerosol optical depth, cloud fraction/LWP, CALIPSO aerosol-cloud overlapping frequency, and CERES radiative fluxes. The modeling results show that the microphysical effect of wildfire aerosols

  15. Atmospheric SO2 oxidation efficiency over a semi-arid region: Seasonal patterns from observations and GEOS-Chem model

    NASA Astrophysics Data System (ADS)

    Francis, Timmy; Sarin, M. M.; Rengarajan, R.

    2016-01-01

    The oxidation efficiency of atmospheric SO2, measured as a molar ratio of SO42- to total SOx (SOx = SO2 + SO42-), referred as S-ratio, have been studied from a high altitude site (Gurushikhar, Mt. Abu: 24.6° N, 72.7° E, 1680 m ASL) in a semi-arid region of western India. A global 3-dimensional Chemical Transport Model (CTM), GEOS-Chem (v8-03-01), is employed to interpret the observed patterns. The S-ratios derived from time series SO2 and SO42- measurements exhibited a pronounced seasonality, with relatively low ratios in Feb-Mar 2010, high ratios in Nov-Dec 2009 and intermediate values in Sep-Oct 2009. The lower S-ratios for Feb '10 and Mar '10 (median values 0.10 and 0.08 respectively) have been attributed to the relatively high planetary boundary layer (PBL) heights - to reduce the SO2 loss from the atmosphere via dry deposition - as well as the lower OH radical levels and low 'aged air mass influx' during these months. On the other hand, low PBL heights and significant long range transport contributions are projected to be the possible causes for the higher S-ratios during Nov '09 and Dec '09 (median values 0.30 and 0.28 respectively). The seasonal patterns for the S-ratios predicted by the CTM for the GEOS-Chem 4° × 5° grid cell containing the sampling site showed highest ratios in Jul-Aug, and the lowest in Apr. The model has been employed further to study the contributions from various parameters to the S-ratios such as PBL, OH, RH, dust load, transport pattern and dry deposition. Sensitivity simulations showed the S-ratios enhancing with dust load with the peak in May (˜4.7% (median)). Similarly, the 'dry deposition' is seen to boost the S-ratios with the peak in August (˜66.3% (median)). Also, model simulations to assess the 'altitudinal dependence of S-ratios' have revealed a pronounced seasonal behaviour.

  16. Photochemical Pollution Modeling of Ozone at Metropolitan Area of Porto Alegre - RS/Brazil using WRF/Chem

    NASA Astrophysics Data System (ADS)

    Cuchiara, G. C.; Carvalho, J.

    2013-05-01

    One of the main problems related to air pollution in urban areas is caused by photochemical oxidants, particularly troposphere ozone (O3), which is considered a harmful substance. The O3 precursors (carbon monoxide CO, nitrogen oxides NOx and hydrocarbons HCs) are predominantly of anthropogenic origin in these areas, and vehicles are the main emission sources. Due to the increased urbanization and industrial development in recent decades, air pollutant emissions have increased likewise, mainly by mobile sources in the highly urbanized and developed areas, such as the Metropolitan Area of Porto Alegre-RS (MAPA). According to legal regulations implemented in Brazil in 2005, which aimed at increasing the fraction of biofuels in the national energy matrix, 2% biodiesel were supposed to be added to the fuel mixture within three years, and up to 5% after eight years of implementation of these regulations. Our work performs an analysis of surface concentrations for O3, NOx, CO, and HCs through numerical simulations with WRF/Chem (Weather Research and Forecasting model with Chemistry). The model is validated against observational data obtained from the local urban air quality network for the period from January 5 to 9, 2009 (96 hours). One part of the study focused on the comparison of simulated meteorological variables, to observational data from two stations in MAPA. The results showed that the model simulates well the diurnal evolution of pressure and temperature at the surface, but is much less accurate for wind speed. Another part included the evaluation of model results of WRF/Chem for O3 versus observed data at air quality stations Esteio and Porto Alegre. Comparisons between simulated and observed O3 revealed that the model simulates well the evolution of the observed values, but on many occasions the model did not reproduce well the maximum and minimum concentrations. Finally, a preliminary quantitative sensitivity study on the impact of biofuel on the

  17. Assessing the CAM5 Physics Suite in the WRF-Chem Model: Implementation, Resolution Sensitivity, and a First Evaluation for a Regional Case Study

    SciTech Connect

    Ma, Po-Lun; Rasch, Philip J.; Fast, Jerome D.; Easter, Richard C.; Gustafson, William I.; Liu, Xiaohong; Ghan, Steven J.; Singh, Balwinder

    2014-05-06

    A suite of physical parameterizations (deep and shallow convection, turbulent boundary layer, aerosols, cloud microphysics, and cloud fraction) from the global climate model Community Atmosphere Model version 5.1 (CAM5) has been implemented in the regional model Weather Research and Forecasting with chemistry (WRF-Chem). A downscaling modeling framework with consistent physics has also been established in which both global and regional simulations use the same emissions and surface fluxes. The WRF-Chem model with the CAM5 physics suite is run at multiple horizontal resolutions over a domain encompassing the northern Pacific Ocean, northeast Asia, and northwest North America for April 2008 when the ARCTAS, ARCPAC, and ISDAC field campaigns took place. These simulations are evaluated against field campaign measurements, satellite retrievals, and ground-based observations, and are compared with simulations that use a set of common WRF-Chem Parameterizations. This manuscript describes the implementation of the CAM5 physics suite in WRF-Chem provides an overview of the modeling framework and an initial evaluation of the simulated meteorology, clouds, and aerosols, and quantifies the resolution dependence of the cloud and aerosol parameterizations. We demonstrate that some of the CAM5 biases, such as high estimates of cloud susceptibility to aerosols and the underestimation of aerosol concentrations in the Arctic, can be reduced simply by increasing horizontal resolution. We also show that the CAM5 physics suite performs similarly to a set of parameterizations commonly used in WRF-Chem, but produces higher ice and liquid water condensate amounts and near-surface black carbon concentration. Further evaluations that use other mesoscale model parameterizations and perform other case studies are needed to infer whether one parameterization consistently produces results more consistent with observations.

  18. The fragility of Al Ni-based glass-forming melts

    NASA Astrophysics Data System (ADS)

    Si, Pengchao; Bian, Xiufang; Zhang, Junyan; Li, Hui; Sun, Minhua; Zhao, Yan

    2003-08-01

    In the original description of fragility, Angell (1988 J. Phys. Chem. Solids 49 863) determined the degree of fragility from the curvature on an Arrhenius plot. This paper discusses a new measurement of the fragility value. The fragility of Al-Ni-based glass-forming melts, which is seldom reported in this field, can be analysed by using data from their viscosity and thermal properties. The fragility is observed to be very high, which is in very good agreement with the low glass-forming ability of Al-Ni-based alloys.

  19. Erratum to "Solar Sources and Geospace Consequences of Interplanetary Magnetic Clouds Observed During Solar Cycle 23-Paper 1" [J. Atmos. Sol.-Terr. Phys. 70(2-4) (2008) 245-253

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P.

    2009-01-01

    One of the figures (Fig. 4) in "Solar sources and geospace consequences of interplanetary magnetic Clouds observed during solar cycle 23 -- Paper 1" by Gopalswamy et al. (2008, JASTP, Vol. 70, Issues 2-4, February 2008, pp. 245-253) is incorrect because of a software error in t he routine that was used to make the plot. The source positions of various magnetic cloud (MC) types are therefore not plotted correctly.

  20. GEOS-Chem AOD (Aerosol Optical Depth) predictions compared with starphotometry and CALIOP estimates during the polar winter

    NASA Astrophysics Data System (ADS)

    Hesaraki, S.; Baibakov, K.; O'Neill, N. T.; Martin, R.; Herber, A. B.; Perro, C. W.; Duck, T. J.; Ritter, C.

    2015-12-01

    We compared AOD (aerosol optical depth) predictions of GEOS-Chem (version 9.01.03) with AOD cloud-screened measurements extracted from starphotometer measurements at Eureka (Nunavut, Canada) and Ny Alesund (Spitsbergen) as well as with the CALIOP AOD product derived for CALIPSO orbit lines within a fixed radius of Eureka and Ny Alesund. The results, supported by Raman lidar measurements at Eureka and Ny Alesund, show degrees of similarity as well as differences that help to understand the quality of cloud-screened, starphotometry optical depths and the AOD / cloud discrimination performance of integrated CALIOP backscatter profiles (in the presence of very challenging statistical sampling constraints) as well as the quality of model predictions in a region and a time period of rare, model evaluation opportunities. The comparisons also help to understand the role of different types of aerosols (predominantly sub-micron) at these high Arctic sites and how one can prepare for the development of long-term, Polar-winter AOD climatologies.

  1. Evaluating Observational Constraints on N2O Emissions via Information Content Analysis Using GEOS-Chem and its Adjoint

    NASA Astrophysics Data System (ADS)

    Wells, K. C.; Millet, D. B.; Bousserez, N.; Henze, D. K.; Chaliyakunnel, S.; Griffis, T. J.; Dlugokencky, E. J.; Prinn, R. G.; O'Doherty, S.; Weiss, R. F.; Dutton, G. S.; Elkins, J. W.; Krummel, P. B.; Langenfelds, R. L.; Steele, P.

    2015-12-01

    Nitrous oxide (N2O) is a long-lived greenhouse gas with a global warming potential approximately 300 times that of CO2, and plays a key role in stratospheric ozone depletion. Human perturbation of the nitrogen cycle has led to a rise in atmospheric N2O, but large uncertainties exist in the spatial and temporal distribution of its emissions. Here we employ a 4D-Var inversion framework for N2O based on the GEOS-Chem chemical transport model and its adjoint to derive new constraints on the space-time distribution of global land and ocean N2O fluxes. Based on an ensemble of global surface measurements, we find that emissions are overestimated over Northern Hemisphere land areas and underestimated in the Southern Hemisphere. Assigning these biases to particular land or ocean regions is more difficult given the long lifetime of N2O. To quantitatively evaluate where the current N2O observing network provides local and regional emission constraints, we apply a new, efficient information content analysis technique involving radial basis functions. The technique yields optimal state vector dimensions for N2O source inversions, with model grid cells grouped in space and time according to the resolution that can actually be provided by the network of global observations. We then use these optimal state vectors in an analytical inversion to refine current top-down emission estimates.

  2. Tracing the boundary layer sources of carbon monoxide in the Asian summer monsoon anticyclone using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Yan, Renchang; Bian, Jianchun

    2015-07-01

    The Asian summer monsoon (ASM) anticyclone is a dominant feature of the circulation in the upper troposphere-lower stratosphere (UTLS) during boreal summer, which is found to have persistent maxima in carbon monoxide (CO). This enhancement is due to the upward transport of air with high CO from the planetary boundary layer (PBL), and confinement within the anticyclonic circulation. With rapid urbanization and industrialization, CO surface emissions are relatively high in the ASM region, especially in India and East China. To reveal the transport pathway of CO surface emissions over these two regions, and investigate the contribution of these to the CO distribution within the ASM anticyclone, a source sensitivity experiment was performed using the Weather Research and Forecasting (WRF) with chemistry model (WRF-Chem). According to the experiment results, the CO within the ASM anticyclone mostly comes from India, while the contribution from East China is insignificant. The result ismainly caused by the different transportation mechanisms. In India, CO transportation is primarily affected by convection. The surface air with high CO over India is directly transported to the upper troposphere, and then confined within the ASM anticyclone, leading to a maximum value in the UTLS region. The CO transportation over East China is affected by deep convection and large-scale circulation, resulting mainly in transportation to Korea, Japan, and the North Pacific Ocean, with little upward transport to the anticyclone, leading to a high CO value at 215 hPa over these regions.

  3. Handheld chem/biosensor using extreme conformational changes in designed binding proteins to enhance surface plasmon resonance (SPR)

    NASA Astrophysics Data System (ADS)

    Lepak, Lori A.; Schnatz, Peter; Bendoym, Igor; Kosciolek, Derek; Koder, Ronald; Crouse, David T.

    2016-05-01

    We present research results centered on development of a highly sensitive handheld chem/biosensor device using a novel class of engineered proteins, designed to undergo extreme conformational changes upon binding their target, which in turn cause extreme changes in refractive index in the protein layer. These proteins are attached to a detector chip with a structured metasurface, to translate the refractive index change into an enhanced shift in surface plasmon resonances (SPR), thereby improving the sensitivity of the overall detector relatively to current commercially available SPR systems. Theoretical calculations have demonstrated the potential of the conformational changes in the engineered proteins to provide the desired change in refractive index. A plasmonic chip with a simple grating metasurface structure was designed to maximize the SPR shift. A prototype chip and a prototype for the overall device housing were fabricated with the inclusion of all other required (commercially available) optical components. The proposed device holds considerable promise as a low-cost, highly sensitive, field-deployable detection system for chemical and biological toxins.

  4. The ChemScreen project to design a pragmatic alternative approach to predict reproductive toxicity of chemicals.

    PubMed

    van der Burg, Bart; Wedebye, Eva Bay; Dietrich, Daniel R; Jaworska, Joanna; Mangelsdorf, Inge; Paune, Eduard; Schwarz, Michael; Piersma, Aldert H; Kroese, E Dinant

    2015-08-01

    There is a great need for rapid testing strategies for reproductive toxicity testing, avoiding animal use. The EU Framework program 7 project ChemScreen aimed to fill this gap in a pragmatic manner preferably using validated existing tools and place them in an innovative alternative testing strategy. In our approach we combined knowledge on critical processes affected by reproductive toxicants with knowledge on the mechanistic basis of such effects. We used in silico methods for prescreening chemicals for relevant toxic effects aiming at reduced testing needs. For those chemicals that need testing we have set up an in vitro screening panel that includes mechanistic high throughput methods and lower throughput assays that measure more integrative endpoints. In silico pharmacokinetic modules were developed for rapid exposure predictions via diverse exposure routes. These modules to match in vitro and in vivo exposure levels greatly improved predictivity of the in vitro tests. As a further step, we have generated examples how to predict reproductive toxicity of chemicals using available data. We have executed formal validations of panel constituents and also used more innovative manners to validate the test panel using mechanistic approaches. We are actively engaged in promoting regulatory acceptance of the tools developed as an essential step towards practical application, including case studies for read-across purposes. With this approach, a significant saving in animal use and associated costs seems very feasible. PMID:25656794

  5. Chemical compound navigator: a web-based chem-BLAST, chemical taxonomy-based search engine for browsing compounds.

    PubMed

    Prasanna, M D; Vondrasek, Jiri; Wlodawer, Alexander; Rodriguez, H; Bhat, T N

    2006-06-01

    A novel technique to annotate, query, and analyze chemical compounds has been developed and is illustrated by using the inhibitor data on HIV protease-inhibitor complexes. In this method, all chemical compounds are annotated in terms of standard chemical structural fragments. These standard fragments are defined by using criteria, such as chemical classification; structural, chemical, or functional groups; and commercial, scientific or common names or synonyms. These fragments are then organized into a data tree based on their chemical substructures. Search engines have been developed to use this data tree to enable query on inhibitors of HIV protease (http://xpdb.nist.gov/hivsdb/hivsdb.html). These search engines use a new novel technique, Chemical Block Layered Alignment of Substructure Technique (Chem-BLAST) to search on the fragments of an inhibitor to look for its chemical structural neighbors. This novel technique to annotate and query compounds lays the foundation for the use of the Semantic Web concept on chemical compounds to allow end users to group, sort, and search structural neighbors accurately and efficiently. During annotation, it enables the attachment of "meaning" (i.e., semantics) to data in a manner that far exceeds the current practice of associating "metadata" with data by creating a knowledge base (or ontology) associated with compounds. Intended users of the technique are the research community and pharmaceutical industry, for which it will provide a new tool to better identify novel chemical structural neighbors to aid drug discovery. PMID:16508960

  6. Projecting Future Changes in Seasonal Vegetative Exposure to Ozone in the Western US Using GEOS-Chem Adjoint

    NASA Astrophysics Data System (ADS)

    Lapina, K.; Henze, D. K.; Milford, J. B.

    2014-12-01

    Frequent exposure to elevated levels of ozone leads to negative impacts on ecosystems including the loss of ozone-sensitive tree species and agricultural crops in many regions of the United States. Information on emission sources contributing to these losses is crucial for developing a successful strategy to mitigate the negative effects of ozone on vegetation. A cumulative ozone exposure metric, W126, has been considered by the US EPA for use as secondary ozone standard. The rural West of the US has been demonstrated to have an especially great potential for disconnect between attaining primary versus W126-based ozone standards. In this work we separate the relative impact of emissions sources for the W126 in the Western US using forward and adjoint simulations with the global chemical transport model GEOS-Chem. The obtained source contributions are separated by different locations, species, and sectors and are combined with representative concentration pathway (RCP) anthropogenic emission scenarios to project future changes in W126 through 2050. Focusing on the foreign influences we find that the change in Chinese emissions alone is projected to lead to up to 20% increase in the W126 levels in the West and is strongly dependent on the RCP scenario. We further use concentration-response functions based on the W126 index to estimate the loss of four ozone-sensitive species in the West - ponderosa pine, Douglas Fir, red alder and quacking aspen.

  7. Investigation of the effect of anthropogenic pollution on typhoon precipitation and microphysical processes using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Jiang, B.

    2015-12-01

    This letter presents an analysis of the influence of anthropogenic aerosols on typhoon, with Usagi as an example, using the Weather Research and Forecasting Model with Chemistry (WRF-Chem). Three simulations (CTL, CLEAN, EXTREME) were designed according to the emission intensity of anthropogenic pollution. The results showed that although anthropogenic pollution did not have a clear influence on typhoon track and strength, it clearly changed precipitation, the distribution of water hydrometeors, and microphysical processes. In the CLEAN experiment, precipitation rate declined because of cloud water collected by rain decreased. Similarly, precipitation rate decreased in the EXTREME experiment, because cloud water auto-conversion to rain water was restrained. Regarding precipitation type, stratiform precipitation rate in the CLEAN and EXTREME simulations was suppressed because the ice phase microphysical processes weakened. Compared to CTL run, stratiform precipitation rate at the periphery was reduced by about 28% in CLEAN and EXTREME simulations. Moreover, convective precipitation rate annulus 140-160km in EXTREME experiment was about 33% larger than that in CTL simulation. It was triggered new convection at the periphery in EXTREME simulation due to cloud water re-evaporation. Finally, compared to the CTL experiment, rainfall peaks of convective and mixed precipitation type in the CLEAN and EXTREME experiments shifted 10km toward the typhoon periphery.

  8. Sensitivity of Arctic mixed-phase clouds simulated with the global climate model ECHAM6-HAM2 to the heterogeneous freezing parameterization

    NASA Astrophysics Data System (ADS)

    Ickes, Luisa; Welti, André; Hoose, Corinna; Lohmann, Ulrike

    2015-04-01

    Different methods can be used to parameterize heterogeneous freezing in mixed-phase clouds either based on field mesurements, laboratory experiments or using theoretical approaches. In this study a parameterization for immersion freezing based on Classical Nucleation Theory (CNT) and laboratory data from Welti et al. [1] is developed for the GCM ECHAM6-HAM2. The scheme is able to incorporate laboratory data to describe microphysical properties of ice nuclei [2]. As CNT is very sensitive to the description of unconstrained kinetic and thermodynamic parameters in case of homogeneous freezing [3] the sensitivity of immersion freezing to these parameters is investigated. Additionally, several approaches to represent ice nuclei properties are tested in terms of their capability to reproduce temperature, time and size dependence of the experimentally observed freezing process. The developed CNT parameterization scheme for kaolinite, illite, montmorillonite, microcline (K-feldspar) and ATD (Arizona test dust) is then introduced into the global climate model ECHAM6-HAM2 with a two-moment cloud microphysics scheme [4] coupled to the aerosol module HAM [5]. The sensitivity of the parameterization is tested in the framework of an Arctic case study. The parameterization will be evaluated against an empirical freezing parameterization to study if the choice of a parameterization scheme can influence the representation of Arctic mixed-phase clouds in ECHAM6-HAM2. [1] A. Welti et al. Time dependence of immersion freezing. Atmos. Chem. Phys.,12:9893-9907, 2012. [2] J.-P. Chen, A. Hazra, and Z. Levin. Parameterizing ice nucleation rates using contact angle and activation energy derived from laboratory data. Atmos. Chem. Phys., 8(24):7431-7449, 2008. [3] L. Ickes, A. Welti, C. Hosse and U. Lohmann. Classical nucleation theory of homogeneous freezing of water: thermodynamic and kinetic parameters. Phys. Chem. Chem. Phys., 2015. [4] U. Lohmann and C. Hoose. Sensitivity studies of

  9. A new WRF-Chem treatment for studying regional-scale impacts of cloud processes on aerosol and trace gases in parameterized cumuli

    DOE PAGESBeta

    Berg, L. K.; Shrivastava, M.; Easter, R. C.; Fast, J. D.; Chapman, E. G.; Liu, Y.; Ferrare, R. A.

    2015-02-24

    A new treatment of cloud effects on aerosol and trace gases within parameterized shallow and deep convection, and aerosol effects on cloud droplet number, has been implemented in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) version 3.2.1 that can be used to better understand the aerosol life cycle over regional to synoptic scales. The modifications to the model include treatment of the cloud droplet number mixing ratio; key cloud microphysical and macrophysical parameters (including the updraft fractional area, updraft and downdraft mass fluxes, and entrainment) averaged over the population of shallow clouds, or a single deep convectivemore » cloud; and vertical transport, activation/resuspension, aqueous chemistry, and wet removal of aerosol and trace gases in warm clouds. These changes have been implemented in both the WRF-Chem chemistry packages as well as the Kain–Fritsch (KF) cumulus parameterization that has been modified to better represent shallow convective clouds. Testing of the modified WRF-Chem has been completed using observations from the Cumulus Humilis Aerosol Processing Study (CHAPS). The simulation results are used to investigate the impact of cloud–aerosol interactions on regional-scale transport of black carbon (BC), organic aerosol (OA), and sulfate aerosol. Based on the simulations presented here, changes in the column-integrated BC can be as large as –50% when cloud–aerosol interactions are considered (due largely to wet removal), or as large as +40% for sulfate under non-precipitating conditions due to sulfate production in the parameterized clouds. The modifications to WRF-Chem are found to account for changes in the cloud droplet number concentration (CDNC) and changes in the chemical composition of cloud droplet residuals in a way that is consistent with observations collected during CHAPS. Efforts are currently underway to port the changes described here to the latest version of WRF-Chem, and it

  10. A new WRF-Chem treatment for studying regional-scale impacts of cloud processes on aerosol and trace gases in parameterized cumuli

    SciTech Connect

    Berg, L. K.; Shrivastava, M.; Easter, R. C.; Fast, J. D.; Chapman, E. G.; Liu, Y.; Ferrare, R. A.

    2015-02-24

    A new treatment of cloud effects on aerosol and trace gases within parameterized shallow and deep convection, and aerosol effects on cloud droplet number, has been implemented in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) version 3.2.1 that can be used to better understand the aerosol life cycle over regional to synoptic scales. The modifications to the model include treatment of the cloud droplet number mixing ratio; key cloud microphysical and macrophysical parameters (including the updraft fractional area, updraft and downdraft mass fluxes, and entrainment) averaged over the population of shallow clouds, or a single deep convective cloud; and vertical transport, activation/resuspension, aqueous chemistry, and wet removal of aerosol and trace gases in warm clouds. These changes have been implemented in both the WRF-Chem chemistry packages as well as the Kain–Fritsch (KF) cumulus parameterization that has been modified to better represent shallow convective clouds. Testing of the modified WRF-Chem has been completed using observations from the Cumulus Humilis Aerosol Processing Study (CHAPS). The simulation results are used to investigate the impact of cloud–aerosol interactions on regional-scale transport of black carbon (BC), organic aerosol (OA), and sulfate aerosol. Based on the simulations presented here, changes in the column-integrated BC can be as large as –50% when cloud–aerosol interactions are considered (due largely to wet removal), or as large as +40% for sulfate under non-precipitating conditions due to sulfate production in the parameterized clouds. The modifications to WRF-Chem are found to account for changes in the cloud droplet number concentration (CDNC) and changes in the chemical composition of cloud droplet residuals in a way that is consistent with observations collected during CHAPS. Efforts are currently underway to port the changes described here to the latest version of WRF-Chem, and it is

  11. Diversity of Rock Compositions at Gale Crater Observed by ChemCam and APXS on Curiosity, and Comparison to Meteorite and Orbital Observations

    NASA Astrophysics Data System (ADS)

    Wiens, R. C.; Maurice, S.; Grotzinger, J. P.; Gellert, R.; Mangold, N.; Sautter, V.; Ollila, A.; Dyar, M. D.; Le Mouelic, S.; Ehlmann, B. L.; Clegg, S. M.; Lanza, N.; Cousin, A.; Forni, O.; Gasnault, O.; Lasue, J.; Blaney, D. L.; Newsom, H. E.; Herkenhoff, K. E.; Anderson, R. B.; D'Uston, L.; Bridges, N. T.; Fabre, C.; Meslin, P.; Johnson, J.; Vaniman, D.; Bridges, J.; Dromart, G.; Schmidt, M. E.; Team, M.

    2013-12-01

    Gale crater was selected as the Curiosity landing site because of the apparent sedimentary spectral signatures seen from orbit. Sedimentary materials on Mars have to this point showed very little expression of major element mobility, so compositions of precursor igneous minerals play a strong role in the compositions of sediments. In addition, pebbles and float rocks on Bradbury Rise (sols 0-50, > 324) appear to be mostly igneous in origin, and are assumed to have been carried down from the crater rim. Overall in the first year on Mars ChemCam obtained >75,000 LIBS spectra on > 2,000 observation points, supported by > 1,000 RMI images, and APXS obtained a significant number of observations. These show surprisingly variable compositions. The mean ChemCam compositions for Bradbury Rise dust-free rocks and pebbles (62 locations) give SiO2 = 56%, FeOT = 16% and show high alkalis consistent with Jake Matijevic (sol ~47) APXS Na2O ~6.6 wt%. ChemCam observations on the conglomerate Link (sol 27) gave Rb > 150 ppm and Sr > 1500 ppm. These compositions imply the presence of abundant alkali feldspars in the material infilling the lower parts of Gale crater. They are generally consistent with the more feldspar-rich SNC meteorites but show a radical departure from larger scale orbital observations, e.g., GRS, raising the question of how widespread these compositions are outside of Gale crater. Sedimentary materials at Yellowknife Bay encompassing the Sheepbed (sols 125-300) and Shaler (sols 121, 311-324) units, potentially including Point Lake (sols 301-310) and Rocknest (sols 57-97), appear to have incorporated varying amounts of igneous source materials. Seven rocks investigated at Rocknest show significant additions of Fe, with mean FeOT = 25% (154 locations), suggesting that FeO was a cementing agent. ChemCam observations at Shaler show varying amounts of alkali feldspar (i.e., related to Bradbury Rise), Fe-rich material (Rocknest-like), and potassium-rich material

  12. Chem Ed Compacts

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1975-01-01

    Five brief items are discussed. They include (1) preservation of reactive ions in solid solution, (2) the molecular partition function, (3) purification of methoxychlor, (4) a kinetics experiment, and (5) determining molecular weights of acids. (RWH)

  13. Eco-Chem

    ERIC Educational Resources Information Center

    Campbell, J. A.

    1975-01-01

    Questions and answers to biochemistry four topics are presented. Items include fatty acid synthesis, reaggregation of sponge cells, enzymic degradation of pollutants, and energy requirements of organisms. (RWH)

  14. Chem Ed Compacts

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1977-01-01

    Presents classroom and laboratory teaching and demonstration ideas, including a demonstration of optical rotation, automatic potentiometric titration, preparation of radioactive lead, and an organic lab practical in library resources. (SL)

  15. Chem Ed Compacts

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1977-01-01

    Discusses the determination of eutectic composition, the mathematics of chemical equilibrium, the wave functions of one-electron orbitals, and the use of pharmacological agents in introductory chemistry courses. (SL)

  16. Chem Ed Compacts

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1976-01-01

    Presents three brief articles that consider the recovery of silver from film, field trips as a supplement to science major general chemistry laboratory, and the construction of a low-cost colorimeter. (MLH)

  17. Chem Ed Compacts.

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1978-01-01

    Reported here are brief descriptions of a common grading and scaling formula for large multi-section courses, an ion exchange amino acid separation and thin layer chromatography identification experiment, a conservation of energy demonstration, a catalyst for synthesizing esters from fatty aids, and an inexpensive method for preparing platinum…

  18. Chem Ed Compacts

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1978-01-01

    Presents teaching notes on the topics of powers of ten notations, physical chemistry projects involving natural products, calorimetry, and solar energy, and learning organic chemistry by playing cards. (SL)

  19. Eco-Chem

    ERIC Educational Resources Information Center

    Campbell, J. A.

    1975-01-01

    Three questions and answers involving chemistry are presented. Question one involves elimination of reptiles from the earth; the second considers chemical effects on taste acuity; the third relates to muzzle velocity of a projectile fired from a gun and temperatures inside the cartridge. (MLH)

  20. Chem Ed Compacts

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1978-01-01

    Presents four simple laboratory procedures for: preparation of organometallic compounds, a realistic qualitative organic analysis project, a computer program to plot potentiometric titration curves, and preparation of stereoscopic transparencies. (SL)

  1. Chem Ed Compacts.

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1980-01-01

    Presents three reports: a description for an upper-level course in protein chemistry; a technique for generating many unique unknowns for the determination of molecular weight by viscosity; and an analogy for quantization of energy levels in which molecules are considered as books in a library. (CS)

  2. Chem Ed Compacts

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1976-01-01

    Presents three activities: (1) the investigation of the purity and stability of nicotinamide and flavin coenzymes; (2) desk-computer fitting of a two-exponential function; and (3) an interesting and inexpensive solubility product experiment for introductory chemistry. (RH)

  3. Elemental Chem Lab

    ERIC Educational Resources Information Center

    Franco Mariscal, Antonio Joaquin

    2008-01-01

    This educative material uses the symbols of 45 elements to spell the names of 32 types of laboratory equipment usually found in chemical labs. This teaching material has been divided into three puzzles according to the type of the laboratory equipment: (i) glassware as reaction vessels or containers; (ii) glassware for measuring, addition or…

  4. Eco-Chem

    ERIC Educational Resources Information Center

    Campbell, J. A.

    1976-01-01

    Presents questions and answers pertaining to yeast fermentation, oxygen content of the air, nutritional requirements of hot water bacteria, the hydrolysis of acetyl coenzyme A, and the stratified distribution of life in the Black Sea. (MLH)

  5. Chem Ed Compacts.

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1979-01-01

    Tips are presented for chemistry teachers on the use of acid-base half-reactions in review lessons, the use of calculators by chemistry students, significant figures, and the preparation of benzoyl peroxide from acne medicine. (BB)

  6. Eco-Chem

    ERIC Educational Resources Information Center

    Campbell, J. A.

    1977-01-01

    Six questions are listed that concern subject matter ranging from toxicity and biochemistry to insect physiology and physics. These questions may be used for study, review, or examination. Answers are also given. All of the questions relate to chemistry and may be adapted to different grade levels. (MR)

  7. Chem 13 News Digest

    ERIC Educational Resources Information Center

    Friesen, R. J., Ed.

    1975-01-01

    Describes an experiment, using a soap bubble raft, intended to provide insight into the orderly packing of spherical objects and the properties of metallic crystals. Also describes a solubility product experiment which uses barium hydroxide. (MLH)

  8. Chem 13 News Digest

    ERIC Educational Resources Information Center

    Friesen, R. J., Ed.

    1975-01-01

    Discusses the chlorination of water supplies. Includes a description of the chemical species present due to chlorination, and the dangers of and alternatives to the chlorination of water systems. (MLH)

  9. Chem-Is-Tree.

    ERIC Educational Resources Information Center

    Barry, Dana M.

    1997-01-01

    Provides details on the chemical composition of trees including a definition of wood. Also includes an activity on anthocyanins as well as a discussion of the resistance of wood to solvents and chemicals. Lists interesting products from trees. (DDR)

  10. Chem Ed Compacts

    ERIC Educational Resources Information Center

    Wolf, Walter A., Ed.

    1977-01-01

    Presents a convenient notation for powers of ten and logarithms, a demonstration of the nonstoichiometry of nickel oxide, a simplification for obtaining Russell-Saunders term symbols, and a scheme for biochemistry laboratory experiments. (SL)

  11. WRF-Chem simulation of NOx and O3 in the L.A. basin during CalNex-2010

    NASA Astrophysics Data System (ADS)

    Chen, Dan; Li, Qinbin; Stutz, Jochen; Mao, Yuhao; Zhang, Li; Pikelnaya, Olga; Tsai, Jui Yi; Haman, Christine; Lefer, Barry; Rappenglück, Bernhard; Alvarez, Sergio L.; Neuman, J. Andrew; Flynn, James; Roberts, James M.; Nowak, John B.; de Gouw, Joost; Holloway, John; Wagner, Nicholas L.; Veres, Patrick; Brown, Steven S.; Ryerson, Thomas B.; Warneke, Carsten; Pollack, Ilana B.

    2013-12-01

    NOx emissions and O3 chemistry in the Los Angeles (L.A.) Basin during the CalNex-2010 field campaign (May-June 2010) have been evaluated by analyzing O3 and NOy (NO, NO2, HNO3, PAN) observations using a regional air quality model (WRF-Chem). Model simulations were conducted at 4-km spatial resolution over the basin using the Carbon-Bond Mechanism version Z (CBM-Z) and NOx emissions reduced by 24% relative to 2005 National Emissions Inventory (NEI’05), according to recent state emission statistics (BASE_NOx scenario). In addition, a 22-26% NOx emission reduction from weekday to weekend was applied. WRF-Chem reproduced the observed diurnal cycle and day-to-day variations in surface O3, Ox, HNO3 and HCHO (correlation r2 = 0.57 - 0.63; pairs of data n > 400; confidence value p < 0.01) at the CalNex supersite at Caltech but consistently overestimated surface NO and NO2. A 45% reduction of NOx emissions relative to NEI’05 (LOW_NOx scenario), as suggested by the OMI-NO2 column trend in California over the same period, improved the agreement of modeled NO2, NOx, and O3 with observations on weekdays. Three-dimensional distributions of daytime O3 and NOy were compared with five daytime NOAA WP-3D flights (three on weekdays and two on weekends) to study the Weekend-to-Weekday (WE-to-WD) effects by using the LOW_NOx scenario. Aircraft data showed a 17.3 ppb O3 increase and a 54% NOy reduction in the boundary layer on weekends relative to weekdays, while modeled WE-to-WD differences were much smaller, with a 2.9 ppb O3 increase and 16% NOy reduction only. Model results on weekends underestimated O3 by 23% and overestimated NOy and HNO3 by 40% and 27%, respectively, which may indicate that weekend NOx emissions (45% reduction relative to NEI’05 with a 22-26% reduction on weekends compared to weekdays) were still overestimated in the model. Comparisons of PAN to HNO3 ratios also indicated that the enhanced photochemistry on weekends was not well represented in the model

  12. Sensitivity of pollutant concentrations towards anthropogenic emissions: A case study over Indian region using WRF/Chem model

    NASA Astrophysics Data System (ADS)

    Ansari, Tabish; Gunthe, Sachin S.

    2015-04-01

    Concentration of an air pollutant over a given region is generally associated with the emissions, regional meteorology, and topographic conditions in addition to the chemical transformation of the pollutant. In general, the role of meteorology is often relegated in policymaking and the entire narrative of air pollution mostly revolves around the emissions. However, there may be regions where the local meteorology, in some seasons or even perennially, may predominantly govern the overall concentration, and the emissions have a little role to play. For instance, the concentrations may be high in a region despite significantly reducing the emissions. Similarly, there may be other regions wherein the prevailing meteorology would cleanse the pollutant even with high emission rates. Thus, if we better understand the seasonal meteorology of smaller regions well and their role in dispersing various pollutants, it would lead to more robust policy formulations. Therefore, there is a need to study the contribution of meteorology as isolated from the emissions, over the pollutant concentrations. In the present study we have used the on-line coupled chemical transport model WRF/Chem to investigate the role of meteorology in determining pollutant concentrations over the Indian tropical region. By using the SEAC4RS emission for the months of April, July, and December, which represents three important meteorological seasons (summer, monsoon, and winter respectively) over India we have performed the simulations of ozone (O3), oxides of nitrogen (NOX), carbon monoxide (CO), and sulphur dioxide (SO2); representative scenario. Further, to assess the role of meteorology alone all the anthropogenic emissions were flattened over the entire continental India (given as one value); flat emission scenario. Our simulations show that during the month of April and December the concentration levels of the major pollutants are largely governed by the meteorology, whereas during the month of July

  13. Analyzing the Effects of Dust on Atmospheric Composition over Northwestern China in Spring 2008 Using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Wang, J.; Allen, D. J.; Pickering, K. E.; Li, Z.

    2014-12-01

    Adjacent to the Taklimakan and Gobi deserts, northwestern China experiences dust storms frequently during the spring season. With the population and industry in northwestern China growing rapidly, anthropogenic pollution also impacts the aerosol composition and therefore optical properties and radiative effects. For instance, NOx emissions from Gansu province increased from ~195 Gg/yr in 2000 to ~323 Gg/yr in 2006 due to the fast growth of transportation vehicles, while SO2 emissions dropped from ~439 Gg/yr to ~338 Gg/yr because flue-gas desulfurization (FGD) devices are widely used in coal-fired powerplants. The WRF-Chem model with CBMZ chemistry mechanism, MOSAIC 8-bins aerosol module and GOCART dust emission algorithm, is applied to simulate the processes responsible for temporal changes in the aerosol distribution, aerosol optical properties and size distribution in Northwestern China due to the impact of dust and anthropogenic emissions during spring 2008, a time period during which an intensive field campaign was conducted at the Zhangye National Climate Observatory (39.082°N, 100.276°E, 1460 m above sea level) of the China Meteorological Administration. This field campaign provided observations of meteorological fields, radiative fluxes, trace gases concentrations, aerosol optical properties, and aerosol size distributions to evaluate the model simulation. The observational data showed a pronounced diurnal variation of trace gases and aerosols: low in the afternoon and high in the morning. Elevated pollutant levels were observed in several dust storms during this campaign. We will investigate the atmospheric processes that are responsible for the atmospheric composition, and assess the relative impact of dust and anthropogenic emissions on local air quality.

  14. Dust Modeling with GEOS-Chem: Evidence for Acidic Uptake on Dust Surfaces during INTEX-B

    NASA Technical Reports Server (NTRS)

    Fairlie, T. Duncan

    2007-01-01

    We use measurements of aerosol ion composition and size made from the DC8 aircraft during the 2006 INTEX-B airborne campaign to identify mineral dust signatures, and look for evidence for interaction of dust with acidic components. Coating of dust with sulfate or nitrate favors the role of dust particles as cloud condensation nucleii, can promote further uptake of SO2 and N2O5, can impact NOx/HNO3 partitioning, and can shift sulfate or nitrate towards larger sizes, affecting atmospheric lifetimes for both aerosol and gas components. Mineral dust had a pervasive presence on flights made during the Northern Pacific deployment of the INTEX-B mission. We use scatter plots of ion mixing ratios with Na+ and Ca(2+) to distinguish sea salt and mineral components of the aerosol distribution, respectively. Positive correlations of non-sea-salt sulfate and nitrate with calcium indicate that the dusty air stream is associated with polluted air masses. Sulfate-ammonium scatter plots indicate sulfate to be primarily in the form of (NH4)2SO4. A positive correlation between Ca(2+) and NO-, but little evidence of NH4NO3, suggests that NO3- may be associated with mineral dust surfaces. 3-d model simulations conducted with the GEOS-Chem chemical transport model indicate that transpacific transport from East Asia was principally responsible for the dust observed from the aircraft over the Pacific. We compare the aerosol component relationships in the model with those observed. Uptake of sulfate and nitrate on the dust is not yet represented in the model.

  15. Dust-induced radiative feedbacks in north China: A dust storm episode modeling study using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Liu, Lixia; Huang, Xin; Ding, Aijun; Fu, Congbin

    2016-03-01

    Radiative forcing of dust aerosol and the radiative feedbacks on the planetary boundary layer (PBL) in North China during a typical Asian dust storm in the early April of 2011 was investigated by an online coupled meteorology-chemistry-aerosol model WRF-Chem. Dust-induced daily mean radiative forcing (RF) at the ground surface and in the atmosphere were estimated to be -21.1 W m-2 and 12.7 W m-2, respectively, over Gobi desert, and -13.1 W m-2 and 4.8 W m-2, respectively, in downwind region over the North China Plain (NCP). Comparatively, radiative perturbation on short-wave radiation was approximately twice that on long-wave radiation in magnitude. In the daytime, when solar radiation dominated, the surface cooling and atmospheric heating due to dust increased PBL stability, leading to reductions of PBL height (PBLH) about 90 m and decreases in wind speed up to 0.4 m s-1. On the contrary, the radiative forcing in terrestrial radiation caused an opposite response at night, especially in the downwind region. Although dust emission was repressed by weakened wind speed during daytime, the elevated PBLH along with larger deflation at night lifted more dust particles to higher altitude (by up to 75 m in average), which prolonged dust residence time in the atmosphere and further intensified dust loading in downwind areas. Taking dust radiative feedbacks into consideration notably narrowed gaps between model-predicted air temperature vertical profiles with corresponding observations, suggesting a significant importance of dust-radiation interaction in PBL meteorology during dust storms.

  16. Wet scavenging of soluble gases in DC3 deep convective storms using WRF-Chem simulations and aircraft observations

    NASA Astrophysics Data System (ADS)

    Bela, Megan M.; Barth, Mary C.; Toon, Owen B.; Fried, Alan; Homeyer, Cameron R.; Morrison, Hugh; Cummings, Kristin A.; Li, Yunyao; Pickering, Kenneth E.; Allen, Dale J.; Yang, Qing; Wennberg, Paul O.; Crounse, John D.; St. Clair, Jason M.; Teng, Alex P.; O'Sullivan, Daniel; Huey, L. Gregory; Chen, Dexian; Liu, Xiaoxi; Blake, Donald R.; Blake, Nicola J.; Apel, Eric C.; Hornbrook, Rebecca S.; Flocke, Frank; Campos, Teresa; Diskin, Glenn

    2016-04-01

    We examine wet scavenging of soluble trace gases in storms observed during the Deep Convective Clouds and Chemistry (DC3) field campaign. We conduct high-resolution simulations with the Weather Research and Forecasting model with Chemistry (WRF-Chem) of a severe storm in Oklahoma. The model represents well the storm location, size, and structure as compared with Next Generation Weather Radar reflectivity, and simulated CO transport is consistent with aircraft observations. Scavenging efficiencies (SEs) between inflow and outflow of soluble species are calculated from aircraft measurements and model simulations. Using a simple wet scavenging scheme, we simulate the SE of each soluble species within the error bars of the observations. The simulated SEs of all species except nitric acid (HNO3) are highly sensitive to the values specified for the fractions retained in ice when cloud water freezes. To reproduce the observations, we must assume zero ice retention for formaldehyde (CH2O) and hydrogen peroxide (H2O2) and complete retention for methyl hydrogen peroxide (CH3OOH) and sulfur dioxide (SO2), likely to compensate for the lack of aqueous chemistry in the model. We then compare scavenging efficiencies among storms that formed in Alabama and northeast Colorado and the Oklahoma storm. Significant differences in SEs are seen among storms and species. More scavenging of HNO3 and less removal of CH3OOH are seen in storms with higher maximum flash rates, an indication of more graupel mass. Graupel is associated with mixed-phase scavenging and lightning production of nitrogen oxides (NOx), processes that may explain the observed differences in HNO3 and CH3OOH scavenging.

  17. Characteristics of aerosols in urban and rural areas: GEOS-Chem+APM nested grid simulation and comparison with observations

    NASA Astrophysics Data System (ADS)

    Luo, G.; Yu, F.

    2011-12-01

    Aerosol microphysics (nucleation, condensation, growth and coagulation) shows significant impact on aerosol size distribution which is important for the investigation of aerosol properties and its associated environment and climate impacts. Here, we use a recently developed global size-resolved aerosol microphysics model (GEOS-Chem+APM, Yu and Luo, ACP, 2009), which uses the ion-mediated nucleation theory to simulate tropospheric particle formation and a new scheme to consider the kinetic condensation of low volatile secondary organic gas (SOG) (in addition to H2SO4 gas) on nucleated particles, to study the major characteristics of aerosol size distribution in urban and rural areas and explore the key factors dominating aerosol properties over these regions. Multiple-year simulations with a nested domain (horizontal resolution 0.5ox0.667o) over Europe have been carried out and compared with long-term continuous particle size distribution measurements at an urban area (Melpitz, Gernmay) and a rural area (Hyytiälä, Finland). The analysis shows that aerosol number concentration at the urban site is generally three times higher than that at the rural site. Significant diurnal and inter-monthly variations of aerosol nucleation events can be found at both sites. Because of high concentration of sulfur acid, freshly nucleated particles at urban site are much easier to grow to large-size particles rather than those at rural site. The model captures the major characteristics of aerosol size distribution observed at the two sites. Model simulation implicates that sulfur acid dominates particle growth process at Melpitz, while SOG shows significant contribution at Hyytiälä, especially during summertime. We also study the mixing state of aerosols at both the urban and rural sites, and aerosol optical property and radiative forcing in urban and rural areas are calculated to investigate the associated environment and climate impacts over these regions.

  18. Modelling atmospheric oxidation of 2-aminoethanol (MEA) emitted from post-combustion capture using WRF-Chem.

    PubMed

    Karl, M; Svendby, T; Walker, S-E; Velken, A S; Castell, N; Solberg, S

    2015-09-15

    Carbon capture and storage (CCS) is a technological solution that can reduce the amount of carbon dioxide (CO2) emissions from the use of fossil fuel in power plants and other industries. A leading method today is amine based post-combustion capture, in which 2-aminoethanol (MEA) is one of the most studied absorption solvents. In this process, amines are released to the atmosphere through evaporation and entrainment from the CO2 absorber column. Modelling is a key instrument for simulating the atmospheric dispersion and chemical transformation of MEA, and for projections of ground-level air concentrations and deposition rates. In this study, the Weather Research and Forecasting model inline coupled with chemistry, WRF-Chem, was applied to quantify the impact of using a comprehensive MEA photo-oxidation sequence compared to using a simplified MEA scheme. Main discrepancies were found for iminoethanol (roughly doubled in the detailed scheme) and 2-nitro aminoethanol, short MEA-nitramine (reduced by factor of two in the detailed scheme). The study indicates that MEA emissions from a full-scale capture plant can modify regional background levels of isocyanic acid. Predicted atmospheric concentrations of isocyanic acid were however below the limit value of 1 ppbv for ambient exposure. The dependence of the formation of hazardous compounds in the OH-initiated oxidation of MEA on ambient level of nitrogen oxides (NOx) was studied in a scenario without NOx emissions from a refinery area in the vicinity of the capture plant. Hourly MEA-nitramine peak concentrations higher than 40 pg m(-3) did only occur when NOx mixing ratios were above 2 ppbv. Therefore, the spatial variability and temporal variability of levels of OH and NOx need to be taken into account in the health risk assessment. The health risk due to direct emissions of nitrosamines and nitramines from full-scale CO2 capture should be investigated in future studies. PMID:25958366

  19. Aerosol-cloud associations over Gangetic Basin during a typical monsoon depression event using WRF-Chem simulation

    NASA Astrophysics Data System (ADS)

    Sarangi, Chandan; Tripathi, S. N.; Tripathi, Shivam; Barth, Mary C.

    2015-10-01

    To study aerosol-cloud interactions over the Gangetic Basin of India, the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) has been applied to a typical monsoon depression event prevalent between the 23 and 29 August 2009. This event was sampled during the Cloud Aerosol Interaction and Precipitation Enhancement EXperiment (CAIPEEX) aircraft campaign, providing measurements of aerosol and cloud microphysical properties from two sorties. Comparison of the simulated meteorological, thermodynamical, and aerosol fields against satellite and in situ aircraft measurements illustrated that the westward propagation of the monsoon depression and the cloud, aerosol, and rainfall spatial distribution was simulated reasonably well using anthropogenic emission rates from Monitoring Atmospheric Composition and Climate project along with cityZEN projects (MACCity)+Intercontinental Chemical Transport Experiment Phase B anthropogenic emission rates. However,the magnitude of aerosol optical depth was underestimated by up to 50%. A simulation with aerosol emissions increased by a factor of 6 over the CAIPEEX campaign domain increased the simulated aerosol concentrations to values close to the observations, mainly within boundary layer. Comparison of the low-aerosol simulation and high-aerosol simulation for the two sorties illustrated that more anthropogenic aerosols increased the cloud condensing nuclei (CCN) and cloud droplet mass concentrations. The number of simulated cloud droplets increased while the cloud droplet effective radii decreased, highlighting the importance of CCN-cloud feedbacks over this region. The increase in simulated anthropogenic aerosols (including absorbing aerosols) also increased the temperature of air parcels below clouds and thus the convective available potential energy (CAPE). The increase in CAPE intensified the updraft and invigorated the cloud, inducing formation of deeper clouds with more ice-phase hydrometeors for both cases

  20. Upper troposphere and stratosphere distribution of hydrocarbon species in ACE-FTS measurements and GEOS-Chem simulations

    NASA Astrophysics Data System (ADS)

    Koo, Ja-Ho; Walker, Kaley A.; Jones, Dylan B. A.; Jones, Ashley; Sheese, Patrick E.; Boone, Chris D.; Bernath, Peter F.; Manney, Gloria L.

    2016-04-01

    Measurements of carbon-containing species, referred to herein as "hydrocarbons", are important components needed for describing and understanding the influence of natural and anthropogenic emissions on atmospheric chemistry. Analysis of the global pattern of hydrocarbons contributes to our understanding of the influence of regional and seasonal variation in air pollution and natural fire events. The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) has monitored trace gases in the upper troposphere and stratosphere based on solar occultation measurements for more than ten years. In this study, we investigate the global pattern of seven "hydrocarbon" species (CO, C2H6, C2H2, HCN, H2CO, CH3OH, and HCOOH) and OCS using the ACE-FTS version 3.5 dataset from 2004 to 2013. All hydrocarbons show strong seasonal variation and regional differences, but the detailed pattern differs according to the speciation of the hydrocarbons. For example, in the Northern Hemisphere, CO, C2H6, and C2H2 show the highest mixing ratios in winter, but high CH3OH and HCOOH appear in summer. In the Southern hemisphere, H2CO, HCN, and HCOOH show high mixing ratios in springtime. These patterns indicate the impact of different emission sources including fuel combustion, wildfire emission, and chemical production. By calculating correlations with CO, these results can provide useful information to characterize each hydrocarbon emission. The ACE-FTS measurements have also been compared with GEOS-Chem output to examine the model performance and spatiotemporal patterns in the simulations.

  1. Impact of various emission control schemes on air quality using WRF-Chem during APEC China 2014

    NASA Astrophysics Data System (ADS)

    Guo, Jianping; He, Jing; Liu, Hongli; Miao, Yucong; Liu, Huan; Zhai, Panmao

    2016-09-01

    Emission control measures have been implemented to make air quality good enough for Asia-Pacific Economic Cooperation (APEC) China 2014, which provides us with an ideal test-bed to determine how these measures affect air quality in Beijing and surrounding areas. Based on hourly observations at eight monitoring sites of Beijing, the concentrations of other primary atmospheric pollutants during APEC were found to have significantly lower magnitudes than those before APEC, with the exception of a higher O3 concentration. Overall, WRF/Chem reproduced the observed time series of PM2.5, PM10, NO2, CO, and O3 notably well. To investigate the impact of emission control measures on air quality on both local and regional scales, four emission control schemes were developed according to the locations where emission reduction had taken place; the corresponding simulations were subsequently run separately. Scheme S2 (emission control implemented in Beijing) resulted in reductions of 22%, 24%, 10% and 22% for the concentrations of PM2.5, PM10, NO2 and CO, respectively, compared with 14%, 14%, 8%, and 13% for scheme S3 (emission controls implemented from outside of Beijing). This finding indicates that the local emission reduction in Beijing contributes more to the improved air quality in Beijing during APEC China 2014 than does the emission reduction from outside of Beijing. In terms of the impact on the regional scale, the real emission control scheme led to significant reduction of PM2.5 throughout the whole domain. Although the regional impact cannot be completely ignored, both emission reduction measures implemented in Beijing and those implemented outside of Beijing favor greater reduction in PM2.5 in the domains where measurements are presumably taken, as compared with other domains. Therefore, to improve the air quality in Beijing, more coordinated efforts should be made, particularly in the aspect of more stringent reduction and control strategies on pollutant emission

  2. The development and evaluation of an adaptable computer aided instruction(CAI) program for acquiring problem solving skills in biochemistry on the WWW: The "BioChem Thinker".

    PubMed Central

    Hershkovitz, B.

    1997-01-01

    BioChem Thinker is a CAI program that was developed to enhance problem solving skills and ability to integrate knowledge in biochemistry for medical and dental students. The program runs on a WWW browser. BioChem Thinker is adaptable, it enables the teacher to create a new problem solving assignment, or edit existing assignments without in-depth knowledge of computer programming. This provides teachers with greater independence and flexibility so as to be able to adapt the program to their own course requirements. The program was implemented and evaluated in the 3rd year biochemistry course of The Hebrew University-Hadassah Medical School. The tool used to develop Biochem Thinker can be utilized to develop similar CAI in other biomedical areas. PMID:9357717

  3. Accuracy Quantification of the Loci-CHEM Code for Chamber Wall Heat Transfer in a GO2/GH2 Single Element Model Problem

    NASA Technical Reports Server (NTRS)

    West, Jeff; Westra, Doug; Lin, Jeff; Tucker, Kevin

    2006-01-01

    All solutions with Loci-CHEM achieved demonstrated steady state and mesh convergence. Preconditioning had no effect on solution accuracy and typically yields a 3-5times solution speed-up. The SST turbulence model has superior performance, relative to the data in the head end region, for the rise rate and peak heat flux. It was slightly worse than the others in the downstream region where all over-predicted the data by 30-100%.There was systematic mesh refinement in the unstructured volume and structured boundary layer areas produced only minor solution differences. Mesh convergence was achieved. Overall, Loci-CHEM satisfactorily predicts heat flux rise rate and peak heat flux and significantly over predicts the downstream heat flux.

  4. Comparison of near-surface CO from multispectral measurements from MOPITT with WRF-Chem simulations using emissions inventory for the Beijing 2008 Olympics

    NASA Astrophysics Data System (ADS)

    Worden, H. M.; Cheng, Y.; Pfister, G.; Carmichael, G.; Deeter, M. N.; Edwards, D. P.; Gille, J. C.; Zhang, Q.; Streets, D. G.

    2010-12-01

    We present initial comparisons of MOPITT multispectral (TIR + NIR) CO measurements with WRF-Chem simulations for the Beijing Olympics in August 2008. The Chinese government made a significant effort to improve air quality during the Olympics by controlling pollution emissions around Beijing before and during Olympics. A new emissions inventory has been created to account for these controls and implemented in WRF-chem. The inventory is specific for pollution sectors such as power, industry, transport and domestic, with corresponding emission factors. By comparing to the MOPITT data, we can test the model predictions for CO and derive improved emissions estimates, then potentially use the emission factors to infer the corresponding reduction in CO2 emissions during the Olympics.

  5. Comparison of two partial least squares-discriminant analysis algorithms for identifying geological samples with the ChemCam laser-induced breakdown spectroscopy instrument.

    PubMed

    Ollila, Ann M; Lasue, Jeremie; Newsom, Horton E; Multari, Rosalie A; Wiens, Roger C; Clegg, Samuel M

    2012-03-01

    ChemCam, a laser-induced breakdown spectroscopy (LIBS) instrument on the Mars Science Laboratory rover, will analyze the chemistry of the martian surface beginning in 2012. Prior to integration on the rover, the ChemCam instrument collected data on a variety of rock types to provide a training set for analysis of data from Mars. Models based on calibration data can be used to classify rocks via multivariate statistical techniques such as partial least squares-discriminant analysis (PLS-DA). In this study, we employ a version of PLS-DA in which modeling is applied in a defined classification flow to a variety of geological materials and compare the results with the traditional PLS-DA technique. Results show that the modified algorithm is more effective at classifying samples. PMID:22410911

  6. Transition Metal-Catalyzed Aerobic Dehydrogenation of Heterocycles and Development, Implementation, and Evaluation of a Student-Generated ChemWiki and its Impact on Student Performance

    NASA Astrophysics Data System (ADS)

    Brown, Jaclyn R.

    Section I describes progress towards the dehydrogenation of heterocycles, specifically tetrahydroquinolines and imidazolines. Chapter 1 details the development of an aerobic Pd catalyst system capable of aromatizing substituted tetrahydroquinolines in moderate to good yields. This catalyst system generally works well for substituted tetrahydroquinolines, although elimination of heteroatom substituents remains problematic. Chapter 2 describes the development of a copper-based catalyst system for the dehydrogenation of substituted imidazolines to imidazoles. This catalyst system is based upon the CuI/bpy/TEMPO/NMI system developed by the Stahl group, which has shown excellent reactivity towards alcohol oxidation. Efforts to adapt this system to imidazolines are described herein. Section II details the development, implementation, and evaluation of a student-generated chemistry wiki in large general chemistry courses. Chapter 3 describes a theoretical framework based in constructivist epistemology for the use of wikis in chemical education and presents previous examples and limitations of wiki usage in chemistry and non-chemistry environments. Chapter 4 details the process of designing the ChemWiki experiment and the ChemWiki website itself. A detailed description of the assessments used to evaluate student performance is also presented. Chapter 5 describes two surveys designed to assess the qualitative aspects of the second generation wiki design. Additionally, an overview of participants' perception of the chemistry wiki and its utility as well as data tracking logs of participants' interactions with the ChemWiki are presented. Chapter 6 presents a quantitative analysis of the efficacy of the chemistry wiki on student posttest scores. Chapter 7 summarizes the findings of this thesis and includes recommended future directions for the use of ChemWikis in chemical education environments.

  7. Assimilating compact phase space retrievals of atmospheric composition with WRF-Chem/DART: a regional chemical transport/ensemble Kalman filter data assimilation system

    NASA Astrophysics Data System (ADS)

    Mizzi, Arthur P.; Arellano, Avelino F., Jr.; Edwards, David P.; Anderson, Jeffrey L.; Pfister, Gabriele G.

    2016-03-01

    This paper introduces the Weather Research and Forecasting Model with chemistry/Data Assimilation Research Testbed (WRF-Chem/DART) chemical transport forecasting/data assimilation system together with the assimilation of compact phase space retrievals of satellite-derived atmospheric composition products. WRF-Chem is a state-of-the-art chemical transport model. DART is a flexible software environment for researching ensemble data assimilation with different assimilation and forecast model options. DART's primary assimilation tool is the ensemble adjustment Kalman filter. WRF-Chem/DART is applied to the assimilation of Terra/Measurement of Pollution in the Troposphere (MOPITT) carbon monoxide (CO) trace gas retrieval profiles. Those CO observations are first assimilated as quasi-optimal retrievals (QORs). Our results show that assimilation of the CO retrievals (i) reduced WRF-Chem's CO bias in retrieval and state space, and (ii) improved the CO forecast skill by reducing the Root Mean Square Error (RMSE) and increasing the Coefficient of Determination (R2). Those CO forecast improvements were significant at the 95 % level. Trace gas retrieval data sets contain (i) large amounts of data with limited information content per observation, (ii) error covariance cross-correlations, and (iii) contributions from the retrieval prior profile that should be removed before assimilation. Those characteristics present challenges to the assimilation of retrievals. This paper addresses those challenges by introducing the assimilation of compact phase space retrievals (CPSRs). CPSRs are obtained by preprocessing retrieval data sets with an algorithm that (i) compresses the retrieval data, (ii) diagonalizes the error covariance, and (iii) removes the retrieval prior profile contribution. Most modern ensemble assimilation algorithms can efficiently assimilate CPSRs. Our results show that assimilation of MOPITT CO CPSRs reduced the number of observations (and assimilation computation

  8. Assimilating compact phase space retrievals of atmospheric composition with WRF-Chem/DART: a regional chemical transport/ensemble Kalman filter data assimilation system

    NASA Astrophysics Data System (ADS)

    Mizzi, A. P.; Arellano, A. F.; Edwards, D. P.; Anderson, J. L.; Pfister, G. G.

    2015-09-01

    This paper introduces the Weather Research and Forecasting Model with chemistry/Data Assimilation Research Testbed (WRF-Chem/DART) chemical transport forecasting/data assimilation system together with the assimilation of "compact phase space retrievals" of satellite-derived atmospheric composition products. WRF-Chem is a state-of-the-art chemical transport model. DART is a flexible software environment for researching ensemble data assimilation with different assimilation and forecast model options. DART's primary assimilation tool is the ensemble adjustment Kalman filter. WRF-Chem/DART is applied to the assimilation of Terra/Measurement of Pollution in the Troposphere (MOPITT) carbon monoxide (CO) trace gas retrieval profiles. Those CO observations are first assimilated as quasi-optimal retrievals (QORs). Our results show that assimilation of the CO retrievals: (i) reduced WRF-Chem's CO bias in retrieval and state space, and (ii) improved the CO forecast skill by reducing the Root Mean Square Error (RMSE) and increasing the Coefficient of Determination (R2). Those CO forecast improvements were significant at the 95 % level. Trace gas retrieval data sets contain: (i) large amounts of data with limited information content per observation, (ii) error covariance cross-correlations, and (iii) contributions from the retrieval prior profile that should be removed before assimilation. Those characteristics present challenges to the assimilation of retrievals. This paper addresses those challenges by introducing the assimilation of "compact phase space retrievals" (CPSRs). CPSRs are obtained by preprocessing retrieval datasets with an algorithm that: (i) compresses the retrieval data, (ii) diagonalizes the error covariance, and (iii) removes the retrieval prior profile contribution. Most modern ensemble assimilation algorithms can efficiently assimilate CPSRs. Our results show that assimilation of MOPITT CO CPSRs reduced the number of observations (and assimilation

  9. Sensitivity of dust emissions to aerosol feedback and the impact of dust loading on climate forcing with varied resolutions using FIM-Chem

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Grell, Georg; Henze, Daven; Mckeen, Stuart; Sun, Shan; Li, Haiqin

    2016-04-01

    Meteorological conditions directly impact aerosol loading, especially dust emissions. Variations in dust emissions on the other hand, will also impact meteorology and climate through direct and indirect aerosol forcing. To study these impacts in more detail we use the global Flow-following finite-volume Icosahedra Model (FIM, http://fim.noaa.gov/), a new global weather prediction model currently under development in the Global Systems Division of NOAA/ESRL, as it is coupled online with the aerosol modules from the Goddard Gobal Ozone Chemistry Aerosol Radiation and Transport (GOCART) model (FIM-Chem). FIM-Chem includes direct and semi direct feedback, and uses the dust schemes of GOCART and the Air Force Weather Agency (AFWA). FIM-Chem is able to investigate the contribution of climate feedbacks to simulated hyperspectral data by considering a range of simulations with different dust emissions and different levels of aerosol feedbacks enabled at four different spatial resolutions. The emitted dust flux and total emissions are highly depending on the wind, soil moisture and model resolution. We compare the dust emissions by including and excluding the aerosol radiative feedback in the simulations to quantify the sensitivity of dust emissions to aerosol feedback. The results show that all aerosol-induced dust emissions increase about 10% globally, which is mainly dominated by the contributions of anthropogenic black carbon (EC) aerosol. While the dust-induced percentage changes of dust emissions are about -5.5%, that indicates reduction effect globally. Also, the simulations based on different resolutions of 240x240 km, 120x120 km, 60x60 km and 30x30 km are performed to test the impacts of model resolution on total dust emissions. By comparing the dust emission sensitivity to aerosol feedback and model resolution, we can estimate the uncertainty of model resolution versus aerosol feedback. We also conduct FIM-Chem simulations to investigate the sensitivity of dust

  10. Implementation of aerosol assimilation in Gridpoint Statistical Interpolation (v. 3.2) and WRF-Chem (v. 3.4.1)

    NASA Astrophysics Data System (ADS)

    Pagowski, M.; Liu, Z.; Grell, G. A.; Hu, M.; Lin, H.-C.; Schwartz, C. S.

    2014-08-01

    Gridpoint Statistical Interpolation (GSI) is an assimilation tool that is used at the National Centers for Environmental Prediction (NCEP) in operational weather forecasting in the USA. In this article, we describe implementation of an extension to the GSI for assimilating surface measurements of PM2.5, PM10, and MODIS aerosol optical depth at 550 nm with WRF-Chem (Weather Research and Forecasting model coupled with Chemistry). We also present illustrative results. In the past, the aerosol assimilation system has been employed to issue daily PM2.5 forecasts at NOAA/ESRL (Earth System Research Laboratory) and, we believe, it is well tested and mature enough to be made available for wider use. We provide a package that, in addition to augmented GSI, consists of software for calculating background error covariance statistics and for converting in situ and satellite data to BUFR (Binary Universal Form for the Representation of meteorological data) format, and sample input files for an assimilation exercise. Thanks to flexibility in the GSI and coupled meteorology-chemistry of WRF-Chem, assimilating aerosol observations can be carried out simultaneously with meteorological data assimilation. Both GSI and WRF-Chem are well documented with user guides available online. This article is primarily intended to be a technical note on the implementation of the aerosol assimilation. Its purpose is also to provide guidance for prospective users of the computer code. Scientific aspects of aerosol assimilation are also briefly discussed.

  11. Implementation of aerosol assimilation in Gridpoint Statistical Interpolation v. 3.2 and WRF-Chem v. 4.3.1

    NASA Astrophysics Data System (ADS)

    Pagowski, M.; Liu, Z.; Grell, G. A.; Hu, M.; Lin, H.-C.; Schwartz, C. S.

    2014-04-01

    Gridpoint Statistical Interpolation (GSI) is an assimilation tool that is used at the National Centers for Environmental Prediction in operational weather forecasting. In this article we describe implementation of an extension to the GSI for assimilating surface measurements of PM2.5, PM10, and MODIS Aerosol Optical Depth at 550 nm with WRF-Chem. We also present illustrations of the results. In the past the aerosol assimilation system has been employed to issue daily PM2.5 forecasts at NOAA/ESRL and, in our belief, is well tested and mature enough to make available for wider use. We provide a package that, in addition to augmented GSI, consists of software for calculating background error covariance statistics and for converting in-situ and satellite data to BUFR format, plus sample input files for an assimilation exercise. Thanks to flexibility in the GSI and coupled meteorology-chemistry of WRF-Chem, assimilating aerosol observations can be carried out simultaneously with meteorological data assimilation. Both GSI and WRF-Chem are well documented with user guides available on-line. This article is primarily intended as a technical note on the implementation of the aerosol assimilation. Its purpose is also to provide guidance for prospective users of the computer code. Limited space is devoted to scientific aspects of aerosol assimilation.

  12. Top-down estimate of dust emissions through integration of MODIS and MISR aerosol retrievals with the GEOS-Chem adjoint model

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Xu, Xiaoguang; Henze, Daven K.; Zeng, Jing; Ji, Qiang; Tsay, Si-Chee; Huang, Jianping

    2012-04-01

    Predicting the influences of dust on atmospheric composition, climate, and human health requires accurate knowledge of dust emissions, but large uncertainties persist in quantifying mineral sources. This study presents a new method for combined use of satellite-measured radiances and inverse modeling to spatially constrain the amount and location of dust emissions. The technique is illustrated with a case study in May 2008; the dust emissions in Taklimakan and Gobi deserts are spatially optimized using the GEOS-Chem chemical transport model and its adjoint constrained by aerosol optical depth (AOD) that are derived over the downwind dark-surface region in China from MODIS (Moderate Resolution Imaging Spectroradiometer) reflectance with the aerosol single scattering properties consistent with GEOS-chem. The adjoint inverse modeling yields an overall 51% decrease in prior dust emissions estimated by GEOS-Chem over the Taklimakan-Gobi area, with more significant reductions south of the Gobi Desert. The model simulation with optimized dust emissions shows much better agreement with independent observations from MISR (Multi-angle Imaging SpectroRadiometer) AOD and MODIS Deep Blue AOD over the dust source region and surface PM10 concentrations. The technique of this study can be applied to global multi-sensor remote sensing data for constraining dust emissions at various temporal and spatial scales, and hence improving the quantification of dust effects on climate, air quality, and human health.

  13. Inverse modelling of radionuclide release rates using gamma dose rate observations

    NASA Astrophysics Data System (ADS)

    Hamburger, Thomas; Evangeliou, Nikolaos; Stohl, Andreas; von Haustein, Christoph; Thummerer, Severin; Wallner, Christian

    2015-04-01

    inversion method uses a Bayesian formulation considering uncertainties for the a priori source term and the observations (Eckhardt et al., 2008, Stohl et al., 2012). The a priori information on the source term is a first guess. The gamma dose rate observations are used to improve the first guess and to retrieve a reliable source term. The details of this method will be presented at the conference. This work is funded by the Bundesamt für Strahlenschutz BfS, Forschungsvorhaben 3612S60026. References Davoine, X. and Bocquet, M., Atmos. Chem. Phys., 7, 1549-1564, 2007. Devell, L., et al., OCDE/GD(96)12, 1995. Eckhardt, S., et al., Atmos. Chem. Phys., 8, 3881-3897, 2008. Saunier, O., et al., Atmos. Chem. Phys., 13, 11403-11421, 2013. Stohl, A., et al., Atmos. Environ., 32, 4245-4264, 1998. Stohl, A., et al., Atmos. Chem. Phys., 5, 2461-2474, 2005. Stohl, A., et al., Atmos. Chem. Phys., 12, 2313-2343, 2012.

  14. Inverse modelling of radionuclide release rates using gamma dose rate observations

    NASA Astrophysics Data System (ADS)

    Hamburger, Thomas; Stohl, Andreas; von Haustein, Christoph; Thummerer, Severin; Wallner, Christian

    2014-05-01

    relatively sparse grid and the temporal resolution of available data may be low within the order of hours or a day. Gamma dose rates on the other hand are observed routinely on a much denser grid and higher temporal resolution. Gamma dose rate measurements contain no explicit information on the observed spectrum of radionuclides and have to be interpreted carefully. Nevertheless, they provide valuable information for the inverse evaluation of the source term due to their availability (Saunier et al., 2013). We present a new inversion approach combining an atmospheric dispersion model and observations of radionuclide activity concentrations and gamma dose rates to obtain the source term of radionuclides. We use the Lagrangian particle dispersion model FLEXPART (Stohl et al., 1998; Stohl et al., 2005) to model the atmospheric transport of the released radionuclides. The gamma dose rates are calculated from the modelled activity concentrations. The inversion method uses a Bayesian formulation considering uncertainties for the a priori source term and the observations (Eckhardt et al., 2008). The a priori information on the source term is a first guess. The gamma dose rate observations will be used with inverse modelling to improve this first guess and to retrieve a reliable source term. The details of this method will be presented at the conference. This work is funded by the Bundesamt für Strahlenschutz BfS, Forschungsvorhaben 3612S60026. References Davoine, X. and Bocquet, M., Atmos. Chem. Phys., 7, 1549-1564, 2007. Devell, L., et al., OCDE/GD(96)12, 1995. Eckhardt, S., et al., Atmos. Chem. Phys., 8, 3881-3897, 2008. Saunier, O., et al., Atmos. Chem. Phys., 13, 11403-11421, 2013. Stohl, A., et al., Atmos. Environ., 32, 4245-4264, 1998. Stohl, A., et al., Atmos. Chem. Phys., 5, 2461-2474, 2005. Stohl, A., et al., Atmos. Chem. Phys., 12, 2313-2343, 2012.

  15. Comparison of Mixed Layer Heights from Airborne High Spectral Resolution Lidar, Ground-based Measurements, and the WRP-Chem Model during CalNex and CARES

    SciTech Connect

    Scarino, Amy Jo; Obland, Michael; Fast, Jerome D.; Burton, S. P.; Ferrare, R. A.; Hostetler, Chris A.; Berg, Larry K.; Lefer, Barry; Haman, C.; Hair, John; Rogers, Ray; Butler, Carolyn; Cook, A. L.; Harper, David

    2014-06-05

    The California Research at the Nexus of Air Quality and Climate Change (CalNex) and Carbonaceous Aerosol and Radiative Effects Study (CARES) field campaigns during May and June 2010 provided a data set appropriate for studying characteristics of the planetary boundary layer (PBL). The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) was deployed to California onboard the NASA LaRC B-200 aircraft to aid incharacterizing aerosol properties during these two field campaigns. Measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 31 flights, many in coordination with other research aircraft and ground sites, constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, as well as the depth and variability of the daytime mixed layer (ML), which is a subset within the PBL. This work illustrates the temporal and spatial variability of the ML in the vicinity of Los Angeles and Sacramento, CA. ML heights derived from HSRL measurements are compared to PBL heights derived from radiosonde profiles, ML heights measured from ceilometers, and simulated PBL heights from the Weather Research and Forecasting Chemistry (WRF-Chem) community model. Comparisons between the HSRL ML heights and the radiosonde profiles in Sacramento result in a correlation coefficient value (R) of 0.93 (root7 mean-square (RMS) difference of 157 m and bias difference (HSRL radiosonde) of 5 m). HSRL ML heights compare well with those from the ceilometer in the LA Basin with an R of 0.89 (RMS difference of 108 m and bias difference (HSRL Ceilometer) of -9.7 m) for distances of up to 30 km between the B-200 flight track and the ceilometer site. Simulated PBL heights from WRF-Chem were compared with those obtained from all flights for each campaign, producing an R of 0.58 (RMS difference of 604 m and a bias difference (WRF-Chem HSRL) of -157 m) for CalNex and 0

  16. Exploring Natural Products from the Biodiversity of Pakistan for Computational Drug Discovery Studies: Collection, Optimization, Design and Development of A Chemical Database (ChemDP).

    PubMed

    Mirza, Shaher Bano; Bokhari, Habib; Fatmi, Muhammad Qaiser

    2015-01-01

    Pakistan possesses a rich and vast source of natural products (NPs). Some of these secondary metabolites have been identified as potent therapeutic agents. However, the medicinal usage of most of these compounds has not yet been fully explored. The discoveries for new scaffolds of NPs as inhibitors of certain enzymes or receptors using advanced computational drug discovery approaches are also limited due to the unavailability of accurate 3D structures of NPs. An organized database incorporating all relevant information, therefore, can facilitate to explore the medicinal importance of the metabolites from Pakistani Biodiversity. The Chemical Database of Pakistan (ChemDP; release 01) is a fully-referenced, evolving, web-based, virtual database which has been designed and developed to introduce natural products (NPs) and their derivatives from the biodiversity of Pakistan to Global scientific communities. The prime aim is to provide quality structures of compounds with relevant information for computer-aided drug discovery studies. For this purpose, over 1000 NPs have been identified from more than 400 published articles, for which 2D and 3D molecular structures have been generated with a special focus on their stereochemistry, where applicable. The PM7 semiempirical quantum chemistry method has been used to energy optimize the 3D structure of NPs. The 2D and 3D structures can be downloaded as .sdf, .mol, .sybyl, .mol2, and .pdb files - readable formats by many chemoinformatics/bioinformatics software packages. Each entry in ChemDP contains over 100 data fields representing various molecular, biological, physico-chemical and pharmacological properties, which have been properly documented in the database for end users. These pieces of information have been either manually extracted from the literatures or computationally calculated using various computational tools. Cross referencing to a major data repository i.e. ChemSpider has been made available for overlapping

  17. A high-resolution atlas of the infrared spectrum of the sun and the earth atmosphere from space. A compilation of ATMOS spectra of the region from 650 to 4800 cm-1 (2.3 to 16 microns). Volume 2: Stratosphere and mesosphere, 650 to 3350 cm-1

    NASA Technical Reports Server (NTRS)

    Farmer, Crofton B.; Norton, Robert H.

    1989-01-01

    During the period April 29 to May 2, 1985, the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment was operated for the first time, as part of the Spacelab-3 payload of the shuttle Challenger. The principal purpose of this experiment was to study the distributions of the atmosphere's minor and trace molecular constituents. The instrument, a modified Michelson interferometer covering the frequency range from 600 to 5000/cm-1 at a spectral resolution of 0.01/cm-1, recorded infrared absorption spectra of the sun and of the earth's atmosphere at times close to entry into and exit from occultation by the earth's limb. Spectra were obtained that are free from absorptions due to constituents of the atmosphere (i.e., they are pure solar spectra), as well as spectra of the atmosphere itself, covering line-of-sight tangent altitudes that span the range from the lower thermosphere to the bottom of the troposphere. This atlas presents a compilation of these spectra arranged in a hardcopy format suitable for quick-look reference purposes. Volume 2 covers the stratosphere and mesosphere (i.e., tangent altitudes from 20 to 80 km) for frequencies from 650 to 3350/cm-1.

  18. A high-resolution atlas of the infrared spectrum of the sun and the earth atmosphere from space. A compilation of ATMOS spectra of the region from 650 to 4800 cm-1 (2.3 to 16 microns). Volume 2: Stratosphere and mesosphere, 650 to 3350 cm-1

    NASA Astrophysics Data System (ADS)

    Farmer, Crofton B.; Norton, Robert H.

    During the period April 29 to May 2, 1985, the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment was operated for the first time, as part of the Spacelab-3 payload of the shuttle Challenger. The principal purpose of this experiment was to study the distributions of the atmosphere's minor and trace molecular constituents. The instrument, a modified Michelson interferometer covering the frequency range from 600 to 5000/cm-1 at a spectral resolution of 0.01/cm-1, recorded infrared absorption spectra of the sun and of the earth's atmosphere at times close to entry into and exit from occultation by the earth's limb. Spectra were obtained that are free from absorptions due to constituents of the atmosphere (i.e., they are pure solar spectra), as well as spectra of the atmosphere itself, covering line-of-sight tangent altitudes that span the range from the lower thermosphere to the bottom of the troposphere. This atlas presents a compilation of these spectra arranged in a hardcopy format suitable for quick-look reference purposes. Volume 2 covers the stratosphere and mesosphere (i.e., tangent altitudes from 20 to 80 km) for frequencies from 650 to 3350/cm-1.

  19. The effect of SRTM and Corine Land Cover data on calculated gas and PM10 concentrations in WRF-Chem

    NASA Astrophysics Data System (ADS)

    De Meij, A.; Bossioli, E.; Penard, C.; Vinuesa, J. F.; Price, I.

    2015-01-01

    The goal of this study is to investigate the impact of the high resolution Shuttle Radar Topography Mission (SRTM) 90 m × 90 m topography data, together with the 100 m × 100 m resolution Corine Land Cover 2006 on the simulated gas and particulate matter (PM10) concentrations by WRF-Chem. We focused our analysis on the well-known highly urbanized region of the Po Valley. Large differences are found in the geographical distribution of the land cover classes between Corine Land Cover and 30 arc seconds USGS. The simulation with the SRTM and Corine Land Cover increases modelled temperature at 2 m and reduces wind speeds due to more friction at the surface induced by the Corine Land Cover. Latent and sensible heat fluxes show large differences between the two simulations and the related boundary layer development and depth. The simulation with the SRTM and Corine Land Cover favours the precipitation amount over a large of part the Alps and follows the pattern of the difference in topography between the two topography data sets. In term of air quality indicators, impacts are also large and geographical dependent. Monthly average of CO, NO and SO2 concentrations over a large part of the Po Valley are higher when using Corine Land Cover, up to ∼20, ∼50 and ∼55%, respectively. With respect to PM10, the impacts are also geographical dependent. Over the Po valley area, calculated PM10 concentrations are in general higher using Corine Land Cover (up to 6.7 ug/m3 [∼26%] westerly of Milan) while differences are smaller over the Alps (∼0.25ug/m3 [∼20%]). Although the scope of this work is not to evaluate the model performance in calculated meteorological parameters and gas and PM10 concentrations, calculated values by the simulation with SRTM and Corine Land Cover show a better agreement with the observations than the simulation with the USGS topography and land cover data sets. A quantitative comparison between modelled and observed monthly average PM10

  20. Coupling Aerosol-Cloud-Radiative Processes in the WRF-Chem Model: Investigating the Radiative Impact of Elevated Point Sources

    SciTech Connect

    Chapman, Elaine G.; Gustafson, William I.; Easter, Richard C.; Barnard, James C.; Ghan, Steven J.; Pekour, Mikhail S.; Fast, Jerome D.

    2009-02-01

    The local and regional influence of elevated point sources on summertime aerosol forcing and cloud-aerosol interactions in northeastern North America was investigated using the WRF-Chem community model. The direct effects of aerosols on incoming solar radiation were simulated using existing modules to relate aerosol sizes and chemical composition to aerosol optical properties. Indirect effects were simulated by adding a prognostic treatment of cloud droplet number and adding modules that activate aerosol particles to form cloud droplets, simulate aqueous phase chemistry, and tie a two-moment treatment of cloud water (cloud water mass and cloud droplet number) to an existing radiation scheme. Fully interactive feedbacks thus were created within the modified model, with aerosols affecting cloud droplet number and cloud radiative properties, and clouds altering aerosol size and composition via aqueous processes, wet scavenging, and gas-phase-related photolytic processes. Comparisons of a baseline simulation with observations show that the model captured the general temporal cycle of aerosol optical depths (AODs) and produced clouds of comparable thickness to observations at approximately the proper times and places. The model slightly overpredicted SO2 mixing ratios and PM2.5 mass, but reproduced the range of observed SO2 to sulfate aerosol ratios, suggesting that atmospheric oxidation processes leading to aerosol sulfate formation are captured in the model. The baseline simulation was compared to a sensitivity simulation in which all emissions at model levels above the surface layer were set to zero, thus removing stack emissions. Instantaneous, site-specific differences for aerosol and cloud related properties between the two simulations could be quite large, as removing above-surface emission sources influenced when and where clouds formed within the modeling domain. When summed spatially over the finest resolution model domain (the extent of which corresponds to

  1. Atmospheric composition in the Eastern Mediterranean: Influence of biomass burning during summertime using the WRF-Chem model

    NASA Astrophysics Data System (ADS)

    Bossioli, E.; Tombrou, M.; Kalogiros, J.; Allan, J.; Bacak, A.; Bezantakos, S.; Biskos, G.; Coe, H.; Jones, B. T.; Kouvarakis, G.; Mihalopoulos, N.; Percival, C. J.

    2016-05-01

    The composition of the atmosphere over the Aegean Sea (AS) during an 'Etesian' outbreak under the influence of biomass burning (BB) activity is investigated. Simulations with the fully coupled WRF-Chem model during the Aegean-GAME campaign (29/8-9/9/2011) are used to examine the BB effect over the region. Two distinct Etesian flow patterns characterized by different transport conditions are analysed. The influence of the off-line calculated BB emissions on the atmospheric chemical composition over the AS under these conditions is estimated. In addition, sensitivity runs are used to examine the influence of the biogenic emissions calculated on-line and the realistic representation of the stratosphere-troposphere exchange processes are investigated through the time-varying chemical boundary conditions from the MOZART global chemical transport model. The horizontal and vertical distributions of gaseous and aerosol species are simulated under long-range transport conditions and interpreted in relation to the evolution of the Planetary Boundary Layer (PBL). In the case of a weaker synoptic system (medium-range transport conditions), even a small variability of meteorological parameters in limited areas become critical for the spatial distribution of gases and aerosols. The BB activity increases O3, PM2.5 and organic matter concentrations up to 5.5 ppb, 5.8 μg m-3 and 3.3 μg m-3, respectively. The spatial extent of the simulated BB plumes is further examined by comparison with airborne measurements of hydrogen cyanide (HCN). The estimated effect of biogenic emissions on O3 and PM2.5 concentrations is either positive or negative (±6 ppb for O3 and up to ± 1 μg m-3 for PM2.5) depending on the emission algorithm employed. The realistic representation of the chemical boundary conditions reproduces an observed layer rich in O3 above 4 km, but also increases O3 concentrations inside the PBL by up to 40%.

  2. The effects of composition, temperature and sample size on the sintering of chem-prep high field varistors.

    SciTech Connect

    Garino, Terry J.

    2007-09-01

    The sintering behavior of Sandia chem-prep high field varistor materials was studied using techniques including in situ shrinkage measurements, optical and scanning electron microscopy and x-ray diffraction. A thorough literature review of phase behavior, sintering and microstructure in Bi{sub 2}O{sub 3}-ZnO varistor systems is included. The effects of Bi{sub 2}O{sub 3} content (from 0.25 to 0.56 mol%) and of sodium doping level (0 to 600 ppm) on the isothermal densification kinetics was determined between 650 and 825 C. At {ge} 750 C samples with {ge}0.41 mol% Bi{sub 2}O{sub 3} have very similar densification kinetics, whereas samples with {le}0.33 mol% begin to densify only after a period of hours at low temperatures. The effect of the sodium content was greatest at {approx}700 C for standard 0.56 mol% Bi{sub 2}O{sub 3} and was greater in samples with 0.30 mol% Bi{sub 2}O{sub 3} than for those with 0.56 mol%. Sintering experiments on samples of differing size and shape found that densification decreases and mass loss increases with increasing surface area to volume ratio. However, these two effects have different causes: the enhancement in densification as samples increase in size appears to be caused by a low oxygen internal atmosphere that develops whereas the mass loss is due to the evaporation of bismuth oxide. In situ XRD experiments showed that the bismuth is initially present as an oxycarbonate that transforms to metastable {beta}-Bi{sub 2}O{sub 3} by 400 C. At {approx}650 C, coincident with the onset of densification, the cubic binary phase, Bi{sub 38}ZnO{sub 58} forms and remains stable to >800 C, indicating that a eutectic liquid does not form during normal varistor sintering ({approx}730 C). Finally, the formation and morphology of bismuth oxide phase regions that form on the varistors surfaces during slow cooling were studied.

  3. DECADE Web Portal: Integrating MaGa, EarthChem and GVP Will Further Our Knowledge on Earth Degassing

    NASA Astrophysics Data System (ADS)

    Cardellini, C.; Frigeri, A.; Lehnert, K. A.; Ash, J.; McCormick, B.; Chiodini, G.; Fischer, T. P.; Cottrell, E.

    2014-12-01

    The release of gases from the Earth's interior to the exosphere takes place in both volcanic and non-volcanic areas of the planet. Fully understanding this complex process requires the integration of geochemical, petrological and volcanological data. At present, major online data repositories relevant to studies of degassing are not linked and interoperable. We are developing interoperability between three of those, which will support more powerful synoptic studies of degassing. The three data systems that will make their data accessible via the DECADE portal are: (1) the Smithsonian Institution's Global Volcanism Program database (GVP) of volcanic activity data, (2) EarthChem databases for geochemical and geochronological data of rocks and melt inclusions, and (3) the MaGa database (Mapping Gas emissions) which contains compositional and flux data of gases released at volcanic and non-volcanic degassing sites. These databases are developed and maintained by institutions or groups of experts in a specific field, and data are archived in formats specific to these databases. In the framework of the Deep Earth Carbon Degassing (DECADE) initiative of the Deep Carbon Observatory (DCO), we are developing a web portal that will create a powerful search engine of these databases from a single entry point. The portal will return comprehensive multi-component datasets, based on the search criteria selected by the user. For example, a single geographic or temporal search will return data relating to compositions of emitted gases and erupted products, the age of the erupted products, and coincident activity at the volcano. The development of this level of capability for the DECADE Portal requires complete synergy between these databases, including availability of standard-based web services (WMS, WFS) at all data systems. Data and metadata can thus be extracted from each system without interfering with each database's local schema or being replicated to achieve integration at

  4. Constraining Black Carbon Aerosol over Asia using OMI Aerosol Absorption Optical Depth and the Adjoint of GEOS-Chem

    NASA Technical Reports Server (NTRS)

    Zhang, Li; Henze, David K.; Grell, Georg A.; Carmichael. Gregory R.; Bousserez, Nicolas; Zhang, Qiang; Torres, Omar; Ahn, Changwoo; Lu, Zifeng; Cao, Junji; Mao, Yuhao

    2015-01-01

    Accurate estimates of the emissions and distribution of black carbon (BC) in the region referred to here as Southeastern Asia (70degE-l50degE, 11degS-55degN) are critical to studies of the atmospheric environment and climate change. Analysis of modeled BC concentrations compared to in situ observations indicates levels are underestimated over most of Southeast Asia when using any of four different emission inventories. We thus attempt to reduce uncertainties in BC emissions and improve BC model simulations by developing top-down, spatially resolved, estimates of BC emissions through assimilation of OMI observations of aerosol absorption optical depth (AAOD) with the GEOS-Chem model and its adjoint for April and October of 2006. Overwhelming enhancements, up to 500%, in anthropogenic BC emissions are shown after optimization over broad areas of Southeast Asia in April. In October, the optimization of anthropogenic emissions yields a slight reduction (1-5%) over India and parts of southern China, while emissions increase by 10-50% over eastern China. Observational data from in situ measurements and AERONET observations are used to evaluate the BC inversions and assess the bias between OMI and AERONET AAOD. Low biases in BC concentrations are improved or corrected in most eastern and central sites over China after optimization, while the constrained model still underestimates concentrations in Indian sites in both April and October, possibly as a. consequence of low prior emissions. Model resolution errors may contribute up to a factor of 2.5 to the underestimate of surface BC concentrations over northern India. We also compare the optimized results using different anthropogenic emission inventories and discuss the sensitivity of top-down constraints on anthropogenic emissions with respect to biomass burning emissions. In addition, the impacts of brown carbon, the formulation of the observation operator, and different a priori constraints on the optimization are

  5. Parameterization of heterogeneous ice nucleation on mineral dust particles: An application in a regional scale model

    NASA Astrophysics Data System (ADS)

    Niemand, M.; Vogel, B.; Vogel, H.; Connolly, P.; Klein, H.; Bingemer, H.; Hoose, C.; Moehler, O.; Leisner, T.

    2010-12-01

    Kleiner Feldberg, where Klein et al. [4] measured a strong increase of aerosol and IN number densities during this period. [1] O. Möhler et al., Atmos. Chem. Phys. 3, 211-223 (2003) [2] P. J. Connolly et al., Atmos. Chem. Phys. 9, 2805-2824 (2009) [3] B. Vogel et al., Atmos. Chem. Phys., 9, 8661-8680 (2009) [4] H. Klein et al., Atmos. Chem. Phys. Discuss., 10, 14993-15022 (2010)

  6. Microstructure of laser clad Ni- Cr- Al- Hf alloy on a γ' strengthened ni- base superalloy

    NASA Astrophysics Data System (ADS)

    Singh, Jogender; Mazumder, J.

    1988-08-01

    Alloys and coatings for alloys for improved high temperature service life under aggressive atmo-spheres are of great contemporary interest. There is a general consensus that the addition of rare earths such as Hf will provide many beneficial effects for such alloys. The laser cladding technique was used to produce Ni-Cr-AI-Hf alloys with extended solid solution of Hf. A 10 kW CO2 laser with mixed powder feed was used for laser cladding. Optical, scanning electron (SEM) and scanning transmission electron (STEM) microscopy were employed to characterize the microstructure of alloys produced during laser cladding processes. Microstructural studies revealed grain refinement, considerable in-crease in solubility of Hf in the matrix, Hf-rich precipitates, and new metastable phases. The size and morphology of γ' (Ni3Al) phase were discussed in relation to its microchemistry and the laser processing conditions. This paper will report the microstructural development in this laser clad Ni-Cr-AI-Hf alloy.

  7. Simulation of atmospheric N2O with GEOS-Chem and its adjoint: evaluation of observational constraints

    NASA Astrophysics Data System (ADS)

    Wells, K. C.; Millet, D. B.; Bousserez, N.; Henze, D. K.; Chaliyakunnel, S.; Griffis, T. J.; Luan, Y.; Dlugokencky, E. J.; Prinn, R. G.; O'Doherty, S.; Weiss, R. F.; Dutton, G. S.; Elkins, J. W.; Krummel, P. B.; Langenfelds, R.; Steele, L. P.; Kort, E. A.; Wofsy, S. C.; Umezawa, T.

    2015-07-01

    We describe a new 4D-Var inversion framework for N2O based on the GEOS-Chem chemical transport model and its adjoint, and apply this framework in a series of observing system simulation experiments to assess how well N2O sources and sinks can be constrained by the current global observing network. The employed measurement ensemble includes approximately weekly and quasi-continuous N2O measurements (hourly averages used) from several long-term monitoring networks, N2O measurements collected from discrete air samples aboard a commercial aircraft (CARIBIC), and quasi-continuous measurements from an airborne pole-to-pole sampling campaign (HIPPO). For a two-year inversion, we find that the surface and HIPPO observations can accurately resolve a uniform bias in emissions during the first year; CARIBIC data provide a somewhat weaker constraint. Variable emission errors are much more difficult to resolve given the long lifetime of N2O, and major parts of the world lack significant constraints on the seasonal cycle of fluxes. Current observations can largely correct a global bias in the stratospheric sink of N2O if emissions are known, but do not provide information on the temporal and spatial distribution of the sink. However, for the more realistic scenario where source and sink are both uncertain, we find that simultaneously optimizing both would require unrealistically small errors in model transport. Regardless, a bias in the magnitude of the N2O sink would not affect the a posteriori N2O emissions for the two-year timescale used here, given realistic initial conditions, due to the timescale required for stratosphere-troposphere exchange (STE). The same does not apply to model errors in the rate of STE itself, which we show exerts a larger influence on the tropospheric burden of N2O than does the chemical loss rate over short (< 3 year) timescales. We use a stochastic estimate of the inverse Hessian for the inversion to evaluate the spatial resolution of emission

  8. Simulation of atmospheric N2O with GEOS-Chem and its adjoint: evaluation of observational constraints

    NASA Astrophysics Data System (ADS)

    Wells, K. C.; Millet, D. B.; Bousserez, N.; Henze, D. K.; Chaliyakunnel, S.; Griffis, T. J.; Luan, Y.; Dlugokencky, E. J.; Prinn, R. G.; O'Doherty, S.; Weiss, R. F.; Dutton, G. S.; Elkins, J. W.; Krummel, P. B.; Langenfelds, R.; Steele, L. P.; Kort, E. A.; Wofsy, S. C.; Umezawa, T.

    2015-10-01

    We describe a new 4D-Var inversion framework for nitrous oxide (N2O) based on the GEOS-Chem chemical transport model and its adjoint, and apply it in a series of observing system simulation experiments to assess how well N2O sources and sinks can be constrained by the current global observing network. The employed measurement ensemble includes approximately weekly and quasi-continuous N2O measurements (hourly averages used) from several long-term monitoring networks, N2O measurements collected from discrete air samples onboard a commercial aircraft (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container; CARIBIC), and quasi-continuous measurements from the airborne HIAPER Pole-to-Pole Observations (HIPPO) campaigns. For a 2-year inversion, we find that the surface and HIPPO observations can accurately resolve a uniform bias in emissions during the first year; CARIBIC data provide a somewhat weaker constraint. Variable emission errors are much more difficult to resolve given the long lifetime of N2O, and major parts of the world lack significant constraints on the seasonal cycle of fluxes. Current observations can largely correct a global bias in the stratospheric sink of N2O if emissions are known, but do not provide information on the temporal and spatial distribution of the sink. However, for the more realistic scenario where source and sink are both uncertain, we find that simultaneously optimizing both would require unrealistically small errors in model transport. Regardless, a bias in the magnitude of the N2O sink would not affect the a posteriori N2O emissions for the 2-year timescale used here, given realistic initial conditions, due to the timescale required for stratosphere-troposphere exchange (STE). The same does not apply to model errors in the rate of STE itself, which we show exerts a larger influence on the tropospheric burden of N2O than does the chemical loss rate over short (< 3 year) timescales. We use a

  9. Source attribution of aerosol size distributions and model evaluation using Whistler Mountain measurements and GEOS-Chem-TOMAS simulations

    NASA Astrophysics Data System (ADS)

    D'Andrea, S. D.; Ng, J. Y.; Kodros, J. K.; Atwood, S. A.; Wheeler, M. J.; Macdonald, A. M.; Leaitch, W. R.; Pierce, J. R.

    2016-01-01

    Remote and free-tropospheric aerosols represent a large fraction of the climatic influence of aerosols; however, aerosol in these regions is less characterized than those polluted boundary layers. We evaluate aerosol size distributions predicted by the GEOS-Chem-TOMAS global chemical transport model with online aerosol microphysics using measurements from the peak of Whistler Mountain, British Columbia, Canada (2182 m a.s.l., hereafter referred to as Whistler Peak). We evaluate the model for predictions of aerosol number, size, and composition during periods of free-tropospheric (FT) and boundary-layer (BL) influence at "coarse" 4° × 5° and "nested" 0.5° × 0.667° resolutions by developing simple FT/BL filtering techniques. We find that using temperature as a proxy for upslope flow (BL influence) improved the model-measurement comparisons. The best threshold temperature was around 2 °C for the coarse simulations and around 6 °C for the nested simulations, with temperatures warmer than the threshold indicating boundary-layer air. Additionally, the site was increasingly likely to be in cloud when the measured relative humidity (RH) was above 90 %, so we do not compare the modeled and measured size distributions during these periods. With the inclusion of these temperature and RH filtering techniques, the model-measurement comparisons improved significantly. The slope of the regression for N80 (the total number of particles with particle diameter, Dp, > 80 nm) in the nested simulations increased from 0.09 to 0.65, R2 increased from 0.04 to 0.46, and log-mean bias improved from 0.95 to 0.07. We also perform simulations at the nested resolution without Asian anthropogenic emissions and without biomass-burning emissions to quantify the contribution of these sources to aerosols at Whistler Peak (through comparison with simulations with these emissions on). The long-range transport of Asian anthropogenic aerosol was found to be significant throughout all particle

  10. Source attribution of aerosol size distributions and model evaluation using Whistler Mountain measurements and GEOS-Chem-TOMAS simulations

    NASA Astrophysics Data System (ADS)

    D'Andrea, S. D.; Ng, J. Y.; Kodros, J. K.; Atwood, S. A.; Wheeler, M. J.; Macdonald, A. M.; Leaitch, W. R.; Pierce, J. R.

    2015-09-01

    Remote and free tropospheric aerosols represent a large fraction of the climatic influence of aerosols; however, aerosol in these regions is less characterized than those polluted boundary layers. We evaluate aerosol size distributions predicted by the GEOS-Chem-TOMAS global chemical transport model with online aerosol microphysics using measurements from the peak of Whistler Mountain, BC, Canada (2182 m a.s.l.). We evaluate the model for predictions of aerosol number, size and composition during periods of free tropospheric (FT) and boundary-layer (BL) influence at "coarse" 4° × 5° and "nested" 0.5° × 0.667° resolutions by developing simple FT/BL filtering techniques. We find that using temperature as a proxy for upslope flow (BL influence) improved the model measurement comparisons. The best threshold temperature was around 2 °C for the coarse simulations and around 6 °C for the nested simulations, with temperatures warmer than the threshold indicating boundary-layer air. Additionally, the site was increasingly likely to be in-cloud when the measured RH was above 90 %, so we do not compare the modeled and measured size distributions during these periods. With the inclusion of these temperature and RH filtering techniques, the model-measurement comparisons improved significantly. The slope of the regression for N80 (the total number of particles with particle diameter, Dp > 80 nm) in the nested simulations increased from 0.09 to 0.65, R2 increased from 0.04 to 0.46, and log-mean bias improved from 0.95 to 0.07. We also perform simulations at the nested resolution without Asian anthropogenic (AA) emissions and without biomass-burning (BB) emissions to quantify the contribution of these sources to aerosols at Whistler Peak (through comparison with simulations with these emissions on). The long-range transport of AA aerosol was found to be significant throughout all particle number concentrations, and increased the number of particles larger than 80 nm (N80

  11. Validating the WRF-Chem model for wind energy applications using High Resolution Doppler Lidar data from a Utah 2012 field campaign

    NASA Astrophysics Data System (ADS)

    Mitchell, M. J.; Pichugina, Y. L.; Banta, R. M.

    2015-12-01

    Models are important tools for assessing potential of wind energy sites, but the accuracy of these projections has not been properly validated. In this study, High Resolution Doppler Lidar (HRDL) data obtained with high temporal and spatial resolution at heights of modern turbine rotors were compared to output from the WRF-chem model in order to help improve the performance of the model in producing accurate wind forecasts for the industry. HRDL data were collected from January 23-March 1, 2012 during the Uintah Basin Winter Ozone Study (UBWOS) field campaign. A model validation method was based on the qualitative comparison of the wind field images, time-series analysis and statistical analysis of the observed and modeled wind speed and direction, both for case studies and for the whole experiment. To compare the WRF-chem model output to the HRDL observations, the model heights and forecast times were interpolated to match the observed times and heights. Then, time-height cross-sections of the HRDL and WRF-Chem wind speed and directions were plotted to select case studies. Cross-sections of the differences between the observed and forecasted wind speed and directions were also plotted to visually analyze the model performance in different wind flow conditions. A statistical analysis includes the calculation of vertical profiles and time series of bias, correlation coefficient, root mean squared error, and coefficient of determination between two datasets. The results from this analysis reveals where and when the model typically struggles in forecasting winds at heights of modern turbine rotors so that in the future the model can be improved for the industry.

  12. ChemCam Exploration of the rocks and soils of Gale Crater from “Rocknest” to “Yellow Knife Bay”

    NASA Astrophysics Data System (ADS)

    Blaney, Diana L.; Clegg, S. M.; Anderson, R.; Wiens, R.; Maurice, S.; Gasnault, O.; Barraclough, B.; Berger, G.; Bridges, J. C.; Bridges, N.; Clark, B.; Dyar, M. D.; Edgar, L.; Ehlmann, B.; Goetz, W.; Kah, L.; King, P.; Lanza, N.; Madsen, M.; LeMouelic, S.; Mangold, N.; Meslin, P. Y.; Newsom, H.; Ollila, A.; Rowland, S.; Schmidt, M.; Schröder, S.; Tokar, R.; MSL Science Team

    2013-10-01

    At the Rocknest location in Gale Crater, ChemCam collected measurements of the rocks surrounding the sandsheet. These rocks are potential in place outcrop related to the larger Yellowknife Bay exposure. ChemCam utilizes Laser Induced Breakdown Spectroscopy to provide elemental composition at distances up to 7 m from the rover. Analysis spot size ranges from 350 μm to 550 μm depending on range. A given analysis spot is fired upon repeatedly by the laser (generally from 30-50 laser shots) and the emission spectra from each laser shots is recorded. Elemental compositions are derived from the spectra vial a Partial Least Squares analysis model based a spectral library of ~70 certified standards collected on the flight instrument before launch. To date more than 60,000 spectra have been obtained on close to 2,000 observation points covering several hundred rock and soil samples. At Rocknest, even though each rock had a variety of textures, the chemistry of each rock varied in a similar manner. The rocks showed no evidence for widespread coatings or rinds. However, there was evidence for calcium sulfate (based on a linear relationship between CaO and SO4), and excess iron oxides (based on increased FeO not associated with SiO2 in specific rock targets). The detection of sulfates, ferric iron oxides and the overall chemistry of the rocks suggest that nearby felsic and olivine-rich material were cemented together by iron oxide cement. Results from the Rocknest area will be compared to other ChemCam results from other rocks at Yellowknife Bay and their geochemical/geological relationship will be presented. Implications for habitability of these deposits will also be discussed. Acknowledgement: This work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration. Funding from the Canadian Space Agency for King and Schmidt.

  13. Evaluating the skill of high-resolution WRF-Chem simulations in describing drivers of aerosol direct climate forcing on the regional scale

    NASA Astrophysics Data System (ADS)

    Crippa, P.; Sullivan, R. C.; Thota, A.; Pryor, S. C.

    2016-01-01

    Assessing the ability of global and regional models to describe aerosol optical properties is essential to reducing uncertainty in aerosol direct radiative forcing in the contemporary climate and to improving confidence in future projections. Here we evaluate the performance of high-resolution simulations conducted using the Weather Research and Forecasting model with coupled with Chemistry (WRF-Chem) in capturing spatiotemporal variability of aerosol optical depth (AOD) and the Ångström exponent (AE) by comparison with ground- and space-based remotely sensed observations. WRF-Chem is run over eastern North America at a resolution of 12 km for a representative year (2008). A systematic positive bias in simulated AOD relative to observations is found (annual mean fractional bias (MFB) is 0.15 and 0.50 relative to MODIS (MODerate resolution Imaging Spectroradiometer) and AERONET, respectively), whereas the spatial variability is well captured during most months. The spatial correlation of observed and simulated AOD shows a clear seasonal cycle with highest correlation during summer months (r = 0.5-0.7) when the aerosol loading is large and more observations are available. The model is biased towards the simulation of coarse-mode aerosols (annual MFB for AE = -0.10 relative to MODIS and -0.59 for AERONET), but the spatial correlation for AE with observations is 0.3-0.5 during most months, despite the fact that AE is retrieved with higher uncertainty from the remote-sensing observations. WRF-Chem also exhibits high skill in identifying areas of extreme and non-extreme aerosol loading, and its ability to correctly simulate the location and relative intensity of extreme aerosol events (i.e., AOD > 75th percentile) varies between 30 and 70 % during winter and summer months, respectively.

  14. Pre-flight calibration and initial data processing for the ChemCam laser-induced breakdown spectroscopy instrument on the Mars Science Laboratory rover

    USGS Publications Warehouse

    Wiens, R.C.; Maurice, S.; Lasue, J.; Forni, O.; Anderson, R.B.; Clegg, S.; Bender, S.; Blaney, D.; Barraclough, B.L.; Cousin, A.; DeFlores, L.; Delapp, D.; Dyar, M.D.; Fabre, C.; Gasnault, O.; Lanza, N.; Mazoyer, J.; Melikechi, N.; Meslin, P.-Y.; Newsom, H.; Ollila, A.; Perez, R.; Tokar, R.; Vaniman, D.

    2013-01-01

    The ChemCam instrument package on the Mars Science Laboratory rover, Curiosity, is the first planetary science instrument to employ laser-induced breakdown spectroscopy (LIBS) to determine the compositions of geological samples on another planet. Pre-processing of the spectra involves subtracting the ambient light background, removing noise, removing the electron continuum, calibrating for the wavelength, correcting for the variable distance to the target, and applying a wavelength-dependent correction for the instrument response. Further processing of the data uses multivariate and univariate comparisons with a LIBS spectral library developed prior to launch as well as comparisons with several on-board standards post-landing. The level-2 data products include semi-quantitative abundances derived from partial least squares regression. A LIBS spectral library was developed using 69 rock standards in the form of pressed powder disks, glasses, and ceramics to minimize heterogeneity on the scale of the observation (350–550 μm dia.). The standards covered typical compositional ranges of igneous materials and also included sulfates, carbonates, and phyllosilicates. The provenance and elemental and mineralogical compositions of these standards are described. Spectral characteristics of this data set are presented, including the size distribution and integrated irradiances of the plasmas, and a proxy for plasma temperature as a function of distance from the instrument. Two laboratory-based clones of ChemCam reside in Los Alamos and Toulouse for the purpose of adding new spectra to the database as the need arises. Sensitivity to differences in wavelength correlation to spectral channels and spectral resolution has been investigated, indicating that spectral registration needs to be within half a pixel and resolution needs to match within 1.5 to 2.6 pixels. Absolute errors are tabulated for derived compositions of each major element in each standard using PLS regression

  15. pH and temperature dual-sensitive liposome gel based on novel cleavable mPEG-Hz-CHEMS polymeric vaginal delivery system

    PubMed Central

    Chen, Daquan; Sun, Kaoxiang; Mu, Hongjie; Tang, Mingtan; Liang, Rongcai; Wang, Aiping; Zhou, Shasha; Sun, Haijun; Zhao, Feng; Yao, Jianwen; Liu, Wanhui

    2012-01-01

    Background In this study, a pH and temperature dual-sensitive liposome gel based on a novel cleavable hydrazone-based pH-sensitive methoxy polyethylene glycol 2000-hydrazone-cholesteryl hemisuccinate (mPEG-Hz-CHEMS) polymer was used for vaginal administration. Methods The pH-sensitive, cleavable mPEG-Hz-CHEMS was designed as a modified pH-sensitive liposome that would selectively degrade under locally acidic vaginal conditions. The novel pH-sensitive liposome was engineered to form a thermogel at body temperature and to degrade in an acidic environment. Results A dual-sensitive liposome gel with a high encapsulation efficiency of arctigenin was formed and improved the solubility of arctigenin characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. The dual-sensitive liposome gel with a sol-gel transition at body temperature was degraded in a pH-dependent manner, and was stable for a long period of time at neutral and basic pH, but cleavable under acidic conditions (pH 5.0). Arctigenin encapsulated in a dual-sensitive liposome gel was more stable and less toxic than arctigenin loaded into pH-sensitive liposomes. In vitro drug release results indicated that dual-sensitive liposome gels showed constant release of arctigenin over 3 days, but showed sustained release of arctigenin in buffers at pH 7.4 and pH 9.0. Conclusion This research has shed some light on a pH and temperature dual-sensitive liposome gel using a cleavable mPEG-Hz-CHEMS polymer for vaginal delivery. PMID:22679372

  16. Pre-flight calibration and initial data processing for the ChemCam laser-induced breakdown spectroscopy instrument on the Mars Science Laboratory rover

    NASA Astrophysics Data System (ADS)

    Wiens, R. C.; Maurice, S.; Lasue, J.; Forni, O.; Anderson, R. B.; Clegg, S.; Bender, S.; Blaney, D.; Barraclough, B. L.; Cousin, A.; Deflores, L.; Delapp, D.; Dyar, M. D.; Fabre, C.; Gasnault, O.; Lanza, N.; Mazoyer, J.; Melikechi, N.; Meslin, P.-Y.; Newsom, H.; Ollila, A.; Perez, R.; Tokar, R. L.; Vaniman, D.

    2013-04-01

    The ChemCam instrument package on the Mars Science Laboratory rover, Curiosity, is the first planetary science instrument to employ laser-induced breakdown spectroscopy (LIBS) to determine the compositions of geological samples on another planet. Pre-processing of the spectra involves subtracting the ambient light background, removing noise, removing the electron continuum, calibrating for the wavelength, correcting for the variable distance to the target, and applying a wavelength-dependent correction for the instrument response. Further processing of the data uses multivariate and univariate comparisons with a LIBS spectral library developed prior to launch as well as comparisons with several on-board standards post-landing. The level-2 data products include semi-quantitative abundances derived from partial least squares regression. A LIBS spectral library was developed using 69 rock standards in the form of pressed powder disks, glasses, and ceramics to minimize heterogeneity on the scale of the observation (350-550 μm dia.). The standards covered typical compositional ranges of igneous materials and also included sulfates, carbonates, and phyllosilicates. The provenance and elemental and mineralogical compositions of these standards are described. Spectral characteristics of this data set are presented, including the size distribution and integrated irradiances of the plasmas, and a proxy for plasma temperature as a function of distance from the instrument. Two laboratory-based clones of ChemCam reside in Los Alamos and Toulouse for the purpose of adding new spectra to the database as the need arises. Sensitivity to differences in wavelength correlation to spectral channels and spectral resolution has been investigated, indicating that spectral registration needs to be within half a pixel and resolution needs to match within 1.5 to 2.6 pixels. Absolute errors are tabulated for derived compositions of each major element in each standard using PLS regression

  17. A Case Study on Observed and Simulated CO2 Concentration Profiles in Hefei based on Raman Lidar and GEOS-Chem Model

    NASA Astrophysics Data System (ADS)

    Wang, Yinan; Lü, Daren; Pan, Weilin; Yuan, Kee

    2016-06-01

    Observations of atmospheric CO2 concentration profiles provide significative constraints on the global/regional inversions of carbon sources and sinks. Anhui Institute of Optics and Fine Mechanics of Chinese Academy of Sciences developed a Raman Lidar system to detect the vertical distribution of atmospheric CO2. This paper compared the observations with the modeled results from a three-dimensional global chemistry transport model-GEOS-Chem, which showed a good agreement in the trend of change with lidar measurements. The case study indicated a potential for better simulating vertical distribution of atmospheric CO2 by combining with lidar measurements.

  18. Comment on ``On the role of dissipation on the Casimir-Polder potential between molecules in dielectric media'' [J. Chem. Phys. 133, 164501 (2010)

    NASA Astrophysics Data System (ADS)

    Dalvit, D. A. R.; Milonni, P. W.

    2011-07-01

    J. J. Rodriguez and A. Salam [J. Chem. Phys. 133, 164501 (2010)], 10.1063/1.3495954 find discrepancies between their calculation and a previously published one [S. Spagnolo, D. A. R. Dalvit, and P. W. Milonni, Phys. Rev. A 75, 052117 (2007)], 10.1103/PhysRevA.75.052117 for the van der Waals interaction of two guest molecules in a host dielectric medium. We trace these discrepancies to what we regard as fundamental errors in the calculation by Rodriguez and Salam.

  19. Sources, seasonality, and trends of Southeast US aerosol: an integrated analysis of surface, aircraft, and satellite observations with the GEOS-Chem chemical transport model

    NASA Astrophysics Data System (ADS)

    Kim, P. S.; Jacob, D. J.; Fisher, J. A.; Travis, K.; Yu, K.; Zhu, L.; Yantosca, R. M.; Sulprizio, M. P.; Jimenez, J. L.; Campuzano-Jost, P.; Froyd, K. D.; Liao, J.; Hair, J. W.; Fenn, M. A.; Butler, C. F.; Wagner, N. L.; Gordon, T. D.; Welti, A.; Wennberg, P. O.; Crounse, J. D.; St. Clair, J. M.; Teng, A. P.; Millet, D. B.; Schwarz, J. P.; Markovic, M. Z.; Perring, A. E.

    2015-07-01

    We use an ensemble of surface (EPA CSN, IMPROVE, SEARCH, AERONET), aircraft (SEAC4RS), and satellite (MODIS, MISR) observations over the Southeast US during the summer-fall of 2013 to better understand aerosol sources in the region and the relationship between surface particulate matter (PM) and aerosol optical depth (AOD). The GEOS-Chem global chemical transport model (CTM) with 25 km × 25 km resolution over North America is used as a common platform to interpret measurements of different aerosol variables made at different times and locations. Sulfate and organic aerosol (OA) are the main contributors to surface PM2.5 (mass concentration of PM finer than 2.5 μm aerodynamic diameter) and AOD over the Southeast US. GEOS-Chem simulation of sulfate requires a missing oxidant, taken here to be stabilized Criegee intermediates, but which could alternatively reflect an unaccounted for heterogeneous process. Biogenic isoprene and monoterpenes account for 60 % of OA, anthropogenic sources for 30 %, and open fires for 10 %. 60 % of total aerosol mass is in the mixed layer below 1.5 km, 20 % in the cloud convective layer at 1.5-3 km, and 20 % in the free troposphere above 3 km. This vertical profile is well captured by GEOS-Chem, arguing against a high-altitude source of OA. The extent of sulfate neutralization (f = [NH4+]/(2[SO42-] + [NO3-])) is only 0.5-0.7 mol mol-1 in the observations, despite an excess of ammonia present, which could reflect suppression of ammonia uptake by organic aerosol. This would explain the long-term decline of ammonium aerosol in the Southeast US, paralleling that of sulfate. The vertical profile of aerosol extinction over the Southeast US follows closely that of aerosol mass. GEOS-Chem reproduces observed total column aerosol mass over the Southeast US within 6 %, column aerosol extinction within 16 %, and space-based AOD within 21 %. The large AOD decline observed from summer to winter is driven by sharp declines in both sulfate and OA from

  20. Impacts of air-sea interactions on regional air quality predictions using WRF/Chem v3.6.1 coupled with ROMS v3.7: southeastern US example

    NASA Astrophysics Data System (ADS)

    He, J.; He, R.; Zhang, Y.

    2015-11-01

    Air-sea interactions have significant impacts on coastal convection and surface fluxes exchange, which are important for the spatial and vertical distributions of air pollutants that affect public health, particularly in densely populated coastal areas. To understand the impacts of air-sea interactions on coastal air quality predictions, sensitivity simulations with different cumulus parameterization schemes and atmosphere-ocean coupling are conducted in this work over southeastern US in July 2010 using the Weather Research and Forecasting Model with Chemistry (WRF/Chem). The results show that different cumulus parameterization schemes can result in an 85 m difference in the domain averaged planetary boundary layer height (PBLH), and 4.8 mm difference in the domain averaged daily precipitation. Comparing to WRF/Chem without air-sea interactions, WRF/Chem with a 1-D ocean mixed layer model (WRF/Chem-OML) and WRF/Chem coupled with a 3-D Regional Ocean Modeling System (WRF/Chem-ROMS) predict the domain averaged changes in the sea surface temperature of 0.1 and 1.0 °C, respectively. The simulated differences in the surface concentrations of ozone (O3) and PM2.5 between WRF/Chem-ROMS and WRF/Chem can be as large as 17.3 ppb and 7.9 μg m-3, respectively. The largest changes simulated from WRF/Chem-ROMS in surface concentrations of O3 and particulate matter with diameter less than and equal to 2.5 μm (PM2.5) occur not only along coast and remote ocean, but also over some inland areas. Extensive validations against observations, show that WRF/Chem-ROMS improves the predictions of most cloud and radiative variables, and surface concentrations of some chemical species such as sulfur dioxide, nitric acid, maximum 1 h and 8 h O3, sulfate, ammonium, nitrate, and particulate matter with diameter less than and equal to 10 μm (PM10). This illustrates the benefits and needs of using coupled atmospheric-ocean model with advanced model representations of air-sea interactions for

  1. Si3AlP: a new promising material for solar cell absorber.

    PubMed

    Yang, Ji-Hui; Zhai, Yingteng; Liu, Hengrui; Xiang, Hongjun; Gong, Xingao; Wei, Su-Huai

    2012-08-01

    First-principles calculations were performed to study the structural and optoelectronic properties of the newly synthesized nonisovalent and lattice-matched (Si(2))(0.6)(AlP)(0.4) alloy (Watkins, T.; et al. J. Am. Chem. Soc.2011, 133, 16212). We found that the most stable structure of Si(3)AlP is a superlattice along the [111] direction with separated AlP and Si layers, which has a similar optical absorption spectrum to silicon. The ordered C1c1-Si(3)AlP is found to be the most stable one among all structures with a basic unit of one P atom surrounded by three Si atoms and one Al atom, in agreement with experimental suggestions. We predict that C1c1-Si(3)AlP has good optical properties, i.e., it has a larger fundamental band gap and a smaller direct band gap than Si; thus, it has much higher absorption in the visible light region. The calculated properties of Si(3)AlP suggest that it is a promising candidate for improving the performance of the existing Si-based solar cells. The understanding on the stability and band structure engineering obtained in this study is general and can be applied for future study of other nonisovalent and lattice-matched semiconductor alloys. PMID:22769022

  2. One decade of space-based isoprene emission estimates: Interannual variations and emission trends between 2005 and 2014

    NASA Astrophysics Data System (ADS)

    Bauwens, Maite; Stavrakou, Trissevgeni; Müller, Jean-François; De Smedt, Isabelle; Van Roozendael, Michel

    2016-04-01

    rainforests of Equatorial Africa and South America. The top-down isoprene fluxes are available at a resolution of 0.5°x0.5° between 2005 and 2014 at the GlobEmission website (http://www.globemission.eu). References: Arneth, A., et al.: Process-based estimates of terrestrial ecosystem isoprene emissions: incorporating the effects of a direct CO 2-isoprene interaction, Atmos. Chem. Phys., 7(1), 31-53, 2007. Arneth, A., et al.: Global terrestrial isoprene emission models: sensitivity to variability in climate and vegetation, Atmos. Chem. Phys., 11(15), 8037-8052, 2011. Bauwens, M., et al.: Satellite-based isoprene emission estimates (2007-2012) from the GlobEmission project, in ACCENT-Plus Symposium 2013 Proceedings., 2014. Stavrakou, T., et al.: Isoprene emissions over Asia 1979 - 2012: impact of climate and land-use changes, Atmos. Chem. Phys., 14(9), 4587-4605, doi:10.5194/acp-14-4587-2014, 2014. Stavrakou, T., et al.: How consistent are top-down hydrocarbon emissions based on formaldehyde observations from GOME-2 and OMI?, Atmos. Chem. Phys., 15(20), 11861-11884, doi:10.5194/acp-15-11861-2015, 2015. Stavrakou, T., et al.: Evaluating the performance of pyrogenic and biogenic emission inventories against one decade of space-based formaldehyde columns, Atmos. Chem. Phys., 9(3), 1037-1060, doi:10.5194/acp-9-1037-2009, 2009.

  3. Accuracy Quantification of the Loci-CHEM Code for Chamber Wall Heat Fluxes in a G02/GH2 Single Element Injector Model Problem

    NASA Technical Reports Server (NTRS)

    West, Jeff; Westra, Doug; Lin, Jeff; Tucker, Kevin

    2006-01-01

    A robust rocket engine combustor design and development process must include tools which can accurately predict the multi-dimensional thermal environments imposed on solid surfaces by the hot combustion products. Currently, empirical methods used in the design process are typically one dimensional and do not adequately account for the heat flux rise rate in the near-injector region of the chamber. Computational Fluid Dynamics holds promise to meet the design tool requirement, but requires accuracy quantification, or validation, before it can be confidently applied in the design process. This effort presents the beginning of such a validation process for the Loci- CHEM CPD code. The model problem examined here is a gaseous oxygen (GO2)/gaseous hydrogen (GH2) shear coaxial single element injector operating at a chamber pressure of 5.42 MPa. The GO2/GH2 propellant combination in this geometry represents one the simplest rocket model problems and is thus foundational to subsequent validation efforts for more complex injectors. Multiple steady state solutions have been produced with Loci-CHEM employing different hybrid grids and two-equation turbulence models. Iterative convergence for each solution is demonstrated via mass conservation, flow variable monitoring at discrete flow field locations as a function of solution iteration and overall residual performance. A baseline hybrid grid was used and then locally refined to demonstrate grid convergence. Solutions were also obtained with three variations of the k-omega turbulence model.

  4. Phase transformation of "chem-prep" PZT 95/5-2Nb HF1035 ceramic under quasi-static loading conditions.

    SciTech Connect

    Montgomery, Stephen Tedford; Lee, Moo Yul; Meier, Diane A.; Hofer, John H.

    2006-07-01

    Specimens of poled and unpoled ''chem-prep'' PNZT ceramic from batch HF1035 were tested under hydrostatic, uniaxial, and constant stress difference loading conditions at -55, 25, and 75 C. The objective of this experimental study was to characterize the mechanical properties and conditions for the ferroelectric (FE) to antiferroelectric (AFE) phase transformations of this ''chem-prep'' PNZT ceramic to aid grain-scale modeling efforts in developing and testing realistic response models for use in simulation codes. As seen from a previously characterized material (batch HF803), poled ceramic from HF1035 was seen to undergo anisotropic deformation during the transition from a FE to an AFE phase. Also, the phase transformation was found to be permanent for the two low temperature conditions, whereas the transformation can be completely reversed at the highest temperature. The rates of increase in the phase transformation pressures with temperature were practically identical for both unpoled and poled PNZT HF1035 specimens. We observed that temperature spread the phase transformation over mean stress analogous to the observed spread over mean stress due to shear stress. Additionally, for poled ceramic samples, the FE to AFE phase transformation was seen to occur when the normal compressive stress, acting perpendicular to a crystallographic plane about the polar axis, equals the hydrostatic pressure at which the transformation otherwise takes place.

  5. ChemTrove: enabling a generic ELN to support chemistry through the use of transferable plug-ins and online data sources.

    PubMed

    Day, Aileen E; Coles, Simon J; Bird, Colin L; Frey, Jeremy G; Whitby, Richard J; Tkachenko, Valery E; Williams, Antony J

    2015-03-23

    In designing an Electronic Lab Notebook (ELN), there is a balance to be struck between keeping it as general and multidisciplinary as possible for simplicity of use and maintenance and introducing more domain-specific functionality to increase its appeal to target research areas. Here, we describe the results of a collaboration between the Royal Society of Chemistry (RSC) and the University of Southampton, guided by the aims of the Dial-a-Molecule Grand Challenge, intended to achieve the best of both worlds and augment a discipline-agnostic ELN, LabTrove, with chemistry-specific functionality and using data provided by the ChemSpider platform. This has been done using plug-in technology to ensure maximum transferability with minimal effort of the chemistry functionality to other ELNs and equally other subject-specific functionality to LabTrove. The resulting product, ChemTrove, has undergone a usability trial by selected academics, and the resulting feedback will guide the future development of the underlying ELN technology. PMID:25679543

  6. Application of WRF/Chem-MADRID and WRF/Polyphemus in Europe - Part 2: Evaluation of chemical concentrations and sensitivity simulations

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Sartelet, K.; Zhu, S.; Wang, W.; Wu, S.-Y.; Zhang, X.; Wang, K.; Tran, P.; Seigneur, C.; Wang, Z.-F.

    2013-07-01

    An offline-coupled model (WRF/Polyphemus) and an online-coupled model (WRF/Chem-MADRID) are applied to simulate air quality in July 2001 at horizontal grid resolutions of 0.5° and 0.125° over Western Europe. The model performance is evaluated against available surface and satellite observations. The two models simulate different concentrations in terms of domainwide performance statistics, spatial distribution, temporal variations, and column abundance. WRF/Chem-MADRID at 0.5° gives higher values than WRF/Polyphemus for the domainwide mean and over polluted regions in Central and southern Europe for all surface concentrations and column variables except for the tropospheric ozone residual (TOR). Compared with observations, WRF/Polyphemus gives better statistical performance for daily HNO3, SO2, and NO2 at the European Monitoring and Evaluation Programme (EMEP) sites, maximum 1 h O3 at the AirBase sites, PM2.5 at the AirBase sites, maximum 8 h O3 and PM10 composition at all sites, column abundance of CO, NO2, TOR, and aerosol optical depth (AOD), whereas WRF/Chem-MADRID gives better statistical performance for NH3, hourly SO2, NO2, and O3 at the AirBase and BDQA (Base de données de la qualité de l'air) sites, maximum 1 h O3 at the BDQA and EMEP sites, and PM10 at all sites. WRF/Chem-MADRID generally reproduces well the observed high hourly concentrations of SO2 and NO2 at most sites except for extremely high episodes at a few sites, and WRF/Polyphemus performs well for hourly SO2 concentrations at most rural or background sites where pollutant levels are relatively low, but it underpredicts the observed hourly NO2 concentrations at most sites. Both models generally capture well the daytime maximum 8 h O3 concentrations and diurnal variations of O3 with more accurate peak daytime and minimal nighttime values by WRF/Chem-MADRID, but neither model reproduces extremely low nighttime O3 concentrations at several urban and suburban sites due to underpredictions of

  7. Application of WRF/Chem-MADRID and WRF/Polyphemus in Europe - Part 2: Evaluation of chemical concentrations, sensitivity simulations, and aerosol-meteorology interactions

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Sartelet, K.; Zhu, S.; Wang, W.; Wu, S.-Y.; Zhang, X.; Wang, K.; Tran, P.; Seigneur, C.; Wang, Z.-F.

    2013-02-01

    An offline-coupled model (WRF/Polyphemus) and an online-coupled model (WRF/Chem-MADRID) are applied to simulate air quality in July 2001 at horizontal grid resolutions of 0.5° and 0.125° over western Europe. The model performance is evaluated against available surface and satellite observations. The two models simulate different concentrations in terms of domainwide performance statistics, spatial distribution, temporal variations, and column abundance. WRF/Chem-MADRID at 0.5° gives higher values than WRF/Polyphemus for the domainwide mean and over polluted regions in central and southern Europe for all surface concentrations and column variables except for TOR. Compared with observations, WRF/Polyphemus gives better statistical performance for daily HNO3, SO2, and NO2 at the EMEP sites, max 1-h O3 at the AirBase sites, PM2.5 at the AirBase sites, max 8-h O3 and PM10 composition at all sites, column abundance of CO, NO2, TOR, and AOD, whereas WRF/Chem-MADRID gives better statistical performance for NH3, hourly SO2, NO2, and O3 at the AirBase and BDQA sites, max 1-h O3 at the BDQA and EMEP sites, and PM10 at all sites. WRF/Chem-MADRID generally reproduces well the observed high hourly concentrations of SO2 and NO2 at most sites except for extremely high episodes at a few sites, and WRF/Polyphemus performs well for hourly SO2 concentrations at most rural or background sites where pollutant levels are relatively low, but it underpredicts the observed hourly NO2 concentrations at most sites. Both models generally capture well the daytime max 8-h O3 concentrations and diurnal variations of O3 with more accurate peak daytime and minimal nighttime values by WRF/Chem-MADRID, but neither models reproduce extremely low nighttime O3 concentrations at several urban and suburban sites due to underpredictions of NOx and thus insufficient titration of O3 at night. WRF/Polyphemus gives more accurate concentrations of PM2.5, and WRF/Chem-MADRID reproduces better the observations

  8. Top-down Estimate of Dust Emissions Through Integration of MODIS and MISR Aerosol Retrievals With the Geos-chem Adjoint Model

    NASA Technical Reports Server (NTRS)

    Wang, Jun; Xu, Xiaoguang; Henze, Daven K.; Zeng, Jing; Ji, Qiang; Tsay, Si-Chee; Huang, Jianping

    2012-01-01

    Predicting the influences of dust on atmospheric composition, climate, and human health requires accurate knowledge of dust emissions, but large uncertainties persist in quantifying mineral sources. This study presents a new method for combined use of satellite-measured radiances and inverse modeling to spatially constrain the amount and location of dust emissions. The technique is illustrated with a case study in May 2008; the dust emissions in Taklimakan and Gobi deserts are spatially optimized using the GEOSChem chemical transport model and its adjoint constrained by aerosol optical depth (AOD) that are derived over the downwind dark-surface region in China from MODIS (Moderate Resolution Imaging Spectroradiometer) reflectance with the aerosol single scattering properties consistent with GEOS-chem. The adjoint inverse modeling yields an overall 51% decrease in prior dust emissions estimated by GEOS-Chem over the Taklimakan-Gobi area, with more significant reductions south of the Gobi Desert. The model simulation with optimized dust emissions shows much better agreement with independent observations from MISR (Multi-angle Imaging SpectroRadiometer) AOD and MODIS Deep Blue AOD over the dust source region and surface PM10 concentrations. The technique of this study can be applied to global multi-sensor remote sensing data for constraining dust emissions at various temporal and spatial scales, and hence improving the quantification of dust effects on climate, air quality, and human health.

  9. The EnVision++ system: a new immunohistochemical method for diagnostics and research. Critical comparison with the APAAP, ChemMate, CSA, LABC, and SABC techniques.

    PubMed Central

    Sabattini, E; Bisgaard, K; Ascani, S; Poggi, S; Piccioli, M; Ceccarelli, C; Pieri, F; Fraternali-Orcioni, G; Pileri, S A

    1998-01-01

    AIM: To assess a newly developed immunohistochemical detection system, the EnVision++. METHODS: A large series of differently processed normal and pathological samples and 53 relevant monoclonal antibodies were chosen. A chessboard titration assay was used to compare the results provided by the EnVision++ system with those of the APAAP, CSA, LSAB, SABC, and ChemMate methods, when applied either manually or in a TechMate 500 immunostainer. RESULTS: With the vast majority of the antibodies, EnVision++ allowed two- to fivefold higher dilutions than the APAAP, LSAB, SABC, and ChemMate techniques, the staining intensity and percentage of expected positive cells being the same. With some critical antibodies (such as the anti-CD5), it turned out to be superior in that it achieved consistently reproducible results with differently fixed or overfixed samples. Only the CSA method, which includes tyramide based enhancement, allowed the same dilutions as the EnVision++ system, and in one instance (with the anti-cyclin D1 antibody) represented the gold standard. CONCLUSIONS: The EnVision++ is an easy to use system, which avoids the possibility of disturbing endogenous biotin and lowers the cost per test by increasing the dilutions of the primary antibodies. Being a two step procedure, it reduces both the assay time and the workload. Images PMID:9797726

  10. in Silico analysis of Escherichia coli polyphosphate kinase (PPK) as a novel antimicrobial drug target and its high throughput virtual screening against PubChem library

    PubMed Central

    Saha, Saurav Bhaskar; Verma, Vivek

    2013-01-01

    Multiple drug resistance (MDR) in bacteria is a global health challenge that needs urgent attention. The 2011 outbreak caused by Escherichia coli O104:H4 in Europe has exposed the inability of present antibiotic arsenal to tackle the problem of antimicrobial infections. It has further posed a tremendous burden on entire pharmaceutical industry to find novel drugs and/or drug targets. Polyphosphate kinase (PPK) in bacteria plays a crucial role in helping latter to adapt to stringent conditions of low nutritional availability thus making it a good target for antibacterials. In spite of this critical role, to best of our knowledge no in-silico work has been carried out to develop PPK as an antibiotic target. In the present study, virtual screening of PPK was carried out against all the 3D compounds with pharmacological action present in PubChem database. Our screening results were further refined by interaction maps to eliminate the false positive data respectively. From our results, compound number 5281927 (PubChem ID) has been found to have significant affinity towards affinity towards PPK active ATP-binding site indicating its therapeutic relevance. PMID:23861568

  11. Impact of chemical and meteorological boundary and initial conditions on air quality modeling: WRF-Chem sensitivity evaluation for a European domain

    NASA Astrophysics Data System (ADS)

    Ritter, Mathias; Müller, Mathias D.; Jorba, Oriol; Parlow, Eberhard; Liu, L.-J. Sally

    2013-01-01

    This study evaluates the impact of different chemical and meteorological boundary and initial conditions on the state-of-the-art Weather Research and Forecasting (WRF) model with its chemistry extension (WRF-Chem). The evaluation is done for July 2005 with 50 km horizontal resolution. The effect of monthly mean chemical boundary conditions derived from the chemical transport model LMDZ-INCA on WRF-Chem is evaluated against the effect of the preset idealized profiles. Likewise, the impact of different meteorological initial and boundary conditions (GFS and Reanalysis II) on the model is evaluated. Pearson correlation coefficient between these different runs range from 0.96 to 1.00. Exceptions exists for chemical boundary conditions on ozone and for meteorological boundary conditions on PM10, where coefficients of 0.90 were obtained. Best results were achieved with boundary and initial conditions from LMDZ-INCA and GFS. Overall, the European simulations show encouraging results for observed air pollutant, with ozone being the most and PM10 being the least satisfying.

  12. Sensitivity Analysis of PM2.5 in Seoul to Emissions and Reaction Rates Using the GEOS-Chem and its Adjoint Model

    NASA Astrophysics Data System (ADS)

    Lee, H. M.; Park, R.; Henze, D. K.; Shim, C.; Shin, H. J.; Song, I. H.; Park, J. S.; Park, S. M.; Moon, K. J.

    2015-12-01

    The sources of PM2.5 are poorly quantified in Seoul, Korea, where tens of millions of populations are daily exposed to the exceedance of PM2.5 concentrations to the air quality criteria. We used