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Coal log pipeline research at University of Missouri. 3rd quarterly report for 1995, July 1, 1995--September 30, 1995

Description: During this quarter (1/1/95-9/30/95), major progress has been made in the following areas of coal log pipeline research, development and technology transfer: (1) Conceptual design of a test machine based on hydraulic presses to mass-produce 5.4-inch-diameter coal logs for testing in a 6-inch-diameter pipeline has been completed. (2) Conceptual design of a rotary-press machine to produce 1.9-inch-diameter coal logs for testing in a 2-inch-diameter pipeline has also been completed. (3) It has been confirmed through experiments that molds with round-edge exit can make logs as good as those made with tapered exit. (4) Conducted a study to determine the effect of surface condition of mold and lubricants on the quality of coal logs. (5) Completed an evaluation of the effect of fiber (wood pulp) on coal log quality. (6) Prepared an apparatus for testing fast compaction of coal logs -- 2 second per log. (7) Compacted coal logs in a 5.3-inch-diameter mold. (8) Completed a preliminary study to assess vacuum and steam heating systems to enhance coal log production and quality. (9) Changed the small-scale-CLP-demo loop from a once-through system to a recirculating system. (10) Completed revision of CLP economic model and revised the 1993 report.
Date: December 31, 1995
Creator: Liu, H.
Partner: UNT Libraries Government Documents Department

A brief review of bacterial transport in natural porous media

Description: This report reviews advances in the descriptions of microbial transport processes. The advances can often be translated into technological advances for solute transport, with potential applicability to a number of subsurface concerns related to solutes. The processes involved in microbial transport include physically controlled processes, chemically controlled processes, and biologically controlled processes. The physical processes involved in the transport of microbes include advection, diffusion, dispersion, straining, filtration, and exclusion. Biomass removal by chemical reactions has received less attention, and included electrostatic attraction and hydrophobic sorption. In addition, microbiologic processes affecting the fate and transport of microbes in the subsurface include growth and decay; motility and chemotaxis; biological adhesion; and predation. Interdependencies among these processes arise through coupling, e.g., as multiscale mixing in heterogeneous environments affects nutrient availability (growth) and filtration velocities (attachment).
Date: December 1, 1995
Creator: Ginn, T.R.
Partner: UNT Libraries Government Documents Department

Measurements of the diffusion of iron and carbon in single crystal NiAl using ion implantation and secondary ion mass spectrometry

Description: Classical diffusion measurements in intermetallic compounds are often complicated by low diffusivities or low solubilities of the elements of interest. Using secondary ion mass spectrometry for measurements over a relatively shallow spatial range may be used to solve the problem of low diffusivity. In order to simultaneously obtain measurements on important impurity elements with low solubilities, the authors have used ion implantation to supersaturate a narrow layer near the surface. Single crystal NiAl was implanted with either {sup 12}C or both {sup 56}Fe and {sup 12}C in order to investigate the measurement of substitutional (Fe) versus interstitial (C) tracer diffusion and the cross effect of both substitutional and interstitial diffusion. When C alone was implanted negligible diffusion was observed over the range of times and temperatures investigated. When both Fe and C were implanted together significantly enhanced diffusion of the C was observed, which is apparently associated with the movement of Fe. This supports one theory of dynamic strain aging in Fe alloys NiAl.
Date: December 31, 1998
Creator: Hanrahan, R.J. Jr.; Withrow, S.P. & Puga-Lambers, M.
Partner: UNT Libraries Government Documents Department

Optical assessment of large marine particles: development of an imaging and analysis system for quantifying large particle distributions and fluxes. Annual report, 1993-1994

Description: The central goal of DOE`s Ocean Margin Program (OMP) is to determine whether continental shelves are quantitatively significant in removing carbon dioxide from the atmosphere and isolating it via burial in sediments or exporting it to the open ocean (Program Announcement, 1991). A major component of the OMP will be to measure carbon flux on the shelf and across the shelf to the slope and open ocean. In the first round of OMP funding we proposed to develop an optical instrument package and the analytical techniques to measure a wide spectrum of the large aggregate population of particles in the shelf/slope environment. This particle population, encompassing the ``marine snow`` size particles (diameters > 0.5 mm), is thought to be the major pathway of material flux in the ocean (McCave, 1975; Asper, 1987; Walsh and Gardner, 1992). The overall objective of this proposal was to develop an instrument package and the analytical techniques to precisely measure a wide spectrum of the large aggregate population of particles in the shelf/slope environment at a rate sufficient to integrate the observed particle distributions into the coupled physical and biogeochemical models necessary to understand the shelf and slope as a system. We envisioned three stages of development of the instrument package: (1) design, assembly, and laboratory testing of all components and the package as a whole, (2) a short period of laboratory and field testing of the instrument package to determine the best operational parameters, and (3) operations within a framework of complementary analytical sampling such as an appropriate process study funded under the OMP. The first two stages were covered by this proposal. A renewal proposal follows to cover the third stage. 6 figs.
Date: December 31, 1994
Creator: Walsh, I. D. & Gardner, W. D.
Partner: UNT Libraries Government Documents Department

Particle filtration: An analysis using the method of volume averaging

Description: The process of filtration of non-charged, submicron particles is analyzed using the method of volume averaging. The particle continuity equation is represented in terms of the first correction to the Smoluchowski equation that takes into account particle inertia effects for small Stokes numbers. This leads to a cellular efficiency that contains a minimum in the efficiency as a function of the particle size, and this allows us to identify the most penetrating particle size. Comparison of the theory with results from Brownian dynamics indicates that the first correction to the Smoluchowski equation gives reasonable results in terms of both the cellular efficiency and the most penetrating particle size. However, the results for larger particles clearly indicate the need to extend the Smoluchowski equation to include higher order corrections. Comparison of the theory with laboratory experiments, in the absence of adjustable parameters, provides interesting agreement for particle diameters that are equal to or less than the diameter of the most penetrating particle.
Date: December 1, 1994
Creator: Quintard, M. & Whitaker, S.
Partner: UNT Libraries Government Documents Department

Concentrations of a water soluble, gas-phase mercury species in ambient air: Results from measurements and modeling

Description: There are few reliable data on the speciation of Hg in ambient air, although this information is critical to understanding the fate of Hg once released from point sources. The water soluble species of Hg that are thought to exist in flue gases would be subject to far greater local removal rates than is elemental Hg vapor, but methods are lacing to quantify this species. The authors developed a method using refluxing mist chambers to measure the airborne concentrations of reactive gaseous mercury (RGM) in short-term samples under ambient conditions. The method exhibits an effective detection limit of 0.02 ng/m{sup 3} and a precision for ambient concentration levels of {+-}20--30%. Using a model that simulates atmospheric transport and fate of anthropogenic mercury emissions over the contiguous United States, the authors generated 24-hr RGM concentrations to compare to the measurement data. The average RGM concentrations measured with their mist chambers at sites in Tennessee (TN) and Indiana (IN) were 0.065 ng/m{sup 3} and 0.100 ng/m{sup 3}, respectively. These averages represent about 3% of total gaseous mercury (TGM), and RGM generally exceeds regional particulate Hg. The 24-hr model-simulated RGM concentration averages in the modeling grid cells representing TN and IN are 0.051 ng/m{sup 3} and 0.098 ng/m{sup 3} respectively, in good agreement with the data. The measured concentrations at the two sites exhibit weak positive correlations with temperature, solar radiation, O{sub 3}, SO{sub 2}, and TGM. These concentrations are high enough to suggest that RGM can play an important role in both wet and dry deposition on a regional scale.
Date: December 31, 1997
Creator: Lindberg, S. E.; Stratton, W. J.; Pai, P. & Allan, M. A.
Partner: UNT Libraries Government Documents Department

Gradient-Drive Diffusion of Multi-Atom Molecules Through Macromolecules and Membranes: LDRD 96-0021 Close-Out Report

Description: The goals of this Laboratory Directed Research and Development (LDRD) effort were to develop and prototype a new molecular simulation method and companion parallel algorithm able to model diffusion of multi-atom molecules through macromolecules under conditions of a chemical potential gradient. At the start of the project no such method existed, thus many important industrial and technological materials problems where gradient driven diffusion of multi-atom molecules is the predominant phenomenon were beyond the reach of molecular simulation (e.g. diffusion in polymers, a fundamental problem underlying polymer degradation in aging weapons).
Date: December 1, 1998
Creator: Ford, D.M.; Heffelfinger, G.S.; Martin, M.G. & Thompson, A.
Partner: UNT Libraries Government Documents Department

Beam Tools for Geant4 (User's Guide)

Description: Geant4 is a tool kit developed by a collaboration of physicists and computer professionals in the high energy physics field for simulation of the passage of particles through matter. The motivation for the development of the Beam Tools is to extend the Geant4 applications to accelerator physics. The Beam Tools are a set of C++ classes designed to facilitate the simulation of accelerator elements: r.f. cavities, magnets, absorbers, etc. These elements are constructed from Geant4 solid volumes like boxes, tubes, trapezoids, or spheers. There are many computer programs for beam physics simulations, but Geant4 is ideal to model a beam through a material or to integrate a beam line with a complex detector. There are many such examples in the current international High Energy Physics programs. For instance, an essential part of the R&D associated with the Neutrino Source/Muon Collider accelerator is the ionization cooling channel, which is a section of the system aimed to reduce the size of the muon beam in phase space. The ionization cooling technique uses a combination of linacs and light absorbers to reduce the transverse momentum and size of the beam, while keeping the longitudinal momentum constant. The MuCool/MICE (muon cooling) experiments need accurate simulations of the beam transport through the cooling channel in addition to a detailed simulation of the detectors designed to measure the size of the beam. The accuracy of the models for physics processes associated with muon ionization and multiple scattering is critical in this type of applications. Another example is the simulation of the interaction region in future accelerators. The high luminosity and background environments expected in the Next Linear Collider (NLC) and the Very Large Hadron Collider (VLHC) pose great demand on the detectors, which may be optimized by means of a simulation of the detector-accelerator interface.
Date: December 2, 2002
Creator: V.Daniel Elvira, Paul Lebrun and Panagiotis Spentzouris
Partner: UNT Libraries Government Documents Department

Test Plan and Test Specifications for Unloading LR-56 Waste at the 204-AR Waste Unloading Facility

Description: The LR-56 cask is an International Atomic Energy Agency (IAEA), type B (U) certified Medium to High Level Radioactive Liquid Waste Transport Cask. The LR-56 consists of a trailer equipped with the following component and systems: cubic meter lead shielded cask; Self-contained ventilation system including an air pressure/vacuum pump for cask loading and unloading; Waste temperature, level, leak detection, and other surveillance equipment; Control room for control of loading and unloading operations and waste surveillance; Hoist system for removing well caps on the cask; Power connection and control connections for operating the cask from a remote facility; The cask may be unloaded or loaded using either the onboard pressure/vacuum pump or by an external waste transfer pump. Rinse heads and connections allow the cask to be rinsed using supplied rinse water. The cask was designed to be vented using the LR-56 onboard ventilation system, which is connected to the cask via a hose through a penetration in the cask. Three wells located on the top of the cask, offer valved penetrations into the cask for venting, waste pumping, and rinsing. Other penetrations in the cask enable surveillance instrumentation to be used to monitor inside the cask. To date, the LR-56 cask system at the Hanford facility has not been used. Since the vessel has never received radioactive waste, the LR-56 is not yet a regulated system. It is desired to use the LR-56 cask to transport waste in calendar year 2000.
Date: December 3, 2000
Creator: BROWN, T.M.
Partner: UNT Libraries Government Documents Department

Final report for Grant No. DOE/DE-FG02-98ER14909: Experimental and modeling studies of nanometer aerosol filtration

Description: The primary objective is to perform a fundamental study of filtration of nanoparticles, and to obtain filtration knowledge necessary to design particle collection devices/systems for nanoparticle processing and for preventing nanoparticle emissions into the environment. The research covered a wide area relevant to nanoparticle filtration, under these main topics: (1) nanoparticle filtration and molecular dynamics simulation, (2) nanoparticle virtual impactor, (3) particle transport under low pressure, and (4) development of a high-throughput nanoparticle generator. A number of novel tools and numerical models have been developed under the DOE support.
Date: December 10, 2002
Creator: Pui, David Y. H. & Chen, Da-Ren
Partner: UNT Libraries Government Documents Department

Final Project Report

Description: This report provides a description of the main accomplishments of the EMSP funded research, including products such as conference presentations and publications (including those still in preparation). The purpose of this study was to better understand the chemical interactions between dissolved aqueous contaminants and carbonate minerals occurring as coatings on mineral grains in the vadose zone beneath the Hanford reserve. This information is important for construction of improved reactive transport models intended to predict the subsurface migration of contaminants. We made improvements to the hydrothermal atomic force microscope (HAFM) design to be used in this project. The original HAFM was built with funding from the U.S. DOE, Office of Basic Energy Sciences. Improvements include operating limits of 70 bars and 170 C, from an original limit of 12 bars and 150 C. This product is patented. We completed a series of studies of magnesite, MgCO3, because this mineral is structurally equivalent to calcite but reacts much more slowly, allowing us to study carbonate reactivity under pH conditions (i.e., low pH) that are much more problematic for studies of calcite but which are nevertheless relevant to in-situ conditions. We found that dissolving magnesite exhibits a dramatic change in step orientation, and therefore etch pit shape, as pH is lowered through 4.2 to 3 and 2. This change in step orientation is NOT accompanied by an increase in step velocity with decreasing pH. We also found that, after growing magnesite on a magnesite substrate, the newly grown magnesite dissolved much more readily than the underlying substrate magnesite, and exhibited far larger etch pit densities. This effect may have been related to the rate of growth or to the presence of an Fe impurity in the growth solutions. We studied the dissolution of magnesite and calcite (104) surfaces under a wider variety of ...
Date: December 12, 2003
Creator: Eggleston, Carrick M.
Partner: UNT Libraries Government Documents Department

STREAM II-V4: Revision for STREAM II-V3 to Allow Mouse-Driven Selection of Release Location from a Graphical User Interface

Description: STREAM II-V3 is an aqueous transport module of the Savannah River Site emergency response Weather INformation Display (WIND) system. Stream II-V3 predicts peak concentration and peak concentration arrival time at downstream locations for releases from the SRS facilities to the Savannah River. Fifteen pre-determined potential release locations from SRS facilities were built into the current STREAM II-V3 model. Therefore, STREAM II-V3 can not be used for situations in which release locations differ from the fifteen pre-determined locations. To eliminate this limitation, STREAM II-V3 was upgraded. The revised STREAM II-V4 allows users to select the release location anywhere along the specified SRS main streams or the Savannah River by mouse clicking on a map displayed on the computer monitor.
Date: December 18, 2002
Creator: Chen, K.F.
Partner: UNT Libraries Government Documents Department

Underground Test Area Subproject Phase I Data Analysis Task. Volume V - Transport Parameter and Source Term Data Documentation Package

Description: Volume V of the documentation for the Phase I Data Analysis Task performed in support of the current Regional Flow Model, Transport Model, and Risk Assessment for the Nevada Test Site Underground Test Area Subproject contains the transport parameter and source term data. Because of the size and complexity of the model area, a considerable quantity of data was collected and analyzed in support of the modeling efforts. The data analysis task was consequently broken into eight subtasks, and descriptions of each subtask's activities are contained in one of the eight volumes that comprise the Phase I Data Analysis Documentation.
Date: December 1, 1996
Partner: UNT Libraries Government Documents Department

Summary Report of two-Dimensional Analysis of Radiochemical Assay Samples

Description: The ''Summary Report of Two-Dimensional Analysis of Radiochemical Assay Samples'' report provides a summary of the analyses comparing calculated isotopics generated by a point-depletion code that uses one-dimensional (1-D) neutron transport theory weighted cross-sections (SAS2H Control Module of the SCALE Modular Code System) and a two-dimensional (2-D) depletion code (GRCASMO3) with that of radiochemical assay (RCA) results.
Date: December 3, 2001
Creator: Connell, C. & Scaglione, J.M.
Partner: UNT Libraries Government Documents Department

Criteria for onsite transfers of radioactive material

Description: A general description of the requirements for making onsite transfers of radioactive material is provided in Chapter 2, along with the required sequencey of activities. Various criteria for package use are identified in Chapters 3-13. These criteria provide protection against undue radiation exposure. Package shielding, containment, and surface contamination requirements are established. Criteria for providing criticality safety are enumerated in Chapter 6. Criteria for providing hazards information are established in Chapter 13. A glossary is provided.
Date: December 31, 1992
Creator: Opperman, E.K.; Jackson, E.J. & Eggers, A.G.
Partner: UNT Libraries Government Documents Department

Baseline risk assessment of ground water contamination at the uranium mill tailings site near Lakeview, Oregon. Revision 1

Description: Surface cleanup at the Uranium Mill Tailings Remedial Action (UMTRA) Project site near Lakeview, Oregon was completed in 1989. The Ground Water Project evaluates the nature and extent of ground water contamination that resulted from the uranium ore processing activities. The Ground Water Project is in its beginning stages. Human health may be at risk from exposure to ground water contaminated by uranium ore processing. Exposure could occur by drinking water pumped out of a hypothetical well drilled in the contaminated areas. Ecological risks to plants or animals may result from exposure to surface water and sediment that have received contaminated ground water. A risk assessment describes a source of contamination, how that contamination reaches people and the environment, the amount of contamination to which people or the ecological environment may be exposed, and the health or ecological effects that could result from that exposure. This risk assessment is a site-specific document that will be used to evaluate current and potential future impacts to the public and the environment from exposure to contaminated ground water. The results of this evaluation and further site characterization will determine whether any action is needed to protect human health or the ecological environment.
Date: December 1, 1995
Partner: UNT Libraries Government Documents Department

Simulation and analysis of the plutonium shipping container subject to 30-foot drops

Description: The shipping container 5320 is a shipping package for radioactive materials. In order to maintain the component in this packaging within the sub-critical state when subjected to any kind of Hypothetical Accident conditions (HAC), this Type B packaging is designed with various impact limiters. The present study is to examine the energy absorbing capacity of the impact limiter design of this container subjected to a 30-foot drop onto a flat unyielding horizontal surface in each of the three critical dropping orientations. This paper presents the results of a three dimensional nonlinear dynamic impact analysis. This analysis shows the deformed configuration of the container caused by the impact and also determines the effects of different stress wave paths in three distinct drops on the stress states in the critical component. The solution to the problem was obtained using the ABAQUS (explicit) finite element computer code. The nonlinearity of this analysis involves large structural deformation, elasto-plastic materials with strain hardening as well as multiple contact interfaces. Three drop orientations were studied, namely, top down impact, bottom down impact and side impact. Results will be compared against actual drop test data.
Date: December 31, 1995
Creator: Gong, C.; Gupta, N.K. & Gromada, R.J.
Partner: UNT Libraries Government Documents Department

Identification and characterization of conservative organic tracers for use as hydrologic tracers for the Yucca Mountain site characterization study. Progress report, October 1, 1994--December 31, 1994

Description: The bromide anion has been used extensively as a tracer for mapping the flow of groundwater. It has proven to be both a safe and reliable groundwater tracer. The goal in this study is to find several tracing compounds with characteristics similar to the bromide anion to be used in multiple well tracing tests. Four groups of fluorinated organic acids were selected as candidates for groundwater tracers. These groups include fluorinated benzoic acids (FBA), fluorinated salicylic acids (FSA), fluorinated toluic acids (FTA), and fluorinated cinnamic acids (FCA). These compounds have been shown to move readily with the flow of water and do not adsorb to soil. They are also non-toxic. In this study, the retention of the fluorinated organic acids on to a soil column is compared to that of the bromide ion. The time required for the elution of each analyte from the soil column is measured using a UV-Vis detector. The soils consist of the light, medium, and dark tuffs used in the batch study. The work performed during this quarter consists of the continuation of the batch studies for the fluorinated benzoic acids and column studies for several potential tracer compounds.
Date: December 31, 1994
Creator: Stetzenbach, K. & Farnham, I.
Partner: UNT Libraries Government Documents Department

Functional description for the Worldwide Port System (WPS) Regional Integrated Cargo Database (ICDB)

Description: This Functional Description for the Worldwide Port System (WPS) Regional Integrated Cargo Database (ICDB) documents the purpose of and requirements for the ICDB in order to ensure a mutual understanding between the development group and the user group of the system. This Functional Description defines ICDB and provides a clear statement of the initial operational capability to be developed.
Date: December 15, 1995
Creator: Truett, L.F.; Rollow, J.P.; Shipe, P.C.; Faby, E.Z.; Fluker, J.; Hancock, W.R. et al.
Partner: UNT Libraries Government Documents Department

Production of x-rays by the interaction of charged particle beams with periodic structures and crystalline materials

Description: The authors describe their recent experimental study of the production of x-rays by an electron beam interacting with a crystal lattice, i.e. parametric x-ray (PX) generation. In this radiation process, the virtual photon field associated with a relativistic electron traveling in a crystal is diffracted by the crystal lattice in the same way that real x-rays are diffracted by crystals. The radiation produced satisfies the Bragg condition associated with the diffraction of the virtual photons which are nearly parallel to the velocity of the electrons. This phenomenon is associated with a more general class of radiation production mechanisms which include transition radiation (TR), diffraction radiation (DR), and Smith-Purcell radiation. In each case, radiation is produced when the particle`s fields are altered by interacting with a material whose dielectric constant varies along or near the particle`s trajectory. The usual acceleration mechanism for the production of radiation is not involved in these phenomena. In the case of a crystal, the periodic electric susceptibility interacting with the particle`s field produces parametric x-rays. They will also present a theoretical overview of this phenomenon which can be used to generate monochromatic, linearly polarized, directional x-rays. Accelerators with energies ranging from a few MeV to hundreds of MeV may be used as drivers for novel parametrix x-ray generators for various applications requiring the unique properties of these sources.
Date: December 31, 1991
Creator: Rule, D.W.; Fiorito, R.B.; Piestrup, M.A.; Gary, C.K. & Maruyama, X.K.
Partner: UNT Libraries Government Documents Department

Metal ion complexation by ionizable crown ethers. Final report, January 1, 1988--June 30, 1994

Description: During the report period a variety of new lipophilic ionizable crown ethers with pendent proton-ionizable groups has been synthesized. The ligands possess one or more ionizable group (carboxylic acid, phosphonic acid monoethyl ester, para-nitrophenol, phosphonic acid) attached to crown ether, monoazacrown ether or diazacrown ether frameworks. These novel chelating agents have either pendent or inward-facing proton-ionizable groups. Such lipophilic proton-ionizable crown ethers are designed for use in multiphase metal ion separations (solvent extraction, liquid membrane transport). In addition a series of proton-ionizable crown ethers without lipophilic groups was prepared to study how structural variations within the ligand influence metal ion complexation in homogeneous media as assessed by NMR spectroscopy or titration calorimetry. A third class of new metal ion-complexing agents is a series of lipophilic acyclic polyether dicarboxylic acids. Competitive solvent extractions of alkali metal and alkaline earth cations and of the mixed species have been conducted to reveal the influence of ring size, nature and attachment site of the lipophilic group, sidearm length, and proton-ionizable group identity and location upon the selectivity and efficiency of metal ion complexation. In addition to such studies of structural variation within the lipophilic proton-ionizable crown ether, the effect of changing the organic solvent and variation of the stripping conditions have been assessed. The influence of structural variations within lipophilic acyclic polyether dicarboxylic acids upon competitive solvent extraction of alkaline earth cations has been probed. Also a new chromogenic, di-ionizable crown ether with extremely high selectivity for Hg{sup 2+} has been discovered.
Date: December 31, 1994
Creator: Bartsch, R. A.
Partner: UNT Libraries Government Documents Department

Inspector General audit report on Transportation Safeguards Division courier work schedules and escort vehicle replacements

Description: The Office of Inspector General`s (OIG) April 1995 report found that couriers received too much overtime and incurred too much unproductive time. This finding occurred because the Transportation Safeguards Division (TSD) employed a traditional work schedule that did not meet the demands of the job. The report recommended implementing an alternative work schedule that corresponded more closely to the couriers` actual work requirements. Management agreed to conduct a comparative analysis of work schedules to evaluate potential savings. The objectives of this audit were to (1) follow up on actions taken as a result of the OIG`s previous report, (2) determine if courier work schedules are cost effective, and (3) determine the cost effectiveness of escort vehicle replacements. The authors recommend: (1) implementing an alternative work schedule for courier which would achieve savings in overtime and unproductive time, while efficiently and cost effectively fulfilling TSD`s mission; (2) reexamining and adjusting the staffing level of each courier section in relation to the workload requirements in the area; and (3) discontinuing payment for travel time between courier lodging and temporary duty stations. The Albuquerque Operations Office agreed with the auditor`s findings and recommendations.
Date: December 1, 1998
Partner: UNT Libraries Government Documents Department

Midtropospheric influences on boundary layer evolution in the Mexico City basin

Description: Mexico City lies in a horseshoe-shaped basin at 2250 m AGL. These authors have simulated the effects of thermally-forced local to regional-scale circulation patterns on the ozone distribution within the basin. On most of the case days studied a relationship could be found between the spatial and temporal evolution of wind patterns and ozone concentration, particularly in the southwestern part of the basin. In this paper, the authors focus upon defining the relationship between the vertical structure of the atmosphere, by examining stability and wind shear, and the near surface pollution. This work was prompted by the need to better understand the role of midtropospheric flow in contributing to, or alleviating, the pollution problem in the basin. The role of vertical exchange processes in this locale has so far been only peripherally explored. From this investigation the authors hope to assess the importance of upper level winds in contributing to ventilation of pollutants out of the basin above the mountaintop level, in flushing the polluted airmass out of the basin, and in the development of basin-wide recirculation patterns. The results of preliminary data analyses are described.
Date: December 31, 1998
Creator: Bossert, J.E.; Stalker, J.R. & Langley, D.L.
Partner: UNT Libraries Government Documents Department