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Description: This second annual report summarizes the research performed from 17 April 2004 through 16 April 2005. Major portions of the research in several of the project's current eight tasks have been completed. We have successfully developed the meteorological inputs using the best possible modeling configurations, resulting in improved representation of atmospheric processes. The development of the variable-grid-resolution emissions model, SMOKE-VGR, is also completed. The development of the MAQSIP-VGR has been completed and a test run was performed to ensure the functionality of this air quality model. Thus, the project is on schedule as planned. During the upcoming reporting period, we expect to perform the first MAQSIP-VGR simulations over the Houston-Galveston region to study the roles of the meteorology, offshore emissions, and chemistry-transport interactions that determine the temporal and spatial evolution of ozone and its precursors.
Date: May 13, 2005
Creator: Alapaty, Kiran
Partner: UNT Libraries Government Documents Department

1995 Protocol for Working Group VIII: Influence of environmental changes on climate. US-Russia agreement on cooperation in the field of protection of the environment and natural resources. Final report, January 1, 1994--December 31, 1994

Description: Cooperative research programs of Russia and the United States concerned with global warming and climatic change are briefly described.
Date: May 1, 1995
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

An exploration of measures for comparing measurements with the results from meteorological models for Mexico City

Description: Los Alamos National Laboratory and Instituto Mexicano del Petroleo have completed a joint study of options for improving air quality in Mexico City. We used a three-dimensional, prognostic, higher-order turbulence model for atmospheric circulation (HOTMAC) to treat domains that include an urbanized area. We tested the model against routine measurements and those of a major field program. During the field program, measurements included: (1) lidar measurements of aerosol transport and dispersion, (2) aircraft measurements of winds, turbulence, and chemical species aloft, (3) aircraft measurements of skin temperatures, and (4) Tethersonde measurements of winds and ozone. We made both graphical and statistical comparisons and we have reported some of the comparisons to provide insight into the meaning of statistical parameters including the index of agreement.
Date: December 31, 1995
Creator: Williams, M.D. & Brown, M.J.
Partner: UNT Libraries Government Documents Department

War climate study

Description: This report provides a discussion of the environmental impacts of warfare involving nuclear weapons. The changes in ozone layer, climate, and changes in earth heating (or cooling) caused by nuclear explosions are discussed with possible implications for public health and agricultural activities.
Date: May 2, 1974
Creator: Batzel, R. E.
Partner: UNT Libraries Government Documents Department

Global emissions inventories

Description: Atmospheric chemistry determines the concentrations of most of the important greenhouse gases except for carbon dioxide. The rate of removal of the greenhouse gases from the atmosphere is also controlled by atmospheric chemistry. The indirect effects of chemical forcing resulting from the chemical interactions of other species can also affect the concentrations of radiatively important gases such as ozone. In order to establish the contribution of any possible climatic change attributable to individual greenhouse gases, spatially and temporally resolved estimates of their emissions need to be established. Unfortunately, for most of the radiatively important species the global magnitudes of their individual fluxes are not known to better than a factor of two and their spatial distributions are even more poorly characterized. Efforts to estimate future projections of potential impacts and to monitor international agreements will require continued research to narrow the uncertainties of magnitude and geographical distribution of emissions.
Date: July 1, 1995
Creator: Dignon, J.
Partner: UNT Libraries Government Documents Department

Atmospheric radiation measurement program facilities newsletter, June 2002.

Description: ARM Intensive Operational Period Scheduled to Validate New NASA Satellite--Beginning in July, all three ARM sites (Southern Great Plains [SGP], North Slope of Alaska, and Tropical Western Pacific; Figure 1) will participate in the AIRS Validation IOP. This three-month intensive operational period (IOP) will validate data collected by the satellite-based Atmospheric Infrared Sounder (AIRS) recently launched into space. On May 4, the National Aeronautics and Space Administration (NASA) launched Aqua, the second spacecraft in the Earth Observing System (EOS) series. The EOS satellites monitor Earth systems including land surfaces, oceans, the atmosphere, and ice cover. The first EOS satellite, named Terra, was launched in December 1999. The second EOS satellite is named Aqua because its primary focus is understanding Earth's water cycle through observation of atmospheric moisture, clouds, temperature, ocean surface, precipitation, and soil moisture. One of the instruments aboard Aqua is the AIRS, built by the Jet Propulsion Laboratory, a NASA agency. The AIRS Validation IOP complements the ARM mission to improve understanding of the interactions of clouds and atmospheric moisture with solar radiation and their influence on weather and climate. In support of satellite validation IOP, ARM will launch dedicated radiosondes at all three ARM sites while the Aqua satellite with the AIRS instrument is orbiting overhead. These radiosonde launches will occur 45 minutes and 5 minutes before selected satellite overpasses. In addition, visiting scientists from the Jet Propulsion Laboratory will launch special radiosondes to measure ozone and humidity over the SGP site. All launches will generate ground-truth data to validate satellite data collected simultaneously. Data gathered daily by ARM meteorological and solar radiation instruments will complete the validation data sets. Data from Aqua-based instruments, including AIRS, will aid in weather forecasting, climate modeling, and greenhouse gas studies. These instruments will provide more accurate, detailed global observations of ...
Date: July 3, 2002
Creator: Holdridge, D. J.
Partner: UNT Libraries Government Documents Department

Local and global effects on ozone from Titan rocket exhaust and deorbiting spacecraft debris

Description: Both the launching and deorbiting of spacecraft introduce foreign material directly into the stratosphere, a region of the atmosphere extending from around 12 to 50km above the earth`s surface. Launching of Titan and similar solid rocket motors adds to the stratospheric inorganic chlorine burden through emissions of HCl, atomic (Cl) and molecular (CL{sub 2}) directly into the stratosphere. Before the exhaust plume disperses, plume concentrations of these species are orders of magnitude above the background values (Denison et al, 1994). Dispersed through the stratosphere over the globe, however, the additional Cl burden is small compared to the background for currently envisioned launch frequencies. Inorganic chlorine is cleared from the atmosphere by wet deposition of HCl in rain after transport processes return air from the stratosphere to the troposphere, with an overall lifetime of a few years. After several year,a continuing fixed injection rate will produce a chlorine enhancement that reaches a steady state, balanced with loss via rainout. We report here on calculations in models in both two- and three dimensions that address three questions in rocket/spacecraft/stratospheric interactions. We have attempted to represent the early evolution (1-50 hours) of a vertical plume in the stratosphere with a Langrangian three- dimensional transport model driven by horizontal winds from a data- assimilating general circulation model. We have also conducted global calculations of the potential steady state effects of Cl injection from a specified rate of continuous launches in a current two- dimensional model of the stratosphere including all known important ozone production and loss processes. And, we have calculated the effect of increasing the steady state particulate surface area density in the stratosphere resulting from particle formation from satellite destruction on reentry.
Date: May 1, 1996
Creator: Connell, P.S.; Walton, J.J.; Penner, J.E. & O`Connor, C.
Partner: UNT Libraries Government Documents Department

OH generation in steam-air pulsed corona

Description: The measurement of OH concentration in a pulsed corona discharge through a steam-air mixture is compared with a chemical kinetics model. The original motivation was to develop a technological hydroxilizer for oxidizing gas pollutants to acids. Time dependent measurements of the 3,064 {angstrom} emission of OH indicate a production of nearly 4 ppm within a spark. This measurement was accomplished by a 1 ns resolution photomultiplier with a 100 {angstrom} filter centered at 3080 {angstrom}. The discharge occurs across a 1 cm coaxial gap between a central anode tube and an outer cylindrical cathode cased in glass and at ground potential. The water-air mixture is of equal proportions and at 1 atmosphere. Pulsed voltage of 38 kV and 60 ns risetime produces a 60 A, 20 ns spark. The model predicts comparable OH production by dissociation in the air-water mixture after 100 ns of 10{sup 12} electrons/cm{sup 3}. The electron density is set to zero during the subsequent 100 {mu}s in the model, and thereafter OH is seen as a short-lived reaction product of HO{sub 2} with O and N atoms. The sequence of reaction is: 100 ns of dissociation to peak OH concentration, 0.2 {mu}s for hydrogen atom loss and HO{sub 2} formation, 20 {mu}s for O atom loss and O{sub 3} formation, beyond 20 {mu}s NO formation from N atoms with OH and HO{sub 2}. In the model HO{sub 2} ultimately decays by slowly forming H{sub 2}O{sub 2}, so it may be viewed as a stable fuel which produces OH when combined with atomic oxygen or nitrogen.
Date: May 1, 1995
Creator: Garcia, M. & Chang, B.
Partner: UNT Libraries Government Documents Department

A search for human influences on the thermal structure of the atmosphere

Description: Several recent studies have compared observed changes in near-surface temperature with patterns of temperature change predicted by climate models in response to combined forcing by carbon dioxide and anthropogenic sulphate aerosols. These results suggest that a combined carbon dioxide + sulphate aerosol signal is easier to identify in the observations than a pattern of temperature change due to carbon dioxide alone. This work compares modelled and observed patterns of vertical temperature change in the atmosphere. Results show that the observed and model-predicted changes in the mid- to low troposphere are in better accord with greenhouse warming predictions when the likely effects of anthropogenic sulphate aerosols and stratospheric ozone reduction are incorporated in model calculations, and that the level of agreement increases with time. This improved correspondence is primarily due to hemispheric-scale temperature contrasts. If current model-based estimates of natural internal variability are realistic, it is likely that the level of time-increasing similarity between modelled and predicted patterns of vertical temperature change is partially due to human activities.
Date: August 1, 1995
Creator: Santer, B.D.; Taylor, K.E. & Penner, J.E.
Partner: UNT Libraries Government Documents Department

Impact of high speed civil transports on stratospheric ozone: A 2-D model investigation

Description: This study investigates the effect on stratospheric ozone from a fleet of proposed High Speed Civil Transports (HSCTs). The new LLNL 2-D operator-split chemical-radiative-transport model of the troposphere and stratosphere is used for this HSCT investigation. This model is integrated in a diurnal manner, using an implicit numerical solver. Therefore, rate coefficients are not modified by any sort of diurnal average factor. This model also does not make any assumptions on lumping of chemical species into families. Comparisons to previous model-derived HSCT assessment of ozone change are made, both to the previous LLNL 2-D model and to other models from the international assessment modeling community. The sensitivity to the NO{sub x} emission index and sulfate surface area density is also explored.
Date: December 1, 1996
Creator: Kinnison, D.E. & Connell, P.S.
Partner: UNT Libraries Government Documents Department

A technique using a stellar spectrographic plate to measure terrestrial ozone column depth

Description: This thesis examines the feasibility of a technique to extract ozone column depths from photographic stellar spectra in the 5000--7000 Angstrom spectral region. A stellar spectrographic plate is measured to yield the relative intensity distribution of a star`s radiation after transmission through the earth`s atmosphere. The amount of stellar radiation absorbed by the ozone Chappuis band is proportional to the ozone column depth. The measured column depth is within 10% the mean monthly value for latitude 36{degree}N, however the uncertainty is too large to make the measurement useful. This thesis shows that a 10% improvement to the photographic sensitivity uncertainty can decrease the column depth uncertainty to a level acceptable for climatic study use. This technique offers the possibility of measuring past ozone column depths.
Date: August 1, 1995
Creator: Wong, A.Y.
Partner: UNT Libraries Government Documents Department

Structure of the tropical lower stratosphere as revealed by three reanalysis data sets

Description: While the skill of climate simulation models has advanced over the last decade, mainly through improvements in modeling, further progress will depend on the availability and the quality of comprehensive validation data sets covering long time periods. A new source of such validation data is atmospheric {open_quotes}reanalysis{close_quotes} where a fixed, state-of-the-art global atmospheric model/data assimilation system is run through archived and recovered observations to produce a consistent set of atmospheric analyses. Although reanalysis will be free of non-physical variability caused by changes in the models and/or the assimilation procedure, it is necessary to assess its quality. A region for stringent testing of the quality of reanalysis is the tropical lower stratosphere. This portion of the atmosphere is sparse in observations but displays the prominent quasi-biennial oscillation (QBO) and an annual cycle, neither of which is fully understood, but which are likely coupled dynamically. We first consider the performance of three reanalyses, from NCEP/NCAR, NASA and ECMWF, against rawinsonde data in depicting the QBO and then examine the structure of the tropical lower stratosphere in NCEP and ECMWF data sets in detail. While the annual cycle and the QBO in wind and temperature are quite successfully represented, the mean meridional circulations in NCEP and ECMWF data sets contain unusual features which may be due to the assimilation process rather than being physically based. Further, the models capture the long-term temperature fluctuations associated with volcanic eruptions, even though the physical mechanisms are not included, thus implying that the model does not mask prominent stratospheric signals in the observational data. We conclude that reanalysis offers a unique opportunity to better understand the dynamics of QBO and can be applied to climate model validation.
Date: May 1, 1996
Creator: Pawson, S. & Fiorino, M.
Partner: UNT Libraries Government Documents Department

O{sub 3} and stratospheric H{sub 2}O radiative forcing resulting from a supersonic jet transport emission scenario

Description: The tropospheric radiative forcing has been calculated for ozone and water vapor perturbations caused by a realistic High Speed Civil Transport (HSCT) aircraft emission scenario. Atmospheric profiles of water vapor and ozone were obtained using the LLNL 2-D chemical-radiative-transport model (CRT) of the global troposphere and stratosphere. IR radiative forcing calculations were made with the LLNL correlated k-distribution radiative transfer model. UV-Visible-Near IR radiative forcing calculations were made with the LLNL two stream solar radiation model. For the case of water vapor the IR and Near IR radiative forcing was determined at five different latitudes and then averaged using an appropriate latitudinal average to obtain the global average value. Global average values of radiative forcing were approximately 1.2--2.6 10{sup {minus}3} W/m{sup 2}, depending on the background atmospheric water vapor profile. This result is consistent with prior published values for a similar aircraft scenario and supports the conclusion that the water vapor climate forcing effect is very small. The radiative forcing in the IR and UV-Visible spectral ranges, due to the ozone perturbation, was calculated for the globally averaged atmosphere. Global average values of the radiative forcing were 0.034 W/m{sup 2} for the UV-Visible spectral range and 0.006 W/m{sup 2} for the IR spectral range (0.04 W/m{sup 2} total). This result is also consistent with the range of published values obtained for a similar HSCT scenario. As was the case for water vapor, the ozone forcing is too small to be of major consequence.
Date: January 1, 1996
Creator: Grossman, A.S.; Kinnison, D.E.; Penner, J.E.; Grant, K.E.; Tamaresis, J. & Connell, P.S.
Partner: UNT Libraries Government Documents Department

LLNL and TRW extend benchmark environmental stress testing for two alternative printed board cleaners

Description: TRW Corporation and LLNL jointly conducted a testing program to evaluate the effectiveness of non-CFC defluxing chemistries on printed boards designed for high reliability military and aerospace applications. TRW assessed existing data for alternative chemistries, selected candidates for further testing, implemented the cleaning processes, and performed ionic conductivity testing on the spent solvents. LLNL designed and fabricated special circuit boards with interdigitated comb patterns to allow insulation resistance (IR) measurements under selected soldered components. LLNL designed the test and measurement setup and conducted accelerated environmental stress testing of flux residues for 28 days following cleaning. Statistical analyses of the IR measurements were correlated with visual observations and spectroscopic (FTIR) measurements. Performance of the alternative chemistries was compared with that of a standard CFC cleaning agent also included in the test program. The program was designed to follow the same environmental stress and electrical measurement requirements as the IPC/DOD/EPA Ad Hoc Solvent Working Group`s benchmark 7-day test plan, but with certain minor modifications and extension to 28 days.
Date: March 1, 1995
Creator: Hersey, R.J. Jr.; Meltzer, M.; Hofstad, H.W.; Lawrence, M.; Sanborn, R. & Arauco, H.
Partner: UNT Libraries Government Documents Department

A methodology for evaluating air pollution strategies to improve the air quality in Mexico City

Description: The Mexico City Air Quality Research Initiative has developed a methodology to assist decision makers in determining optimum pollution control strategies for atmospheric pollutants. The methodology introduces both objective and subjective factors in the comparison of various strategies for improving air quality. Strategies or group of options are first selected using linear programming. These strategies are then compared using Multi-Attribute Decision Analysis. The decision tree for the Multi-Attribute Decision Analysis was generated by a panel of experts representing the organizations in Mexico that are responsible for formulating policy on air quality improvement. Three sample strategies were analyzed using the methodology: one to reduce ozone by 33% using the most cost effective group of options, the second to reduce ozone by 43% using the most cost effective group of options and the third to reduce ozone by 43% emphasizing the reduction of emissions from industrial sources. Of the three strategies, the analysis indicated that strategy 2 would be the preferred strategy for improving air quality in Mexico City.
Date: May 1, 1995
Creator: Barrera-Roldan, A.S.; Guzman, F.; Hardie, R.W. & Thayer, G.R.
Partner: UNT Libraries Government Documents Department

Quantum resonance effects in exchange, photodissociation, and recombination reactions

Description: This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project studied quantum resonance effects on chemical reactions. The authors accurate reactive scattering calculations showed that quantum resonance phenomena dominate most chemical reactions and are essential to any real understanding of reactivity. It was found that, as long-lived metastable states of the colliding system, resonances can decay to reactants, products, or a mixture of both. Only the latter contribute to reaction. Conditions under which resonances can be neglected or treated statistically were studied. Important implications about the mechanism of recombination reactions were discovered, and some remarkable effects of geometric phases on the symmetries and energies of resonances were also discovered. Calculations were completed for the reaction H + O{sub 2} {yields} OH + O, which is the rate limiting step in the combustion of all hydrocarbons and the single most important reaction in all of combustion chemistry.
Date: April 1, 1996
Creator: Pack, R.; Kendrick, B.; Kress, J.; Walker, R.; Hayes, E.; Lagana, A. et al.
Partner: UNT Libraries Government Documents Department

Heterogeneous Chemistry: Understanding Aerosol/Oxidant Interactions

Description: Global radiative forcing of nitrate and ammonium aerosols has mostly been estimated from aerosol concentrations calculated at thermodynamic equilibrium or using approximate treatments for their uptake by aerosols. In this study, a more accurate hybrid dynamical approach (DYN) was used to simulate the uptake of nitrate and ammonium by aerosols and the interaction with tropospheric reactive nitrogen chemistry in a three-dimensional global aerosol and chemistry model, IMPACT, which also treats sulfate, sea salt and mineral dust aerosol. 43% of the global annual average nitrate aerosol burden, 0.16 TgN, and 92% of the global annual average ammonium aerosol burden, 0.29 TgN, exist in the fine mode (D<1.25 {micro}m) that scatters most efficiently. Results from an equilibrium calculation differ significantly from those of DYN since the fraction of fine-mode nitrate to total nitrate (gas plus aerosol) is 9.8%, compared to 13% in DYN. Our results suggest that the estimates of aerosol forcing from equilibrium concentrations will be underestimated. We also show that two common approaches used to treat nitrate and ammonium in aerosol in global models, including the first-order gas-to-particle approximation based on uptake coefficients (UPTAKE) and a hybrid method that combines the former with an equilibrium model (HYB), significantly overpredict the nitrate uptake by aerosols especially that by coarse particles, resulting in total nitrate aerosol burdens higher than that in DYN by +106% and +47%, respectively. Thus, nitrate aerosol in the coarse mode calculated by HYB is 0.18 Tg N, a factor of 2 more than that in DYN (0.086 Tg N). Excessive formation of the coarse-mode nitrate in HYB leads to near surface nitrate concentrations in the fine mode lower than that in DYN by up to 50% over continents. In addition, near-surface HNO{sub 3} and NO{sub x} concentrations are underpredicted by HYB by up to 90% and 5%, respectively. ...
Date: March 14, 2005
Creator: Penner, Joyce E.
Partner: UNT Libraries Government Documents Department

Influence of meteorology in assessing energy externalities: application of the damage function approach

Description: This paper describes a methodology for estimating energy externalities. These externalities are environmental, health, and other damages and benefits that traditionally have not been considered as part of the cost of producing and consuming goods and services. An example of externalities is the effect on human health from exposure to ozone formed by NO{sub x} and other emissions from electric power plants. These damages are valued adversely by individuals (and by society) but are not reflected in the price of electricity. The damage function approach is a methodology which is used for developing quantitative estimates of externalities. This paper describes the five major steps in the damage function approach, focuses on the use of ozone models in that framework, and points out the effects of meteorological variables on estimates of ozone concentrations.
Date: September 14, 1993
Creator: Lee, R.; Miller, R.L. & McIlvaine, C.M.
Partner: UNT Libraries Government Documents Department

Energy and global warming impacts of HFC refrigerants and emerging technologies: TEWI-III

Description: The use of hydrofluorocarbons (BFCs) which were developed as alternative refrigerants and insulating foam blowing agents to replace chlorofluorocarbons (CFCs) is now being affected by scientific investigations of greenhouse warming and questions about the effects of refrigerants and blowing agents on global warming. A Total Equivalent Warming Impact (TEWI) assessment analyzes the environmental affects of these halogenated working fluids in energy consuming applications by combining a direct effect resulting from the inadvertent release of HFCs to the atmosphere with an indirect effect resulting from the combustion of fossil fuels needed to provide the energy to operate equipment using these compounds as working fluids. TEWI is a more balanced measure of environmental impact because it is not based solely on the global warming potential (GWP) of the working fluid. It also shows the environmental benefit of efficient technologies that result in less CO{sub 2} generation and eventual emission to the earth`s atmosphere. The goal of TEWI is to assess total global warming impact of all the gases released to the atmosphere, including CO{sub 2} emissions from energy conversion. Alternative chemicals and technologies have been proposed as substitutes for HFCs in the vapor-compression cycle for refrigeration and air conditioning and for polymer foams in appliance and building insulations which claim substantial environmental benefits. Among these alternatives are: (1) Hydrocarbon (HC) refrigerants and blowing agents which have zero ozone depleting potential and a negligible global warming potential, (2) CO{sub 2} as a refrigerant and blowing agent, (3) Ammonia (NH{sub 3}) vapor compression systems, (4) Absorption chiller and heat pumping cycles using ammonia/water or lithium bromide/water, and (5) Evacuated panel insulations. This paper summarizes major results and conclusions of the detailed final report on the TEWI-111 study.
Date: June 1, 1997
Creator: Sand, J.R.; Fischer, S.K. & Baxter, V.D.
Partner: UNT Libraries Government Documents Department

Photoinduced degradation of PAHs in the presence of ozone

Description: Polycyclic Aromatic Hydrocarbons (PAH) are formed from both anthropogenic and natural sources. In order to assess the environmental impact caused by the surface-adsorbed PAHs, the chemical lifetimes of these compounds in the atmosphere must be determined. Although ozone is known to be a primary reactant in the chemical transformation of surface-adsorbed PAHs in the atmosphere, the kinetics of these reactions have not been investigated in detail. In addition to the experimental difficulties that arise in using an oxygen-ozone stream while monitoring the PAH with fluorescence, complications in analyzing the kinetic mechanism also exist. It is difficult to determine whether the ozone or oxygen initially quenches the excited state of PAH. Ozone could enhance the degradation rate by simply reacting with a product derived from the excited state of PAH and oxygen. The focus of this study is to demonstrate the use of fluorescence spectroscopy in monitoring the degradation of PAH adsorbed on a three dimensional particle in the presence of gaseous ozone free from the interference of oxygen. More specifically, the experimental procedure will involve the generation of an ozone-nitrogen gas stream to be used in the investigation of dark and photochemical reactions between ozone and naphthalene. The absence of oxygen in the system will allow for the accurate monitoring of PAH fluorescence decay due solely to ozone quenching. It will also aid in the determination of the reaction mechanism. This is the first time that the direct interaction of ozone with an excited state of PAH has been demonstrated.
Date: December 31, 1995
Creator: Schutt, W.S.; Li, Y. & Sigman, M.E.
Partner: UNT Libraries Government Documents Department

Comparison of CCM3 simulations using two climatological ozone data sets

Description: A comparison of two six year simulations with the CCM3 using different monthly mean, zonally symmetric ozone climatologies is presented. Each run was identical except for the ozone specification. The climatological SSTs supplied with CCM3 were cycled for the extent of the simulation. The ozone data sets were used were the data distributed with the CCM3 code and that compiled at SUNY Albany. The SUNYA data set reflects contemporary ozone measurements extensively using remote sensing data. The CCM3 data were produced from measurements prior to 1974. A brief comparison of the two ozone climatologies is presented. The monthly mean difference fields were computed for the six years of the simulations. A t-test was applied to the monthly mean difference to judge if the changes between the integrations were significant. The significant changes in temperature were for the most part confined to the levels above 200 hPa. In the zonal mean the patterns of differences were largely consistent with regions of the ozone variations, deeper tropospheric penetration of temperature difference occurred in October near the South Pole in the region of the `ozone hole`. The significant temperature changes at the lowest model level (approximately 992 hPa) were confined to very small areas. The 200 hPa zonal wind differences demonstrated that the stationary wave structure was evidently altered by the ozone difference. Although the ozone specifications were zonally symmetric, the zonal wind differences were zonally asymmetric at 200 hPa.
Date: February 1, 1997
Creator: Boyle, J.S.
Partner: UNT Libraries Government Documents Department

A new approach to the characterization of long-term changes in total atmospheric ozone: Applications of frequency and extreme value statistics

Description: This paper sets forth a new approach for describing long-term changes in total ozone by using extreme value statistics and firquency distributions. We applied this methodology to the database of column ozone provided by the Total Ozone Mapping Spectrometer aboard Nimbus 7. We examined a geographic region measuring 7.0 degrees in latitude by 6.25 degrees in longitude in the midwestern United States from 1979--1991. On any given spring day, individual ozone measurements in this region show a large variability, where the differences between noontime maximum and minimum values sometimes exceed 100 Dobson units. During spring, the frequency of extremely low ozone values decreased over the period 1980--1991, while the opposite situation prevailed during fall.
Date: February 1, 1996
Creator: Reck, R.A.; Bornick, R.M.; Wen, G.; Frederick, J.E. & Weinberg, B.L.
Partner: UNT Libraries Government Documents Department