Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 36

Full-Text Articles in Physics

Spectra Of Atmospheric And Astronomical Molecules, W. D. Cameron May 2023

Spectra Of Atmospheric And Astronomical Molecules, W. D. Cameron

Physics Theses & Dissertations

Spectroscopy techniques are focused on spectra of molecules of interest to the Earth’s atmosphere and/or astronomy and astrophysics. Laboratory spectroscopy as well as remote satellite sensing are applied. Using the Fourier transform spectrometer aboard the Atmospheric Chemistry Experiment (ACE) satellite to measure the absorption spectra of the Earth’s atmosphere through solar occultation limb observation demonstrates that volcanic eruption plumes can be located and tracked through their SO2 content. The presence of those plumes is corroborated by overlaying infrared atmospheric aerosol extinction observed by the 1 μm imager on the same satellite. Tracking atmospheric aerosol movement with the ACE …


Solutions For Fermi Questions, January 2022: Question 1: Snow Volume; Question 2: Longbow Arrow Velocity, Larry Weinstein Jan 2022

Solutions For Fermi Questions, January 2022: Question 1: Snow Volume; Question 2: Longbow Arrow Velocity, Larry Weinstein

Physics Faculty Publications

No abstract provided.


Vertical Artifacts In High-Resolution Worldview-2 And Worldview-3 Satellite Imagery Of Aquatic Systems, Megan M. Coffer, Peter J. Whitman, Blake A. Schaeffer, Victoria Hill, Richard C. Zimmerman, Wilson B. Salls, Marie C. Lebrasse, David D. Graybill Jan 2022

Vertical Artifacts In High-Resolution Worldview-2 And Worldview-3 Satellite Imagery Of Aquatic Systems, Megan M. Coffer, Peter J. Whitman, Blake A. Schaeffer, Victoria Hill, Richard C. Zimmerman, Wilson B. Salls, Marie C. Lebrasse, David D. Graybill

OES Faculty Publications

Satellite image artefacts are features that appear in an image but not in the original imaged object and can negatively impact the interpretation of satellite data. Vertical artefacts are linear features oriented in the along-track direction of an image system and can present as either banding or striping; banding are features with a consistent width, and striping are features with inconsistent widths. This study used high-resolution data from DigitalGlobeʻs (now Maxar) WorldView-3 satellite collected at Lake Okeechobee, Florida (FL), on 30 August 2017. This study investigated the impact of vertical artefacts on both at-sensor radiance and a spectral index for …


The Aquatic Particle Number Quandry, Alexander B. Bochdansky, Huanqing Huang, Maureen H. Conte Jan 2022

The Aquatic Particle Number Quandry, Alexander B. Bochdansky, Huanqing Huang, Maureen H. Conte

OES Faculty Publications

Optical surveys of aquatic particles and their particle size spectra have become important tools in studies of light propagation in water, classification of water masses, and the dynamics of trophic interactions affecting particle aggregation and flux. Here, we demonstrate that typical settings used in image analysis vastly underestimate particle numbers due to the particle – gel continuum. Applying a wide range of threshold values to change the sensitivity of our detection system, we show that macrogels cannot be separated from more dense particles, and that a true particle number per volume cannot be ascertained; only relative numbers in relation to …


Examining Ecological Succession Of Diatoms In California Current System Cyclonic Mesoscale Eddies, Zuzanna M. Abdala, Sophie Clayton, Sveinn V. Einarsson, Kimberly Powell, Claire P. Till, Tyler H. Coale, P. Dreux Chappell Jan 2022

Examining Ecological Succession Of Diatoms In California Current System Cyclonic Mesoscale Eddies, Zuzanna M. Abdala, Sophie Clayton, Sveinn V. Einarsson, Kimberly Powell, Claire P. Till, Tyler H. Coale, P. Dreux Chappell

OES Faculty Publications

The California Current System is a diatom-dominated region characterized by seasonal coastal upwelling and additional elevated mesoscale activity. Cyclonic mesoscale eddies in the region trap productive coastal waters with their planktonic communities and transport them offshore with limited interaction with surrounding waters, effectively acting as natural mesocosms, where phytoplankton populations undergo ecological succession as eddies age. This study examines diatom community composition within two mesoscale cyclonic eddies that formed in the same region of the California Current System 2 months apart and in the California Current waters surrounding them. The diatom communities were analyzed in the context of shifting environmental …


Shipboard Lidar As A Tool For Remotely Measuring The Distribution And Bulk Characteristics Of Marine Particles, Brian Leigh Collister Dec 2021

Shipboard Lidar As A Tool For Remotely Measuring The Distribution And Bulk Characteristics Of Marine Particles, Brian Leigh Collister

OES Theses and Dissertations

Light detection and ranging (lidar) can provide remote estimates of the vertical distribution of optical properties in the ocean, potentially revolutionizing our ability to characterize the spatial structure of upper ocean ecosystems. However, challenges associated with quantifying the relationship between lidar measurements and biogeochemical properties of interest have prevented its adoption for routinely mapping the vertical structure of marine ecosystems. To address this, we developed a shipboard oceanographic lidar that measures attenuation (α) and linear depolarization (δ) at scales identical to those of in-water optical and biogeochemical measurements. The instrument’s ability to resolve the distribution of optical and biogeochemical properties …


Examining Melt Pond Dynamics And Light Availability In The Arctic Ocean Via High Resolution Satellite Imagery, Austin Wesley Abbott Jul 2021

Examining Melt Pond Dynamics And Light Availability In The Arctic Ocean Via High Resolution Satellite Imagery, Austin Wesley Abbott

OES Theses and Dissertations

As the Arctic experiences consequences of climate change, a shift from thicker, multi-year ice to thinner, first-year ice has been observed. First-year ice is prone to extensive pools of meltwater (“melt ponds”) forming on its surface, which enhance light transmission to the ocean. Changes in the timing and distribution of melt pond formation and associated increases in under-ice light availability are the primary drivers for seasonal progression of water column primary production and warming. Observations of melt pond development and distribution require meter scale resolution and have traditionally been limited to airborne images. However, recent advances in high spatial resolution …


Rapid Quantification Of Biofouling With An Inexpensive, Underwater Camera And Image Analysis, Matthew R. First, Scott C. Riley, Kazi Aminul Islam, Victoria Hill, Jiang Li, Richard C. Zimmerman, Lisa A. Drake Jan 2021

Rapid Quantification Of Biofouling With An Inexpensive, Underwater Camera And Image Analysis, Matthew R. First, Scott C. Riley, Kazi Aminul Islam, Victoria Hill, Jiang Li, Richard C. Zimmerman, Lisa A. Drake

Electrical & Computer Engineering Faculty Publications

To reduce the transport of potentially invasive species on ships' submerged surfaces, rapid-and accurate-estimates of biofouling are needed so shipowners and regulators can effectively assess and manage biofouling. This pilot study developed a model approach for that task. First, photographic images were collected in situ with a submersible, inexpensive pocket camera. These images were used to develop image processing algorithms and train machine learning models to classify images containing natural assemblages of fouling organisms. All of the algorithms and models were implemented in a widely available software package (MATLAB©). Initially, an unsupervised clustering model was used, and three …


Sulfur Dioxide From The Atmospheric Chemistry Experiment Satellite, Doug Cameron Apr 2020

Sulfur Dioxide From The Atmospheric Chemistry Experiment Satellite, Doug Cameron

College of Sciences Posters

The version 4.0 dataset from the Atmospheric Chemistry Experiment – Fourier Transform Spectrometer (ACE-FTS) on SCISAT, released in March of 2019, has sulfur dioxide (SO2) volume mixing ratio (VMR) profiles as a routine data product. From this dataset, global SO2 distributions between the altitudes of 10.5 km and 23.5 km are analyzed. The global distribution of all SO2 VMR data by altitude is broken down into 30° and 5° latitude zones. Seasonality of the global SO2 distribution is explored. Volcanic SO2 plumes are isolated in the dataset and compared with extinction data from the …


Trend Analyses Of The Abundances Of Atmospheric Molecules, Anton Fernando Apr 2020

Trend Analyses Of The Abundances Of Atmospheric Molecules, Anton Fernando

Physics Theses & Dissertations

A new line list for the A3Π - X3Σ- electronic transition of NH has been prepared using line positions from the literature and calculated line intensities. High level ab initio calculations were performed with the MOLPRO program to obtain the A - X transition dipole moment function. Potential energy curves and line strengths were calculated with Le Roy's RKR1 and LEVEL programs. Line intensities and Einstein A values were calculated with Western's PGOPHER program after converting the Hund's case (b) output of LEVEL to Hund's case (a) input needed for PGOPHER. The Herman- Wallis effect is …


Analysis Of The Red And Green Optical Absorption Spectrum Of Gas Phase Ammonia, Nikolai F. Zobov, Phillip A. Coles, Roman I. Ovsyannikov, Aleksandra A. Kyuberis, Robert J. Hargreaves, Peter F. Bernath, Jonathan Tennyson, Sergei N. Yurchenko, Oleg L. Polyansky Jan 2018

Analysis Of The Red And Green Optical Absorption Spectrum Of Gas Phase Ammonia, Nikolai F. Zobov, Phillip A. Coles, Roman I. Ovsyannikov, Aleksandra A. Kyuberis, Robert J. Hargreaves, Peter F. Bernath, Jonathan Tennyson, Sergei N. Yurchenko, Oleg L. Polyansky

Chemistry & Biochemistry Faculty Publications

Room temperature NH3 absorption spectra recorded at the Kitt Peak National Solar Observatory in 1980 are analyzed. The spectra cover two regions in the visible: 15,200 - 15,700 cm-1 and 17,950 - 18,250 cm-1. These high overtone rotation-vibration spectra are analyzed using both combination differences and variational line lists. Two variational line lists were computed using the TROVE nuclear motion program: one is based on an ab initio potential energy surface (PES) while the other used a semi-empirical PES. Ab initio dipole moment surfaces are used in both cases. 95 energy levels with J = 1 …


Improved Ballistic Wind Prediction Using Projectile Tracking Data, William Arthur Kenney Jul 2017

Improved Ballistic Wind Prediction Using Projectile Tracking Data, William Arthur Kenney

Computational Modeling & Simulation Engineering Theses & Dissertations

The United States Air Force AC-130 gunships have been in operation since the Vietnam War and have seen frequent use during recent conflicts. They are able to employ gun weapon systems from above a target in a way that maximizes possible time on target. When firing, the gun operators must deal with miss distances caused by winds acting on the projectile in flight. Operators currently perform a “tweak” to predict a ballistic wind affecting fired rounds which is then used in the fire-control to correct for the real winds and bring shots onto target. This correction, a single-point wind prediction, …


New And Improved Infra-Red Absorption Cross Sections And Ace-Fts Retrievals Of Carbon Tetrachloride (Ccl4), Jeremy J. Harrison, Christopher D. Boone, Peter F. Bernath Jan 2017

New And Improved Infra-Red Absorption Cross Sections And Ace-Fts Retrievals Of Carbon Tetrachloride (Ccl4), Jeremy J. Harrison, Christopher D. Boone, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

Carbon tetrachloride (CCl4) is one of the species regulated by the Montreal Protocol on account of its ability to deplete stratospheric ozone. As such, the inconsistency between observations of its abundance and estimated sources and sinks is an important problem requiring urgent attention (Carpenter et al., 2014) [5]. Satellite remote-sensing has a role to play, particularly limb sounders which can provide vertical profiles into the stratosphere and therefore validate stratospheric loss rates in atmospheric models. This work is in two parts. The first describes new and improved high-resolution infra-red absorption cross sections of carbon tetrachloride/dry synthetic air over …


Exploring The Reasons For The Seasons Using Google Earth, 3d Models, And Plots, Declan G. De Paor, Mladen M. Dordevic, Paul Karabinos, Stephen Burgin, Filis Coba, Steven J. Whitmeyer Jan 2017

Exploring The Reasons For The Seasons Using Google Earth, 3d Models, And Plots, Declan G. De Paor, Mladen M. Dordevic, Paul Karabinos, Stephen Burgin, Filis Coba, Steven J. Whitmeyer

Physics Faculty Publications

Public understanding of climate and climate change is of broad societal importance. However, misconceptions regarding reasons for the seasons abound amongst students, teachers, and the public, many of whom believe that seasonality is caused by large variations in Earth's distance from the Sun. Misconceptions may be reinforced by textbook illustrations that exaggerate eccentricity or show an inclined view of Earth's near-circular orbit. Textbook explanations that omit multiple factors influencing seasons, that do not mesh with students' experiences, or that are erroneous, hinder scientifically valid reasoning. Studies show that many teachers share their students' misconceptions, and even when they understand basic …


Impact Of Glacial/Interglacial Sea Level Change On The Ocean Nitrogen Cycle, Haojia Ren, Daniel M. Sigman, Alfredo Martínez-García, Robert F. Anderson, Chen Min-Te, Ana Christina Ravelo, Marietta Straub, George T. F. Wong, Gerald H. Haug Jan 2017

Impact Of Glacial/Interglacial Sea Level Change On The Ocean Nitrogen Cycle, Haojia Ren, Daniel M. Sigman, Alfredo Martínez-García, Robert F. Anderson, Chen Min-Te, Ana Christina Ravelo, Marietta Straub, George T. F. Wong, Gerald H. Haug

OES Faculty Publications

The continental shelves are the most biologically dynamic regions of the ocean, and they are extensive worldwide, especially in the western North Pacific. Their area has varied dramatically over the glacial/interglacial cycles of the last million years, but the effects of this variation on ocean biological and chemical processes remain poorly understood. Conversion of nitrate to N2 by denitrification in sediments accounts for half or more of the removal of biologically available nitrogen ("fixed N") from the ocean. The emergence of continental shelves during ice ages and their flooding during interglacials have been hypothesized to drive changes in sedimentary denitrification. …


The Hitran2016 Molecular Spectroscopic Database, I. E. Gordon, L. S. Rothman, C. Hill, R. V. Kochanov, Y. Tan, P. F. Bernath, M. Birk, V. Boudon, A. Campargue, K. V. Chance Jan 2017

The Hitran2016 Molecular Spectroscopic Database, I. E. Gordon, L. S. Rothman, C. Hill, R. V. Kochanov, Y. Tan, P. F. Bernath, M. Birk, V. Boudon, A. Campargue, K. V. Chance

Chemistry & Biochemistry Faculty Publications

This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional …


Mipas Imk/Iaa Cfc-11 (Ccl3f) And Cfc-12 (Ccl2f2) Measurements: Accuracy, Precision And Long-Term Stability, E. Eckert, A. Laeng, S. Lossow, S. Kellmann, G. Stiller, T. Von Clarmann, N. Glatthor, M. Hopfner, M. Kiefer, H. Oelhaf, P. F. Bernath Jan 2016

Mipas Imk/Iaa Cfc-11 (Ccl3f) And Cfc-12 (Ccl2f2) Measurements: Accuracy, Precision And Long-Term Stability, E. Eckert, A. Laeng, S. Lossow, S. Kellmann, G. Stiller, T. Von Clarmann, N. Glatthor, M. Hopfner, M. Kiefer, H. Oelhaf, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Profiles of CFC-11 (CCl3F) and CFC-12 (CCl2F2) of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the European satellite Envisat have been retrieved from versions MIPAS/4.61 to MI-PAS/4.62 and MIPAS/5.02 to MIPAS/5.06 level-1b data using the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK) and Consejo Superior de Investigaciones Cientificas (CSIC), Instituto de Astrofisica de Andalucia (IAA). These profiles have been compared to measurements taken by the balloon-borne cryosampler, Mark IV (MkIV) and MIPAS-Balloon (MIPAS-B), the airborne MIPAS-STRatospheric aircraft (MIPAS-STR), the satellite-borne Atmospheric Chemistry …


Relative Permeability Of Homogenous-Wet And Mixed-Wet Porous Media As Determined By Pore-Scale Lattice Boltzmann Modeling, C. J. Landry, Z. T. Karpyn, O. Ayala Jan 2014

Relative Permeability Of Homogenous-Wet And Mixed-Wet Porous Media As Determined By Pore-Scale Lattice Boltzmann Modeling, C. J. Landry, Z. T. Karpyn, O. Ayala

Engineering Technology Faculty Publications

We present a pore-scale study of two-phase relative permeability in homogenous-wet porous media, and porous media altered to a mixed-wet state. A Shan-Chen type multicomponent lattice Boltzmann (LB) model is employed to determine pore-scale fluid distributions and relative permeability. Mixed-wet states are created by altering the wettability of solid surfaces in contact with the nonwetting phase at the end of steady state simulation of initially homogenous-wet porous media. To ensure accurate representation of fluid-solid interfacial areas, we compare LB simulation results to experimental measurements of interfacial fluid-fluid and fluid-solid areas determined by X-ray computed microtomography imaging of water and oil …


Middle Atmospheric Changes Caused By The January And March 2012 Solar Proton Events, C. H. Jackman, C. E. Randall, V. L. Harvey, S. Wang, E. L. Fleming, M. López-Puertas, B. Funke, P. F. Bernath Jan 2014

Middle Atmospheric Changes Caused By The January And March 2012 Solar Proton Events, C. H. Jackman, C. E. Randall, V. L. Harvey, S. Wang, E. L. Fleming, M. López-Puertas, B. Funke, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

The recent 23-30 January and 7-11 March 2012 solar proton event (SPE) periods were substantial and caused significant impacts on the middle atmosphere. These were the two largest SPE periods of solar cycle 24 so far. The highly energetic solar protons produced considerable ionization of the neutral atmosphere as well as HOx (H, OH, HO2) and NOx (N, NO, NO2). We compute a NOx production of 1.9 and 2.1 Gigamoles due to these SPE periods in January and March 2012, respectively, which places these SPE periods among the 12 largest in the past 50 yr. Aura Microwave Limb Sounder (MLS) …


Validation Of Mipas Imk/Iaa V5r_O3_224 Ozone Profiles, A. Laeng, U. Grabowski, T. Von Clarmann, G. Stiller, N. Glatthor, M. Höpfner, S. Kellmann, M. Kiefer, A. Linden, S. Lossow, P. F. Bernath Jan 2014

Validation Of Mipas Imk/Iaa V5r_O3_224 Ozone Profiles, A. Laeng, U. Grabowski, T. Von Clarmann, G. Stiller, N. Glatthor, M. Höpfner, S. Kellmann, M. Kiefer, A. Linden, S. Lossow, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

We present the results of an extensive validation program of the most recent version of ozone vertical profiles retrieved with the IMK/IAA (Institute for Meteorology and Climate Research/Instituto de Astrofisica de Andalucia) MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) research level 2 processor from version 5 spectral level 1 data. The time period covered corresponds to the reduced spectral resolution period of the MIPAS instrument, i.e., January 2005-April 2012. The comparison with satellite instruments includes all post-2005 satellite limb and occultation sensors that have measured the vertical profiles of tropospheric and stratospheric ozone: ACE-FTS, GOMOS, HALOE, HIRDLS, MLS, OSIRIS, POAM, …


Uncertainties In Modelling Heterogeneous Chemistry And Arctic Ozone Depletion In The Winter 2009/2010, I. Wohltmann, T. Wegner, R. Müller, R. Lehmann, M. Rex, G. L. Manney, M. L. Santee, P. Bernath, O. Suminska-Ebersoldt Jan 2013

Uncertainties In Modelling Heterogeneous Chemistry And Arctic Ozone Depletion In The Winter 2009/2010, I. Wohltmann, T. Wegner, R. Müller, R. Lehmann, M. Rex, G. L. Manney, M. L. Santee, P. Bernath, O. Suminska-Ebersoldt

Chemistry & Biochemistry Faculty Publications

Stratospheric chemistry and denitrification are simulated for the Arctic winter 2009/2010 with the Lagrangian Chemistry and Transport Model ATLAS. A number of sensitivity runs is used to explore the impact of uncertainties in chlorine activation and denitrification on the model results. In particular, the efficiency of chlorine activation on different types of liquid aerosol versus activation on nitric acid trihydrate clouds is examined. Additionally, the impact of changes in reaction rate coefficients, in the particle number density of polar stratospheric clouds, in supersaturation, temperature or the extent of denitrification is investigated. Results are compared to satellite measurements of MLS and …


Global Variations Of Hdo And Hdo/H2o Ratios In The Upper Troposphere And Lower Stratosphere Derived From Ace-Fts Satellite Measurements, William J. Randel, Elisabeth Moyer, Mijeong Park, Eric Jensen, Peter Bernath Mar 2012

Global Variations Of Hdo And Hdo/H2o Ratios In The Upper Troposphere And Lower Stratosphere Derived From Ace-Fts Satellite Measurements, William J. Randel, Elisabeth Moyer, Mijeong Park, Eric Jensen, Peter Bernath

Chemistry & Biochemistry Faculty Publications

High-quality satellite observations of water and deuterated water in the upper troposphere and lower stratosphere (UTLS) from the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) are used to map global climatological behavior. Spatial and temporal variability in these data suggest that convection plays a significant role in setting water vapor isotopic composition in these regions. In many instances, enhancements in HDO/H2O (i.e., δD) are closely tied to patterns of climatological deep convection and uncorrelated with water vapor, although convection appears to have different isotopic effects in different locations. The ACE-FTS data reveal seasonal variations in the tropics …


Introduction To Special Section On Recent Advances In The Study Of Optical Variability In The Near-Surface And Upper Ocean, T. Dickey, M. L. Banner, P. Bhandari, T. Boyd, L. Carvalho, O. Wurl Jan 2012

Introduction To Special Section On Recent Advances In The Study Of Optical Variability In The Near-Surface And Upper Ocean, T. Dickey, M. L. Banner, P. Bhandari, T. Boyd, L. Carvalho, O. Wurl

OES Faculty Publications

Optical variability occurs in the near-surface and upper ocean on very short time and space scales (e.g., milliseconds and millimeters and less) as well as greater scales. This variability is caused by solar, meteorological, and other physical forcing as well as biological and chemical processes that affect optical properties and their distributions, which in turn control the propagation of light across the air-sea interface and within the upper ocean. Recent developments in several technologies and modeling capabilities have enabled the investigation of a variety of fundamental and applied problems related to upper ocean physics, chemistry, and light propagation and utilization …


Technical Note: A Trace Gas Climatology Derived From The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (Ace-Fts) Data Set, A. Jones, K. A. Walker, J. J. Jin, J. R. Taylor, C. D. Boone, P. F. Bernath, S. Brohede, G. L. Manney, S. Mcleod, R. Hughes, W. H. Daffer Jan 2012

Technical Note: A Trace Gas Climatology Derived From The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (Ace-Fts) Data Set, A. Jones, K. A. Walker, J. J. Jin, J. R. Taylor, C. D. Boone, P. F. Bernath, S. Brohede, G. L. Manney, S. Mcleod, R. Hughes, W. H. Daffer

Chemistry & Biochemistry Faculty Publications

The Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) aboard the Canadian satellite SCISAT (launched in August 2003) was designed to investigate the composition of the upper troposphere, stratosphere, and mesosphere. ACE-FTS utilizes solar occultation to measure temperature and pressure as well as vertical profiles of over thirty chemical species including O3, H2O, CH4, N2O, CO, NO, NO2, N2O5, HNO3, HCl, ClONO2, CCl3F, CCl2F2, and HF. Global coverage for each species is obtained approximately over a three month …


First Remote Sensing Observations Of Trifluoromethane (Hfc-23) In The Upper Troposphere And Lower Stratosphere, Jeremy J. Harrison, Christopher D. Boone, Alexander T. Brown, Nicholas D. C. Allen, Geoffrey C. Toon, Peter F. Bernath Jan 2012

First Remote Sensing Observations Of Trifluoromethane (Hfc-23) In The Upper Troposphere And Lower Stratosphere, Jeremy J. Harrison, Christopher D. Boone, Alexander T. Brown, Nicholas D. C. Allen, Geoffrey C. Toon, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

This work reports the first remote sensing measurements of atmospheric HFC-23 (CHF3) using solar occultation measurements made by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) and the Jet Propulsion Laboratory Mark IV (MkIV) balloon interferometer. A total of 8809 ACE occultations measured between 2004 and 2010 have been processed, along with 24 MkIV occultations measured between 1989 and 2007. ACE data (yearly averages over the 10-25 km altitude range) in the tropics/subtropics (40°S-40°N) reveal a trend of 4.0 ± 1.6% per year in the growth of HFC-23 for 2004-2009 (or 3.9 ± 1.2% per year for 2004-2010), …


Quantifying Vertical Mixing In Estuaries, W. Rockwell Geyer, Malcolm E. Scully, David K. Ralston Jan 2008

Quantifying Vertical Mixing In Estuaries, W. Rockwell Geyer, Malcolm E. Scully, David K. Ralston

CCPO Publications

Estuarine turbulence is notable in that both the dissipation rate and the buoyancy frequency extend to much higher values than in other natural environments. The high dissipation rates lead to a distinct inertial subrange in the velocity and scalar spectra, which can be exploited for quantifying the turbulence quantities. However, high buoyancy frequencies lead to small Ozmidov scales, which require high sampling rates and small spatial aperture to resolve the turbulent fluxes. A set of observations in a highly stratified estuary demonstrate the effectiveness of a vessel-mounted turbulence array for resolving turbulent processes, and for relating the turbulence to the …


Sublethal And Killing Effects Of Atmospheric-Pressure, Nonthermal Plasma On Eukaryotic Microalgae In Aqueous Media, Ying Zhong Tang, Xin Pei Lu, Mounir Laroussi, Fred C. Dobbs Jan 2008

Sublethal And Killing Effects Of Atmospheric-Pressure, Nonthermal Plasma On Eukaryotic Microalgae In Aqueous Media, Ying Zhong Tang, Xin Pei Lu, Mounir Laroussi, Fred C. Dobbs

OES Faculty Publications

In-depth studies on the interaction of nonthermal plasmas with microorganisms usually focus on bacteria; only little attention has been given to their effects on more complex eukaryotic cells. We report here nonthermal plasma's effects on cell motility, viability staining, and morphology of eukaryotic microalgae, with three marine dinoflagellates and a marine diatom as major targets. The effects on motility and viability staining depended on the time of exposure to plasma and the species of microalgae. We observed a strong pH decrease in aqueous samples (marine and freshwater algal cultures, their culture media, and deionized water) after exposure to plasma, and …


A Temporal Approximate Deconvolution Model For Large-Eddy Simulation, C. D. Pruett, B. C. Thomas, C. E. Grosch, T. B. Gatski Feb 2006

A Temporal Approximate Deconvolution Model For Large-Eddy Simulation, C. D. Pruett, B. C. Thomas, C. E. Grosch, T. B. Gatski

CCPO Publications

A temporal approximate deconvolution model (TADM) is developed for large-eddy simulation and is demonstrated for plane-channel flow at Re-tau=590. The TADM combines explicit causal time-domain filtering with linear deconvolution (defiltering) to approximate unfiltered fields and residual stress to arbitrarily high order. The TADM methodology appears to lead to a robust family of residual-stress models that should provide a viable alternative to conventional (spatial) filtering for applications in which spatial filtering is problematic, e.g., for problems requiring unstructured or highly stretched grids. (c) 2006 American Institute of Physics.


Measurement Of Proton Transfer Reaction Rates In A Microwave Cavity Discharge Flowing Afterglow, George M. Brooke Iv Apr 2003

Measurement Of Proton Transfer Reaction Rates In A Microwave Cavity Discharge Flowing Afterglow, George M. Brooke Iv

Physics Theses & Dissertations

The reaction rate coefficients between the hydronium ion and the molecules ethene (C2H4), propene (C3H6), 1-butene (C4H8) and hydrogen sulfide (H2S) were measured at 296 K. The measured reaction rates were compared to collision rates calculated using average dipole orientation (ADO) theory. Reaction efficiency depends primarily upon the proton affinity of the molecules. All the measurements were obtained using the newly developed microwave cavity discharge flowing afterglow (MCD-FA) apparatus. This device uses an Asmussen-type microwave cavity discharge ion source that is …


The Temporally Filtered Navier-Stokes Equations: Propertes Of The Residual Stress, C. D. Pruett, T. B. Gatski, Chester E. Grosch, W. D. Thacker Jan 2003

The Temporally Filtered Navier-Stokes Equations: Propertes Of The Residual Stress, C. D. Pruett, T. B. Gatski, Chester E. Grosch, W. D. Thacker

CCPO Publications

Recent interest in the development of a unifying framework among direct numerical simulations, large-eddy simulations, and statistically averaged formulations of the Navier-Stokes equations, provides the motivation for the present paper. Toward that goal, the properties of the residual (subgrid-scale) stress of the temporally filtered Navier-Stokes equations are carefully examined. This includes the frame-invariance properties of the filtered equations and the resulting residual stress. Causal time-domain filters, parametrized by a temporal filter width 0infinity, the residual stress is equivalent to the long-time averaged stress, and the Reynolds-averaged Navier-Stokes equations are recovered from the temporally filtered equations. The predicted behavior at the …