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Articles 1 - 18 of 18
Full-Text Articles in Atmospheric Sciences
Wet Deposition In A Global Size-Dependent Aerosol Transport Model: 2. Influence Of The Scavenging Scheme On 210pb Vertical Profiles, Surface Concentrations, And Deposition, W Guelle, Y J. Balkanski, Jack E. Dibb, M Schulz, F Dulac
Wet Deposition In A Global Size-Dependent Aerosol Transport Model: 2. Influence Of The Scavenging Scheme On 210pb Vertical Profiles, Surface Concentrations, And Deposition, W Guelle, Y J. Balkanski, Jack E. Dibb, M Schulz, F Dulac
Earth Sciences
The main atmospheric sink for submicron aerosols is wet removal. Lead 210, the radioactive decay product of 222Rn, attaches immediately after being formed to submicron particles. Here we compare the effects of three different wet-scavenging schemes used in global aerosol simulations on the 210Pb aerosol distribution using an off-line, size-resolved, global atmospheric transport model. We highlight the merits and shortcomings of each scavenging scheme at reproducing available measurements, which include concentrations in surface air and deposition, as well as vertical profiles observed over North America and western and central North Pacific. We show that model-measurement comparison of total …
Soluble Species In Aerosol And Snow And Their Relationship At Glacier 1, Tien Shan, China, Junying Sun, Dahe Qin, Paul A. Mayewski, Jack E. Dibb, Sallie I. Whitlow, Zhongqin Lee, Qinzhao Yang
Soluble Species In Aerosol And Snow And Their Relationship At Glacier 1, Tien Shan, China, Junying Sun, Dahe Qin, Paul A. Mayewski, Jack E. Dibb, Sallie I. Whitlow, Zhongqin Lee, Qinzhao Yang
Earth Sciences
Simultaneous sampling of aerosol (n = 20) and snow (n = 114) was made at Glacier 1, Tien Shan, between May 19 and June 29, 1996. Similar temporal patterns of some major ion (calcium, magnesium, potassium, sodium, chloride, and sulfate) concentrations between snow and aerosol show that snow chemistry basically reflects changes in the chemistry of the atmosphere. This gives us confidence in the reconstruction of past atmospheric change using some snow data. There are no significant correlations between aerosol and snow samples for ammonium and nitrate. This suggests that post-depositional and/or post-collection processes may alter ammonium and nitrate concentrations …
Soluble Species In Aerosol And Snow And Their Relationship At Glacier 1, Tien Shan, China, Junying Sun, Dahe Qin, Paul Andrew Mayewski, Jack E. Dibb, Sallie Whitlow, Zhongqin Li, Qinzhao Yang
Soluble Species In Aerosol And Snow And Their Relationship At Glacier 1, Tien Shan, China, Junying Sun, Dahe Qin, Paul Andrew Mayewski, Jack E. Dibb, Sallie Whitlow, Zhongqin Li, Qinzhao Yang
Earth Science Faculty Scholarship
Simultaneous sampling of aerosol (n = 20) and snow (n = 114) was made at Glacier 1, Tien Shan, between May 19 and June 29, 1996. Similar temporal patterns of some major ion (calcium, magnesium, potassium, sodium, chloride, and sulfate) concentrations between snow and aerosol show that snow chemistry basically reflects changes in the chemistry of the atmosphere. This gives us confidence in the reconstruction of past atmospheric change using some snow data. There are no significant correlations between aerosol and snow samples for ammonium and nitrate. This suggests that postdepositional and/or postcollection processes may alter ammonium and …
Nitric Acid Scavenging By Mineral And Biomass Burning Aerosols, A Tabazadeh, M Z. Jacobson, H B. Singh, O Brian Toon, J S. Lin, R B. Chatfield, A N. Thakur, R. Talbot, Jack E. Dibb
Nitric Acid Scavenging By Mineral And Biomass Burning Aerosols, A Tabazadeh, M Z. Jacobson, H B. Singh, O Brian Toon, J S. Lin, R B. Chatfield, A N. Thakur, R. Talbot, Jack E. Dibb
Earth Sciences
The abundance of gas phase nitric acid in the upper troposphere is overestimated by global chemistry-transport models, especially during the spring and summer seasons. Recent aircraft data obtained over the central US show that mineral aerosols were abundant in the upper troposphere during spring. Chemical reactions on mineral dust may provide an important sink for nitric acid. In regions where the mineral dust abundance is low in the upper troposphere similar HNO3 removal processes may occur on biomass burning aerosols. We propose that mineral and biomass burning aerosols may provide an important global sink for gas phase nitric acid, …
Analytic Forms Of Bidirectional Reflectance Functions For Application To Earth Radiation Budget Studies, N. Manalo-Smith, G. L. Smith, S. N. Tiwari, W. F. Staylor
Analytic Forms Of Bidirectional Reflectance Functions For Application To Earth Radiation Budget Studies, N. Manalo-Smith, G. L. Smith, S. N. Tiwari, W. F. Staylor
Mechanical & Aerospace Engineering Faculty Publications
Analytic expressions for the bidirectional reflectance functions are formulated and fit to the Earth Radiation Budget Experiment (ERBE) operational models, which were developed using Nimbus 7 ERB data. The analytic bidirectional reflectance distribution functions (BRDFs) are based on theoretical considerations and are functions of viewing geometry and scene type. The models consist of a Rayleigh scattering term and a term for scattering due to clouds and surface. The darkness of the ocean permits the empirical determination of the Rayleigh component of scattering from the atmosphere. The models have the advantage that they are smooth in terms of view and solar …
Influence Of Vertical Transport On Free Tropospheric Aerosols Over The Central Usa In Springtime, R. Talbot, Jack E. Dibb, M Loomis
Influence Of Vertical Transport On Free Tropospheric Aerosols Over The Central Usa In Springtime, R. Talbot, Jack E. Dibb, M Loomis
Earth Sciences
Measurements of the atmospheric aerosol chemical composition during the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) indicate substantial vertical transport of boundary layer aerosol to the free troposphere over the south-central United States during springtime. Mixing ratios of water-soluble aerosol Ca 2+ at 6 - 12 km altitude exhibited a median mixing ratio of 20 pptv, with 15% of the measurements > 100 pptv and a maximum of ! 235 pptv. In air parcels with enhanced Ca 2+, the ratios K+/Ca 2+, Mg2+/Ca 2+, and Na+/Ca 2+ in the bulk aerosol were distinctly characteristic of those in limestone and/or …
Tropospheric Sulfate Distribution During Success: Contributions From Jet Exhaust And Surface Sources, Jack E. Dibb, R. Talbot, M Loomis
Tropospheric Sulfate Distribution During Success: Contributions From Jet Exhaust And Surface Sources, Jack E. Dibb, R. Talbot, M Loomis
Earth Sciences
The distribution of SO4= aerosol over the central US during SUCCESS indicates that surface sources of SO4= and SO2 in the western US caused SO4= enhancements up to 10 km altitude. The mean (median) SO4= mixing ratio in the mid- and upper-troposphere increased from 24 (16) pptv over the Pacific ocean to 58 (29) pptv over the central plains. Above 10 km the SO4=mixing ratio was essentially the same in both regions, and also when the geographic classifications were further partitioned into upper tropospheric and lower stratospheric categories …
Relationship Between Continuous Aerosol Measurements And Firn Core Chemistry Over A 10-Year Period At The South Pole, M H. Bergin, E A. Meyerson, Jack E. Dibb, Paul A. Mayewski
Relationship Between Continuous Aerosol Measurements And Firn Core Chemistry Over A 10-Year Period At The South Pole, M H. Bergin, E A. Meyerson, Jack E. Dibb, Paul A. Mayewski
Earth Sciences
Before ice core chemistry can be used to estimate past atmospheric chemistry it is necessary to establish an unambiguous link between concentrations of chemical species in the air and snow. For the first time a continuous long-term record of aerosol properties (aerosol light scattering coefficient, σsp, and Ångström exponent, å) at the South Pole are compared with the chemical record from a high resolution firn core (∼10 samples per year) covering the period from 1981 to 1991. Seasonal signals in å, associated with winter minima due to coarse mode seasalt and summer maxima due to accumulation mode sulfate …
Inversion And Analysis Of Remotely Sensed Atmospheric Water Vapor Measurements At 940nm, Jack Cutler Larsen
Inversion And Analysis Of Remotely Sensed Atmospheric Water Vapor Measurements At 940nm, Jack Cutler Larsen
Mechanical & Aerospace Engineering Theses & Dissertations
The understanding and acceptance of remotely sensed atmospheric data depends strongly on the steps taken to characterize experiment error and validate observations through comparisons to other independent measurements. A formal error analysis of the Stratospheric Aerosol and Gas Experiment II (SAGE II) water vapor operational inversion algorithm is performed and compared to previous results. Random measurement errors were characterized by segmented least-squares profile fitting of the slant path absorption which found the error to be uncorrelated in the stratosphere with estimated variances significantly smaller than expected from 18-30 km. Estimates of null space error were developed from radiosonde hygrometers in …
Full-Wave Modeling Of Small-Scale Gravity Waves Using Airborne Lidar And Observations Of The Hawaiian Airglow (Aloha-93) O(¹S) Images And Coincident Na Wind/Temperature Lidar Measurements, Michael P. Hickey Ph.D., Michael J. Taylor, Chester S. Gardner, Christian R. Gibbons
Full-Wave Modeling Of Small-Scale Gravity Waves Using Airborne Lidar And Observations Of The Hawaiian Airglow (Aloha-93) O(¹S) Images And Coincident Na Wind/Temperature Lidar Measurements, Michael P. Hickey Ph.D., Michael J. Taylor, Chester S. Gardner, Christian R. Gibbons
Publications
Measurements were made of mesospheric gravity waves in the OI (5577 Å) nightglow observed from Maui, Hawaii, during the Airborne Lidar and Observations of Hawaiian Airglow (ALOHA-93) campaign. Clear, monochromatic gravity waves were observed on several nights. By using a full-wave model that realistically includes the major physical processes in this region, we have simulated the propagation of four waves through the mesopause region and calculated the O(¹S) nightglow response to the waves. Mean winds derived from Na wind/temperature lidar observations were employed in the computations. Wave amplitudes were calculated based on the requirement that the observed and …
An Analytical Study Of Ozone Feedbacks On Kelvin And Rossby–Gravity Waves: Effects On The Qbo, Eugene Cordero, Terrence R. Nathan, Robert S. Echols
An Analytical Study Of Ozone Feedbacks On Kelvin And Rossby–Gravity Waves: Effects On The Qbo, Eugene Cordero, Terrence R. Nathan, Robert S. Echols
Faculty Publications, Meteorology and Climate Science
An equatorial beta-plane model of the middle atmosphere is used to analytically examine the effects of radiative cooling and ozone heating on the spatial and temporal evolution of the quasi-biennial oscillation (QBO). Under the assumption that the diabatic heating is weak and the background fields of wind, temperature, and ozone are slowly varying, a perturbation analysis yields expressions describing the vertical spatial modulation of Kelvin and Rossby–gravity waves in the presence of ozone. These expressions show that wave-induced changes in the diabatic heating arising from the advection of basic-state ozone reduce the local radiative damping rate by up to 15% …
An Analytical Study Of Ozone Feedbacks On Kelvin And Rossby–Gravity Waves: Effects On The Qbo, Eugene Cordero, Terrence R. Nathan, Robert S. Echols
An Analytical Study Of Ozone Feedbacks On Kelvin And Rossby–Gravity Waves: Effects On The Qbo, Eugene Cordero, Terrence R. Nathan, Robert S. Echols
Eugene C. Cordero
An equatorial beta-plane model of the middle atmosphere is used to analytically examine the effects of radiative cooling and ozone heating on the spatial and temporal evolution of the quasi-biennial oscillation (QBO). Under the assumption that the diabatic heating is weak and the background fields of wind, temperature, and ozone are slowly varying, a perturbation analysis yields expressions describing the vertical spatial modulation of Kelvin and Rossby–gravity waves in the presence of ozone. These expressions show that wave-induced changes in the diabatic heating arising from the advection of basic-state ozone reduce the local radiative damping rate by up to 15% …
Regression Analysis Of Radar Measured Optical Turbulence With Synoptic Scale Meteorological Variables, Diana L. Hajek
Regression Analysis Of Radar Measured Optical Turbulence With Synoptic Scale Meteorological Variables, Diana L. Hajek
Theses and Dissertations
A key issue to the USAF's Airborne Laser (ABL) program is the ability to accurately predict the level of optical turbulence that the ABL will encounter at its flight levels. The optical turbulence must be characterized so that the range and range variation of the ABL can be determined. Gravity wave spectra resulting from frontal or jet stream passage are presumed to cause layers of optical turbulence; however, exact relationships between optical turbulence and synoptic scale meteorological phenomena are unclear. This study assesses the statistical relationship between optical turbulence and synoptic scale variables through multiple linear regression. The optical turbulence …
Air-Snow Exchange Of Hno3 And Noy At Summit, Greenland, Jack E. Dibb, R. Talbot, J W. Munger, Daniel J. Jacob, S M. Fan
Air-Snow Exchange Of Hno3 And Noy At Summit, Greenland, Jack E. Dibb, R. Talbot, J W. Munger, Daniel J. Jacob, S M. Fan
Earth Sciences
Ice core records of NO3− deposition to polar glaciers could provide unrivaled information on past photochemical status and N cycling dynamics of the troposphere, if the ice core records could be inverted to yield concentrations of reactive N oxides in the atmosphere at past times. Limited previous investigations at Summit, Greenland, have suggested that this inversion may be difficult, since the levels of HNO3 and aerosol-associated NO3− over the snow are very low in comparison with those of NO3− in the snow. In addition, it appears that some fraction of the NO3 …
Limited Migration Of Soluble Ionic Species In A Siple Dome, Antarctica, Ice Core, Karl J. Kreutz, Paul Andrew Mayewski, Sallie I. Whitlow, Mark S. Twickler
Limited Migration Of Soluble Ionic Species In A Siple Dome, Antarctica, Ice Core, Karl J. Kreutz, Paul Andrew Mayewski, Sallie I. Whitlow, Mark S. Twickler
Earth Science Faculty Scholarship
High-resolution (>10 samples a -1) glaciochemical analyses covering the last 110 years from a Siple Dome, Antarctica, ice core reveal limited migration of certain soluble ionic species (methane sulfonic acid, NO3 and Mg2+). Th e observed chemical migration m ay be due in part to seasonal alternation between less acidic winter (from high sea-salt concentrations) and m ore acidic summer (from high marine biogenic acid concentrations) layers, common at coastal sites such as Siple Dome. Exact mechanisms to explain the migration are unclear, although simple diffusion and gravitational movement are unlikely since new peaks are …
Spatial Variability Of Snow Chemistry In Western Dronning Maud Land, Antarctica, Malin Stenberg, Elisabeth Isaksson, Margareta Hansson, Wibjörn Karlén, Paul Andrew Mayewski, Mark S. Twickler, Sallie I. Whitlow, Niels Gundestrup
Spatial Variability Of Snow Chemistry In Western Dronning Maud Land, Antarctica, Malin Stenberg, Elisabeth Isaksson, Margareta Hansson, Wibjörn Karlén, Paul Andrew Mayewski, Mark S. Twickler, Sallie I. Whitlow, Niels Gundestrup
Earth Science Faculty Scholarship
During the austral summer of 1993-94 a number of 1-2 m deep snow pits were sampled in connection with firn-coring in western Dronning Maud Land, Antarctica. The traverse went from 800 to about 3000 m a.s.l. upon the high-altitude plateau. Profiles of cations (Na+, K+, Mg2+, Ca2+), anions (CI-, NO3-, SO42-, CH3SO3-) and stable oxygen isotopes (δ18O) from II snow pits are presented here. Close to the coast 2 m of snow accumulates in about 2-3 years, whilst …
The Pursuit Of Isotopic And Molecular Fire Tracers In The Polar Atmosphere And Cryosphere, L A. Currie, Jack E. Dibb, G A. Klouda, B A. Benner Jr., J M. Conny, S R. Biegalski, D B. Klinedinst, D R. Cahoon, N C. Hsu
The Pursuit Of Isotopic And Molecular Fire Tracers In The Polar Atmosphere And Cryosphere, L A. Currie, Jack E. Dibb, G A. Klouda, B A. Benner Jr., J M. Conny, S R. Biegalski, D B. Klinedinst, D R. Cahoon, N C. Hsu
Earth Sciences
We present an overview of recent multidisciplinary, multi-institutional efforts to identify and date major sources of combustion aerosol in the current and paleoatmospheres. The work was stimulated, in part, by an atmospheric particle 'sample of opportunity' collected at Summit, Greenland in August 1994, that bore the 14C imprint of biomass burning. During the summer field seasons of 1995 and 1996, we collected air filter, surface snow and snowpit samples to investigate chemical and isotopic evidence of combustion particles that had been transported from distant fires. Among the chemical tracers employed for source identification are organic acids, potassium and ammonium ions, …
Africa As A Regional And Global Source Of Atmospheric Gases And Particulates, Lawrence Mtetwa
Africa As A Regional And Global Source Of Atmospheric Gases And Particulates, Lawrence Mtetwa
Dissertations, Theses, and Masters Projects
The role of the continent of Africa as a source of gaseous and particulate emissions to the atmosphere is investigated in this study. Sources of gases and particulates from Africa include fossil fuel combustion, biomass burning, and biogenic soil emissions of nitric oxide. This study represents the first comprehensive database of gaseous and particulate emissions developed for the continent of Africa on a country by country basis and establishes the framework for country-by-country, assessment of greenhouse gases emissions as required by the Kyoto Conference on Global Warming, which was attended by representatives from more than 100 countries. Calculations of gases …