Oceanography and Atmospheric Sciences and Meteorology Commons^™

Photochemical Production Of Gas Phase No X From Ice Crystal No3 −, R E. Honrath, S Guo, Matthew C. Peterson, M P. Dziobak, Jack E. Dibb, Matthew Arsenault

Earth Sciences

Recent measurements have demonstrated that sunlight irradiation of snow results in the release of significant amounts of gas phase NO_x (NO+NO₂). We report here the results of a series of experiments designed to test the hypothesis that the observed NO_x production is the result of nitrate photolysis. Snow produced from deionized water with and without the addition of nitrate was exposed to natural sunlight in an outdoor flow chamber. While NO_x release from snow produced without added NO⁻₃ was minimal, the addition of 100 µM NO⁻₃resulted in the release …

The Influence Of Wave– And Zonal Mean–Ozone Feedbacks On The Quasi-Biennial Oscillation, Eugene Cordero, Terrence R. Nathan

Faculty Publications, Meteorology and Climate Science

The effects of wave and zonal mean ozone heating on the evolution of the quasi-biennial oscillation (QBO) are examined using a two-dimensional mechanistic model of the equatorial stratosphere. The model atmosphere is governed by coupled equations for the zonal mean and (linear) wave fields of ozone, temperature, and wind, and is driven by specifying the amplitudes of a Kelvin wave and a Rossby–gravity wave at the lower boundary. Wave–mean flow interactions are accounted for in the model, but not wave–wave interactions.

A reference simulation (RS) of the QBO, in which ozone feedbacks are neglected, is carried out and the results …

Experimental Goes Sounder Products For The Assessment Of Downburst Potential, Gary P. Ellrod, James P. Nelson Iii, Michael R. Witiw, Lynda Bottos, William P. Roeder

Aeronautics Faculty Publications

Several experimental products derived from Geostationary Operational Environmental Satellite (GOES) Sounder retrievals (vertical profiles of temperature and moisture) have been developed to assist weather forecasters in assessing the potential for convective downbursts. The product suite currently includes the wind index (WINDEX), a dry microburst index, and the maximum difference in equivalent potential temperature (θe) from the surface to 300 hPa. The products are displayed as color-coded boxes or numerical values, superimposed on GOES visible, infrared, or water vapor imagery, and are available hourly, day and night, via the Internet. After two full summers of evaluation, the products have been shown …

Resolving Ambiguities In Gravity Wave Propagation Directions Inherent In Satellite Observations: A Simulation Study, Michael P. Hickey Ph.D., Jason S. Brown

Publications

We simulate space-based, sub-limb viewing observations of airglow brightness fluctuations caused by atmospheric gravity wave interactions with the O2 atmospheric airglow, and we demonstrate that, due to the geometry associated with such observations, the brightness fluctuations observed for the optically thick 0–0 band emission will always appear stronger for waves traveling towards the observer (satellite). The effect should be most noticeable for waves having relatively small vertical wavelengths (∼10 km) and horizontal wavelengths of 50 km or greater. For waves of short (∼100 km) horizontal wavelength, the brightness fluctuation anisotropy with respect to viewing direction may also be evident in …

Release Of No(X) From Sunlight-Irradiated Midlatitude Snow, R E. Honrath, Matthew C. Peterson, M P. Dziobak, Jack E. Dibb, Matthew Arsenault, S A. Green

Earth Sciences

Photochemical production and release of gas-phase NO(x) (NO + NO2) from the natural snowpack at a remote site in northern Michigan were investigated during the Snow Nitrogen and Oxidants in Winter study in January 1999. Snow was collected in an open 34 L chamber, which was then sealed with a transparent Teflon cover and used as an outdoor flow and reaction chamber. Significant increases in NO(x) mixing ratio were observed in synthetic and ambient air pulled through the sunlit chamber. [NO(x)] enhancements were correlated to ultraviolet sunlight intensity, reaching ~300 pptv under partially overcast midday, mid-winter conditions. These findings are …

Trajectory Mapping: A Tool For Validation Of Trace Gas Observations, Gary A. Morris, James F. Gleason, Jerald Ziemke, Mark R. Schoeberl

Physics and Astronomy Faculty Publications

We investigate the effectiveness of trajectory mapping(TM) as a data validation tool. TM combines a dynamical model of the atmosphere with trace gas observations to provide more statistically robust estimates of instrument performance over much broader geographic areas than traditional techniques are able to provide. We present four detailed case studies selected so that the traditional techniques are expected to work well. In each case the TM results are equivalent to or improve upon the measurement comparisons performed with traditional approaches. The TM results are statistically more robust than those achieved using traditional approaches since the TM comparisons occur over …

Effects Of Planetary Wave-Breaking On The Seasonal Variation Of Total Column Ozone, Terrence R. Nathan, Eugene C. Cordero, Long Li, Donald J. Wuebbles

Faculty Publications, Meteorology and Climate Science

The effects of planetary wave breaking on the seasonal variation of total column ozone are investigated using a zonally averaged chemical-radiative-transport model of the atmosphere. The planetary wave breaking effects of zonal wavenumbers k=1 and k=2 are significant in the middle latitude stratosphere during Northern Hemisphere (NH) winter, whereas only wave k=1 is important during Southern Hemisphere (SH) winter. The mixing and induced meridional circulation due to the planetary wave breaking increases the seasonal variation of total column ozone in NH (SH) middle latitudes by ∼20% (∼10%).

Advanced Atmospheric Water Vapor Dial Detection System, Tamer Refaat

Electrical & Computer Engineering Theses & Dissertations

Measurement of atmospheric water vapor is very important for understanding the Earth's climate and water cycle. The remote sensing Differential Absorption Lidar (DIAL) technique is a powerful method to perform such measurement from aircraft and space. This thesis describes a new advanced detection system, which incorporates major improvements regarding sensitivity and size. These improvements include a low noise advanced avalanche photodiode detector, a custom analog circuit, a 14-bit digitizer, a microcontroller for on board averaging and finally a fast computer interface.

This thesis describes the design and validation of this new water vapor DIAL detection system which was integrated onto …

Influence Of Advection On Measurements Of The Net Ecosystem-Atmosphere Exchange Of Co2 From A Very Tall Tower, Chuixiang Yi, Kenneth J. Davis, Peter S. Bakwin, Bernard W. Berger, Linsey C. Marr

Publications and Research

In most studies of the net ecosystem-atmosphere exchange of CO₂ (NEE) using tower-based eddy covariance( EC) systems it has been assumed that advection is negligible. In this study we use a scalar conservation budget method to estimate the contribution of advection to NEE measurements from a very tall tower in northern Wisconsin. We examine data for June-August 1997. Measured NEEo, calculated as the sum of the EC flux plus the rate of change of storage below the EC measurement level, is expected to be constant with measurement height, and we take the differences between levels as a measure of …

Wavelength Modulation Spectroscopy Of Water Vapor And Line Center Stabilization At 1.462 Μm For Lidar Applications, Colleen Marie Fitzgerald

Electrical & Computer Engineering Theses & Dissertations

Wavelength modulation spectroscopy was employed to investigate water vapor absorption lines in the 1.462 µm wavelength region using an external-cavity diode laser. These measurements were necessary in the development of a lidar (light detection and ranging) instrument for differential absorption measurement of the concentration and movement of water vapor in the Earth's atmosphere. Differential absorption measurements require that the laser frequency remain stable throughout the duration of the measurement. To ensure this stability, the laser output wavelength is monitored and a feedback control loop set up to minimize laser line drift. Three lines were investigated in the 1.462 µm region. …

Tropospheric Reactive Odd Nitrogen Over The South Pacific In Austral Springtime, Jack E. Dibb, R. Talbot, Eric Scheuer, J D. Bradshaw, S T. Sandholm, D R. Blake, N J. Blake, Elliot Atlas, F Flocke

Earth Sciences

The distribution of reactive nitrogen species over the South Pacific during austral springtime appears to be dominated by biomass burning emissions and possibly lightning and stratospheric inputs. The absence of robust correlations of reactive nitrogen species with source-specific tracers (e.g., C₂H₂ [combustion], CH₃Cl [biomass burning], C₂Cl₄ [industrial],²¹⁰Pb [continental], and ⁷Be [stratospheric]) suggests significant aging and processing of the sampled air parcels due to losses by surface deposition, OH attack, and dilution processes. Classification of the air parcels based on CO enhancements indicates that the greatest influence was found in …

Validation Of The Ionospheric Forecast Model (Ifm) Version 3, Michael D. Scott

Theses and Dissertations

The purpose of this research was to validate the Ionospheric Forecast Model (IFM) Version 3 to assess its suitability and usefulness as an operational tool. The Ionospheric forecast model is a first principles computer model designed to forecast the state of the global ionosphere to 24 hours. The scope was limited to a comparison of the F2 layer critical frequency (foF2) and peak electron density (hmF2) against observed ionosonde data. The model was run with global solar and geomagnetic indices and Information from Digitial Ionospheric Sounding System (DISS) observations as inputs. The DISS observations were input through the Parameterized Real-Time …

Chemical Nox Budget In The Upper Troposphere Over The Tropical South Pacific, Martin G. Schultz, Daniel J. Jacob, J D. Bradshaw, S T. Sandholm, Jack E. Dibb, R. Talbot, Hanwant B. Singh

Earth Sciences

The chemical NOx budget in the upper troposphere over the tropical South Pacific is analyzed using aircraft measurements made at 6-12 km altitude in September 1996 during the Global Tropospheric Experiment (GTE) Pacific Exploratory Mission (PEM) Tropics A campaign. Chemical loss and production rates of NOx along the aircraft flight tracks are calculated with a photochemical model constrained by observations. Calculations using a standard chemical mechanism show a large missing source for NOx; chemical loss exceeds chemical production by a factor of 2.4 on average. Similar or greater NOx budget imbalances have been reported in analyses of data from previous …

Quantifying The Protonospheric Effect On Prism, Kelly B. Doser

Theses and Dissertations

The total electron content (TEC) contribution to a Parameterized Real-time Ionospheric Specification Model (PRISM) calculation has been studied using protonospheric TEC measurements made by Global Positioning Satellites (GPS). Including the protonosphere proved challenging to both the calibration of GPS measurements and execution of PRISM. Though 46 days of GPS measurements were acquired, only 40 were successfully calibrated, and only 35 of those were used in the study. Data issues such as availability and completeness as well as measurement quality affected 6 of the days used. Calibration was done at Pittsburgh by excluding all measurements below 40.750 N. latitude cutoff. This …

Tunable Mid-Ir Optical Parametric Oscillator Using Periodically Poled Rubidum Titanyl Arsenate, Frank J. Glavic

Theses and Dissertations

Tunable sources of coherent radiation are needed for a variety of military and commercial applications, including infrared countermeasures and atmospheric remote sensing. This research investigates a tunable mid-infrared coherent source using periodically-poled rubidium titanyl arsenate (PPRTA) as a quasi-phase matched (QPM) optical parametric oscillator (OPO). The advantages of PPRTA over periodically poled lithium niobate (PPLN) are presented. Quasi-phase matching and periodic poling theory are discussed, along with some important historical results and current developments. Experimental setups for determining threshold, conversion efficiency, pump depletion, and beam quality are presented along with experimental results. The research effort is focused on characterizing PPRTA …

Atmospheric Temperature Profiles By Ground-Based Infrared Spectrometer Measurements, Jon M. Saul

Theses and Dissertations

A method to recover atmospheric temperature profiles using a ground-based Fourier Transform Infrared spectrometer was investigated. The method used a difference form of the radiative transfer equation, a Bomem MR series Fourier Transform Infrared Spectrometer to collect atmospheric radiance values, and the Phillips Laboratory Expert- assisted User Software (PLEXUS) atmospheric radiance model, to recover an atmospheric temperature profile. The method researched uses radiance values from both the spectrometer measurements and the atmospheric model, along with kernel functions calculated by the atmospheric model as input to a difference form of the radiation transfer equation. From this the change in brightness temperatures …

Composition And Distribution Of Aerosols Over The North Atlantic During The Subsonic Assessment Ozone And Nitrogen Oxide Experiment (Sonex), Jack E. Dibb, R. Talbot, Eric Scheuer

Earth Sciences

We report the mixing ratios of aerosol-associated soluble ions (focusing on SO₄⁼ and NO₃⁻) and HNO₃ over the North Atlantic during NASA's Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX). The SONEX campaign was designed to quantify the impacts of jet emissions in the North Atlantic Flight Corridor (NAFC) by sampling both directly within and far removed from the organized track system. Beryllium-7 activities were also measured to assess the magnitude of stratospheric influence in the SONEX study region. Mixing ratios of aerosol-associated SO₄⁼ and NO₃⁻ above 8 km during …

Estimating The Probability Of Severe Convective Storms: A Local Perspective For The Central And Northern Plains, Preston W. Leftwich Jr.

National Oceanographic and Atmospheric Administration: Technical Reports and Related Materials

Summary and Conclusions

A procedure to estimate probabilities of the occurrence of severe convective storms within local areas has been described. Probabilities were based on a simulated climatology and the relative frequency of severe convective events when a selected site was contained within an operational Outlook or Watch. Combined data from five local areas were used to develop a general model for local probabilities within the central and northern Plains region. Attachment of probabilities to specific products placed values within a framework familiar to both forecasters and "end-users." Application of results in an operational scenario demonstrated representative local probabilities and …

Reactive Nitrogen Budget During The Nasa Sonex Mission, R. Talbot, Jack E. Dibb, Eric Scheuer, Y Kondo, M Koike, H B. Singh, L Salas, F Fukui, J O. Ballenthin, R F. Meads, T M. Miller, D E. Hunton, A A. Viggiano, D R. Blake, N J. Blake, Elliot Atlas, F Flocke, D J. Jacob, L Jaegle

Earth Sciences

The SASS Ozone and Nitrogen Oxides Experiment (SONEX) over the North Atlantic during October/November 1997 offered an excellent opportunity to examine the budget of reactive nitrogen in the upper troposphere (8–12 km altitude). The median measured total reactive nitrogen (NO_y) mixing ratio was 425 parts per trillion by volume (pptv). A data set merged to the HNO₃ measurement time resolution was used to calculate NO_y (NO_y sum) by summing the reactive nitrogen species (a combination of measured plus modeled results) and comparing it to measured NO_y (NO_y meas.). Comparisons were done for tropospheric …

Maximum Temperature Trends In The Himalaya And Its Vicinity: An Analysis Based On Temperature Records From Nepal For The Period 1971–94, Arun B. Shrestha, Cameron P. Wake, Paul A. Mayewski, Jack E. Dibb

Earth Sciences

Analyses of maximum temperature data from 49 stations in Nepal for the period 1971–94 reveal warming trends after 1977 ranging from 0.068 to 0.128C yr21 in most of the Middle Mountain and Himalayan regions, while the Siwalik and Terai (southern plains) regions show warming trends less than 0.038C yr21. The subset of records (14 stations) extending back to the early 1960s suggests that the recent warming trends were preceded by similar widespread cooling trends. Distributions of seasonal and annual temperature trends show high rates of warming in the high-elevation regions of the country (Middle Mountains and Himalaya), while low warming …

Chemical Characteristics Of Air From Differing Source Regions During The Pacific Exploratory Mission-Tropics A (Pem-Tropics A), Ashley S. Board, H Fuelberg, G L. Gregory, B J. Heikes, Martin G. Schultz, D R. Blake, Jack E. Dibb, S T. Sandholm, R. Talbot

Earth Sciences

Ten-day backward trajectories are used to determine the origins of air parcels arriving at airborne DC-8 chemical measurement sites during NASA's Pacific Exploratory Mission-Tropics A (PEM-T) that was conducted during August-October 1996. Those sites at which the air had a common geographical origin and transport history are grouped together, and statistical measures of chemical characteristics are computed. Temporal changes in potential temperature are used to determine whether trajectories experience a significant convective influence during the 10-day period. Those trajectories that do not experience a significant convective influence are divided into four geographical categories depending on their origins and paths. Air …

Constraints On The Age And Dilution Of Pacific Exploratory Mission-Tropics Biomass Burning Plumes From The Natural Radionuclide Tracer 210pb, Jack E. Dibb, R. Talbot, David Meeker, Eric Scheuer, N J. Blake, D R. Blake, G L. Gregory, G W. Sachse

Earth Sciences

During the NASA Global Troposphere Experiment Pacific Exploratory Mission-Tropics (PEM-Tropics) airborne sampling campaign we found unexpectedly high concentrations of aerosol-associated ²¹⁰Pb throughout the free troposphere over the South Pacific. Because of the remoteness of the study region, we expected specific activities to be generally less than 35 μBq m⁻³ but found an average in the free troposphere of 107 μBq m⁻³. This average was elevated by a large number of very active (up to 405 μBq m⁻³) samples that were associated with biomass burning plumes encountered on nearly every PEM-Tropics flight in the southern …

Ozone And Aerosol Distributions And Air Mass Characteristics Over The South Pacific During The Burning Season, Marta Fenn, Edward V. Browell, Carolyn Butler, William B. Grant, Susan A. Kooi, Marian B. Clayton, G L. Gregory, Reginald E. Newell, Yong Zhu, Jack E. Dibb, H Fuelberg, Bruce E. Anderson, A R. Bandy, D R. Blake, J D. Bradshaw, B J. Heikes, G W. Sachse, S T. Sandholm, H B. Singh, R. Talbot, D C. Thornton

Earth Sciences

In situ and laser remote measurements of gases and aerosols were made with airborne instrumentation to establish a baseline chemical signature of the atmosphere above the South Pacific Ocean during the NASA Global Tropospheric Experiment (GTE)/Pacific Exploratory Mission-Tropics A (PEM-Tropics A) conducted in August-October 1996. This paper discusses general characteristics of the air masses encountered during this experiment using an airborne lidar system for measurements of the large-scale variations in ozone (O₃) and aerosol distributions across the troposphere, calculated potential vorticity (PV) from the European Centre for Medium-Range Weather Forecasting (ECMWF), and in situ measurements for comprehensive air …

Observations And Interpretation Of Gravity Wave Induced Fluctuations In The O I (557.7 Nm) Airglow, G. Schubert, R. L. Walterscheid, Michael P. Hickey Ph.D., C. A. Tepley

Publications

Observations of fluctuations in the intensity and temperature of the O I (557.7 nm) airglow taken at Arecibo in 1989 are reported and interpreted on the assumption that they are caused by gravity waves propagating through the emission layer. The data give the magnitude of Krassovsky's ratio as 3.5 ± 2.2, at periods between about 5 and 10 hours. Comparison with theory shows that the gravity waves responsible for the measured airglow variations must have long wavelengths of several thousand kilometers. The observed phases of Krassovsky's ratio are in good agreement with theoretically predicted values at the long wavelengths and …

Concentrations And Snow-Atmosphere Fluxes Of Reactive Nitrogen At Summit, Greenland, J W. Munger, D J. Jacob, S M. Fan, A S. Colman, Jack E. Dibb

Earth Sciences

Concentrations and fluxes of NO_y (total reactive nitrogen), ozone concentrations and fluxes of sensible heat, water vapor, and momentum were measured from May 1 to July 20, 1995 at Summit, Greenland. Median NO_y concentrations declined from 947 ppt in May to 444 ppt by July. NO_y fluxes were observed into and out of the snow, but the magnitudes were usually below 1 μmol m⁻² h⁻¹ because of the low HNO₃ concentration and weak turbulence over the snow surface. Some of the highest observed fluxes may be due to temporary storage by equilibrium sorption of …

Fiber-Optic Coupled Lidar Receiver System To Measure Stratospheric Ozone, David Brent Harper

Electrical & Computer Engineering Theses & Dissertations

A fiber-optic coupled lidar receiver system was constructed to determine ozone concentrations in the stratosphere. The system was used to make ground-based measurements of lidar returns from a UV DIAL system. A fiber-optic cable was used to couple the light from the receiver telescope to the light detector. Photon counting was implemented as the light detection technique. This technique allowed detection of 301 and 311 nm lidar returns up to 27.5 and 32.5 km respectively. A software application was developed to control the photon counting system and perform real-time data analysis of measured lidar returns. DIAL measurements of stratospheric ozone …

Influence Of Biomass Combustion Emissions On The Distribution Of Acidic Trace Gases Over The Southern Pacific Basin During Austral Springtime, R. Talbot, Jack E. Dibb, Eric Scheuer, D R. Blake, N J. Blake, G L. Gregory, G W. Sachse, J D. Bradshaw, S T. Sandholm, H B. Singh

Earth Sciences

This paper describes the large-scale distributions of HNO₃, HCOOH, and CH₃COOH over the central and South Pacific basins during the Pacific Exploratory Mission-Tropics (PEM-Tropics) in austral springtime. Because of the remoteness of this region from continental areas, low part per trillion by volume (pptv) mixing ratios of acidic gases were anticipated to be pervasive over the South Pacific basin. However, at altitudes of 2–12 km over the South Pacific, air parcels were encountered frequently with significantly enhanced mixing ratios (up to 1200 pptv) of acidic gases. Most of these air parcels were centered in the 3–7 …

Aerosol Chemical Composition And Distribution During The Pacific Exploratory Mission (Pem) Tropics, Jack E. Dibb, R. Talbot, Eric Scheuer, D R. Blake, N J. Blake, G L. Gregory, G W. Sachse, D C. Thornton

Earth Sciences

Distributions of aerosol-associated soluble ions over much of the South Pacific were determined by sampling from the NASA DC-8 as part of the Pacific Exploratory Mission (PEM) Tropics campaign. The mixing ratios of all ionic species were surprisingly low throughout the free troposphere (2-12 km), despite the pervasive influence from biomass burning plumes advecting over the South Pacific from the west during PEM-Tropics. At the same time, the specific activity of 7Be frequently exceeded 1000 fCi m-3 through much of the depth of the troposphere. These distributions indicate that the plumes must have been efficiently scavenged by precipitation (removing the …

Evidence Of Nox Production Within Or Upon Ice Particles In The Greenland Snowpack, R E. Honrath, Matthew C. Peterson, S Guo, Jack E. Dibb, P B. Shepson, Bradley M. Campbell

Earth Sciences

NOx and NOy were determined in the interstitial air of surface snow and in ambient air at Summit, Greenland. NOx levels in interstitial air were 3 to >10 times those in ambient air, and were generally greater than ambient NOy levels. [NOy] in interstitial air varied diurnally in a manner consistent with photochemical generation within the snowpack. These observations imply that photochemical reactions occurring within or upon the ice crystals of surface snow produced NOx from a N-reservoir compound within the snow. Average [NOX]:[HNO3] and [NOx]:[NOy] ratios in ambient air above the snow were elevated relative to other remote sites, …

Validation Of The Gallagher Protonospheric Model, Kelly M. Law

Theses and Dissertations

Ionospheric models are used in many systems throughout the Department of Defense: for example, they are useful in correcting range errors in radio signals. However, correction models don't incorporate the protonosphere, the torus-shaped plasma volume above the ionosphere. The Gallagher Protonospheric Model, recently incorporated into the Parameterized Ionospheric Model 1.7 (PIM 1.7), was validated against protonospheric total electron content (PTEC) measurements made by the GPS system. Gallagher model calculations of slant PTEC for Pittsburgh ground station looking south with a raypath at an elevation of 26 degrees were compared against GPS PTEC measurements for the same configuration derived from the …