Oceanography and Atmospheric Sciences and Meteorology Commons^™

Automatic Digital Processing For Calibration Data Of Open Skies Treaty Sensors, Donna D. Keating

Theses and Dissertations

The Open Skies Treaty provides guidelines allowing participants to fly in air space over other participants' countries to monitor strategic military placement and development. The treaty restricts the ground size of the smallest detail recorded by these aerial imaging systems to any size larger than 30 cm. This restriction is enforced by placing a lower limit on the altitude at which a participating aircraft can fly and it is computed as the value of Hmin. Current techniques rely on human photographic interpreters to select the value of Hmin for every calibration pass and is very resource intensive. The Open Skies …

A 200-Year 210pb Record From Greenland, Jack E. Dibb, Henrick B. Clausen

Earth Sciences

A continuous profile of ²¹⁰Pb activity extending back to 1766 has been developed for a firn/ice core collected at Site D in central Greenland in 1984. Unexpectedly high activities of ²¹⁰Pb were found at the base of this core (0.032 pCi kg⁻¹ in samples more than 200 years old), calling into question the common assumption that supported ²¹⁰Pb can be neglected when constructing chronologies in glacial snow and ice. It is problematic to assert that all of the ²¹⁰Pb measured at depth should be attributed to the supported fraction, given previous estimates of dust loading …

Analysis Of Multimode Low-Probability-Of-Intercept (Lpi) Communications With Atmospheric Effects, Ala Ghordlo

Theses and Dissertations

This research expanded Low Probability of Intercept (LPI) communications analysis in two areas. First, multimode communication was included to account for ground to ground and air to ground links in addition to the standard air to air links traditionally used in LPI analysis. The propagation equations for the three modes of interest were derived and included in LPI analytic models in the form of a mode quality factor to account for multimode LPI scenarios. This new quality factor was used in studying several communication and interception link combinations. Variations due to differences between the communication and interception modes were presented …

Performance Analysis Of A Hartman Wavefront Sensor Used For Sensing Atmospheric Turbulence Statistics, Toby D. Reeves

Theses and Dissertations

Atmospheric turbulence parameters, such as Fried's coherence diameter, the outer scale of turbulence, and the turbulence power law, are related to the wavefront slope structure function (SSF). The SSF is defined as the second moment of the wavefront slope difference as a function of both time and position. Knowledge of the SSF allows turbulence parameters to be estimated. Hartmann wavefront sensor (H-WFS) slope measurements composed of both signal and noise, allow the SSF to be estimated by computing a mean square difference of H-WFS slope measurements. The quality of the SSF estimate is quantified by the signal-to-noise ratio (SNR) of …

Deconvolution From Wavefront Sensing Using Optimal Wavefront Estimators, Scott R. Maethner

Theses and Dissertations

A cost effective method to improve the space surveillance mission performance of United States Air Force (USAF) ground-based telescopes is investigated and improved. A minimum variance wavefront estimation technique is used to improve Deconvolution from Wavefront Sensing (DWFS), a method to mitigate the effects of atmospheric turbulence on imaging systems that does not require expensive adaptive optics. Both least-squares and minimum variance wavefront phase estimation techniques are investigated, using both Gaussian and Zernike polynomial elementary functions. Imaging simulations and established performance metrics are used to evaluate these wavefront estimation techniques for a one-meter optical telescope. Performance metrics include the average …

Investigation Of Ba, Bao, Sr And Sro Pulsed Laser-Induced Vapor Plumes In N2, O2, Microwave Discharged O2, And Vacuum At Low Laser Fluence, David L. Byers

Theses and Dissertations

Ba, BaO, Sr and SrO were ablated by 248 nm laser pulses at fluences ranging from 270 mJ-/sq cm to 575 mJ-/sq cm in vacuum and in 25 mtorr atmospheres of N2, O2 and microwave-discharged O2. The spectral emissions of these plumes were compared for indications of ionization due to Ba or Sr collisions with each gas. The addition of a background gas increased the ion and neutral signature across the spectrum. SrO band emission was observed at 16,600-16,900/cm and possible BaO band emissions were observed in the 18,250-18,400/cm, 19,000-19700/cm and 19,800-20,000/cm regions. A screened plate ion probe was use …

Modeling Of The Processing And Removal Of Trace Gas And Aerosol Species By Arctic Radiation Fogs And Comparison With Measurements, M H. Bergin, S N. Pandis, C Davidson, J L. Jaffrezo, Jack E. Dibb, A G. Russell, H D. Kuhns

Earth Sciences

A Lagrangian radiation fog model is applied to a fog event at Summit, Greenland. The model simulates the formation and dissipation of fog. Included in the model are detailed gas and aqueous phase chemistry, and deposition of chemical species with fog droplets. Model predictions of the gas phase concentrations of H₂O₂, HCOOH, SO₂, and HNO₃ as well as the fog fluxes of S(VI), N(V), H₂O₂, and water are compared with measurements. The predicted fluxes of S(VI), N(V), H₂O₂, and fog water generally agree with measured …

Investigation Of Radio Wave Propagation In The Martian Ionosphere Utilizing Hf Sounding Techniques, Robert J. Yowell

Theses and Dissertations

This thesis presents a preliminary design of an ionospheric sounder to be carried aboard one or more of NASA's Mars Surveyor landers. Past Russian and American probes have indicated the existence of an ionosphere, but none of these missions remotely sensed this atmospheric layer from the surface. The rationale for utilizing a surface-based Martian ionospheric sounder is discussed. Based on NASA's choice of launch vehicle and power source, a low-weight, low-powered Chirp sounder using a horizontally-polarized dipole antenna is recommended for the sounder experiment. The sounder experiment should be conducted for at least one Martian year, in order to investigate …

Recent Climate Anomalies And Their Impact On Snow Chemistry At South Pole, 1987 - 1994, Jack E. Dibb, Sallie I. Whitlow

Earth Sciences

Three 2-m deep snowpits sampled at South Pole in 1994 provide detailed (2-cm resolution) profiles of the concentrations of soluble ionic species for the period 1987 - 1994. The most prominent feature is a large concentration spike of SO4 = in snow deposited in 1992 reflecting fallout from the eruptions of Pinatubo and Hudson in 1991. Concentrations of MSA and values of the MSA/(non-sea-salt SO4 =) ratio are elevated for about three years centered on the prominent volcanic signal. These changes appear to be due to the extended 1991 - 1993 El Nino. The overlapping effects of the volcanic eruptions …

Asian Influence Over The Western North Pacific During The Fall Season: Inferences From Lead 210, Soluble Ionic Species And Ozone, Jack E. Dibb, R. Talbot, Anthony Klemm, G L. Gregory, H B. Singh, J D. Bradshaw, S T. Sandholm

Earth Sciences

Aerosol samples collected over the western Pacific during the NASA/Global Tropospheric Experiment Pacific Exploratory Mission (PEM-West A) expedition (September–October 1991) revealed mean ²¹⁰Pb concentrations in the free troposphere in the 5–10 fCi m⁻³ STP range. Most soluble ionic aerosol-associated species were near detection limits [≪40 parts per trillion by volume (pptv)] in these same samples. The altitude distribution of O₃ near Asia closely resembled that of ²¹⁰Pb, while no relationship was found between the concentrations of O₃ and ⁷Be. Free tropospheric air over the western Pacific was depleted in soluble aerosol-associated species but enriched …

Chemical Characteristics Of Continental Outflow From Asia To The Troposphere Over The Western Pacific Ocean During September-October 1991: Results From Pem-West A, R. Talbot, Jack E. Dibb, K I. Klemm, J D. Bradshaw, S T. Sandholm, D R. Blake, G W. Sachse, J E. Collins Jr, B J. Heikes, G L. Gregory, B E. Anderson, H B. Singh, D C. Thornton, J T. Merrill

Earth Sciences

An important objective of the Pacific Exploratory Mission-West A (PEM-West A) was the chemical characterization of the outflow of tropospheric trace gases and aerosol particles from the Asian continent over the western Pacific Ocean. This paper summarizes the chemistry of this outflow during the period September – October 1991. The vertical distributions of CO, C₂H₆, and NO_xshowed regions of outflow at altitudes below 2 km and from 8 to 12 km. Mixing ratios of CO were ≈130 parts per billion by volume (ppbv), ≈1000 parts per trillion by volume (pptv) for C₂H …

Atmospheric Sampling Of Supertyphoon Mireille With Nasa Dc-8 Aircraft On September 27,1991, During Pem-West A, G W. Sachse, R E. Newall, W Hu, Z X. Wu, H Akimoto, B E. Anderson, E V. Browell, G L. Gregory, G W. Sachse, M C. Shipman, A S. Bachmeier, A R. Bandy, D C. Thornton, D R. Blake, F Sherwood Rowland, J D. Bradshaw, J H. Crawford, D D. Davis, S T. Sandholm, W Brockett, L Degreef, D Lewis, D Mccormick, E Monitz, J E. Collins Jr, B J. Heikes, J T. Merrill, K K. Kelly, S C. Liu, Y Kondo, M Koike, C M. Liu, F Sakama, H B. Singh, Jack E. Dibb, R. Talbot

Earth Sciences

The DC-8 mission of September 27, 1991, was designed to sample air flowing into Typhoon Mireille in the boundary layer, air in the upper tropospheric eye region, and air emerging from the typhoon and ahead of the system, also in the upper troposphere. The objective was to find how a typhoon redistributes trace constituents in the West Pacific region and whether any such redistribution is important on the global scale. The boundary layer air (300 m), in a region to the SE of the eye, contained low mixing ratios of the tracer species O3, CO, C2H6, C2H2, C3H8, C6H6and CS2 …

Application Of Autoregressive Moving Average Linear Prediction Filters To The Characterization Of Solar Wind-Magnetosphere Coupling, Carter N. Borst

Theses and Dissertations

Linear prediction filtering techniques have been used in studying the coupling processes between the solar wind and magnetosphere. The magnetosphere is a complex, dynamic system with at least two independent coupling methods for energy input, driven and unloading. Linear models were built and tested on the Bargatze data set, consisting of over 70 days of geomagnetic indices and solar wind data ordered in 34 intervals of increasing geomagnetic activity. Linear filtering techniques employing single-and multiple-input, autoregressive models predicted values of the magnetic index AL from solar wind data. The impulse response curves of the AL-coupling function groups showed amplitude peaks …

A Simple Model To Estimate Atmospheric Concentrations Of Aerosol Chemical Species Based On Snow Core Chemistry At Summit, Greenland, M H. Bergin, C Davidson, Jack E. Dibb, J L. Jaffrezo, H D. Kuhns, S N. Pandis

Earth Sciences

A simple model is presented to estimate atmospheric concentrations of chemical species that exist primarily as aerosols based on snow core/ice core chemistry at Summit, Greenland. The model considers the processes of snow, fog, and dry deposition. The deposition parameters for each of the processes are estimated for SO₄²⁻ and Ca²⁺ and are based on experiments conducted during the 1993 and 1994 summer field seasons. The seasonal mean atmospheric concentrations are estimated based on the deposition parameters and snow cores obtained during the field seasons. The ratios of the estimated seasonal mean airborne concentration divided by the …

The Role Of Frame Selection And Bispectrum Phase Reconstruction For Speckle Imaging Through Atmospheric Turbulence, Elizabeth A. Harpold

Theses and Dissertations

Frame selection using quality sharpness metrics have been shown in previous AFIT theses, to be effective in improving the final product of images obtained using adaptive optics. This thesis extends this idea to noncompensated speckle image data. Speckle image reconstruction is simulated with and without frame selection. Speckle images require the processing of hundreds of data frames. Frame selection is a method of reducing the amount of data required to reconstruct the image. A collection of short exposure image data frames of a single object are sorted based on sharpness metrics. Only the highest quality frames are retained and processed …

Analysis And Interpretation Of Ion Data Associated With Neutral Gas Releases In The Earth's Ionosphere, Timothy M. Shadid

Theses and Dissertations

Barium and strontium release experiments were conducted throughout 1991 from the Combined Release and Radiation Effects Satellite (CRRES) to study both natural and man-made disturbances in the earth's ionosphere. A mass spectrometer on the spacecraft counted the Ba and Sr ions as the cloud expanded. In this study, data from the G-1 (in sunlight) and G-11b (in darkness) releases were modeled to understand the source of the ion signals. The model reproduced the Ba⁺ sun data well assuming photoionization (τ = 28 s) was the primary ionization mechanism. However, it was not able to account for the remaining ion …

The Effects Of Vegetative Canopies On Atmospheric Dispersion, John R. Lindell

Theses and Dissertations

This research was conducted to improve our understanding of the effects of vegetative canopy-induced turbulence on the dispersion of air pollution. The computer model most often used to calculate atmospheric dispersion is the Gaussian plume model, which requires some method to compute the downwind dispersions coefficients. These coefficients are a parameterization of the atmospheric stability or the level of turbulence in the atmosphere. The Environmental Protection Agency's recommended parameterization scheme is the Pasquill-Gifford method. By comparing the Pasquill-Gifford method to the Modified Mitchell method using sigma theta, the standard deviation of the horizontal wind fluctuations, the relative precision of each …

The Effect Of Meteorological Data Averaging Times On Plume Concentrations From Explosive Ordnance Disposal Open Burning Operations, Ida L. Widmann

Theses and Dissertations

Explosive Ordnance Disposal (EOD) Open Burning (OB) operations are performed to treat and dispose of unserviceable munitions in the Department of Defense (DOD) inventory. Air pollution modeling of OB operations is an Environmental Protection Agency requirement for permit issuance at OB sites. Specific OB regulation is still in its infancy; therefore, establishment of OB modeling techniques is still in the early stages. This thesis effort sought to develop a computer model, based upon the Gaussian Puff Equation. The model varies from standard plume modeling practices by not making the assumption that the wind direction, wind speed and turbulence are uniform …

Characterization Of Atmospheric Turbulence Over Long Horizontal Paths Using Optical Slope Measurements, Eric E. Silbaugh

Theses and Dissertations

Atmospheric turbulence has long been recognized as one of the fundamental factors affecting optical systems operating through the atmosphere. Turbulence over vertical paths has been well characterized, both theoretically and experimentally. Much less is known about turbulence over long, horizontal paths. Perturbations of the wave front phase can be measured using a Hartmann wave front sensor (H-WFS). Theoretical expressions for the tilt removed structure function of the H-WFS slope measurements were derived and evaluated using quadrature. These slope structure functions are functions of the phase structure function. The Kolmogorov turbulence model was assumed. Simulated H-WFS slope measurements were generated using …

A Comparison Of Methods For Estimating Rms Error: A `Brute Force" Approach Versus A Mathematically-Elegant Approach, As Applied To The Calculation Of A Specific Retrieval Error For A Limb-Scanning Microwave Radiometer-Spectrometer, Larry L. Johnson

Theses and Dissertations

The Millimeter-wave Atmospheric Sounder (MAS) is a high resolution limb- scanning microwave radiometer-spectrometer which has been flown aboard the Space Shuttle. The instrument was designed to sense the microwave emission from several upper atmospheric constituents, including water vapor and ozone. The resonant frequencies of water vapor and ozone are extremely close (183 and 184 GHz, respectively), so that the high-frequency wing of the water vapor spectrum overlaps the low frequency wing of the ozone spectrum. Consequently, the measured ozone spectrum incorporates a slight water vapor contribution; therefore, the retrieved ozone profile is dependent on the true water vapor profile. The …

A Chemical-Dynamical Model Of Wave-Driven Sodium Fluctuations, Michael P. Hickey Ph.D., John M.C. Plane

Publications

A comprehensive chemical-dynamical model is used to investigate the interaction of gravity waves with twenty minor species involved in the atomic sodium chemistry in the mesopause region. We find that chemistry becomes important on the underside of the sodium layer, primarily below 85 km altitude, where the relative importance of chemistry in wave-driven sodium fluctuations increases with increasing wave period and increasing horizontal wavelength. We also find that for altitudes below 80 km an adequate determination of the effects of chemistry in these fluctuations requires the inclusion of several reactions related to ozone chemistry. However, the atomic Na density is …

Diel Variations Of H2o2 In Greenland: A Discussion Of The Cause And Effect Relationship, R Bales, Joe Mcconnell, Mark V. Losleben, Martha H. Conklin, Katrin Fuhrer, Albrecht Neftel, Jack E. Dibb, D W. Kahl, C Stearns

Earth Sciences

Atmospheric hydrogen peroxide (H₂O₂) measurements at Summit, Greenland, in May–June, 1993 exhibited a diel variation, with afternoon highs typically 1–2 parts per billion by volume (ppbv) and nighttime lows about 0.5 ppbv lower. This variation closely followed that for temperature; specific humidity exhibited the same general trend. During a 17-day snowfall-free period, surface snow was accumulating H₂O₂, apparently from nighttime cocondensation of H₂O and H₂O₂. Previous photochemical modeling (Neftel et al., 1995) suggests that daytime H₂O₂ should be about 1 ppbv, significantly lower …

New Sources For The Hot Oxygen Geocorona: Solar Cycle, Seasonal, Latitudinal, And Diurnal Variations, Michael P. Hickey Ph.D., P. G. Richards, D. G. Torr

Publications

This paper demonstrates the variability of thermospheric sources of hot oxygen atoms. Numerical calculations were performed for day and night, high and low solar activity, summer and winter, and low- and middle-latitude conditions. Under most conditions, reactions involving metastable species are more important hot O sources than previously considered dissociative recombination of O2+ and NO+. All the hot O sources are an order of magnitude lower at midnight than at noon. At night, dissociative recombination of O2+and NO+ are the most important sources. Quenching of vibrationally excited N2 (N2*) by O is the most important metastable source at night. Above …

The Contributions Of Snow, Fog, And Dry Deposition To The Summer Flux Of Anions And Cations At Summit, Greenland, M H. Bergin, J L. Jaffrezo, C Davidson, Jack E. Dibb, S N. Pandis, R Hillamo, W Maenhaut, H D. Kuhns, T Makela

Earth Sciences

Experiments were performed during the period May–July of 1993 at Summit, Greenland. Aerosol mass size distributions as well as daily average concentrations of several anionic and cationic species were measured. Dry deposition velocities for SO₄²⁻ were estimated using surrogate surfaces (symmetric airfoils) as well as impactor data. Real-time concentrations of particles greater than 0.5 μm and greater than 0.01 μm were measured. Snow and fog samples from nearly all of the events occurring during the field season were collected. Filter sampler results indicate that SO₄²⁻ is the dominant aerosol anion species, with Na⁺, NH …

A Feasibility Study Of Dynamical Assimilation Of Tide Gauge Data In The Chesapeake Bay, Yvette H. Spitz

OES Theses and Dissertations

The feasibility of dynamical assimilation of surface elevation from tide gauges is investigated to estimate the bottom drag coefficient and surface stress as a first step in improving modeled tidal and wind-driven circulation in the Chesapeake Bay. A two-dimensional shallow water model and an adjoint variational method with a limited memory quasi-Newton optimization algorithm are used to achieve this goal.

Assimilation of tide gauge observations from ten permanent stations in the Bay and use of a two-dimensional model adequately estimate the bottom drag coefficient, wind stress and surface elevation at the Bay mouth. Subsequent use of these estimates in the …

Dynamics Of Dipoles In The Middle Atlantic Bight, Bruce L. Lipphardt Jr.

OES Theses and Dissertations

Beginning with the observations made by the Warm-Core Rings program in the early 1980's, several Gulf Stream warm-core rings (WCR's) in the Middle Atlantic Bight (MAB) have been observed with one or more cyclones around their periphery. These ring systems are observed in the slope water between the Gulf Stream's western boundary and the shelf break. Observations of ring systems have motivated a reanalysis of existing satellite surface temperature imagery, which revealed that multipole structure is common for both warm and cold core rings. This suggests that rings are better characterized as one part of multipole systems rather than as …

Global Perspective Of Nitrate Flux In Ice Cores, Qinzhao Yang, Paul A. Mayewski, Sallie I. Whitlow, Mark S. Twickler, Michael Morrison, R. Talbot, Jack E. Dibb, Ernst Linder

Earth Sciences

The relationships between the concentration and the flux of chemical species (Cl-, NO3 - , SO42-, Na +, K + , NH4 + , Mg 2+ , Ca 2+) versus snow accumulation rate were examined at GISP2 and 20D in Greenland, Mount Logan from the St. Elias Range, Yukon Territory, Canada, and Sentik Glacier from the northwest end of the Zanskar Range in the Indian Himalayas. At all sites, only nitrate flux is significantly (a = 0.05) related to snow accumulation rate. Of all the chemical series, only nitrate concentration data are normally distributed. Therefore we suggest that nitrate concentration …

Fisheries And Oceanography Off Galicia, Nw Spain: Mesoscale Spatial And Temporal Changes In Physical Processes And Resultant Patterns Of Biological Productivity, K. R. Tenore, M. Alonsonval, L. P. Atkinson, J. M. Cabanas, R. M. Cal, H. J. Campos, F. Castillejo, E. J, Chesney, N. Gonzalez, R. B. Hanson, C. R. Mcclain, A. Miranda, M. R. Roman, J. Sanchez, G. Santiago, L. Valdes, M. Varela, J. Yoder

CCPO Publications

The Galician shelf off NW Spain (43N degrees 9W degrees) exhibits mesoscale spatial and temporal changes in biological productivity associated with upwelling. Spatial heterogeneity results from local geomorphic and land-sea interactions superimposed on the large scale atmospheric processes that produce upwelling. Wind-induced upwelling events, commonly of short (i.e., week) duration, are more common in the summer than in the winter. A Series of cruises, including some time series sampling, and satellite imagery analysis showed that surface upwelling was more common and persistent on the northern coast compared with the western coast off the coastal embayments, the Rias Bajas. Nearshore off …

A Guide To Floodplain Cattle Fencing, Department Of Agriculture, Western Australia, Main Roads, Western Australia

Animal production and livestock published reports

A seminar and workshop was held at Fitzroy Crossing in October 1993 to address the consequences of flooding to landholders and communities.

Damage to flood plain fencing was identified as one of the major concerns to landholders.

An outcome from the workshop was the decision to draw on local knowledge and collate information on options for fence and floodgate designs.

This information was to be made available to land holders and other interested parties - hence this publication.

Laser Beam Propagation In Non-Kolmogorov Atmospheric Turbulence, Bruce E. Stribling

Theses and Dissertations

Several observations of atmospheric turbulence statistics have been reported which do not obey Kolmogorov's power spectral density model. These observations have prompted the study of optical propagation through turbulence described by non-classical power spectra. This thesis presents an analysis of optical propagation through turbulence which causes index of refraction fluctuations to have spatial power spectra that obey arbitrary power laws. The spherical and plane wave structure functions are derived using Mellin transform techniques and are applied to the field mutual coherence function (MCF) using the extended Huygens-Fresnel principle. The MCF is used to compute the Strehl ratio of a focused, …