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Howarth, David A.An analysis of the seasonal variations in the water vapor transport fields over the southern hemisphere /
Doctor of Philosophy, The Ohio State University, 1984, Graduate School

Committee:

Not Provided (Other)

Subjects:

Physical Geography

Keywords:

Water vapor transport

Pugh, Larry AndersonA detailed study of the near infrared spectrum of water vapor /
Doctor of Philosophy, The Ohio State University, 1972, Graduate School

Committee:

Not Provided (Other)

Subjects:

Physics

Keywords:

Water vapor

Muvvala, PriyankaFeasibility of Troposphere Propagation Delay Modeling of GPS Signals using Three-Dimensional Weather Radar Reflectivity Returns
Master of Science (MS), Ohio University, 2011, Electrical Engineering (Engineering and Technology)
The objective of this thesis is to determine the feasibility of using 3D weather radar data for troposphere propagation delay modeling as well as to improve the understanding of GPS signal propagation through the troposphere during severe weather conditions. Equations are summarized to calculate the atmospheric index of refraction along the signal propagation path, including the effects of severe weather conditions. A ray tracing algorithm is developed and implemented to incorporate 3-Dimensional (3D) weather radar reflectivity data to calculate the troposphere propagation delay due to the index of refraction and ray bending. Ray tracing differences using 3D weather reflectivity data between two locations separated by 5 km are compared with differences obtained from GPS measurements at the two locations. It is found that the propagation differences between the two locations are dominated by the temperature and relative humidity along the signal propagation path. It is also found that the 3D radar reflectivity data is insufficient to extract the temperature and relative humidity profiles. The 3D radar reflectivity data is a good source to calculate the effects due to rain rate and suspended water droplets; however, the impact of these on troposphere delay differences was found to be less significant. Applications of improved understanding of troposphere propagation delays include not only aircraft precision approach operations, but also precision agriculture, construction, atmospheric sciences and surveying.

Committee:

Frank van Graas (Advisor); Trent Skidmore (Committee Member); Zhen Zhu (Committee Member); Maarten Uijt de Haag (Committee Member)

Subjects:

Aerospace Engineering; Atmosphere; Electrical Engineering; Engineering

Keywords:

ray tracing; weather radar troposphere delay modeling; troposphere index of refraction; refractivity; GPS troposphere delay; real time troposphere mitigation; atmopshere refractivity; gps signal propagation through rain clouds water vapor and humidity

Brown, Abel K.A global GPS data reprocessing strategy: Implications for the reference frame, orbital solutions, and trends in zenith delay parameters and total column water vapor (1994 - 2011)
Doctor of Philosophy, The Ohio State University, 2011, Geological Sciences
The primary focus of this work is to derive a long-term global trends in precipitable water vapor using atmospheric path delays as observed by continuously operating GPS stations from 1994 to present. Atmospheric water vapor plays a key role in global climate change but the exact mechanics of this process is poorly under- stood. Measuring the atmospheric path delay between the GPS satellite and ground station, it is possible to estimate the total water vapor content as a derived quantity independent of hardware configuration or environmental factors at continuous GPS locations. Globally distributed continuous GPS stations have existed with sufficient density for climate studies since around 1994 making GPS derived atmospheric path delay an excellent tool for global water vapor studies. A global GPS data set of more than 1000 stations has been reprocessed from 1994 to present to ensure maximum homogeneity of satellite orbits, ground station coordinates, and thus atmospheric delay estimates. The observed mean trend in precipitable water vapor based on zenith total delay measurements at GPS station locations is small at 0.094 ± 0.030 mm per decade while regional trends are often quite large w.r.t this mean trend, at times by an order of magnitude. Furthermore these large regional trends are polarized where positive trend regions are cancelled out by other negative trend regions. Precipitable water vapor estimates from the meteorological model ERA-Interim yield a mean trend over all land of 0.113 ± 0.007 mm per decade and a mean trend of 0.078 ± 0.017 mm per decade when restricted to GPS station locations only.

Committee:

Bevis Michael, PhD (Advisor); Shum C.K., PhD (Committee Member); Saalfeld Alan, PhD (Committee Member); Barton Michael, PhD (Committee Member)

Subjects:

Atmospheric Sciences; Earth; Geophysical; Geophysics

Keywords:

GPS; precipitable water vapor; zenith delay; global trend; reprocessing

Lee, Shuh-Chai.Water vapor transfer in the atmosphere and its relation to the water balance in the Ohio River basin /
Doctor of Philosophy, The Ohio State University, 1971, Graduate School

Committee:

Not Provided (Other)

Subjects:

Hydrology

Keywords:

Water vapor transport;Hydrology;Hydrologic cycle

Nessel, James AaronEstimation of Atmospheric Phase Scintillation Via Decorrelation of Water Vapor Radiometer Signals
Doctor of Philosophy, University of Akron, 2015, Electrical Engineering
The coherent arraying of antenna elements by widely distributed ground-based antenna systems has proven to be a valuable technological approach for high precision astrometric measurements and imaging via Very Long Baseline Interferometry (VLBI) and has been performed with considerable success by radio astronomers for several decades. The fundamental factor limiting the precision in which these measurements can be conducted, however, is due to the turbulence-induced refractivity changes of the atmospheric medium (troposphere) through which the propagating waves must traverse. For radio science applications, this problem can be significantly reduced via three well-demonstrated means: (1) proper choice of ground site location (i.e., dry, high altitude climates), (2) conducting observations during non-turbulent times (i.e., nights vs. days, winter vs. summer), and (3) employing relatively long integration time (on the order of minutes) compensation through the use of water vapor radiometers in data post-processing. For communications applications, however, this may not necessarily be the case, and a means to accurately estimate the water vapor variability of the troposphere at short time scales will be required to efficiently combine signals from ground-based antenna elements in an array environment, particularly for transmit arraying. It is thus the goal of this research effort to identify and validate a means in which phase fluctuations induced by the atmosphere can be accurately measured which could be employed to ultimately improve the coherent combining of several spatially separated signals transmitted from ground to space without the use of an active source (i.e., receive signal). The method in which this will be accomplished is through the use of a passive radiometric technique capable of accurately determining phase fluctuations on the necessary time scales to provide real-time phase compensation to realize transmit arraying at Ka-band frequencies and higher. To improve the accuracy over the state of the art in radiometric water vapor retrieval techniques, a novel blind source separation technique has been developed and demonstrated. Utilizing experimental data using a water vapor radiometer and a two-element interferometer, it is statistically shown that the approach described herein improves water vapor retrieval accuracy, particularly during cloudy conditions, over the state of the art.

Committee:

Nathan Ida, Dr. (Advisor); Igor Tsukerman, Dr. (Committee Member); Arjuna Madanayake, Dr. (Committee Member); Kevin Kreider, Dr. (Committee Member); Ernian Pan, Dr. (Committee Member)

Subjects:

Communication; Electrical Engineering; Electromagnetics

Keywords:

propagation; atmosphere; microwave; antenna array; Ka-band; water vapor radiometer; phase scintillation; interferometer; blind source separation

Liang, HuayanEvaporation Enhancement for Condensational Nanoparticle Growth in Hydrophobic Evaporation - Condensation Tube
MS, University of Cincinnati, 2014, Engineering and Applied Science: Mechanical Engineering
In present study, the enhancement of meniscus evaporation by changing meniscus shape and area was investigated. Rather than observing the meniscus shape directly, an alternative method has been utilized. A Condensation Particle Counter (CPC) structure, which benefits from meniscus evaporation of a porous media to make vapor for water droplet growth, has been introduced to analyze the production water droplet. By analyzing the size and concentration of the condensed water droplet from CPC, the enhancement of meniscus evaporation taken place at the porous media was determined. The meniscus shape and area alterations were controlled by applying an additional pressure onto the meniscus. The results of the bigger condensed water droplet and higher concentration clearly demonstrate that the enhancement has been achieved to the meniscus evaporation, which was led by changing of the additional pressure applied to the meniscus of the porous media.

Committee:

Sang Young Son, Ph.D. (Committee Chair); Pramod Kulkarni, D.Sc. (Committee Member); Frank Gerner, Ph.D. (Committee Member)

Subjects:

Mechanics

Keywords:

Condensation;Particle growth;Non-wetting porous structure;Water vapor condensation;Interferometric Mie Imaging;Evaporation Condensation Tube

Toohey, Caitlin MaureenNovel Environmental Barrier Coatings for Resistance Against Degradation by Molten Glassy Deposits in the Presence of Water Vapor
Master of Science, The Ohio State University, 2011, Materials Science and Engineering
Environmental barrier coatings (EBCs) are used to prevent oxidation of underlying ceramic-matrix composite (CMC) structural components in aircraft gas-turbine engines. As operating temperatures increase, ingested airborne sand poses a serious threat to the stability of these coatings, because the sand adheres to the hot EBC surfaces and melts, forming calcium–magnesium–aluminosilicate (CMAS) glass. The reaction of EBCs with molten CMAS can lead to EBC delamination. Additionally, the interaction of water vapor with the CMAS–reacted EBCs can result in the formation of undesirable phases. Yb2Si2O7 has been identified as a promising EBC ceramic, based on its desirable properties: phase stability up to 1600°C, low thermal expansion coefficient mismatch with common CMCs, and potential resistance against degradation by CMAS and water vapor. As–sintered Yb2Si2O7 and CMAS–coated Yb2Si2O7 are tested in an air environment and in a water vapor environment, at a temperature of 1300°C in both cases. The behavior of these ceramics is compared to that of reference materials. Results from oxidation and chemical stability studies and analyses are presented.

Committee:

Nitin P. Padture, PhD (Advisor); Rudolph G. Buchheit, PhD (Committee Member)

Subjects:

Materials Science

Keywords:

environmental barrier coating; EBC; Yb2Si2O7; ytterbium disilicate; CMAS; water vapor corrosion

Nguyen, QuynhGiao N.High Temperature Volatility and Oxidation Measurements of Titanium and Silicon Containing Ceramic Materials
Doctor of Philosophy in Clinical-Bioanalytical Chemistry, Cleveland State University, 2008, College of Science
Titanium (Ti) and silicon (Si) containing materials are of high interest to the aerospace industry due to its high temperature capability, strength, and light weight. A continuous exterior oxide layer is desirable to reduce the oxidation rate of these two materials. At high temperatures, water vapor plays a key role in the volatility of materials including oxide surfaces. This study first evaluated several hot-pressed Ti and Si-containing compositions at high temperatures as a function of oxidation resistance. This study also evaluated cold pressed titanium dioxide (TiO2) powder pellets at a temperature range of 1400°C - 1200°C in water containing environments to determine the volatile hydoxyl species using the transpiration method. The water content ranged from 0-76 mole % and the oxygen content range was 0-100 mole % during the 20-250 hour exposure times. Results indicate that oxygen is not a key contributor at these temperatures and a volatile Ti-O-H species has been identified.

Committee:

Lily M. Ng, PhD (Committee Chair); James L. Smialek, PhD (Advisor); Kang N. Lee, PhD (Committee Member); John F. Turner II, PhD (Committee Member); Mary V. Zeller, PhD (Committee Member)

Subjects:

Aerospace Materials; Chemistry; Materials Science

Keywords:

aerospace; ceramic; combustion environment; high temperature; hydroxyl species; oxidation; materials; Si; silicon; titanium dioxide; TiO2; Ti-O-H; transpiration method; transpiration technique; volatility; water vapor