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Estimation of Refractivity Conditions in the Marine Atmospheric Boundary Layer from Range and Height Measurement of X-band EM Propagation and Inverse Solutions

Wang, Qi
http://rave.ohiolink.edu/etdc/view?acc_num=osu1565885420888906

Abstract Details

2019, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
An important application of air-sea interaction research is in characterizing marine atmospheric boundary layer (MABL) properties, electromagnetic ducting in particular, in order to predict radar and radio communication conditions in the maritime environment. Ducting propagation is highly dependent on atmospheric conditions; experiments that combine propagation measurements with detailed atmospheric characterization can offer opportunities for improving modeling of the MABL effects on propagation. While refractive conditions can be directly measured or calculated using numerous methods, inversion methods using electromagnetic measurements can directly determine the impact of the atmosphere on radio frequency systems. A new X-band vertical array system is developed for measuring and characterizing electromagnetic (EM) propagation in the MABL. In particular, the evaporation duct that commonly forms over water is investigated as part of the CASPER (Coupled Air-Sea Processes and Electromagnetic ducting Research) at-sea experimental campaign conducted off the coast of Duck, NC, during October-November of 2015. Monte Carlo simulations are first used to develop an optimal array of four vertically spaced receiving antennas. In the experiment, the antennas are mounted on the stern A-frame of a research vessel and measure EM signals transmitted from beacons mounted on another research vessel and on the pier at the Army Field Research Facility. While the propagation loss vs. range provides a dataset similar to previous work, the vertical array can provide sampling of modes in the leaky waveguide formed in the duct. Combining both range and height sampling results in a robust inversion method for evaporation duct estimation. In this dissertation the efficacy of the 4-element array is demonstrated by estimation of the evaporation duct height through comparison with a library of precomputed propagation curves generated using the parabolic wave equation (PWE). Low model error gives confidence in the estimates, which are consistent with concurrent environmental measurements performed by the CASPER team. The environmental measurements acted as input to the Navy Atmospheric Vertical Surface Layer Model (NAVSLaM) to compute evaporation duct refractivity profiles for comparison with the estimate. It is found that the evaporation duct can vary significantly with range and time over the duration of a data collection run. The second phase of CASPER measurements, CASPER West, provided an opportunity to model the time dependence of the evaporation duct as well as range dependence. It was conducted off the coast of Point Mugu, CA, during September-October of 2017. A fixed point-to-point EM propagation measurement using the X-band vertical array can be used to estimate the evaporation duct in real time. A novel refractivity profile model is also proposed to estimate parameters defining both the evaporation duct and surface-based duct using the measured one-way propagation loss obtained with the receiving X-band array at multiple ranges. Lastly, a theoretical study of waveguide mode is conducted to provide insight into the physical picture of the field distribution near the sea surface and the effects of long-distance ducting propagation. The result corroborates the numerical Monte Carlo study used to design the 4-antenna array, and the ability of the designed X-band system to characterize the EM propagation in the homogeneous and inhomogeneous environment from range and height sampling measurements.
Robert Burkholder (Advisor)
147 p.
Electrical Engineering
Environmental factors, parabolic wave equation, propagation measurements, refractivity, weather forecasting

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Citations

  • Wang, Q. (2019). Estimation of Refractivity Conditions in the Marine Atmospheric Boundary Layer from Range and Height Measurement of X-band EM Propagation and Inverse Solutions [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565885420888906

    APA Style (7th edition)

  • Wang, Qi. Estimation of Refractivity Conditions in the Marine Atmospheric Boundary Layer from Range and Height Measurement of X-band EM Propagation and Inverse Solutions . 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1565885420888906.

    MLA Style (8th edition)

  • Wang, Qi. "Estimation of Refractivity Conditions in the Marine Atmospheric Boundary Layer from Range and Height Measurement of X-band EM Propagation and Inverse Solutions ." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565885420888906

    Chicago Manual of Style (17th edition)

osu1565885420888906
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This open access ETD is published by The Ohio State University and OhioLINK.