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Dissertations / Theses on the topic 'Refractivity'

Author: Grafiati

Published: 4 June 2021

Last updated: 25 July 2025

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1

Stahlhut, Keir D. "Refractivity in the Artic regions." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Sep%5FStahlhut.pdf.

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Thesis (M.S. in Meterology and Physical Oceanography)--Naval Postgraduate School, September 2006.<br>Thesis Advisor(s): Peter Guest. "September 2006." Includes bibliographical references (p. 35). Also available in print.

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2

Xu, Luyao. "Multi-frequency Atmospheric Refractivity InversionDissertation." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574550558934232.

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3

Stahlhut, Keir D. "Refractivity in the Arctic regions." Thesis, Monterey, California. Naval Postgraduate School, 2006. http://hdl.handle.net/10945/2650.

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The purpose of this study is to quantify patterns or trends of electromagnetic ducting conditions in the Arctic. On average, ducts occurred 5% of the time in the summer months, and 2-3% in the spring, fall, and winter months. This is considered a low approximation due to the vertical resolution of the sounding data. For some local regions, ducts occurred up to 20% of the time, especially in summer months. In general, local areas near coast lines or near the pole over ice/ocean had higher frequency of ducts than local areas over land mass. For summer and fall months, humidity gradients con

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4

Creese, Charles W. "Meteorological interpretation of near-surface refractivity measurements." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ64336.pdf.

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5

Creese, Charles W. "Meteorological interpretation of near-surface refractivity measurements." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30360.

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Measurements of the radio refractive index (or refractivity) of near-surface air using phase information from radar ground echoes can be used to provide valuable humidity information on storm-scale anomalies not adequately resolved by the surface observations. Using changes in the phase of ground targets as proxies for changes in the two-way travel times of radar pulses, fields of near-surface refractivity have been generated in real time on McGill University's Doppler S-band radar since 1996. Retrieval of meteorological information from refractivity is possible because of its strong dependenc

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6

Mabey, Deborah L. "Variability of refractivity in the surface layer." Thesis, Monterey, California. Naval Postgraduate School, 2002. http://hdl.handle.net/10945/5877.

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The author and members of the Boundary Layer Studies Group collected atmospheric surface layer profile properties affecting RF propagation during the Roughness and Evaporation Duct experiment off the windward coast of Oahu. We measured temperature, humidity and pressure profiles from the surface and up to 100 m by multi-level buoy-mounted sensors and a rawinsonde attached to a kite flown from a small vessel. We obtained the profiles concurrently with S-, X- and Ku-Band propagation measurements along a 26-km path. Using existing surface-layer bulk models, profiles of the gradient of modified re

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7

Mabey, Deborah L. "Variability of refractivity in the suface layer." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FMabey.pdf.

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8

Pozderac, Jonathan M. "Refractivity Inversion Utilizing X-Band Array Measurement System." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1498690950705285.

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9

Yardim, Caglar. "Statistical estimation and tracking of refractivity from radar clutter." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3249667.

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Thesis (Ph. D.)--University of California, San Diego, 2007.<br>Title from first page of PDF file (viewed March 23, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

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10

Martinez, Anthony A. "High frequency analyses of coastal meteorological phenomena affecting refractivity." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28260.

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11

Park, ShinJu. "Water vapor estimation using near-surface radar refractivity during IHOP_2002." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81424.

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A ground-based radar refractivity mapping technique is used to measure water vapor near the surface during the International H2O Project in May and June, 2002 (IHOP_2002). Radar-measured refractivity is compared with refractivity estimated from surface station observations during this field experiment. Bias in radar and station refractivity is found to occur often when humidity is high. Possible reasons for this difference between radar and station observations are discussed. Most of the biases were associated either with inaccurate humidity observations by stations or with the small he

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12

Cherrett, Robin C. "Capturing characteristics of atmospheric refractivity using observation and modeling approaches." Diss., Monterey, California: Naval Postgraduate School, 2015. http://hdl.handle.net/10945/45825.

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Approved for public release; distribution is unlimited<br>Electromagnetic wave propagation is sensitive to gradients of refractivity derived from atmospheric temperature, humidity, and pressure. It is thus critical to understand the atmospheric conditions leading to the formation of the gradient layers and explore methods to better represent the gradients in forecast models. This study first examines the sensitivity of the surface evaporative ducts to key physical parameters of the atmospheric surface layers. This analytical study is followed by analyses of relationships between the ducting/pr

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13

Bhattacharjea, Rajib. "The effects of atmospheric refractivity in near-earth UHF channels." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53002.

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The design of emergent wireless sensor networks operating near the ground requires channel models that account for previously unconsidered propagation phenomena. Most models used for link planning and radio design of the last century were designed for use in situations where the transmitters were at least tens of meters above the earth surface. However, near the earth surface, the specifics of the ground composition and atmospheric effects have been postulated to play a significant role. This dissertation describes the first set of investigations in this emergent environment. A novel computati

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14

Yang, Zhijun. "Incoherent Imaging in the Presence of Atmospheric Turbulence and Refractivity." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1500284170323378.

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15

Bartholomew, Kimberley E. A. "Assessing the potential of radar refractivity retrievals for improved high resolution weather prediction." Thesis, University of Reading, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.567579.

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16

Newton, D. Adam. "COAMPS modeled surface layer refractivity in the Roughness and Evaporation Duct experiment 2001." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FNewton.pdf.

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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, June 2003.<br>Thesis advisor(s): Kenneth Davidson, Douglas Miller. Includes bibliographical references (p. 59-60). Also available online.

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17

Ledesma, Roy R. "Coastal boundary layer and refractivity measurements using the Ground-Based High Resolution Interferometer Sounder (GB-HIS)." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA277980.

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18

MacPherson, Douglass A. "Optical and radio frequency refractivity fluctuations from high resolution point sensors sea breezes and other observations." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FMacPherson.pdf.

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Thesis (M.S. in Meteorology)--Naval Postgraduate School, March 2007.<br>Thesis Advisor(s): Donald L. Walters, Kenneth L. Davidson. "March 2007." Includes bibliographical references (p. 37-38). Also available in print.

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19

Alam, Imtiaz. "Investigation into the effect of refractivity on propagation at UHF and VHF frequencies – modelled and experimental analysis." Thesis, University of Leicester, 2015. http://hdl.handle.net/2381/33163.

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The goal of this research was to use weather parameters to compute refractivity variation of the atmosphere that can be used to predict refractivity distribution in the first kilometre of the atmosphere over the English Channel for UHF and VHF propagation and to understand the influence of meteorology on propagation. Different refractivity profiles are constructed based on meteorological data taken from the UK Meteorological Office in order to investigate their effects on wave propagation. The hourly experimental path loss between the transmitter and receiver obtained from the experimental set

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20

Compaleo, Joshua. "Accurate Clutter Power Modeling Technique for Very LowGrazing Angles with RFC Capable Radar Design and Demonstration." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595563370860726.

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21

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." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565885420888906.

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22

Hallali, Ruben. "Variabilité de la réfractivité dans la couche limite atmosphérique par observation radar." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV083/document.

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L'observation de la variabilité de l'humidité dans les basses couches de l'atmosphère peut être réalisée en passant par la mesure du paramètre thermodynamique appelé réfractivité. Les radars météorologiques peuvent mesurer les changements de réfractivité dans la couche limite de l'atmosphère en exploitant la phase des signaux de retour des cibles fixes situées aux alentours. La cartographie de ce paramètre a été mise en place à plusieurs reprises lors de campagne de mesures aux Etats-Unis et en Europe, ce qui a démontré qu'elle est maintenant possible dans un rayon de 30 km autour du radar, av

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23

Gaviria, Maldonado Mauricio. "Assessment of the effects of refractive conditions on electronic warfare in central America." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA240523.

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Thesis (M.S. in Systems Engineering (Electronic Warfare))--Naval Postgraduate School, September 1990.<br>Thesis Advisor(s): Davidson, Kenneth L. Second Reader: Hershey, Scott H. "September 1990." Description based on title screen as viewed on December 29, 2009. Author(s) subject terms: Retractive conditions, prongation, Central America, radar, microwave. Includes bibliographical references (p. 60-61). Also available in print.

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24

Cong, Xiaoying [Verfasser], Michael [Akademischer Betreuer] Eineder, Richard [Akademischer Betreuer] Bamler, and Stefan [Akademischer Betreuer] Hinz. "SAR Interferometry for Volcano Monitoring: 3D-PSI Analysis and Mitigation of Atmospheric Refractivity / Xiaoying Cong. Gutachter: Richard Bamler ; Stefan Hinz ; Michael Eineder. Betreuer: Michael Eineder." München : Universitätsbibliothek der TU München, 2014. http://d-nb.info/1052627730/34.

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25

Muvvala, Priyanka. "Feasibility of Troposphere Propagation Delay Modeling of GPS Signals using Three-Dimensional Weather Radar Reflectivity Returns." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1307041652.

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26

Hallali, Ruben. "Variabilité de la réfractivité dans la couche limite atmosphérique par observation radar." Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV083.

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L'observation de la variabilité de l'humidité dans les basses couches de l'atmosphère peut être réalisée en passant par la mesure du paramètre thermodynamique appelé réfractivité. Les radars météorologiques peuvent mesurer les changements de réfractivité dans la couche limite de l'atmosphère en exploitant la phase des signaux de retour des cibles fixes situées aux alentours. La cartographie de ce paramètre a été mise en place à plusieurs reprises lors de campagne de mesures aux Etats-Unis et en Europe, ce qui a démontré qu'elle est maintenant possible dans un rayon de 30 km autour du radar, av

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27

Aboualmal, Abdulhadi M. A. "Analysis and modelling of the impact of anomalous propagation on terrestrial microwave links in a subtropical region, based on long-term measurements : statistical analysis of long-term meteorological and signal strength measurements in a subtropical region and investigation of the impact of anomalous refractivity profiles on radio propagation in terrestrial microwave wireless systems." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14804.

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Prevailing propagation phenomena in certain areas play a vital role in deciding terrestrial wireless systems performance. Vertical refractivity profile below 1 km is a critical parameter for designing reliable systems; noting that there is a shortage of upper-air data worldwide. Anomalous phenomena may cause severe signal fading and interference beyond the horizon. The objectives of this thesis are to investigate dominant refractive conditions in the subtropical Arabian Gulf region, develop new approaches and empirical models for evaluating vertical refractivity profiles and relevant propagati

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28

Chen, Szu-Lin. "An empirical potential for hydrogen bond energies determination of the orientation of anthracene molecules in the unit cell by means of a refractivity method: some ab initio calculations involving acetonitrile exchange reaction." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/76509.

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Topic I An empirical potential for calculating hydrogen bonding energies is developed for systems of the type A-H--B, where A and/or B is oxygen or nitrogen. Point charge and van der Waals interaction are included in the potential. The parameters of the potential were optimized by means of a simplex algorithm within a range of A-B distances from 2.8 A through 5.0 A. The root mean square deviation between the empirical potential and the ab initio results of 216 configurations of (H₂O)₂, (NH₃)₂ and NH₃•H₂O is 0.9 kcal/mol and 0.5 kcal/mol for 61 configurations of methanol dimers. Applications o

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29

Khan, Kamran. "Refractive conditions in Arabian Sea and their effects on ESM and airborne radar operations." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA238273.

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Thesis (M.S. in Systems Engineering (Electronic Warfare))--Naval Postgraduate School, September 1990.<br>Thesis Advisor(s): Davidson, Kenneth L. ; Powell, James R. "September 1990." Description based on title screen as viewed on December 29, 2009. DTIC Descriptor(s): Frequency, Electronic Warfare, Aircraft, Airborne, Electronic Equipment, Microwave Equipment, Radar, Profiles, Ducts, Meteorology, Communication And Radio Systems, Refraction, Arabian Sea, Refractometers, Military Operations. DTIC Identifier(s): Radar interference, meteorological phenomena, theses. Author(s) subject terms: Refract

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30

Zarate, Jorge V. Vazquez. "Effects of METOC factors on EW systems against low detectable targets in a tropical littoral environment." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FZarate.pdf.

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Thesis (M.S. in Systems Engineering Management)--Naval Postgraduate School, Sept. 2004.<br>Thesis Advisor(s): Kenneth L. Davidson. Includes bibliographical references (p. 83-85). Also available online.

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31

Silander, Isak. "Cavity enhanced optical sensing." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-110278.

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An optical cavity comprises a set of mirrors between which light can be reflected a number of times. The selectivity and stability of optical cavities make them extremely useful as frequency references or discriminators. With light coupled into the cavity, a sample placed inside a cavity will experience a significantly increased interaction length. Hence, they can be used also as amplifiers for sensing purposes. In the field of laser spectroscopy, some of the most sensitive techniques are therefore built upon optical cavities. In this work optical cavities are used to measure properties of g

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32

Bettouche, Y., A. Kouki, B. Agba, et al. "Long term evolution of the surface refractivity for arctic regions." 2019. http://hdl.handle.net/10454/17153.

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Yes<br>In this paper, local meteorological data for a period of 35 years (from 1979 to 2013) from Kuujuaq station have been used to calculate the surface refractivity, N and to estimate the vertical refractivity gradient, dN1, in the lowest atmospheric layer above the ground. Monthly and yearly variations of the mean of N and dN1 are provided. The values obtained are compared with the corresponding values from the ITU maps. The long-term trend of the surface refractivity is also investigated. The data demonstrate that the indices N and dN1 are subject to an evolution which may have significanc

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33

Chen, Wei-Jiun, and 陳薇鈞. "Characteristics of Radar Refractivity During IOP8 SoWMEX/TiMREX 2008." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/67264733678255564286.

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碩士<br>國立中央大學<br>大氣物理研究所<br>99<br>The major goal of SoWMEX/TiMREX is to provide the better data set to understand the kinematic and thermodynamic characteristics of the southwesterly flows during Asian summer monsoon. This unique data set is able to strengthen our basic understanding of physical processes leading to development of heavy orographic precipitation through intensive field observation campaign during the 2008 Mei-Yu season. This research used the refractivity data from NCAR SPOL (S-band polarimetric Doppler radar system) and the temperature/pressure data from the surface stations t

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34

AbouAlmal, A., Raed A. Abd-Alhameed, Abubakar S. Hussaini, et al. "Comparison of three vertical refractivity profiles in the Gulf region." 2013. http://hdl.handle.net/10454/9590.

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In this paper, a set of local radiosonde meteorological data, from 1990 to 2005, have been used to statistically analyze the refractivity gradient, DeltaN, at the lowest 65 m, 100 m and 1 km of the atmosphere above the surface of the Earth in the Gulf region. These three levels are the reference atmospheric layers in which the refractivity gradients have been evaluated by the ITU-R Recommendations P.453-10 and P.452-12The vertical variations of the refractivity profile aredisplayed through the cumulative distributions of the refractivity gradients at the targeted levels. The obtained results a

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Hsu, Hsiu-Wei, and 許修維. "The Characteristics and Application of Radar Refractivity During 2008 SoWMEX." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/78n3z3.

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碩士<br>國立中央大學<br>大氣科學學系<br>107<br>Near-surface high temporal and spatial moisture information is important for research of convection initiation(CI) and boundary layer evolution, but the in-situ water vapor observation is limited to the surface station points and quite deficient. The change of refractivity is caused by variations of the pressure, temperature, and particularly humidity. The result of fixed stations shows that the variation of refractivity is mainly from water vapor contribution. Therefore, this study combines the refractivity retrieved from NCAR S-band dual-Polarization Doppler

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36

AbouAlmal, A., Raed A. Abd-Alhameed, Steven M. R. Jones, and Hussain Al-Ahmad. "New methodology for predicting vertical atmospheric profile and propagation parameters in sub-tropical Arabian Gulf region." 2015. http://hdl.handle.net/10454/7645.

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Yes<br>A new simplified approach is proposed to evaluate the vertical refractivity profile within the lowest 1 km of atmosphere from the analysis of surface refractivity, Ns, in areas where upper air data are not available. Upper-air measurements from the nearest available radiosonde location with similar surface profile to these sites are utilized. The profiles of Ns and refractivity extrapolated to sea level, No, obtained from surface meteorological data using both fixed stations and radiosonde are investigated and compared. Vertical refractivity gradient, ΔN, is evaluated at three atmospher

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37

Brecht, A., A. Raabe, and M. Bender. "Comparison of refractivity profiles derived by Radiosonde soundings and GNSS tomography." 2011. https://ul.qucosa.de/id/qucosa%3A16385.

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By tomography of GNSS slant delay data the refractivity fields of the atmosphere can be reconstructed. The resolution of the tomography field is about 40 km in horizontal and several 100 m in vertical direction. In 2009 about 270 GNSS stations were available in Germany. The tomographically reconstructed humidity fields have to be validated with other observation methods which are able to detect the refractivity profiles of the atmosphere. The data used to compare is from radiosonde soundings, by which the refractivity can be calculated. The first results of the comparison of GNSS data with rad

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Nel, Johannes Willem. "Tyd-ruimtelike variasie in radiogolf-refraktiwiteit oor Suidelike Afrika." Thesis, 2014. http://hdl.handle.net/10210/11864.

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M.Sc. (Geography)<br>In this study the spatial and temporal variation of radio-refractivity over southern Africa is investigated. Climatological data from 8 upper-air stations and 49 surface stations were used and transformed. into values of refractivity to establish a data base of radio refractivity information. The spatial analysis yielded maps of surface refractivity (Ns ) and height corrected surface refractivity (No) for southern Africa. In order to calculate the height correction factors, a radio-climatological classification of southern Africa was drawn: up. These maps are a refinement

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AbouAlmal, A., Raed A. Abd-Alhameed, K. Al-Ansari та ін. "Statistical Analysis of Refractivity Gradient And β0 Parameter In The Gulf Region". 2013. http://hdl.handle.net/10454/7625.

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Yes<br>In this communication, nine years of local radiosonde meteorological data, from 1997 to 2005, have been used to calculate the vertical refractivity gradient, ΔN, in the lowest atmospheric layer above the ground surface. The values obtained are used to estimate the parameter β0, which represents the probability of non-standard propagation. Hourly, monthly and yearly distributions of ΔN in the first 100 meters above the ground are given. Monthly and yearly variations of the mean of ΔN and β0 are provided and the β0 values are compared with the ITU maps.

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JIANG, BI, and 江筆. "Variations of the tropospheric refractivity and their influences on transmission loss in Tawian." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/40882024045301571698.

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AbouAlmal, A., Raed A. Abd-Alhameed, and Steven M. R. Jones. "Seasonal statistics of anomalous propagation in United Arab Emirates." 2014. http://hdl.handle.net/10454/10569.

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No<br>In this paper, the seasonal variations of vertical refractivity gradients and statistics of anomalous Refractive Conditions in the United Arab Emirates (UAE) have been analyzed. Nine years of local radiosonde meteorological data, from 1997 to 2005, for the lowest atmospheric layer above the ground surface have been used. Monthly variations and cumulative distributions of refractivity gradients in the first 100 meters of the atmosphere are presented.

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42

Kimball, Andrew R. Zou Xiaolei. "Exploring potential applications of QuikSCAT surface winds and GPS radio occultation data to tropical cyclone initialization and prediction." Diss., 2005. http://etd.lib.fsu.edu/theses/available/etd-07182005-182534.

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Thesis (M.S.)--Florida State University, 2005.<br>Advisor: Dr. Xiaolei Zou, Florida State University, College of Arts and Sciences, Dept. of Meteorology. Title and description from dissertation home page (viewed Sept. 29, 2005). Document formatted into pages; contains xvi, 119 pages. Includes bibliographical references.

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Chang, Kai-Wei, and 張凱威. "The Retrieval of Atmospheric Temperature and Humidity Using Radio Occultation Refractivity and Hyperspectral Infrared Radiances." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/60547538389334406826.

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碩士<br>國立中央大學<br>遙測科技碩士學位學程<br>101<br>Hyperspectral infrared spectrometers and the radio occultation (RO) technique have become crucial for observing the atmosphere, and past studies showed that these two types of observations have complementary characteristics. Temperature retrievals from infrared sounders, such as the Atmospheric InfraRed Sounder (AIRS), tend to have higher error in the upper troposphere. In contrast, radio occultation measurements have a high vertical resolution, are highly accurate for temperature estimates in the upper troposphere and lower stratosphere, and can potentiall

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Chiang, Chen-Ching, and 江振慶. "A simulation study on the use of GPS signals to infer 3-D atmospheric wet refractivity structure." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/62767323653526711969.

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碩士<br>國立中央大學<br>太空科學研究所<br>91<br>Atmospheric water vapor is a key variable in numerical weather prediction (NWP) models. On the other hand, it is a crucial factor to limit the accuracy of high-precision GPS positioning technique. For both issues, knowledge about the amount of water vapor is extremely important. In this study, we perform a simulation study to employ GPS signals through a developed tomographic scheme to retrieve 3D structure of atmospheric wet refractivity, which may be assimilated into NWP models for advancing forecasting or position calculation for improving GPS positioning ac

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AbouAlmal, A., Raed A. Abd-Alhameed, Steven M. R. Jones, and H. AlAhmad. "New approaches and algorithms for the analysis of vertical refractivity profile below 1 KM in a subtropical region." 2014. http://hdl.handle.net/10454/7632.

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Yes<br>In this paper, 17 years of high resolution surface and radiosonde meteorological data from 1997-2013 for the subtropical Gulf region are analysed. Relationships between the upper air refractivity, Nh, and vertical refractivity gradient, ΔN, in the low troposphere and the commonly available data of surface refractivity, Ns are investigated. A new approach is discussed to estimate Nh and ΔN from the analysis of the dry and wet components of Ns, which gives better results for certain cases. Results are compared with those obtained from existing linear and exponential models in the literatu

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Anderson, Nathan John. "Effects of the troposphere upon radio communications and implications for weather measurement." Thesis, 2018. http://hdl.handle.net/2440/118192.

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The aim of this research is to use observations of Very High Frequency (VHF) radio wave propagation to estimate the refractive index of air over a propagation path and subsequently the pressure, temperature, and water vapour. This can be accomplished by transmitting a known signal from one spatial location to another, and accurately timing the signal. The research develops methods for accomplishing the required measurements by means of a passive bistatic radar setup with a cooperative target. Such an approach overcomes the timing problems that are normally associated with propagation measureme

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Wu, Chun-Tse, and 吳俊澤. "Application of MM5 4DVAR with FORMOSAT-3 Refractivity Data and Bogus Data Assimilation to Impacts on Numerical Simulations of Typhoons." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/81824342408556204711.

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碩士<br>國立中央大學<br>大氣物理研究所<br>95<br>Improvement of the initial conditions of typhoon plays the crucial role in the prediction of typhoon. Therefore, observations helpful for analyzing a typhoon should be used to adjust initial fields. This study employs the MM5 4DVAR model not only with CHAMP and FORMOSAT-3 GPS radio occultation data but also with bogus data assimilation (BDA) to provide the optimal initialization that gives a positive impact on typhoon prediction. In this paper, two typhoon cases, Dujuan (2003) and Shanshan (2006), were chosen for such an impact study. In the simulation experi

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楊佳玲. "The Development of Novel Process for (Al2O3)x(TiO2)1-x Thin Films with Tunable Refractivity by Spray Pyrolysis Method." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/00852910745231602060.

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碩士<br>國立清華大學<br>工程與系統科學系<br>101<br>Spray pyrolysis has been used to deposit (Al2O3)x(TiO2)1-x thin films with controllable properties successfully in this work. The deposition temperatures and the ratios between titanium precursors and aluminum precursors are main parameters controlling film properties, including the refractive index, components of the thin films and the electrical properties. When the deposition temperature is below 380 oC, the refractive index of (Al2O3)x(TiO2)1-x thin films are about 2.2 which is close to refractive index of titanium dioxide. From energy-dispersive X-ray sp

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Kao, Chen-Chieh, and 高晟傑. "Impact of Idealized GPS Radio Occultation Refractivity in predicting a Heavy Rainfall Event with the WRF-Local Ensemble Transform Kalman Filter System." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/31769054574710697697.

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碩士<br>國立中央大學<br>大氣物理研究所<br>100<br>In this study, we perform OSSE experiment to evaluate the impact of next-generation satellites GPS radio occultation for regional data assimilation and prediction, particularly focusing on an event with heavy rainfall in Taiwan. The evaluation is based on the accuracy of the analyses derived from the WRF-LETKF system and the following prediction. 　　For the OSSE experiment, the natural run is a 3-day simulation with a rainfall distribution similar to a real case (SoWMEX 2008 IOP-8) from the strong convection of the Mei-Yu front. There are three sets of experime

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Palmer, Andrew J. "A novel empirical model of the k-factor for radiowave propagation in Southern Africa for communication planning applications." Thesis, 2003. http://hdl.handle.net/2263/28102.

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The objective of this study was to provide an adequate model of the k-factor for scientific radio planning in South Africa for terrestrial propagation. An extensive literature survey played an essential role in the research and provided verification and confirmation for the novelty of the research on historical grounds. The approach of the research was initially structured around theoretical analysis of existing data, which resulted from the work of J. W. Nel. The search for analytical models was extended further to empirical studies of primary data obtained from the South African Weather Serv

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