Effect of random medium on wave propagation in evaporation ducts above a rough sea surface

Chou, Yung-Hsiang; Kiang, Jean‐Fu

doi:10.1109/usnc-ursi.2013.6715504

Cited by 4 publications

(12 citation statements)

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“…where 𝜅 is the spatial wavenumber (where subscript indicates directional component), 𝐶 4 & is the refractive index structure constant (with units of m -2/3 ), and 𝐿 / is the outer length scale delineating the border between energy containing or "mixing" scales from those in the inertial subrange, with units of meters. To account for anisotropy in the MASL, the 2-D Kolmogorov spectrum from ( 12) can be modified [5], [31]:…”

Section: B Atmospheric Refractivity Modelmentioning

confidence: 99%

“…Commonly, parametric refractivity models are implemented to model refractivity profiles [2], [6], [9], [12], [14], where model parameters generally include refractive characteristics that are known to affect propagation -such as evaporation duct height (EDH), duct curvature, and mixed layer slope [3], [9], [11], [14]- [16]. Parametric models such as these typically neglect turbulent fluctuations and spatial heterogeneity in the refractive environment, which can lead to discrepancies between measured and modeled EM propagation [4], [5], [17], [18].…”

Section: Introductionmentioning

confidence: 99%

“…While the atmospheric and sea-surface estimation methods discussed are widely verified within PWEs [2], [6], [9], [12], [14], [22], differences between measured and modeled propagation persist. These differences stem from shortcomings of these estimation methods and can potentially be attributed to: (i) not accounting for refractive fluctuations due to turbulence, (ii) inaccurate representation of the sea-surface, and (iii) not accounting for spatially heterogenous environments in which evaporation duct height (EDH) and strength can vary with range [5], [17], [18], or any combination thereof. Inclusion of seasurface roughness, turbulence, and spatial heterogeneity is computationally expensive, so few studies have explored their coupled effects on EM propagation predictions [5].…”

Section: Introductionmentioning

confidence: 99%

“…The current study explores the global sensitivity of a PWE to a comprehensive evaporation duct refractivity model (including mean, turbulent, and spatially heterogenous components) and to sea-surface wave model parameters [23]. The eFAST technique is implemented to perform global sensitivity experiments for stable, neutral, and unstable atmospheric regimes because turbulent variations in the refractive index are stability dependent [5]. Furthermore, these stability-based eFAST experiments are broken up into scenarios where the EDH is above and below the transmitter height, i.e., comparing notional trapping and non-trapping effects, giving more insight into the sensitivity of the PWE under certain regimes for comparison.…”

Section: Introductionmentioning

confidence: 99%

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Relative Influence of Sea State and Mean, Turbulent, and Heterogenous Refractivity on X-Band Propagation

Pastore,

Hackett

2024

IEEE Trans. Antennas Propagat.

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In predicting electromagnetic wave propagation within the marine atmospheric surface layer, it is common to assume steady homogenous conditions. However, discrepancies between predicted and measured propagation remain, which could be due in-part to turbulent fluctuations of the refractive index, spatially heterogenous evaporative ducting environments, and mischaracterization of the rough ocean bottom boundary. To better understand the relative importance of these contributors, this study explores the sensitivity of X-band propagation to parameters describing sea-state conditions and refractive environments, including turbulent fluctuations and spatially heterogenous conditions. This study employs the extended Fourier Amplitude Sensitivity Test to compute sensitivity indices that evaluate the leading-order effects and effects due to non-linear interactions between these refractive and sea state parameters on a parabolic wave equation electromagnetic wave propagation simulation. The parameters are delineated and evaluated in three atmospheric stability regime experiments: stable, neutral, and unstable, and consider both trapping and non-trapping propagation conditions. Parameter sensitivity indices are ranked for each experiment to examine the relative effects of the parameters on X-band propagation prediction. The results show that in neutral and stable regimes, mean evaporation duct characteristics have the greatest impact on propagation beyond the geometric horizon, while in unstable conditions, turbulence also plays a significant role. Additionally, in the lowest 10 m of the atmosphere, forward scattering from the rough sea-surface has the greatest effect on propagation predictions regardless of atmospheric stability.

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Section: B Atmospheric Refractivity Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Relative Influence of Sea State and Mean, Turbulent, and Heterogenous Refractivity on X-Band Propagation

Pastore,

Hackett

2024

IEEE Trans. Antennas Propagat.

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“…Tal fato é justificado pela presença de inversões térmicas nos meses de inverno, em situações onde a TSM é maior do que o ar adjacente, favorecendo condições para a ocorrência de uma camada instável adjacente à superfície e, acima dela, uma camada inversão térmica elevada (Twigg, 2007). Quando a atmosfera se torna mais instável, o gradiente de umidade aumenta em magnitude e, com isso, ocorre a formação do duto atmosférico (Turton et al, 1988;Chou & Kiang, 2014;Gürbüz, 2016).…”

Section: Estatísticas Descritiva E Exploratória Aplicadas a Série Temporalunclassified

Refratividade Atmosférica em Áreas Oceânicas Baseada em Dados de Sondagem Atmosférica na Região da Ilha de Trindade

Baptista¹,

Candella

Oliveira‐Júnior

et al. 2020

Anu. Inst. Geoc.

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Geostatistical Distribution of Vertical Refractivity Gradient Over Nigeria

et al. 2020

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Anomalous propagation conditions may cause multipath fading and strong signal enhancement on terrestrial line of sight links or interference on transhorizon paths. In detecting this conditions, spatial distribution of vertical refractivity gradient and ducting index were estimated across Nigeria using atmospheric data obtained from Era5 archive of European Centre for Medium-Range Weather Forecasts (ECMWF). Refractivity and refractivity gradient were calculated from the obtained temperature, relative humidity, and pressure data using International Telecommunication Union (ITU) recommendation expression. Vertical refractivity gradient (VRG) and ducting index (D i) were deducted from refractivity gradient and modified the refractivity gradient. Correlation between vertical refractivity gradient, D i , and latitude were also computed. The result shows that the VRG values range between −5 and −65 N units/km in the Coastal and Guinea Savannah regions, and between −30 and −95 N units/km in the Midland and Sahelian regions. The D i values range between 10 and 60 in the Coastal and Guinea Savannah regions, between −10 and 110 in Midland and Sahelian region. Likewise, superrefraction and ducting are more prominent in the northern part, while superrefraction with minor subrefraction were noticed in the south. The D i performed better than VRG in detecting propagation conditions. Correlation between VRG and latitude ranges between −0.75 and −0.92. Correlation between D i and latitude is between 0.84 and 0.95. The values of VRG decrease northward, while those of the D i increase northward. Both VRG and D i revealed high variability in the dry months than in the wet months.

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Effect of random medium on wave propagation in evaporation ducts above a rough sea surface

Cited by 4 publications

References 0 publications

Relative Influence of Sea State and Mean, Turbulent, and Heterogenous Refractivity on X-Band Propagation

Relative Influence of Sea State and Mean, Turbulent, and Heterogenous Refractivity on X-Band Propagation

Refratividade Atmosférica em Áreas Oceânicas Baseada em Dados de Sondagem Atmosférica na Região da Ilha de Trindade

Geostatistical Distribution of Vertical Refractivity Gradient Over Nigeria

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