Linkage of meteorological parameters and anomalous radio propagation profile over Nigeria

Emmanuel, Israel

doi:10.1016/j.jastp.2019.05.011

Cited by 2 publications

(2 citation statements)

References 14 publications

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“…Surface refractivity and refractivity at 100 m above ground, which is a function of temperature, pressure, and water vapor were obtained from Equation (453–12 I.‐R. P., 2016; Emmanuel, 2019).

N = ((), n - 1) = \frac{77.6}{T} ((), P + \frac{4810 e}{T})

where P is the atmospheric pressure (hPa), e is the water vapor pressure (hPa), and T is the air temperature (K) at the surface and 100 m above ground.…”

Section: Methodsmentioning

confidence: 99%

“…This will aid in radio circuitry design and installation. In Nigeria, many researchers had earlier worked on estimation and investigation of anomalous radio propagation condition in Nigeria (Adediji et al, 2011; Adeyemi & Emmanuel, 2011; Emmanuel, 2019; Emmanuel et al, 2017; Oyedum, 2012). However, it is necessary to critically examine spatial distribution and latitudinal relation of vertical refractivity gradient and ducting index across Nigeria.…”

Section: Introductionmentioning

confidence: 99%

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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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N = ((), n - 1) = \frac{77.6}{T} ((), P + \frac{4810 e}{T})

where P is the atmospheric pressure (hPa), e is the water vapor pressure (hPa), and T is the air temperature (K) at the surface and 100 m above ground.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Geostatistical Distribution of Vertical Refractivity Gradient Over Nigeria

et al. 2020

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Interconnection between Inter Tropical Convergence Zone Migration and Variation of Anomalous Radio Propagation in Tropical Region

Emmanuel

Adedayo

2023

Preprint

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Seasonal cycle of radio refractivity aloft the tropical region have been studied in relation to the migration of the Intertropical Convergence Zone (ITCZ). Radio refractivity values were calculated from meteorological parameters obtained from the archive of the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim). ITCZ position is obtained using maritime and continental winds. Refractivity conditions of anomalous radio propagation were evaluated from refractivity using ITU-recommendation. Multilinear empirical model was developed from ITCZ position determinant factors and refractivity values. The performance of the model was evaluated against ITU-R values using standard metrics. The result showed that the values of refractivity gradient and the position of the ITCZ vary seasonally across Nigeria. ITCZ reached its maximum position northward in August with highest value of refractivity gradient ranges between − 100 N-units/km and − 50 N-units/km across the regions. with the movement of ITCZ across Nigeria. High values of refractivity gradient ranges between Southward position of ITCZ correlate with minimum position of refractivity gradient, which typified ducting. Ducting occurrence prevailed around the ITCZ position.

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Linkage of meteorological parameters and anomalous radio propagation profile over Nigeria

Cited by 2 publications

References 14 publications

Geostatistical Distribution of Vertical Refractivity Gradient Over Nigeria

Geostatistical Distribution of Vertical Refractivity Gradient Over Nigeria

Interconnection between Inter Tropical Convergence Zone Migration and Variation of Anomalous Radio Propagation in Tropical Region

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