Estimation of radio refractivity from satellite-derived meteorological data over a decade for West Africa

Abimbola, O. J.; Bada, S.O.; Falaiye, A. O.; Sukam, Yakubu Musa; Otto, M.S.; Muhammad, Sani

doi:10.1016/j.sciaf.2021.e01054

Cited by 9 publications

(8 citation statements)

References 8 publications

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“…The spatial and seasonal variation of tropospheric radio refractivity of Nigeria has been studied from a satellite meteorological parameters (temperature, relative humidity and pressure) sourced from NASA. Just like [10], [11], [12], [3], [13], [15] and [16], this work established a seasonal variation. These researches looked into more than 5 stations each covering most part of Nigeria randomly.…”

Section: Discussionmentioning

confidence: 90%

Spatial and Seasonal Estimation of Tropospheric Radio Refractivity in Nigeria

et al. 2022

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The spatial and seasonal variation of tropospheric radio refractivity of Nigeria has been studied using meteorological variables (temperature, relative humidity and pressure) retrieved from the archive of the United States’ National Aeronautics for Space Administration (NASA). This work established a seasonal variation. The results also revealed an increase in radio refractivity from minimum of about 270N-units at Abadam to maximum of about 415N-units at Warri. The variation of radio refractivity is synchronous with rainfall in most of the stations especially those in the Guinea Savannah, Tropical Rainforest and Coastal areas where the effects of august break manifest vividly on the curves. Intense refractivity was measured mostly in the tropical rainforest and coastal areas. This could be attributed to the intensity of rain and the length of the wet season in those locations. The Sahel, Sudan and Guinea savannah which experience less rain with short period of wet season recorded reduced refractivity. Just like rainfall, the movement of Inter Tropical Discontinuity (ITD) is also found to be linked to the variation of the radio refractivity. The northward movement of the ITD brings with it elevated refractivity while the southward movement leads to reduced refractivity. This is because the ITD is an element of two high pressure cells which influences its motion. Majorly, the seasonal variation is found to be the product of climate except in some high ground areas where the topography was found to be majorly responsible.

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Section: Discussionmentioning

confidence: 90%

Spatial and Seasonal Estimation of Tropospheric Radio Refractivity in Nigeria

et al. 2022

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“…By inserting values of A and B obtained from the models deduced [5,12] for the tropical region in equation ( 3), estimates of −∆N within the first km above ground can be made [15,16,17], thereby enabling the deduction of the k factor, geoclimatic factor and d horizon , and other related radio propagation parameters. Refractivity-altitude profiles can also be obtained from equation (2).…”

Section: Methodsmentioning

confidence: 99%

“…From a ten-year database of daily radiosonde soundings, Willoughby et al [5] deduced values of A = 9.36 and B = 4.856E-03 and a correlation of 0.78 for the whole of Nigeria, while Kolawole and Owonubi [12] obtained the values of A = 2.30 and B = 8.630E-03 and a correlation of 0.80 for the whole of Africa. −∆N is used in estimating the effects of the atmosphere on the refraction of radio waves and the simplification of radio propagation engineering problems [5,13,14,15,16,17]. Its variation produces the phenomena of scattering, scintillation and discontinuities or fading of propagated radio energy.…”

Section: Radio Refractivity Nmentioning

confidence: 99%

Estimation of some Radio Propagation Parameters using Measurements of Surface Meteorological Variables in Ede, Southwest Nigeria

Willoughby

Sanyaolu

Osinowo

et al. 2022

J. Nig. Soc. Phys. Sci.

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A data acquisition system that utilised the open-source Arduino platform was developed to take real-time ground measurements of primary radio climatological variables of pressure, temperature, and relative humidity at Ede, a tropical station in southwest Nigeria (7.7349^{o} N, 4.4439^{o} E). Surface radio refractivity was deduced from these variables and used to estimate refractivity gradients at 100 m and 1000 m heights from the exponential reference atmosphere model for terrestrial propagation. Secondary radio propagation parameters such as refractivity gradients, the effective-earth-radius-factor, k, and geoclimatic factor, K, essential parameters for quick application in the planning and design of line-of-sight radio link systems, were also deduced. Data acquired from the device were compared to those obtained from the Re-Analyses (ERA-5) satellite database of the European Centre for Medium-Range Weather Forecast (ECMWF) 2020/2021. Aside from logging data on a micro secure digital (SD) card, measurements were displayed on a liquid crystal display (LCD). The peripheral Arduino-compatible meteorological sensors were connected to the analog inputs of the ATMega328 in the Arduino independent development environment (IDE), and the unit was powered by a 12 V battery charged by a 50-watt solar module. Results showed that slightly higher values of the ERA-5 data characterise the dry months from November to March, while the wet months displayed higher values of the Arduino-derived measured data. The accuracies of the data collected were compared using Mean Percentage Error (MPE) performance indicator. The interpretation is that the mean difference between the Arduino inferred measurements and the ERA-5 data is less than 10%, which is an indication of the measurement accuracy.

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“…The analysis further describes ducting as that which provides a mechanism for Radio wave signals of sufficiently high frequencies to propagate far beyond their normal line-of-sight range. Abimbola et al [10] denotes the gradient as G and equates it to The existence of atmospherics ducts is important in the realization of over the horizon propagation. However, due to the chaotic nature of weather in the troposphere, signal attenuation, interference of reflected rays, noise; atmospheric ducts may not be effective in every scenario.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Modified Refractivity Across the Arid Region of Nigeria

Imaga

Emmanuel

Egoigwe

2023

Preprint

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Over time, atmospheric ducts have been studied in a bid to understand and harness for optimal tropospheric propagation of radio waves. The most useful quantity in the study of ducts is the modified refractivity. The gradient of modified refractivity is used in the classification of anomalous propagation conditions. This study characterizes modified refractivity across arid regions of Nigeria, using meteorological data obtained from the European Centre for Medium – Range Weather Forecasts (ECMWF) Re-analysis 5 (ERA-5. It takes a bit - by - bit look at the variables that form radio signal trapping from the very fundamental temperature and relative humidity to the modified refractivity gradient which describes the radio signal trapping characteristics. The study location of relevance is the arid region of Nigeria, and five locations are randomly selected. The analyses of results show a high occurrence of ducts through diurnal and seasonal variations in the arid region. These results are in agreement with the physics of the meteorological parameters in which modified refractivity is dependent upon.

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Estimation of radio refractivity from satellite-derived meteorological data over a decade for West Africa

Cited by 9 publications

References 8 publications

Spatial and Seasonal Estimation of Tropospheric Radio Refractivity in Nigeria

Spatial and Seasonal Estimation of Tropospheric Radio Refractivity in Nigeria

Estimation of some Radio Propagation Parameters using Measurements of Surface Meteorological Variables in Ede, Southwest Nigeria

Characterization of Modified Refractivity Across the Arid Region of Nigeria

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