Empirical Models for Estimating Tropospheric Radio Refractivity Over Osogbo, Nigeria

Akpootu, D. O.; Rabiu, A. M.

doi:10.2174/1874282301913010043

Cited by 3 publications

(3 citation statements)

References 19 publications

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“…and the radio refractivity of the wet term is given by equation (3) through expansion of equation ( 2) (Akpootu and Rabiu, 2019;Akpootu et al, 2024). Nwet = 3.73 x 10 5 𝑒𝑒 𝑇𝑇 2…”

Section: Methodsmentioning

confidence: 99%

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Assessment of Tropospheric Radio Refractivity and its Variation with Climatic Variables in the Guinea Savannah Region of Nigeria

Bello,

Akpootu,

Sharafa

2024

ejtas

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In studies involving terrestrial atmospheric electromagnetic propagation, such as point-to-point microwave communication, terrestrial radio, television radio, television broadcast, and mobile communication systems, radio refractivity—the bending of a radio signal as it propagates through media—is crucial. In this study, the seasonal tropospheric radio refractivity was estimated and its variations with other meteorological parameters and refractive index were investigated using the measured monthly climatic data of atmospheric pressure, relative humidity, and temperature obtained from the National Aeronautic and Space Administration (NASA) for Makurdi and Ibadan during the period of forty-two (42) years (1981 to 2022). The refractivity gradiant, effective earth radius, and percentage contribution of the dry and wet term radio refractivity were examined. The findings indicated that for the two locations, high values of radio refractivity were observed during the rainy season and low values during the dry season. The maximum and minimum average values of radio refractivity observed for Makurdi and Ibadan during the rainy and dry seasons are, respectively, 380.0641 N-units in the month of May, 331.9776 N-units in January, and 379.9479 N-units in the month of May, 352.2143 N-units in January. The dry term (Ndry) contributes 70.8764 % and 69.4504 % to the total value of radio refractivity, while the wet term (Nwet) contributes to the major variation with 29.1236 % and 30.5496 % for Makurdi and Ibadan, respectively. The study areas under investigation yielded average refractivity gradients of -43.8583 and -43.1480 N-units/km. Additionally, the average effective earth radius (k – factor) for Makurdi and Ibadan was found to be 1.3876 and 1.3790, respectively. These values align with the conditions of super refraction propagation.

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Section: Methodsmentioning

confidence: 99%

“…The refractivity gradient is obtained by differentiating equation ( 7) with respect to h, therefore, the refractivity gradient is given by (Akpootu et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

Assessment of Tropospheric Radio Refractivity and its Variation with Climatic Variables in the Guinea Savannah Region of Nigeria

Bello,

Akpootu,

Sharafa

2024

ejtas

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“…They discovered also that the sub-refraction condition which is common from January to May and August to December while superrefraction was noticed predominantly between June and July respectively. Akpootu et al (2019) developed empirical models for estimating tropospheric radio refractivity in Osogbo, Nigeria. In another study, Akpootu et al (2021a) estimated and investigate the variability of tropospheric radio refractivity and radio field strength over Accra Ghana, the result of their study revealed that tropospheric radio refractivity is higher during the rainy season than in the dry season in the months of April and January with 384.356 N-units and 371.6318 N-units respectively.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Tropospheric Radio Refractivity and Its Variation with Climatic Variables Over Zaria, Nigeria

Akpootu,

Aminu,

Nouhou

et al. 2024

dujopas

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To achieve optimal performances, radio link/system planning and design must take radio refractivity estimation very seriously. This study utilizes measured average daily temperature, relative humidity, and atmospheric pressure for forty-one-year period (1981–2021) obtained from the National Aeronautics and Space Administration (NASA) archives for Zaria (latitude 11.100 N, longitude 7.680 E) strategically located in Nigeria’s midland climate zone to calculate the monthly tropospheric radio refractivity and look into how it varies with other meteorological factors and radio refractive index. The percentage of the contribution of dry term (Ndry) and wet term (Nwet) to radio refractivity and refractivity gradient were investigated. The findings indicated that radio refractivity was higher during the rainy season (August) and lower’during the dry season (February), with a maximum mean value of 350.8733 N-units and a minimum mean value of 284.1975 N-units, respectively, found in those months. The wet term contributes to the significant fluctuation of the radio refractivity, whereas the dry term makes up 76.03% of the total value. The gradient of mean refractivity estimated for Zaria was found to be – 43.8709 N – units/km indicating super-refraction propagation condition.

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Investigation of Tropospheric Radio Refractivity and Other Relevant Parameters Using Meteorological Variables Over Bauchi, Nigeria

Akpootu,

Aminu,

Yusuf

et al. 2024

FJS

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The National Aeronautics and Space Administration (NASA) archives were used in this work to obtain the measured monthly average daily temperature, relative humidity, and atmospheric pressure over a 41-years period (1981–2021) for Bauchi (latitude , longitude ) to calculate the monthly tropospheric radio refractivity. The site is located in Nigeria's midland climate zone. We also looked into the variation with other factors, the refractivity gradient, and the percentage contribution of the dry term (Ndry) and wet term (Nwet) radio refractivity. The results showed that during the rainy and dry seasons, respectively, the months of August and February had the highest and lowest average values of radio refractivity, measuring 355.032 (N-units) and 273.255 (N-units), respectively. This suggests that radio refractivity is higher during the rainy season than it is during the dry season. The wet term contributes to the significant fluctuation in radio refractivity values, while the dry term makes up 77.60 % of the total value. The average refractivity gradient estimate was found to be – 40.854 N – units/km suggesting super-refraction propagation for Bauchi indicating that electromagnetic waves are often bent downward towards the earth when the super refraction condition occurs.

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Empirical Models for Estimating Tropospheric Radio Refractivity Over Osogbo, Nigeria

Cited by 3 publications

References 19 publications

Assessment of Tropospheric Radio Refractivity and its Variation with Climatic Variables in the Guinea Savannah Region of Nigeria

Assessment of Tropospheric Radio Refractivity and its Variation with Climatic Variables in the Guinea Savannah Region of Nigeria

Assessment of Tropospheric Radio Refractivity and Its Variation with Climatic Variables Over Zaria, Nigeria

Investigation of Tropospheric Radio Refractivity and Other Relevant Parameters Using Meteorological Variables Over Bauchi, Nigeria

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