Spatio-Temporal Variation of Nonlinearity in Tropospheric Zenith Wet Delay Over West Africa

Ogunjo, Samuel; Dada, Joseph Babatunde; Fuwape, I. A.

doi:10.1615/telecomradeng.v79.i11.100

Cited by 4 publications

(3 citation statements)

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“…The lines between these regions represent more of a transition along a continuous ecological gradient than sharp boundaries. Temperatures in the lowlands of West Africa are high throughout the year, with annual means usually above 18°C, whereas in the Sahel, maximum temperatures can reach above 40°C [18]. The four climatic zones in the Sub-Saharan part of Africa are Desert, Semiarid, Savannah, and Tropical forests.…”

Section: Methodsmentioning

confidence: 99%

Diurnal and Monthly Variability of Lightning Observation Over West Africa

Ajadi

Balogun

2022

EJGEO

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This study examines in detail lightning activities over West Africa using the worldwide lightning location network (WWLLN). The Worldwide Lightning Location Network (WWLLN; operated by the University of Washington) is a developing, experimental lightning detection network increasingly used for applications. In West Africa, there are many studies on the diurnal process of lightning activity at the regional level, but there is a shortage of literature examining the diurnal variation of lightning observation in this region. Therefore the main objective of the study is to examine the lightning activities over West Africa by presenting an evaluation of the WWLLN data as ground truth to improve the knowledge of ground-based lightning location system. For this study, the diurnal variability of flash counts (frequency) was measured over West Africa for the three climatic sub-region (Guinea, Savannah and Sahel) sub-regions using a line graph to plot the flash counts (frequency) over time. All regions exhibit a strong diurnal variation, with lightning activity peaking in the late afternoon between 1500 and 1700 WAT and decreased in the late morning between 0900 and 1100 WAT. The diurnal amplitude varies by location throughout West Africa.

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Section: Methodsmentioning

confidence: 99%

Diurnal and Monthly Variability of Lightning Observation Over West Africa

Ajadi

Balogun

2022

EJGEO

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“…The increasing number of satellite‐based products require Quality of Service (QoS) with high integrity for a large number of users across different geographical regions. Satellite to earth communication links face significant challenges such as tropospheric zenith delay (Ogunjo et al., 2020), as well as, stratospheric scintillation and atmospheric attenuation (Yakovlev et al., 1995). In the lower atmosphere, satellite signals suffer from refraction, delay (Ogunjo et al., 2018), and attenuation by fog (Nadeem et al., 2010), rain (J. S. Ojo et al., 2008), and dust (Ahmed et al., 1987).…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of Worst Month Rain Rate and Attenuation Statistics for Satellite Links in Nigeria

2023

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There is an increasing demand for communication-based technology in different sectors of the economy. This is fueled by growing population, dropping cost of technology, and increasing demand for technology products. Some of these technology products such as electronic banking and telemedicine require high quality satellite connection for efficiency. The increasing number of satellite-based products require Quality of Service (QoS) with high integrity for a large number of users across different geographical regions. Satellite to earth communication links face significant challenges such as tropospheric zenith delay (Ogunjo et al., 2020), as well as, stratospheric scintillation and atmospheric attenuation (Yakovlev et al., 1995). In the lower atmosphere, satellite signals suffer from refraction, delay (Ogunjo et al., 2018), and attenuation by fog (Nadeem et al., 2010), rain (J. S. Ojo et al., 2008), and dust (Ahmed et al., 1987). Phase synchronization has been established between rain rate and radio refractivity in different locations within Nigeria (Fuwape et al., 2016).At high frequency, rain is the greatest factor in radio communication systems in tropical region due to their peculiar rainfall characteristics. This has increased the research interest on rain attenuation within the region. Different models have been proposed for the estimation of rain attenuation. One of the earliest models was based on the geophysical properties of rainfall at a point and temperature profile at that location (R. Crane, 1980). The model was extended by considering the probability of occurrence of a convective cell (R. K. Crane, 1982). Assis and Einloft (1977) introduced a simple algorithm for rain attenuation at frequencies greater than 10 GHz based on rain rate statistics alone. In the Australian model Flavin (1996) estimates the attenuation as frequencies less than 60 GHz and is based on rain rate distribution. Other rain attenuation models proposed in literature are Bryant model (

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“…Different empirical models have been developed to estimate delays [5]. The uncertainty in estimating water vapour makes the wet component of tropospheric delay variable and complex [6]. Hence, the need for efficient algorithms to model and predict wet delay.…”

Section: Introductionmentioning

confidence: 99%

Forecasting tropospheric wet delay using LSTM neural network

Ogunjo

Dada

Ajayi

2022

IOP Conf. Ser.: Earth Environ. Sci.

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Tropospheric wet delay is a critical factor in radio communication. Accurate estimation of the wet delay is difficult due to the variability in water vapour. In this study, we aim to model and predict tropospheric wet delay over four tropical locations using Long Short-Term Memory (LSTM) neural network. Results obtained in this study showed RMSE and MAE within the range 18.96–21.16 and 14.08–16.38 respectively. LSTM model was able to capture the different regimes of wet delays in each of the locations under consideration. This approach can significantly improve link budget and planning within tropical regions.

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Spatio-Temporal Variation of Nonlinearity in Tropospheric Zenith Wet Delay Over West Africa

Cited by 4 publications

References 0 publications

Diurnal and Monthly Variability of Lightning Observation Over West Africa

Diurnal and Monthly Variability of Lightning Observation Over West Africa

Comparative Study of Worst Month Rain Rate and Attenuation Statistics for Satellite Links in Nigeria

Forecasting tropospheric wet delay using LSTM neural network

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