Diurnal, Seasonal and Annual Variation of Microwave Radio Refractivity Gradient over Akure, South West Nigeria

Adediji, A. T.; Dada, Joseph Babatunde; Ajewole, M. O.

doi:10.9734/psij/2019/v23i430161

Cited by 3 publications

(1 citation statement)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They have many practical fields of application, for instance, system identification and process control, resource management, quantum chemistry, financial applications, medical diagnoses, decision-making, and data mining [ 31 ]. Various researchers have already applied ANNs in the prediction of meteorological parameters, [ 9 , 32 ]. Although the proposed technique was implemented on a smart grid [ 33 ], it remains a novel method for the prediction of meteorological parameters and consequently, radio refractivity.…”

Section: Introductionmentioning

confidence: 99%

A modified artificial neural network based prediction technique for tropospheric radio refractivity

et al. 2018

View full text Add to dashboard Cite

Radio refractivity plays a significant role in the development and design of radio systems for attaining the best level of performance. Refractivity in the troposphere is one of the features affecting electromagnetic waves, and hence the communication system interrupts. In this work, a modified artificial neural network (ANN) based model is applied to predict the refractivity. The suggested ANN model comprises three modules: the data preparation module, the feature selection module, and the forecast module. The first module applies pre-processing to make the data compatible for the feature selection module. The second module discards irrelevant and redundant data from the input set. The third module uses ANN for prediction. The ANN model applies a sigmoid activation function and a multi-variate auto regressive model to update the weights during the training process. In this work, the refractivity is predicted and estimated based on ten years (2002–2011) of meteorological data, such as the temperature, pressure, and humidity, obtained from the Pakistan Meteorological Department (PMD), Islamabad. The refractivity is estimated using the method suggested by the International Telecommunication Union (ITU). The refractivity is predicted for the year 2012 using the database of the previous ten years, with the help of ANN. The ANN model is implemented in MATLAB. Next, the estimated and predicted refractivity levels are validated against each other. The predicted and actual values (PMD data) of the atmospheric parameters agree with each other well, and demonstrate the accuracy of the proposed ANN method. It was further found that all parameters have a strong relationship with refractivity, in particular the temperature and humidity. The refractivity values are higher during the rainy season owing to a strong association with the relative humidity. Therefore, it is important to properly cater the signal communication system during hot and humid weather. Based on the results, the proposed ANN method can be used to develop a refractivity database, which is highly important in a radio communication system.

show abstract

Section: Introductionmentioning

confidence: 99%

A modified artificial neural network based prediction technique for tropospheric radio refractivity

et al. 2018

View full text Add to dashboard Cite

show abstract

Climatology of super‐refraction and trapping layers conditions over Central and West Africa

Kaïssassou

Djiotang

Komkoua

et al. 2021

Meteorological Applications

View full text Add to dashboard Cite

The propagation of radio electric waves emitted from ground-based meteorological instruments is determined through stratification of the atmosphere. In super-refractive cases characterized by strong temperature inversions or strong vertical moisture gradients, the radar beam can be deflected towards the ground (trapping). This phenomenon often results in spurious returned echoes and misinterpretation of radar images such as erroneous precipitation, wind, and temperature detection. In this study, a 5-year Central and West Africa (CWA) climatology of the frequency of super-refractive and trapping-layer base height has been produced using refractivity computations from European Centre for Medium-Range Weather Forecasts (ECMWF) analyses at a 40-km horizontal resolution and 60 levels in the vertical direction. The aim of this climatology is to improve the understanding on how frequent such anomalous propagations conditions are, which is a prerequisite for fully benefiting from radar data information for the multiple purposes of model validation, precipitation analysis, and data assimilation. First, the main climatological features are summarized for the whole CWA: Sahara and inlands seldom experience super-refraction, whereas coastal areas are strongly affected, especially in regions where the temperature inversion and the trade winds are intense lying near the surface. Over land, seasonal averages of super-refraction frequencies reach 80% (40%) over moist areas year-round but remain below 40% (15%) in most other regions. Seasonal statistics exhibit a pronounced diurnal cycle of super-refraction occurrences, with averaged frequencies peaking at 60% in summer late afternoon over the areas located on the Atlantic Ocean border but inlands region are less affected with super-refractive cases by midday.

show abstract

The influence of primary radio climatology parameters on radio refractive index over the African region: a 30-year satellite study

Dada

Adedayo

Adediji

et al. 2021

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

Diurnal, Seasonal and Annual Variation of Microwave Radio Refractivity Gradient over Akure, South West Nigeria

Cited by 3 publications

References 12 publications

A modified artificial neural network based prediction technique for tropospheric radio refractivity

A modified artificial neural network based prediction technique for tropospheric radio refractivity

Climatology of super‐refraction and trapping layers conditions over Central and West Africa

The influence of primary radio climatology parameters on radio refractive index over the African region: a 30-year satellite study

Contact Info

Product

Resources

About