Characterization and Investigation of Nonlinear Behaviour of Radio Refractivity during the Rainy and Dry Seasons in the Coastal Region of Nigeria

A.E Adeniji,E.M Ajeigbe,K.S Ojo

doi:10.4314/jasem.v25i7.8

Abstract

            The transmission and receiving of good quality of signals globally has been impaired due to the internal activities of the troposphere linked to the nonlinear behaviour of the meteorological parameters. This paper focusses on characterizing and investigating the nonlinear behaviour of radio refractivity during the rainy and dry seasons in the coastal region of Nigeria using temperature, pressure and relative humidity data collected over a period of two years by the Centre for Atmospheric Research, National Space Research and Development Agency (NASRDA) from Lagos state. Data obtained were analyzed by False Nearest Neighbour (FNN) and Recurrence Quantification Analysis (RQA). The results show that recurrence techniques are able to identify the periods where there are high predictability and low predictability. The investigation of nonlinear effects of meteorological parameters and the hydrometeors on the troposphere help to avoid fading of radio signals along with the radio communication links.           

Highlights

The propagation of electromagnetic waves in the troposphere has been a major challenge due to variation of the atmospheric refractivity. This variation is linked to the turbulence in the troposphere with a high proportion of moisture which causes the tropospheric scatter radio signals to refract and the receiving antennas collect only a tiny proportion of the radio energy
The weather phenomenon occurs in the troposphere, which is the lowest atmosphere with almost all the atmospheric water vapour content
Ogunjo et al (2016) investigated chaos in surface radio refractivity in eleven locations over Nigeria using Brock- DechertScheinkmen (BDS) test and reported that the BDS values in the dry season for surface radio refractivity are in a state of chaos while surface radio refractivity in rainy seasons was found to be regular

Summary

Introduction

The propagation of electromagnetic waves in the troposphere has been a major challenge due to variation of the atmospheric refractivity. The atmospheric conditions or different states of the atmosphere at different times, locations and frequencies have significant impact degrading the quality of the signal but sometimes completely eradicate the communication link This impact on Atmospheric refractivity depends solely on atmospheric parameters of air such as pressure, temperature and water content. The weather phenomenon occurs in the troposphere, which is the lowest atmosphere with almost all the atmospheric water vapour content These atmospheric parameters in most cases appear to be nonlinear considering the variability in their trends. Fuwape and Ogunjo (2016), considered different quantification parameters including the Hurst exponents, LLE correlation dimension, recurrence quantification analysis (RQA) for the analysis of the forecast data from (ECMWF) and (ERA- interim) project. Radio refractivity, (N), which is the sum of the dry and wet parametric values, can be expressed as

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Conclusion