Atmospheric chaoticity and complexity from radio refractivity derived from Akure station

Ogunsua, B. O.; Ojo, J. S.; Adediji, A. T.

doi:10.1016/j.asr.2018.06.035

Cited by 8 publications

(3 citation statements)

References 28 publications

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“…The relation for radio refractivity (N); which is dependent on the independent variables; temperature, pressure and relative humidity, has two constituents; the wet and dry term, denoted as Ndry and Nwet respectively. Ogunsua et al [19] and Emmanuel et al [20] gave the contracted relation as;…”

Section: Methodsmentioning

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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Section: Methodsmentioning

confidence: 99%

Characterization of Modified Refractivity Across the Arid Region of Nigeria

Imaga

Emmanuel

Egoigwe

2023

Preprint

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“…Hypothetically, studying the atmosphere (specifically the troposphere) is like looking at a prism with an almost unity index of refraction ); this "almost unity" index of refraction, although negligible, has enormous effects on the climatic conditions of a region. The M-K test is a famous test for time series variations and is majorly applied in climatology and related studies (Roboaa and Al-Barazanji, 2015;Mondal et al 2012;Atta-ur-Rahman and Dawood 2017;Kisi and Ay., 2014) to understand the significance (if any) of the increasing (positive Kendall Z statistic value) or decreasing (negative Kendall Z statistic value) variations (Chattopadhyay et al 2012). We will apply this test method to understand the trend of each parameter over time individually.…”

Section: Introductionmentioning

confidence: 99%

Meteorological Analysis of the Relationship between Climatic Parameters: Understanding the Dynamics of the Troposphere

Agbo¹,

Edet²

2021

Preprint

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Understanding the relationship between the variations of meteorological parameters is vital in tackling the climatic problem. This paper presents methods for analyzing parameters that relate directly and indirectly to each other and accurate methods for interpreting their results. Using obtained data for 14 years and calculated data for other parameters, we adopt the Mann-Kendall (M-K) test for the trend analysis of the annual and seasonal variations, the correlation matrixes, and linear regression pair plots to discern the relationship between all parameters using the python programming software. To crystalize results, partial derivatives relating the equivalent potential temperature (EPT) for a pseudo-adiabatic process with parameters affecting its variation from equations are being obtained. The magnitude of these derivatives' gradients was used to bolster regression results, showing the mixing ratio (MR) of air as the parameter with the most effect on EPT variation. The MK test results show that the atmospheric pressure (AP) and average ambient temperature (AT) were all increasing significantly for all variations (annual, dry and wet seasons). In contrast, others varied between dry and wet seasons after adopting a benchmark significance level of 5% (0.05). The correlation matrixes and linear regression pair plots show a strong relationship between the variations of refractivity, EPT, the temperature at the lifting condensation level (TL), MR, vapor pressure (VP), specific humidity (SH), and the dew point temperature (DPT). The potential temperature (PT), saturated vapor pressure (SVP), saturated mixing ratio (SMR), and the AT relationships showed a robust positive correlation/regression. This correlation offers a connection between the AT and the PT. The processes, including the partial derivatives, pair plots, correlation matrixes, and tests for trends, provide a solution to the meteorological analysis problem. Results and methods can be applied in other regions.

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“…Aside from time series and phase plot reconstruction, the paper also employed Average Mutual Information (AMI), False Nearest Neighbor (FNN), Lyapunov Exponent (LE), Tsallis Entropy (TE) and Recurrence Plot (RP) to analyze radio refractivity gradient between 2011 and 2012 using Atmospheric data. Unlike previous research, where the focus is mainly on a single station “Akure” in Nigeria using different heights [8], [9], while the present research actually covers selected stations across Nigeria with emphasis on rainy season, dry season and transition periods. The onset of the dry season, October and November, and the onset of the rainy season, March and April, serves as the rain-harmattan transition phase and it was chosen for consideration.…”

Section: Introductionmentioning

confidence: 99%

Comparative study on Radio Refractivity Gradient in the troposphere using Chaotic Quantifiers

Ojo

Adelakun

Edward

2019

Heliyon

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Complexity and nonlinear trend in the internal activities of the troposphere has been a great factor affecting the transmission and receiving of good quality of signals globally. In lieu of this, prediction of chaos and positive refractivity gradients for line-of-sight microwave radio paths is necessary for designing radio systems. Complexity in the troposphere due to changes in meteorological parameters can lead to the strong negative gradient (or super-refraction) which afterward lead to interference between terrestrial links and satellite earth stations. In this paper, a comparative study on the degree of complexity of Radio Refractivity Gradient (RRG) using Chaotic Quantifiers (CQ) such as Phase Plot Reconstruction (PPR), Average Mutual Information (AMI), False Nearest Neighbor (FNN), Lyapunov Exponent (LE), Tsallis Entropy (TS) and Recurrence Plot (RP) are discussed extensively. The RRG data (2011-2012) used in this work were obtained for 0 m to 100 m, from the archives of Tropospheric Data Acquisition Network (TRODAN) from five different stations namely; Akure ( Geo . ), Enugu ( Geo . ), Jos ( Geo . ), Minna ( Geo . ) and Sokoto ( Geo . ). The chaotic quantifiers are used to investigate the degree of complexity in the 30 minutes interval atmospheric data from the selected locations which is specified into rainy, dry and transition season months. The parallel and short diagonal lines observed depicts the evidence of chaos. However, the observed result shows that the RRG is higher during the rainy season than the dry season. In other words, the information is valid for the proposed data analysis, since the LE is actually directly proportional to the TE. Also, the results further show that the rainy season months exhibit higher chaoticity than the dry season months, which is equivalent to high radio refractivity gradient observed across the selected stations.

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Atmospheric chaoticity and complexity from radio refractivity derived from Akure station

Cited by 8 publications

References 28 publications

Characterization of Modified Refractivity Across the Arid Region of Nigeria

Characterization of Modified Refractivity Across the Arid Region of Nigeria

Meteorological Analysis of the Relationship between Climatic Parameters: Understanding the Dynamics of the Troposphere

Comparative study on Radio Refractivity Gradient in the troposphere using Chaotic Quantifiers

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