A. B. Rabiu

Obafemi Awolowo University

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Daniel Okoh

National Space Research and Development Agency

Ibiyinka Fuwape

Federal University of Technology

O. S. Bolaji

Petrozavodsk State University

Samuel Ogunjo

Federal University of Technology

Aderonke Obafaye

Obafemi Awolowo University

John Bosco Habarulema

Rhodes University

E.O. Oyeyemi

University of Lagos

E.O. Falayi

Tai Solarin University of Education

J.O. Adeniyi

University of Ilorin

Gopi K. Seemala

Geological Survey of India

Cooperative Institutions

National Space Research and Development Agency

University of Zagreb

University of Lagos

Federal University of Technology

Obafemi Awolowo University

Kogi State University

South African National Space Agency

Kyushu University

Slovak University of Technology in Bratislava

University of Ilorin

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

Meteorological Models for Determination of Surface Radio Refractivity over Nigeria

Current Journal of Applied Science and Technology (2019)

O. O. Ajileye Oladimeji Samuel Popoola F. F. Kayode A. B. Rabiu

Previous studies showed that linear meteorological expressions obtained were localized and could not be generally applied. It is therefore required that more locations should be investigated to deduce new linear meteorological models best suitable for estimation of surface refractivity. Surface meteorological data, including pressure, temperature and relative humidity, was downloaded from Modern-Era Retrospective analysis for Research and Application (MERRA - 2) for six locations defined by different climatic conditions over Nigeria, namely Yenagoa, Abakaliki, Ibadan, Anyigba, Jalingo and Sokoto for a period of 40 years partitioned into two periods of 20 years each. The 1979 – 1998 dataset of atmospheric temperature, T (K), atmospheric pressure, P (hPa) and relative humidity, Rh (%) were extracted using text import wizard to calculate surface refractivity using existing model (Nitu-r). Regression analysis was carried out to obtain new linear meteorological expressions as function of temperature (Nt), relative humidity (Nrh), and combination of relative humidity and temperature (Nrh,t). The new expressions were tested using 1999 – 2018 meteorological dataset and the results of surface refractivity from the new linear expressions were compared with values from existing equations. It was observed that high relative humidity and low temperature values prevalent in the three southern stations – Yenagoa, Abakaliki and Ibadan – significantly enhanced the suitability of Nrh,t linear meteorological model for estimation of surface refractivity values comparable toNitu-r. Contrary to the observations in the southern stations, in the northern stations, relative humidity contributions (Nrh) had the best linear correlation of 0.96 at Anyigba, 0.98 at Jalingo and Sokoto. Estimation of surface refractivity from the new linear meteorological models was found to be best as a function of temperature and relative humidity in the south and a function of relative humidity in the north. Linear meteorological models as a function of relative humidity and temperature were best suitable for stations in the south with minimum correlation of 0.98 while linear expressions as a function of relative humidity only were best suitable for the stations in the north with minimum correlation of 0.96.

Surface pressure

10.9734/cjast/2019/v36i330235

Cite

Citations (4)

Identification of Fractal Properties in Geomagnetic Data of Southeast Asian Region during Various Solar Activity Levels

Universe (2021)

Farhan Naufal Rifqi Nurul Shazana Abdul Hamid A. B. Rabiu Akimasa Yoshikawa

The fractal properties of geomagnetic northward component data (H-component) in the equatorial region during various phases of solar activity over Southeast Asia were investigated and then quantified using the parameter of the Hurst exponent (H). This study began with the identification of existence of spectral peaks and scaling properties in international quiet day H-component data which were measured during three levels of solar activity: low, intermediate, and high. Then, various cases of quiet and disturbed days during different solar activity levels were analyzed using the method that performed the best in the preceding part. In all the years analyzed, multifractal scaling and spectral peaks exist, signifying that the data have fractal properties and that there are external factors driving the fluctuations of geomagnetic activity other than solar activity. The analysis of various cases of quiet and disturbed days generally showed that quiet days had anti-persistence tendencies (H < 0.5) while disturbed days had persistence tendencies (H > 0.5)—generally a higher level of Hurst exponent compared to quiet days. As for long-term quiet day H-component data, it had a Hurst exponent value that was near H ≃ 0.50, while the long-term disturbed day H-component data showed higher values than that of the quiet day.

QUIET

Hurst exponent

Multifractal system

Exponent

10.3390/universe7070248

Cite

Citations (10)

Solar Activity and Total Column Ozone Variation in Lagos, Nigeria

Deleted Journal (2003)

A. B. Rabiu T. V. Omotosho

Impacts of solar activity on the total column ozone variation within an interval of four years (1993-1997) have been investigated at an equatorial station of Lagos (06°33' N, 03°21' E) Nigeria. The linear regression analysis shows a significant negative correlation between mean total column ozone and solar activity both at monthly level (r = -0.0652, r2 = 0.0043) and annual level (r = -0.2671, r2 = 0.07138). Significant negative correlation (r = -3798, r2 = 0.1375) exists between the two variables during low solar activity. The total column ozone decreases with increasing solar activity. Linear fits of the data were proposed. The data length needs to be extended and more data points created in equatorial regions. (Nigeria Journal of Pure and Applied Physics: 2003 2 (1): 17-20)

Linear correlation

Seasonality

Linear relationship

Negative correlation

Variation (astronomy)

10.4314/njpap.v2i1.21433

Cite

Citations (5)

A comparative empirical method of estimating net radiation over a tropical station in Lagos

cosp (2006)

E. O. Ogolo S. S. Oluyamo Adekunle Titus Adediji A. B. Rabiu E. O. Olaniran

This study focused on the estimation of net radiation over a tropical station, (Ikeja, Lagos state located on lat. 6.5N, long. 3.2E, Nigeria) using two empirical methods. The data used for the study were extracted from records of daily meteorological observation, Ikeja station. The data collected were mainly on meteorological and weather parameters, which include temperature, rate of sunshine, global radiation and vapour pressure. All the readings were on diurnal basis except the vapour pressure and sunshine rate, which were taken hourly. The level of reliability and precision of the two methods were determined by investigating the correlation coefficient and computing the Standard Error of Estimate (SEE), the results indicate that either of the two methods can be used as an alternative procedure for estimating net radiation over any station, particularly in a tropical region like Nigeria, where instruments for this type of measurement are scarce. The level of accuracy for both methods was well above 90%. In addition, the results from both methods were found to be stable and dependable. Furthermore, the results of the two empirical methods were found to be highly correlated.

Sunshine duration

Source

Cite

Citations (0)

Spatial Dynamical Complexity of Precipitation and Temperature Extremes over Africa and South America

Asia-Pacific Journal of Atmospheric Sciences (2019)

Samuel Ogunjo Ibiyinka Fuwape S. S. Oluyamo A. B. Rabiu

Hurst exponent

Climate extremes

10.1007/s13143-019-00131-y

Cite

Citations (12)

The comparative study of chaoticity and dynamical complexity of the low-latitude ionosphere, over Nigeria, during quiet and disturbed days

Nonlinear processes in geophysics (2014)

B. O. Ogunsua J. A. Laoye Ibiyinka Fuwape A. B. Rabiu

Abstract. The deterministic chaotic behavior and dynamical complexity of the space plasma dynamical system over Nigeria are analyzed in this study and characterized. The study was carried out using GPS (Global Positioning System) TEC (Total Electron Content) time series, measured in the year 2011 at three GPS receiver stations within Nigeria, which lies within the equatorial ionization anomaly region. The TEC time series for the five quietest and five most disturbed days of each month of the year were selected for the study. The nonlinear aspect of the TEC time series was obtained by detrending the data. The detrended TEC time series were subjected to various analyses for phase space reconstruction and to obtain the values of chaotic quantifiers like Lyapunov exponents, correlation dimension and also Tsallis entropy for the measurement of dynamical complexity. The observations made show positive Lyapunov exponents (LE) for both quiet and disturbed days, which indicates chaoticity, and for different days the chaoticity of the ionosphere exhibits no definite pattern for either quiet or disturbed days. However, values of LE were lower for the storm period compared with its nearest relative quiet periods for all the stations. The monthly averages of LE and entropy also show no definite pattern for the month of the year. The values of the correlation dimension computed range from 2.8 to 3.5, with the lowest values recorded at the storm period of October 2011. The surrogate data test shows a significance of difference greater than 2 for all the quantifiers. The entropy values remain relatively close, with slight changes in these values during storm periods. The values of Tsallis entropy show similar variation patterns to those of Lyapunov exponents, with a lot of agreement in their comparison, with all computed values of Lyapunov exponents correlating with values of Tsallis entropy within the range of 0.79 to 0.81. These results show that both quantifiers can be used together as indices in the study of the variation of the dynamical complexity of the ionosphere. The results also show a strong play between determinism and stochasticity. The behavior of the ionosphere during these storm and quiet periods for the seasons of the year are discussed based on the results obtained from the chaotic quantifiers.

Correlation dimension

QUIET

Tsallis entropy

10.5194/npg-21-127-2014

Cite

Citations (31)

Prediction of diffuse solar radiation using simple model

cosp (2006)

E.O. Falayi A. B. Rabiu

Source

Cite

Citations (0)