Vol. 4

Front:[PDF file] Back:[PDF file]
Latest Volume
All Volumes
All Issues
2008-09-17

Vertical Profile of Radio Refractivity Gradient in Akure South-West Nigeria.

By Adekunle Titus Adediji and Moses Ajewole
Progress In Electromagnetics Research C, Vol. 4, 157-168, 2008

Abstract

In the planning and design of microwave communication links, the structure of the radio refractive index in the lower part of the atmospheric boundary layer is very important. In this work, measurements of atmospheric pressure, temperature and relative humidity were made in Akure (7.15oN, 5.12oE), South Western Nigeria. Wireless weather stations (Integrated Sensor Suite, ISS) were positioned at five different height levels beginning from the ground surface and at intervals of 50m from the ground to a height of 200m (0, 50, 100, 150 and 200 m) on a 220m Nigeria Television Authority TV tower at Iju in Akure North Local Government area of Ondo State. The measurement of the atmospheric variables was made every 30 minutes everyday. The study utilized the data for the first year of measurement (January-December 2007) to compute the radio refractivity and its refractivity gradient in Akure. From these parameters, the vertical distributions of radio refractivity are then determined. The results obtained show that the propagation conditions have varying degree of occurrence with sub-refractive conditions observed to be prevalent between January-July while Super-refraction and Ducting were observed mostly between August-December.

Citation


Adekunle Titus Adediji and Moses Ajewole, "Vertical Profile of Radio Refractivity Gradient in Akure South-West Nigeria.," Progress In Electromagnetics Research C, Vol. 4, 157-168, 2008.
http://jpier.org/PIERC/pier.php?paper=08082104

References


    1. Babin, S. M., G. S. Young, and J. A. Carton, "A new model of the oceanic evaporation duct," Journal of Applied Meteorology, Vol. 36, 193-204, 1997.
    doi:10.1175/1520-0450(1997)036<0193:ANMOTO>2.0.CO;2

    2. Falodun, S. E. and L. B. Kolawole, "Studies of super-refractivity and ducting of radiowaves in Nigeria," Nigeria journal of Pure and Applied Physics, Vol. 1, 5-10, 2000.

    3. Falodun, S. E. and M. O. Ajewole, "Radio refractive index in the lowest 100m layer of the troposphere in Akure, South Western Nigeria," Journal of Atmospheric and Solar-Terrestrial Physics, Vol. 68, 236-243, 2006.
    doi:10.1016/j.jastp.2005.10.002

    4. Grabner, M. and V. Kvicera, "Clear-air propagation modelling using parabolic equation method," Radio Engineering, Vol. 12, No. 4, 50-54, 2003.

    5. Hajj, G. A., E. R. Kursinski, L. J. Romans, W. I. Bertiger, and S. S. Leroy, "A technical description of atmospheric sounding by GPS occultation," Journal of Atmospheric and Solar-Terrestrial Physics, Vol. 64, 451-469, 2002.
    doi:10.1016/S1364-6826(01)00114-6

    6. ITU-R, The Refractive Index: Its Formula and Refractivity Data, 453-9, 2003.

    7. Kolawole, L. B., "Statistics of radio refractivity and atmospheric attenuation in tropical climates," Proceedings of the URSI Commission F Symposium, 69-75, Belgium, 1983.

    8. Lowry, A. R., C. Rocken, and S. V. Sokolovskiy, "Vertical profiling of atmospheric refractivity from ground-based GPS," Radio Science, Vol. 37, No. 3, 13-1-13-10, 2002.
    doi:10.1029/2000RS002565

    9. Oyinloye, J. O., "The troposphere in tropical and sub-tropical latitudes," Handbook on Radio Propagation for Tropical and Sub-Tropical Countries, 77-79, URSI Committee on Developing Countries, 1987.

    10. Willoughby, A. A., T. O. Aro, and I. E. Owolabi, "Seasonal variations of radio refractivity gradients in Nigeria," Journal of Atmospheric and Solar-Terrestrial Physics, Vol. 64, 417-425, 2002.
    doi:10.1016/S1364-6826(01)00111-0