PROJECT REPORT ON DIURNAL VARIATION OF SURFACE RADIO REFRACTIVITY OVER NIGERIA BY ASHAYE, ADEMOLA ADEWALE (PHY/01/9935) SUBMITTED TO THE DEPARTMENT OF PHYSICS, FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE, ONDO STATE. IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF BACHELOR OF TECHNOLOGY DEGREE IN PHYSICS ELECTRONICS SEPTEMBER, 2007
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Diurnal Variation of Surface Radio Refractivity over Nigeria
A good knowledge of the spatial behaviour of the refractivity in the lower troposphere is essential information for the design of UHF, VHF and SHF radio links, as well as for the evaluation of interference between terrestrial communication systems. This report presents the diurnal variation of surface radio refractivity over five meteorological stations spread across Nigeria. The stations include Port Harcourt (04o 51' N, 07o 01' E), Ibadan (07o 20' N, 03o 54' E), Abuja (09o 15' N, 07o 00' E), Jos (09o 52' N, 08o 54' E) and Maiduguri (11o 51' N, 13o 05' E). Monthly mean values of temperature, pressure and relative humidity values were used to calculate the mean refractivity for all the stations. It was observed that surface refractivity has considerable latitudinal and seasonal variations.
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PROJECT REPORT
ON
DIURNAL VARIATION OF SURFACE RADIO REFRACTIVITY
OVER NIGERIA
BY
ASHAYE, ADEMOLA ADEWALE
(PHY/01/9935)
SUBMITTED TO
THE DEPARTMENT OF PHYSICS,
FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE, ONDO STATE.
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD
OF BACHELOR OF TECHNOLOGY DEGREE IN PHYSICS ELECTRONICS
SEPTEMBER, 2007
ii
CERTIFICATION
This is to certify that this project report was written by Ashaye, Ademola Adewale
(PHY/01/9935) and submitted to the Department of Physics, Federal University of
Technology, Akure, Ondo state, Nigeria.
Dr. Falodun, S.E.
PROJECT SUPERVISOR
iii
DEDICATION
This report is dedicated to the Incomparable God for his favour and protection throughout my
study years.
iv
ACKNOWLEDGEMENT
I am grateful to God who preserved my life throughout the period of my study in the Federal
University of Technology, Akure.
A lot of thanks go to my supervisor, Dr. Falodun, S.E. for the guidance and assistance offered
during the project. I appreciate very much his understanding and encouragement to see the
project trough.
I also thank my parents Mr. & Mrs. B.O Ashaye for their unflinching support through out the
period of my study. You are the best parents in the world.
v
ABSTRACT
A good knowledge of the spatial behaviour of the refractivity in the lower troposphere
is essential information for the design of UHF, VHF and SHF radio links, as well as for the
evaluation of interference between terrestrial communication systems. This report presents
the diurnal variation of surface radio refractivity over five meteorological stations spread
across Nigeria. The stations include Port Harcourt (04o 51' N, 07
o 01' E), Ibadan (07
o 20' N,
03o 54' E), Abuja (09
o 15' N, 07
o 00' E), Jos (09
o 52' N, 08
o 54' E) and Maiduguri (11
o 51' N,
13o 05' E). Monthly mean values of temperature, pressure and relative humidity values were
used to calculate the mean refractivity for all the stations. It was observed that surface
refractivity has considerable latitudinal and seasonal variations.
vi
TABLE OF CONTENT
Title Page No
Title Page i
Certification ii
Dedication iii
Acknowledgement iv
Abstract v
Table of content vi
List of Figures vii
List of Tables ix
CHAPTER ONE
1.0 Introduction 1
CHAPTER TWO
2.0 Literature Review 5
2.1 Electromagnetic Radiation and Propagation 5
2.2 Refractive Index and Refractivity 5
2.3 Causes and Effects of Refractivity in the Troposphere 6
2.3.1 Absorption, Refraction and Anomalous Propagation 6
vii
2.4 The Refractivity Equation 11
CHAPTER THREE
3.0 Results 13
3.1 Source and Scope of Data 13
CHAPTER FOUR
4.0 Discussion 39
4.1 Diurnal Variations of Surface Refractivity Values 39
4.2 Seasonal Variations and Range 42
CHAPTER FIVE
5.0 Summary and Conclusion 47
References 48
viii
LIST OF FIGURES
FIGURE 1.1 Division of the Atmosphere 2
FIGURE 2.1 A simple refraction 7
FIGURE 2.2 Four Classifications of Refraction 9
FIGURE 3.1 Map of Nigeria showing location of the meteorological stations 13
FIGURE 3.2 Graphs showing Refractivity Variations for January 2000 – 2005 16
FIGURE 3.3 Graphs showing Refractivity Variations for February 2000 – 2005 18
FIGURE 3.4 Graphs showing Refractivity Variations for March 2000 – 2005 20
FIGURE 3.5 Graphs showing Refractivity Variations for April 2000 – 2005 22
FIGURE 3.6 Graphs showing Refractivity Variations for May 2000 – 2005 24
FIGURE 3.7 Graphs showing Refractivity Variations for June 2000 – 2005 26
FIGURE 3.8 Graphs showing Refractivity Variations for July 2000 – 2005 28
FIGURE 3.9 Graphs showing Refractivity Variations for August 2000 – 2005 30
FIGURE 3.10 Graphs showing Refractivity Variations for September 2000 – 2005 32
FIGURE 3.11 Graphs showing Refractivity Variations for October 2000 – 2005 34
FIGURE 3.12 Graphs showing Refractivity Variations for November 2000 – 2005 36
FIGURE 3.13 Graphs showing Refractivity Variations for December 2000 – 2005 38
FIGURE 4.1 Diurnal Variation of Surface Radio Refractivity for March 2002 39
FIGURE 4.2 Diurnal Variation of Surface Refractivity for Ibadan, March 2002 40
FIGURE 4.3 Diurnal Variation of Water Vapour Pressure for Ibadan, March 2002 40
FIGURE 4.4 Diurnal Variation of Temperature for Ibadan, March 2002 41
FIGURE 4.5 Diurnal Variation of Pressure for Ibadan, March 2002 41
FIGURE 4.6 Table and graph showing seasonal variation
of Ns values for Port-Harcourt, 2002 44
ix
FIGURE 4.7 Table and graph showing seasonal variation
of Ns values for Ibadan, 2002 44
FIGURE 4.8 Table and graph showing seasonal variation
of Ns values for Abuja, 2002 45
FIGURE 4.9 Table and graph showing seasonal variation
of Ns values for Jos, 2002 45
FIGURE 4.10 Table and graph showing seasonal variation
of Ns values for Maiduguri, 2002 46
x
LIST OF TABLES
TABLE 3.1 Typical Refractivity values calculated for January 2000 14
TABLE 3.2 Computed Refractivity data for January 2000 – 2005 15
TABLE 3.3 Computed Refractivity data for February 2000 – 2005 17
TABLE 3.4 Computed Refractivity data for March 2000 – 2005 19
TABLE 3.5 Computed Refractivity data for April 2000 – 2005 21
TABLE 3.6 Computed Refractivity data for May 2000 – 2005 23
TABLE 3.7 Computed Refractivity data for June 2000 – 2005 25
TABLE 3.8 Computed Refractivity data for July 2000 – 2005 27
TABLE 3.9 Computed Refractivity data for August 2000 – 2005 29
TABLE 3.10 Computed Refractivity data for September 2000 – 2005 31
TABLE 3.11 Computed Refractivity data for October 2000 – 2005 33
TABLE 3.12 Computed Refractivity data for November 2000 – 2005 35
TABLE 3.13 Computed Refractivity data for December 2000 – 2005 37
TABLE 4.1 Surface Refractivity values for Port-Harcourt, Ibadan, Abuja,
Maiduguri, and Jos, March 2002 42
TABLE 4.2 Table showing seasonal variation and range of Surface refractivity 39
1
CHAPTER ONE
1.0 INTRODUCTION
The Atmosphere
The Earth's atmosphere is a layer of gases surrounding the planet Earth and retained
by its gravity. It contains roughly (by molar content/volume) 78% nitrogen, 20.95% oxygen,
0.93% argon, 0.038% carbon dioxide, and the remaining 0.07 percent is a mixture of
hydrogen, water, ozone, neon, helium, krypton, xenon, and other trace components. This
mixture of gases is commonly known as air. The atmosphere protects life on Earth by
absorbing ultraviolet solar radiation and reducing temperature extremes between day and
night.
The layers of the atmosphere are the troposphere, the stratosphere, the mesosphere,
the thermosphere, and the exosphere. The troposphere is the layer in which weather occurs
and extends from the surface to about 16 km above sea level at the equator. Above the
troposphere is the stratosphere, which has an upper boundary of about 50 km above sea level.
The layer from 50 to 90 km is called the mesosphere. At an altitude of about 90 km,
temperatures begin to rise. The layer that begins at this altitude is called the thermosphere
because of the high temperatures that can be reached in this layer (about 1200°C). The region
beyond the thermosphere is called the exosphere. The thermosphere and the exosphere
overlap with another region of the atmosphere known as the ionosphere, a layer of ionized air
extending from almost 60 km above Earth’s surface to altitudes of over 1,000 km.