Effect of Variations in Meteorological Parameters on the Tropospheric Radio Refractivity Over Lapai, Niger State, Nigeria

ABSTRACT

The aim of this work is to examine the variations in meteorological parameters (Temperature, Atmospheric pressure, and Relative humidity)on the surface radio refractivity, N, in Lapai town, Niger state of Nigeria, with focus on the wet and dry seasons. Lapai town, being the study area, is located within latitude 9º 02ʺ N and longitude 6º 34ʺ E along Suleja road, about 56 km east of Minna, Niger state capital. Meteorological data obtained from the Nigerian Meteorological Agency (NIMET) was used to obtain mean monthly refractivity for each month of the six years under review. It was observed that the refractivity values are lower in the dry season months (January, February, November and December) due to lower relative humidity, as compared to the wet season. On the other hand, the wet season months (March, April, May, June, July, August, September and October) characterized by higher refractivity values can be attributed mainly to high relative humidity values. The result also indicated that the month of January for the year 2018 has the minimum refractivity value of 325 N-units. The month of April, 2018 with N value of 444 N-units has the maximum value of refractivity, and the k-factor, from the radio refractivity gradient (RRG), was used to establish the fact that the study area has been found to be super refractive during both seasons, with values of 3/2 and 1.87 for dry and wet seasons respectively for the years in focus. The fact that these months are classified under the dry and wet seasons respectively makes it clear that the wet season has high refractivity and vice versa.

TABLE OF CONTENT

Title page         i

Declaration         ii

Turnitin certification             iii

Certification         iv

Dedication                              v

Acknowledgement        vi

Abstract                       vii

Table of Contents     viii

List of Tables                             ix

List of Figures                                      x

CHAPTER ONE1

1.1Background to the Study1

1.2Statement of Research Problem3

1.3Aim and Objectives3

1.3.1Aim3

1.3.2Objectives4

1.4Scope and limitation of the study4

CHAPTER TWO6

2.1Introduction6

2.2Layers of the atmosphere6

2.3Theory of Surface Refractivity Gradient7

2.4Influence of Clear-Air Aspect of the Troposphere on VHF and UHF 

Propagation9

CHAPTER THREE14

3.1Introduction14

3.2Source of Data16

3.3Data Analysis16

CHAPTER FOUR22

4.1Introduction22

4.2Average Monthly Refractivity and Refractive Index22

4.2.1Dry and wet seasons refractivity (Ndry and Nwet) for 201523

4.2.2Dry and wet seasons refractivity (Ndry  and Nwet) for 201624

4.2.3Dry and wet seasons refractivity (Ndry andNwet) for 201726

4.2.4Dry and wet seasons refractivity (Ndry andNwet) for 201828

4.2.5Dry and wet seasons refractivity (Ndry andNwet) for 201929

4.2.6Dry and wet seasons refractivity (Ndry and Nwet) for 202031

4.3Comparative analysis of the radio refractivity values32

4.4Effect of variations in the parameters (Temperature, Relative humidity and Atmospheric pressure) on the refractivity values.32

4.5Computation of RRG and the effective earth radius, K34

CHAPTER FIVE36

5.1Summary36

5.2Conclusion36

5.3Recommendation37

References      39

LIST OF TABLES

Table Title  Page

3.1Sample monthly data for the year 201519

3.2Sample monthly data for the year 201619

3.3Sample monthly data for 201720

3.4Sample monthly data for 201820

3.5Sample monthly data for 201921

3.6Sample monthly data for 202021

4.1Average Monthly data, refractive index and radio refractivity over 

Lapai town for 201522

4.2Average monthly data, refractive index and refractivity over Lapai 

town for 2016.24

4.3Average monthly data, refractive index and refractivity over Lapai town 

for 201726

4.4Average monthly data, refractive index and refractivity over Lapai town

for 201827

4.5Average monthly data, refractive index and refractivity over Lapai town 

for 201929

4.6Average monthly data, refractive index and refractivity over Lapai town

for 202030

4.7Average values of temperature, relative humidity, atmospheric pressure 

and radio refractivity from 2015-202032

LIST OF FIGURES

FigureTitlePage

2.1Layers of the atmosphere source: (Okpani et al., 2015)6

3.1Map of Nigeria showing the location of Niger state and its borders14

3.2Map of Niger state showing the position of the study area (Lapai).15

4.1Average monthly refractivity for 201523

4.2Average monthly refractivity for 201625

4.3Average monthly refractivity for 201726

4.4Average monthly refractivity for 201828

4.5Average monthly refractivity for 201929

4.6Average monthly refractivity for 202031

4.7Effect of the meteorological parameters on the refractivity values33