vii
TABLE OF CONTENTS
CHAPTER
1
TITLE
PAGE
DECLARATIONS
ii
DEDICATIONS
iii
ACKNOWLEDGEMENTS
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
x
LIST OF FIGURES
xi
LIST OF SYMBOLS
xii
LIST OF ABBREVIATIONS
xv
LIST OF APPENDICES
xvi
INTRODUCTION
1
1.1
Introduction
1
1.2
Problem Statement
3
1.3
Objective
4
1.4
Scope of work
4
1.5 Thesis Outline
2
5
RAINFALL CHARACTERISTIC AND RAIN
6
ATTENUATION
2.1
Introduction
6
2.2
Malaysian Climate
6
2.2.1
Rainfall Regions in Peninsular Malaysia
7
2.2.2
Rainfall Region on Sabah and Sarawak
9
viii
2.2.3
Rainfall Characteristic
10
2.3
Types of Rain
10
2.4
Development of Rain Attenuation Studies
11
2.5
Attenuation in Atmosphere
13
2.6
Rain Attenuation
15
2.6.1
16
Specific Attenuation
2.6.1.1
ITU-R Model for Specific
Attenuation
2.7
Effective Path Length
21
2.8
Terminal Velocity
22
2.9
Refractive Index
22
2.9
Temperature
23
3
DROP SIZE DISTRIBUTION MEASUREMENT
3.1
Introduction
3.2
A Brief Review of Tipping Bucket Rain Gauge, And
24
24
Joss- Waldvogel, Parsivel And Poss Disdrometers
26
3.2.1
Joss-Waldvogel disdrometer (JW)
26
3.2.2
Parsivel disdrometer
29
3.2.3
Precipitation
Occurrence
Sensor
System
(POSS)
32
Tipping bucket gauges
34
3.3
Drop Size Distribution Models
35
3.4
Literature Review on DSD
37
3.2.4
4
19
DROP SIZE DISTRIBUTION EQUATIONS
44
4.1
Introduction
44
4.2
Rain Attenuation
44
4.3
Rain Specific Attenuation
45
4.4
Drop Size Distribution
45
4.5
Summery
47
ix
5
THE METHODOLOGY AND RESULTS
48
5.1
Introduction
48
5.2
The overall Project Methodology
49
5.3
ITU-R Study group Three Data Bank
50
5.4
Rainfall rate data
51
5.4.1
Rainfall Rate Data at UTM-Skudai site
52
5.4.2
Data Collection
58
5.4.3
Designing the Algorithm Flow
59
5.4.4 The Program Development for extracting Drop
Size Distribution
5.4.4.1 Loading the data into MATLAB
5.4.4.2
6
60
5.7.3.1.1 Sub-Program in MATLAB
61
Conversion of Voltage to dBm
62
5.4.4.2.1 Sub-Program in MATLAB
62
5.4.4.2.1 Analyzing the Database
63
5.4.4.3 Extracting Drop Size Distribution
5.5
60
Summary
64
70
CONCLUSION AND RECOMMENDATIONS
71
6.1
Introduction
71
6.2
Conclusion
6.3
Future of work and recommendations
72
REFERENCES
74
Appendices A – F
76
x
LIST OF TABLES
TABLE NO
3.1
TITLE
PAGE
Log Normal coefficients for Malaysia, Singapore, Nigeria and
39
Brazil
3.2
Annual rain distributions
41
5.1
Rainfall measurement specifications at UTM-Skudai
53
5.2
The average one year cumulative distribution at UTM-Skudai
55
5.3
Proposed and measured values for the parameters a and b for 26
and 38 GHz with horizontal Polarization
5.4
The Investigated 38 GHz Links Connected to Measuring Nodes
Located in WCC, UTM, Malaysia
56
59
5.5
Comparison between extracted DSD and other models at 38 GHz
66
5.6
Correlations between extracted DSD and other models at 38 GHz
67
5.7
Comparison between extracted DSD and other models at 26 GHz
68
5.8
Correlations between extracted DSD and other models at 26 GHz
69
xi
LIST OF FIGURES
FIGURE NO
TITLE
PAGE
2.1
Rainfall regions in Malaysia peninsular
8
2.2
Volume of spherical, uniformly distributed raindrops
12
2.3
Attenuation due to water vapor and oxygen at sea level
15
2.4
Calculated drop shapes of 13 water drops for equivolumetric
sphere radius of 0.25 – 3.25 mm
17
2.5
Specific attenuation at different rain rates and frequencies
19
3.1
Joss-Waldvogel Disdrometer
27
3.2
The size of the impacting drop is retrieved from measured
impact velocity through an empirical relationship between fall
velocity-D (straight line).
28
3.3
Parsivel disdrometer
30
3.4
Two operating Parsivel measured mean velocities
31
3.5
POSS disdrometer
33
3.6
Sample volume for the different disdrometers
34
3.7
Tipping bucket rain gauge
35
3.8
Comparison models of the raindrop size distribution for
Malaysia, Singapore, Nigeria and Brazil
3.9
Specific rain attenuation at Guwahati, Calcutta, Dehradun,
compared with the ITU-R model at different rain rates
3.10
38
40
Specific rain attenuations exceeded for different percentages
of time over a year at Guwahati, Calcutta, and Dehradun.
41
xii
5.1
Screen shoot of the user graphical interface window of
DBSG5.exe program
5.2
51
The rainfall and rain attention data conducted at UTM
companied using computer program
53
5.3
Several years measurement of rainfall rate at UTM-Skudai
54
5.4
Measured Rain Attenuation for 38 and 26 GHz from July 1
1998 to June 30 1999 at UTM Skudai
55
5.5
Measured and predicted specific rain attenuation for 26 GHz
57
5.6
Measured and predicted specific rain attenuation for 38 GHz
57
5.7
Ericsson
Microwave
Link
at
38
GHz
in
Wireless
Communication Centre (WCC)
59
5.8
Example of Data Collected
61
5.9
Graph of dBm versus Voltage, V
62
5.10
Graph of Attenuation Threshold (dB) versus Time (hour)
63
5.11
The extracted DSD at 38GHz and other DSD models
65
5.12
Comparison between the extracted DSD and other models
66
5.13
The extracted DSD at 26GHz and other DSD models
68
5.14
Comparison between the extracted DSD and other models
69
xiii
LIST OF SYMBOLS
A
-
Attenuation
a, b
-
Regression coefficients
A0.01
-
Attenuation at 0.01% of time
a1
-
excess attenuation (dB) due to water vapor
a2
-
excess attenuation (dB) due to mist and fog
a3
-
excess attenuation (dB) due to oxygen
a4
-
sum of absorption losses (dB) due to other gases
a5
-
excess attenuation due to rainfall
Am
-
Measured attenuation
Ap
-
Predicted attenuation
AreaP
-
Drop cross section area (m2)
CP
-
Number of drops in the pth size
dB
-
Decibel unite
d
-
Separation (km) between the two sites
DP
-
Mid size of the pth channel (mm)
f
-
Frequency
GHz
-
Giga Hertz
k, α
-
Regression coefficients
km
-
Kilometer
Leff
-
Effective Path length
L
-
path length
m
-
Meter
mm
-
Millimeter
-
Number density of raindrops with equivalent diameter D in the
interval
xiv
Nt
-
Total number of drops per cubic meter per millimeter
P
-
Probability
P (%)
-
Percentage in time of the year
-
Total extinction cross section
R(p)
-
Rain rate at percentage in time of the year
r(P)
-
Horizontal reduction factor of percentage in time of the year
r0.01
-
Horizontal reduction factor for 0.01% time of the year
R0.01
-
Rain rate at 0.01% of time of the year
-
The terminal velocity of drops in m/s
ΔDp
-
Width of the pth channel (mm)
Δt
-
Sampling time (s).
θ
-
The path elevation angle
γR
-
Specific attenuation
xv
LIST OF ABBREVIATIONS
AGCV
-
Automatic Gain Control Voltage
C
-
Centigrade
dB
-
Decibel
dBm
-
Decibel mili watt
DBSG5
-
ITU-R Study Group Three Data Bank
GHz
-
Giga Hertz
IEEE
-
Institute of Electrical and Electronic Engineering
ITU-R
-
International Telecommunication Union Radio-Broadcasting
mm/h
-
milimetre per hour
MMS
-
Malaysia Metrological Services
NASA
-
National American Space Agency
S
-
second
TRMM
-
Tropical Rainfall Measuring Mission
UTM
-
Universiti Teknologi Malaysia
xvi
LIST OF APPENDICES
APPENDIX
A
B
C
TITLE
PAGE
The ITU-R specific attenuation parameters
(ITU-R, P. 838-3)
78
The experimental specific attenuation parameters
UTM-Skudai. Feb 2001-Feb2002
79
Comparison of event rain totals using different
distrometers
D
Composite DSD for Distrometers
E
Scattering Coefficient result for frequency at 26
80
81
GHz, temperature at 27° C, Ray refractive index,
Oblate Spheroid Raindrop Shapes, Horizontal
Polarization
F
82
Scattering Coefficient result for frequency at 38
GHz, temperature at 27° C, Ray refractive index,
Oblate Spheroid Raindrop Shapes, Horizontal
Polarization
88