A VHF boundary-layer radar

t-a

A VHF BOUNDARY.LAYER RADAR

Scott N.M. Dullaway B.Sc. (Hons)

Thesis

submitted for the degree of MASTER OF SCIENCE

at the

UNIVERSITY OF ADELAIDE

(Department of Physics and Mathematical Physics)

By

January

1999

II

Contents

Abstract

Originality Declaration

Acknowledgements

List of

Figures

List of

Tables

1 Introduction To The Planetary Boundary-Layer

1.1

Introduction, Motivation

&

Scope

1.1.1

Outline of Thesis

L.2

^{The Atmosphere}

1.3

The Planetary Boundary-Layer

7.4

Summary

2 Atmos. Observation: Equipment and

Techniques

2.7

Introduction

2.2

MST Radars and Observation Techniques

2.2.7

Scattering of EM Waves by the Atmosphere

2.2.2

UHF Boundary-Layer Radars

2.2.3

VHF Boundary-Layer Radars

vll lx xl xvl xvtl

1 2 4 5 10

t4

L7 77

t7

18 20 23 25

I

2.2.3.I

The Doppler Technique

IV CON"E¡ú"S

2.3 2.4 2.5 2.6

26 27 28 30 31

2.2.3.2

Spaced Antenna Analysis Acousiic Sounders

Radio-Acoustic Sounding Systems Radiosondes

Summary

3 The Adelaide VHF Boundary-Layer

Radar

3.1

Introduction

3.2

The Antenna System

3.3

Antenna Ringing and Circuitry for its Removal

3.3.1

Coaxial Cable Tuning Circuits

3.3.2

LC Tuning Circuits using Coiled Wire Inductors

3.3.3

LC Tuning Circuits using Toroidal Wound Inductors

3.4

Ground Clutter

3.5

Optimal Antenna Spacing

3.6

Summary

4 Prelim. Results of the Boundary-Layer

System

4.7

September 1995 - Single Module Observation .

4.2

Comparison of Single Module with Radiosonde .

4.3

Pattern Scale Measurements for Antenna Spacing

4.4

Summary

5 Campaign with Final Configuration of

Radar

5.1

First Adelaide Boundary-Layer Spaced Antenna Experiment

5.2

Co-Located Radar and Sonde Campaigns

5.2.7

Experiment Description

5.2.2

Results

5.2.2.7

Campaign 1: July 31 to August 1, 1997

5.2.2.2

Campaign 2: September 12 to September 14, t997

33 33 36 38 39 40 47 44 47 51

53 55 59

fÕ

76

79 80 85 86 86 86 98

COIVTE¡\ITS

5.2.2.3 5.2.2.4

5.3

^Summary

6

Conclusions

and F\rture

Research

6.1

Conclusions

6.2

^{Future Research .}

A Tlansmitter and RDAS Description

B A VHF boundary layer radar:

First

Results References

Campaign 3: September 26

to

September 27, 7997

Pattern Scales Profiles from the Joint Campaigns

V

98 116 119

L2L

rzt

123

1.25

L27

L29

VI CO¡\rTE¡\r"S

Abstract

This thesis is concerned with the development of a VHF wind profiler capable of mea- suring from a height of 300 metres up to 4 kilometres. This region of the troposphere contains the mixed-layer, which is more commonly known as the convective boundary layer region.

The different types of atmospheric detection equipment used to measure the bound- ary layer region of the atmosphere are reviewed, along with wind profiling observation techniques.

The factors considered during the development of the antenna arrays are described, which includes

the

beam patterns

of

antenna arrays, and

the

technical aspects of impedance matching from the individual antennas through

to

the transmission and acquisition system to minimise the effect of antenna ringing. The effects of scattering and ground clutter on the performance of boundary-layer VHF wind profilers are also discussed.

Results from

initial

tests of a single module of Yagi antennas of the system are shown, demonstrating

the ability of

the radar during

the

developmental stages for probing the boundary layer. A comparison of radar reflectivities with values calculated using radiosonde data from the Adelaide airport is also performed.

An

examination of pattern scales in the boundary layer is then carried out to determine the optimum configuration of the antenna arrays for spaced antenna mode operation.

v11

vlll ABSTR.ACT

This thesis then concludes

with

the the first results of the boundary layer radar

in

its optimum configuration.

A

study of pattern scales and the angular spectrum of scatterers

in

the lower troposphere \ryas performed, and the comparison of results of campaigns of co-located high resolution GPS radiosondes and Omega Navaid radioson- des with the Adelaide Boundary Layer Radar are shown completing this research.

Altogether this thesis examines the potential of VHF radars in the application of boundary layer monitoring. These radars

will

not only have research applications due

to

their high spatial and temporal resolution for investigating the lower troposphere, but are potentially an important tool for meteorologists for continuous monitoring of the atmosphere in all weather conditions, even in remote locations.

l

'I

Originality Declaration

This work contains no material which has been accepted for the award of any other degree or diploma in any university or other tertiary institution and, to the best of my knowledge and belief, contains no material previously published or

written

by another personT except where due reference has been made in the text.

I

^give consent

to

this copy of my thesis, when deposited

in

the University Library, being available for loan and photocopying.

Signed:

^dated

11 fu*tV l?(t

Scott N.M. Dullaway, B.Sc. (Hons)

tx

ORIGI¡úA

LITY

D ECL ARATIO¡\¡

Acknowledgements

I

would like

to

thank my supervisors,

Dr

Robert Vincent and

Dr

Iain Reid for their direction during my project. Dr Vincent's drive and encouragement to me were always a ^good motivator to complete this thesis.

I

also thank Dr Peter May of the Bureau of Meteorology Research Centre for pro- viding me

with

access

to

the radiosonde data from Adelaide airport and discussions

on meteorological phenomena occurring

in

the boundary

layer.

Thanks also

to

Jeff Stickland of the Bureau of Meteorology for supplying the radiosondes for the inter- comparison campaign of the sonde's results with the radar's results,

Dr

Graham Elford and

Dr

Harish Chandra also provided useful insights into the larger field

of

atmospheric physics through our regular atmospheric physics ^group meetings.

A number of individuals have provided me assistance through my studies especially my fellow students Andrew MacKinnon, Jonathon Woithe and Florian

Zink.

They have always been willing to help

with

the development of this system, through to the analysis of data, which has been greatly appreciated.

There have also been many friends in the atmospheric physics group some of which have come and gone over the period of my studies, whom I also wish to thank including Dr Simon AIIen, Andrew Badger, Karen Berkefeld, Dr Laurence Campbell, Dr Manuel Cervera,

Dr

Steve Eckermann,

Dr

Dorothy Gibson-Wilde, Stephen Grant,

Dr

Trevor Harris, Bridget Hobbs,

Dr

David Holdsworth,

Ali

Kazempour, Dr Patrick Klövekörn,

Dr

Sujatta Kovalam,

Dr

Drazen Lesicar, Dr David Low,

Dr

Chris ^Lucas,

Dr

Damien Murphy,

Minh

Nguyen,

Dr

Deepak Rajopadhyaya,

Dr

Andrew Taylor,

Dr

Brenton

X1

XII ACKNOWLEDGEMENTS

Vandepeer, and Rupa Vuthaluru.

I

^{would also like}

to

thank the technicai support given

to the

group

by

Simon Ludborsz, Shane Dillon, Alex Didenko, and Lesley Rutherford. The assistance given

by ATRAD,

Tomco, and Brian Fuller

with

Genesis

is

also appreciated during the testing of the transmitter and receiver systems.

I

^am also grateful to Lyn Birchby and Dallas Kirby in the atmospheric administrative office whom always provided _assistance when required.

Lastly,

I

would like to thank my family whom this thesis is dedicated to for their love and support throughout

my studies. My

sister Janelle, my parents, and my grandmother, all provided the support and encouragement

I

needed to complete this thesis. Thank you.

List of Figures

1.1

Temperature profrle of the atmosphere

2.7

Figure from Rajopadhyaya (1994) showing the relative radar reflectivi- ties due

to

clear air turbulence and hydrometeors as a function of op- erating frequency. The increased sensitivity of UHF systems over VHF

to precipitation is

shown.

²²

2.2

Figure from Fi,llol et al. (1997) demonstrating the problem large beamwidth VHF boundary layer systems have when operating with oblique beams

for contamination from adjacent range

gates.

²⁴

2.3

Auto and cross-correlation parameters of the FCA technique for a pair

of

antennas.

²⁶

3.1

^Antenna layout for a single module of Yagis

3.2

Theoretical power pattern of a single Yagi antenna.

3,3

Method using a signal generator and a vector voltmeter

to

correct the relative phasing of circuitry used to match antenna array components.

6

3.4

3.5 3.6 3.7

Power response of a typical combiner box with frequency using coaxial cable for matching circuit components.

Circuit diagram for balun tuning box. ^. Circuit diagram for splitter/combiner box.

Power response of a typical combiner box with frequency.

xiii

ùt 38

39

40 42 43 44

xlv LIST OF FIGURES

3.8

Typical complex raw time series. The application of a third order poly- nomial

fit

to the in-phase and quadrature components of the time series can be seen in the left diagrams, with the resultant time series with the clutter removed shown in the right

diagrams.

46

3.9

Spatial correlation function with separation of antenna

modules.

^b0

4,L

4.2 4.3

4.4

4.5

4.6 4.7 4.8

4.9

4.t0

4.17 4.72 4.73 4.r4 4.15 4.76 4.17

Map

of

Buckland Park

from

May

(1986).

The relative locations of Buckland Park, the city of Adelaide, Adelaide airpor.t, and the Gulf of St. Vincent are shown.

First preliminary results of echo signal strength returns.

Figure from Low (1995) displaying a typical autocorrelation function

with

its measurement parameters.

SNR & Average Vertical Velocity using a single module of Yagi antennas

on 13 September 1995 from 15.0

to

16.4 CST.

Returned power profile derived from a wide beamwidth single module from 20f 03196

to

24103196

SNR for 201031e6

ñ 2alßle6 . .

^.

Range Corrected Power for 20103196

to

24108196

Vertical Velocity Variance derived from a wide beamwidth single module from 20f 03196 ro 24103196

Reflectivities and Range Corrected Power for

2Il03lg6

Radiosonde specific humidity from 20/03196

to

2410J196 Reflectivities and Range Corrected Power for 221031g6 Reflectivities and Range Corrected Power for 231031g6 Reflectivities and Range Corrected Power for 241031g6

Potential temperatures from 20103196 Lo

2alß196 .

^.

Radiosonde determined temperatures from 20f 031g6 to 2410T196 Specific Humidity from 20f 03196

to

24103196

Configuration of antenna modules for determining pattern scales

54 56

57

58

60 61 63

64 65 66 68 69 70 77 72

JDJÙ

75

LIST

OF FIGURES

4.18 Spatial-Correlations for determining correct antenna module separation. 77 XV

5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.72 5.13 5.74

5.15 5.16 5.77 5.18 5.19 5.20 5.2L 5.22 5.23 5.24 5.25

Final Spaced Antenna configuration of the Boundary Layer Radar.

.

⁸¹

Signal

to

Noise Ratio for

Campaignlalß197 to 16103197

⁸²

Meridional Velocity for Campaign

7alß197 to 16103197

⁸³

Zonal Velocity for Campaign

lalß197 to 16103197

⁸⁴

Radar and GPS Radiosonde comparison for 72:36 CST on 31107197

. .

⁸⁸

As for Figure 5.5 but for the launch

atlg:27

CST on

3L107197.

⁹⁰

As for Figure 5.5 but for the launch at23:24 CST on

31107197.

⁹¹

As for Figure 5.5 but for the launch at 02:06 CST on

07108197.

⁹²

As for Figure 5.5 but for the launch at04:57 CST on

0Ll0Sl97.

⁹³

As for Figure 5.5 but for the launch at 08:07 CST on

07108197.

⁹⁴

As for Figure 5.5 but for the launch at70:25 CST on

0L108197.

⁹⁵

As for Figure 5.5 but for the launch

at

13:30 CST on

07108197.

⁹⁶

As for Figure 5.5 but for the launch at75:22 CST on

01108197.

⁹⁷

Radar and Omega Navaid Radiosonde comparison

for

18:48 CST on

tzlosle7

^ee

As for Figure 5.14 but for the launch at22:59 CST on

72109197.

¹⁰⁰

As for Figure 5.14 but for the launch at 07:10 CST on

13109197.

¹⁰¹

As for Figure 5.14 but for the launch

at

10:57 CST on

13109197.

¹⁰²

As for Figure 5.14 but for the launch

at

15:07 CST on

73109197.

¹⁰³

As for Figure 5.14 but for the launch

at

18:56 CST on

73109197.

¹⁰⁴

As for Figure 5.14 but for the launch at23:48 CST on

73109197.

¹⁰⁵

As for Figure 5.14 but for the launch at 03:18 CST on

14109197.

¹⁰⁶

As for Figure 5.14 but for the launch at07:29 CST on

14109197.

^L07

As for Figure 5.14 but for the launch

at

11:03 CST on

74109197.

¹⁰⁸

As for Figure 5.14 but for the launch

at

15:06 CST on

14109197.

¹⁰⁹

Radar and Omega Navaid Radiosonde comparison

for

15:20 CST on

26loele7

¹¹⁰

XVI LIST OF FIGURES

5.26 5.27 5.28 5.29 5.30 5.31 5.32 5.33

As for Figure As for Figure As for Figure As for Figure As for Figure Pattern Scale

Pattern Scale

Pattern Scale

5.25 but for the launch at 5.25 but for the launctr at 5.25 but for the launch at 5.25 but for the launch at 5.25 but for the launch at for 31107197

to

0t108197 for 12109197

to

t5109197 ror 26109197 to 2710s197

18:06 21:01 00:05 03:03 06:05

CST CST CST CST CST

on on oll on on

26loels7 26l0ele7

27

l\e

le7

27l\sle7 27ljele7

111

t12

113 774 115 116 717 118

List of Tables

Circuit components for baluns.

Circuit components for combiner box. ^.

Radar parameters for the campaign of

lalß197 to

^t6103197.

.

^.

4.1

Tlansmitter and receiver allowable parameters

3.1 3.2 5.1

4T 42

80

L25

xvll

XVlII LIST OF TABLES