Western Australia Tropical Cyclone Surges: Tide Gauge Observations

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Western Australia
Tropical Cyclone Surges
Tide Gauge Observations
Matthew Eliot
Damara WA
Australian Meteorological &
Oceanographic Society Conference 2008
Geelong 30 January 2008

Research Context and
Intended Application
Application intended for planning
purposes & definition of minimum setback
analyses
Data Provision by WA Department for
Planning & Infrastructure

Tide Gauge
Observations
Many locations
have short records
(many from 1966)
Data quality is
variable
Generally taken at
sheltered Port
locations

Coastal Planning Needs
Used for 100-year planning horizon
•Horizontal Setback Definition
•Building Fill Levels

Tide, Surge & Mean Sea Level
Harmonic Analysis & Temporal Filtering
Each component has seasonal & inter-annual variation
Classic Definition of Water Level Components by Pugh (1987)

Tropical Cyclones
Cyclone Paths
0
5
10
15
20
25
30
35
40
45
80 85 90 95 100 105 110 115 120 125 130 135 140 145 150
Long
Lat
TC1998/10 VANCE (1999)
14-Mar-99 to 23-Mar-99

Identifying Impact on WL
Time Scale
101102103104105106
100
Cyclone Data
WL Data
Overlap Data
Modelling

Cyclone Surge Components
Analytic Techniques Largely Determined from
US Practice
Barometric Pressure, including forward
speed
Wind Setup
Wave Setup
Shelf Waves
Resonance

Skew Surge
Tidal strain exaggerates surge response in
a tidal residual signal

Shelf Waves
Shelf waves enable wider transit of cyclone influence

WL Decomposition
Port Hedland
Observations
Tide
Mean Sea Level
Surges

WL Decomposition
Fremantle
Observations
Tide
Mean Sea Level
Surges

Regional Tides
Significant variation in
tidal character across
north and western
Australia

Tidal Features
-60.0
-40.0
-20.0
0.0
20.0
40.0
60.0
-400
-300
-200
-100
0
100
200
300
400
3-Nov-88 23-Dec-88 11-Feb-89 2-Apr-89 22-May-89 11-Jul-89 30-Aug-89 19-Oct-89 8-Dec-89 27-Jan-90
Port Hedland
Fremantle

MSL Features
Steric, Basin-scale and/or Current Driven
Seasonal
Inter-annual
Tectonic

Inter-annual Coherence
0
500
1000
1500
2000
2500
3000
3500
4000
4500
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Darwin
Wyndham
Broome
Port Hedland
Cape Lambert
Dampier
Onslow
Carnarvon
Geraldton
Fremantle
Bunbury
Albany
Esperance

Seasonal MSL
-600
-400
-200
0
200
400
600
800
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Darwin
Port
Hedland
Onslow
Carnarvon
Geraldton
Fremantle
Bunbury
Albany
Esperance

Broome
Surges more
commonly
associated with
distant cyclones,
although did suffer
direct hit from
Rosita
Apparently low risk
due to dominance
of tides
Broome protected by
aspect
Cyclone Paths
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
105.0 110.0 115.0 120.0 125.0 130.0
Long
Lat
TC918 CHRIS (2002)
02-Feb-02 to 07-Feb-02

Port Hedland
Most heavily exposed
region
Combination of direct
impacts and shelf
waves
0
5
10
15
20
25
30
35
40
45
100 105 110 115 120 125 130
Long
Lat

King Bay
Dampier
West side of the
Burrup
Greater influence from
shelf waves
0
5
10
15
20
25
30
35
40
45
100 105 110 115 120 125 130
Long
Lat

Cape Lambert
Cape Lambert Cyclonic Surge
1982 - 2006
0
20
40
60
80
100
120
140
160
180
200
110 100
ARI (yrs)
Cyclone Surge (cm)
Observations
Fitted Curve
TC Olivia (Apr-96)
TC Ilona (Dec-88)
TC Vance (Mar-99)
TC Gertie (Jan-85)
TC Orson (Apr-89)
TC Jacob (Feb-96)
TC John (Dec-99)
TC Clare (Jan-06)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0100 200 300 400 500 600 700
Distance from Cape Lambert (km)
Observed Surge (m)
< 960 hPa
960-980 hPa
> 980 hPa
envelope
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 5 10 15 20 25 30 35
Cyclone Speed (km/h)
Observed Surge (m)
< 200 km
200-400 km
> 400 km
Cyclone Paths - High Surge
0
5
10
15
20
25
30
35
40
45
100 105 110 115 120 125 130
Long
Lat
Cape Lambert
Cyclone Paths - Moderate Surge
0
5
10
15
20
25
30
35
40
45
100 105 110 115 120 125 130
Long
Lat
Cape Lambert

Exmouth
Experienced most
severe land-falling
cyclone recorded
3.4m tidal residual
-23.0
-22.5
-22.0
-21.5
-21.0
113.0 113.5 114.0 114.5 115.0 115.5 116.0
Exmouth
Muiron
Islands
Pt Cloates
Learmonth
Onslow
Exmouth Extreme Water Levels
1990-1993 & 1998-2003*
150
200
250
300
350
400
110 100
ARI (yrs)
Total Water Level (cm CD)
Observations
Cyclonic
Non-cyclonic
* Excludes TC Vance / TC Elaine in March 1999
0.0
0.5
1.0
1.5
2.0
2.5
3.0
110 100 1000
Maunsell & Partners (1981)
Reidel & Byrne (1986)
Steedman & Russ ell (1986)
CIES (1996)
Egis (1999)
Distribution range derived
from obs ervations

Carnarvon
Region exposed to mixture of
storm types –not just tropical
cyclones
Dominated by west coast tropical
cyclones
Impacted by more unusual Indian
Ocean cyclones
Carnarvon Cyclonic Extreme Daily Water Levels
1966-2004
120
130
140
150
160
170
180
190
200
110 100 1,000
ARI (yrs)
Water Level (cm CD)
Observations
Fitted Curve
TC Vanessa (1976)
TC Ingrid (1970)
TC Hazel (1979)
TC Glynis (1970)
0
5
10
15
20
25
30
35
40
45
100 105 110 115 120 125 130
Long
Lat

Geraldton
Geraldton Cyclonic Extreme Water Levels
1966 - 2004
130
140
150
160
170
180
190
200
210
110 100 1,000
ARI (yrs)
Water Level (cm CD)
Observations
Fitted Curve
TC Alby (1978)
TC Wally (1976)
TC Mavis (1971)
TC Vincent (1990)
TC Glynis (1970)
Geraldton Extreme Water Levels
1966 - 2004
130
140
150
160
170
180
190
200
210
110 100 1,000
ARI (yrs)
Water Level (cm CD)
Storms
Cyclones
Storm Dist
Cyclone Dist

Fremantle to Albany
Timing of seasonal
MSL shift reduces
the effect of TCs
Microtidal Zone not heavily impacted by
cyclones
Significant shelf wave activity
Severe impact from TC Alby, especially
Bunbury region

Fremantle
Timing of seasonal MSL shift reduces the
effect of TCs
Fremantle Extreme Water Levels (1897 - 2003)
120
130
140
150
160
170
180
190
200
210
110 100 1,000
ARI (yrs)
Water Level (cm CD)
TC Alby
(1978)
TC Rosita
(2000)
TC Clara
(1975)
TC Glynis
(1970)
?

Conclusions
Effects of tide & MSL cycles critical
for management
Need to be careful when selecting cyclone
models
Tide gauge observations possibly indicate
more events than direct interpretation of
met signals
Can not always use simple tide-surge
statistics

Pathway Ahead
Projections may
need to consider
possible changes in
climate
Program of progressive future analysis
Tide & MSL processes better understood
Identification of key storms for verification

Assessment Scales
Regional Assessment
Local Assessment
Site Specific Studies

Thankyou!
Projections may
need to consider
possible changes in
climate
Acknowledgments to
Bill Andrew, Tony Lamberto, Reena Lowry,
Peter McNally & Charlie Bicknell (DPI)
Graeme Hubbert & Steve Oliver (GEMS)

Extras –Regional RLR Trends

Extras –Fremantle High WL
Events
0
20
40
60
80
100
120
1897
1900
1903
1906
1909
1912
1915
1918
1921
1924
1927
1930
1933
1936
1939
1942
1945
1948
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
Event Count
> 120
> 130
> 140
> 150
> 160
> 170
> 180

Extras –Lifetime Risk

Extras –Cyclone Frequency

Extras –Modal Paths
5
10
15
20
25
30
35
100 105 110 115 120 125 130 135 140

Extras –Vance & Elaine
Paths of TC's Elaine & Vance (March 1999)
10.0
15.0
20.0
25.0
30.0
35.0
100.0 105.0 110.0 115.0 120.0 125.0 130.0 135.0 140.0
Long
Lat
15 March
14 March
18 March
16 March
23 March
22 March
20 March
21 March
19 March
19 March
17 March
TC Vance
Min CP 910 hPa
TC Elaine
Min CP 945 hPa

Extras –Tiffany Shelf Wave
-50
0
50
100
150
200
250
20-Jan-98 25-Jan-98 30-Jan-98 4-Feb-98 9-Feb-98 14-Feb-98 19-Feb-98 24-Feb-98
Darwin
Broome
Hedland
Dampier
Exmouth
Carnarvon
Geraldton
Fremantle
TC Les only
affected Darwin
TC Tiffany
generated a
shelf wave
along WA coast

Extras –Groote
Cyclone Paths
0
5
10
15
20
25
30
35
40
100 105 110 115 120 125 130 135 140 145 150 155 160 165 170
Long
Lat
All Paths
Coast
TC Craig Mar-03
TC Winsome Feb-01
TC Sid Dec-97
TC Sadie Jan-94

Extras –Karumba
Cyclone Paths
0
5
10
15
20
25
30
35
40
100 105 110 115 120 125 130 135 140 145 150 155 160 165 170
Long
Lat
All Paths
Coast
TC Abigail Feb-01
TC Winsome Feb-01
TC Warren Mar-95
TC Sid Dec-97
TC Sandy Mar-85

Extras –Weipa
Cyclone Paths
0
5
10
15
20
25
30
35
40
100 105 110 115 120 125 130 135 140 145 150 155 160 165 170
Long
Lat
All Paths
Coast
TC Mark Jan-92
TC Craig Mar-03
TC Sid Dec-97
TC Sadie Jan-94
TC Ivor Mar-90
TC Warren Mar-95