Forerunner simulation and sensitivity tests for typhoons using ADCIRC

Forerunner simulation and sensitivity tests
for typhoons using ADCIRC
13th IMUM for coastal, shelf, and global ocean dynamics
25-27 August 2014
Lisbon, Portugal
SeungWon Suh, Kunsan Nat’l Univ., Korea
HwaYoung Lee
HyeonJeong Kim
0
Background
Surge height, ~ 1 - 2 m
Occurs prior to main surge, 12h - 24h
Due to geostrophic effects, Ekman setup, size of wind field etc.
FS = fn of (geostrophic parameter, Vs, R, Ds, ...)
(Kennedy et al., 2011; Hope et al., 2013; Sebastian et al., 2014)
LATEX along GOM, hurricanes Rita(2005) & Ike(2008) caused
forerunner surges (FS)
WCK in YS, typhoons Prapiroon(2000) & Bolaven(2012) yielded FS
1
Previous studies
Kennedy et al.(2011); Hope et al.(2013); Kerr et al.(2013); Sebastian et
al.(2014)
Using ADCIRC+unSWAN
FS analyses for LATEX in Gulf of Mexico by Hurricane Ike
Large wind field, Ekman setup (approximately geostrophic balance between the
Coriolis force acting on the along‐‐shelf current and the across shelf pressure gradient)
resonant time ~12 hr(oscillations)
Bertin et al.(2012)
Using SELFE+WaveWatch III
FS analyses in Bay of Biscay indueced by storm Xynthia
Ekman setup, young wind-wave, oscillations
resonant time ~6 hr caused 10-20% of peak surge
2
Purposes
To enhance near real-time forecasting of storm surges including FS
Sensitivity tests on FS = fn of (geostrophic parameter, Vs, R, Ds, ...)
FS analyses for shallow macro-tidal coast along (WCK) in perigean
spring tide
To test YS semi-diurnal tides dominances and resonant time ≈ 12h
effect on FS
To find FS similarities or differences between GOM and YS
3
FS along WCK, YS - Bolaven(TY1215)
24 hr
20 hr
18 hr
14 hr
4
Grid refinement
NWP-G57k
NWP-G116k
Grid
Resolution
5
NWP-G258k
Comparison of grid refinement - results
NWP-G57k
NWP-G116k
NWP-G258k
RMSD(m)
0.3092
0.3397
0.3228
SI
1.7039
1.7861
1.7401
RMSD(m)
0.2377
0.2119
0.2153
SI
1.7266
1.7221
1.7007
RMSD(m)
0.1891
0.2207
0.2056
SI
1.6932
1.7676
1.6994
RMSD(m)
0.1742
0.1718
0.1865
SI
1.5626
1.5496
1.5639
RMSD(m)
0.1696
0.1676
0.1660
SI
2.0959
2.0850
2.1197
Incheon
Gunsan
outer port
Mokpo
Heuksando
Seogwipo
6
Geostrophic setup effect in GOM
Coriolis setup effects in FS
parallel flow along LATEX coast
(Kennedy et al., 2011; Hope et al., 2013)
Landfall -24 hr
Ike
Only tide
7
Geostrophic setup effect along WCK in YS
Macro-tidal area, strong tidal currents flood tide could increase FS
ebb tide
decrease
Landfall -12
-24 hr
Prapiroon
Surface elevation and Wind vector
Tide+Typhoon
Tidal current vector
Recursive currents
8
Only tide
Effects of Ds (separation distance)
- GOM, Hurricane Ike
Best track
EC2001 grid
9
Effects of Ds
-YS, Typhoon Bolaven
Change of
forerunner surge
Best track
Forerunner surge (m)
10
Analyses of FS for hypothetical storm
Bolaven
Bolaven track + Ike
Prapiroon
Prapiroon track + Ike
Historical TY track
with Ike characteristics
Pc, Rmax, Vmax, etc.
Prapiroon Bolaven
Pc (hPa)
975
982
Ike
951
Radius (34 kt, km)
-
74
56
Vmax (m/s)
31
28
49
11
Analyses of FS for hypothetical storm
SH ~ 5-6 m
FS ~ 2 m depending on Ds, track routes
12
Wave effect
ADCIRC+SWAN
Without wave
Difference
With wave
13
Wave effect
(red solid line: forerunner surge time, black dashed line: landfall time, black
arrow head: pass through time)
14
Bottom friction effect
0.005
(red solid line: forerunner surge time, black dashed line: landfall time, black
arrow head: pass through time)
15
Bottom friction – sensitivities
Chezy Eq.
H
Cz =
n
1
6
g
gn 2
Cf = 2 = 3
Cz
H
Manning’s n: 0.02~0.025 ± 0.005
Main surge (m)
0.02-0.025
Forerunner surge (m) 0.02-0.025
+ 0.005
+ 0.005
- 0.005
- 0.005
Incheon
Incheon
1.07
0.50
0.96 (-10%)
0.45 (-9%)
1.24 (+16%)
0.54 (+9%)
Gunsan outer port
Gunsan outer port
0.65
0.43
0.56 (-13%)
0.39 (-9%)
0.75 (+17%)
0.45 (+6%)
Mokpo
Mokpo
0.61
0.31
0.57 (-6%)
0.29 (-6%)
0.64 (+6%)
0.33 (+5%)
Heuksando
Heuksando
0.56
0.34
0.56 (-)
0.33 (-3%)
0.56 (-)
0.35 (+2%)
Seogwipo
Seogwipo
0.46
0.29
16
0.47 (+3%)
0.29 (-)
0.45 (-3%)
0.29 (-)
Vortex shape effects
(red solid line: forerunner surge time, black dashed line: landfall time, black
arrow head: pass through time)
17
Vortex shape effects
Gridded
wind vel. &
pressure
(NWS=6,
RDAPS)
Asymmetric
vortex
(NWS=9)
Symmetric
vortex
(NWS=8)
Dynamic
asymmetric
vortex
(NWS=19)
RMSD(m)
0.3092
0.3565
0.3751
0.3074
SI
1.7039
1.7553
1.8088
1.6198
RMSD(m)
0.2377
0.2608
0.3087
0.3144
SI
1.7266
1.7014
1.8605
1.9786
RMSD(m)
0.1891
0.2253
0.2369
0.2825
SI
1.6932
1.5945
1.6901
1.9440
RMSD(m)
0.1742
0.2861
0.2457
0.2392
SI
1.5626
1.7679
1.6122
1.7765
RMSD(m)
0.1696
0.1669
0.2398
0.2310
SI
2.0959
2.0943
2.4872
2.4615
Incheon
Gunsan
outer port
Mokpo
Heuksando
Seogwipo
Peak forerunner surge
Incheon
m
Gunsan outer port
%
m
%
0.61
Mokpo
m
%
Observed
0.47
0.38
NWS=9
0.49
-4
0.42
-31
0.31
-18
NWS=8
0.12
-74
0.1
-84
0.08
-79
NWS=19
0.12
-74
0.17
-72
0.14
-63
NWS=6 (RDAPS)
0.40
-15
0.42
-31
0.27
-29
RDAPS(KMA): Regional Data Assimilation and Prediction System
18
Vortex effects - sensitivities
19
FS depending on main force term
20
Results of FS tests
Primary factor is vortex size, bigger size causes higher FS
Vortex size ± 20% causes 67~-56%
Slow Vs (-20%) cause 9% of FS height
Major forcing on FS; Wind 91%, Coriolis f 35%
Typhoon Bolaven
peak forerunner surge
Gunsan
outer port
Incheon
Mokpo
Best track(NWS=9)
m
0.49
%
-
m
0.42
%
-
m
0.31
%
-
Moving spd-20%
0.52
6
0.5
19
0.32
3
Moving spd+20%
0.48
-2
0.36
-14
0.3
-3
Wind field-20%
Wind field+20%
0.23
0.82
-53
67
0.15
0.75
-64
79
0.15
0.48
-52
55
Vmax-20%
0.6
22
0.5
19
0.34
10
Vmax+20%
0.58
18
0.53
26
0.37
19
Tide off
0.43
-12
0.33
-21
0.31
0
Coriolis off
0.35
-29
0.22
-48
0.22
-29
Wind off
0.01
-98
0.02
-95
0.06
-81
Pressure off
0.50
2
0.42
0
0.29
-6
21
Results of SH
Primary factor is Cp
Vortex size is insensitive
Slow Vs cause decrease of SH
Major forcing on SH; Wind 56%, Coriolis f 34%
Typhoon Bolaven
peak surge
Gunsan
outer port
Incheon
Mokpo
Best track(NWS=9)
m
1.07
%
-
m
0.64
%
-
m
0.61
%
-
Moving spd-20%
0.97
-9
0.77
20
0.53
-13
Moving spd+20%
1.14
7
0.57
-11
0.88
44
Wind field-20%
1.08
1
0.64
0
0.63
3
Wind field+20%
1.07
0
0.75
17
0.59
-3
Vmax-20%
1.04
-3
0.62
-3
0.61
0
Vmax+20%
1.07
0
0.68
6
0.63
3
Tide off
0.98
-8
0.51
-20
0.57
-7
Coriolis off
1.2
12
0.65
2
0.56
-8
Wind off
0.28
-74
0.35
-45
0.31
-49
Pressure off
0.76
-29
0.42
-34
0.38
-38
22
Geophysical similarity effects on FS
FS = F of (geostrophic parameter, Vs, R, Ds, ...)
GOM vs YS
LATEX vs WCK
Ike, Rita vs Bolaven, Prapiroon
Similarity?
Differences?
23
Yellow Sea vs Gulf of Mexico
24
Yellow Sea vs Gulf of Mexico
Typhoon Bolaven
Hurricane Ike
Cp
(hPa)
982
951
Radius
(34 kt, km)
74
56
Vmax
(m/s)
28
49
YS
GOM
WCK
LATEX
Area (km2)
427,000
1,568,684
64,752
89,680
Volume (km3)
16,795
7,738,239
2,064
7,297
Avg. depth (m)
40
1,490
50
145
Width length (km)
490
870
200
200
Coast line length (km)
6,800
6,210
2,686
742
-
0.17~0.28
(Mixed, mainly semidiurnal)
1.5~2.6
(Mixed, mainly diurnal)
Form factor
-
25
Comparison of tidal environment
Form factor
Tidal station
26
WC
LATEX
0.17~0.28
(Mixed, mainly semidiurnal)
1.5~2.6
(Mixed, mainly diurnal)
Comparison of topography
- YS vs GOM
N
N
6
7
4
1
2
5
3
Sea bottom slope
Average Depth (m)
Maximum Depth (m)
7
5
4
6
3
2
West coast(Yellow sea)
1
LATEX(Gulf of Mexico)
West Coast of Korea (WCK)
LATEX
0.0003
50
110
0.004(A: 0.0005)
145
1430
A
27
Comparison of resonant period
Yellow sea
Gulf of Mexico
3
L = 82 km
Tn =
4L
n gh
L = 820 km
g = 9.8 m/s2
H = 60 m
T1=37.8 hr
T3=12.6 hr
L = 185 km
g = 9.8 m/s2
H = 30 m
T1= 11.9=12 hr
Moon et al.(2003)
Hope et al.(2013)
average L= 185 km
LATEX
28
Comparison of bottom materials
mud and sand dominant
Manning’s N 0.012 ~ 0.025
Yellow sea
Gulf of Mexico
http://csdms.colorado.edu/wiki/DBSEABED
http://gulfatlas.noaa.gov
29
Hurricane vs Typhoon characteristics
Ike, Rita vs Prapiroon, Bolaven
Vmax
Vs
Cp
R34
30
Summary and Conclusion
FS characteristics along WCK in YS
Efficiency ↑ with unstructured grids; dense nodes in shallow coast
Vortex shape affects to FS, asymmetrical shape > symm
Ds ↑ causes FS ↑, max. SH ≈
Wave coupling ↑ 0.1 m of FS
Bottom friction ↑ FS 6%, max. SH 8% ↓
Bottom friction ↓ FS 6%, max. SH 9% ↑
FS, SH depend on tidal current
Resonant time ≈ 12h affects to FS
Geostrophic setup effect : WCK ≠ LATEX
recursive tidal current ≠ uni-directional wind induced flow
31
Ekman setup effect behaves differently due to macro-tidal environ.
Ds, Vs, vortex shape are important factors in FS analyses
Proper bottom friction coeff, wave coupling are essential in FS
analyses
FS should be incorporated in near real-time forecasting of SH
Studied further on similarities between GOM and YS
32
Thank you
33

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