resolution sensitivity of isolated eddy evolution with/without steep topography · 2009-05-23 ·...
TRANSCRIPT
Resolution sensitivity of isolated eddy evolution
with/without steep topography
24-26 April 2007 HYCOM meeting, NRL, Stennis Space Center, MS, USA
Kyung Hoon Hyun* and Patrick J. Hogan**
[email protected] [email protected]
* University of Southern Mississippi** Naval Research Laboratory
1
• Motivation• Model configuration• Resolution sensitivity on the flat bottom
– Propagation (trajectory, speed), dissipation– Resolution convergence
• Resolution sensitivity to eddy-topography interaction– Eddy driven surface/deep currents– Collision trajectory over steep topography– Cross-shelf currents, shelf break jets– Shelf-slope, slope-abyssal exchange
• Conclusions• Future works
Overview
Hurlburt & Hogan (2000, DAO) Ffield (2005, DSR)
Motivation
What is the effect of resolution on eddy propagation, eddy-topography interaction?
NBC rings-slope interaction
3
• HYCOM– Version 2.1, vertical 10 layers– Closed boundary with idealized domain– No forcing, horizontally uniform density from GDEM (Teague 1990)– Biharmonic viscosity factor visco4= 0.2– Biharmonic diffusion velocity veldf4= 0.01 m/s (momentum),
thkdf4=0.005 m/s (thickness)– Laplacian diffusion velocity temdf2= 0.005 m/s (T,S)– Linear bottom friction cbar=0.05 m/s– quadratic bottom friction cb=2x10-3
• Domain– Horizontal resolution: 1/3, 1/5, 1/10, 1/20, 1/40 degrees resolution– 2000x2000km (800x800 nodes for 1/40 resolution)– depth: 50m-3500m
• Initialization of Eddy (Herbette et al. 2003 JPO)– R=80km– PVA (t=0)= 3.0f (f=7.0 x 10-5 s-1)– Max. Speed ~50 cm/s
Model Details
1. flat bottom
15 16 17 18
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98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 -20
-15
-10
-5
0
5
10
15
20
10.0cm/s 5.0cm/s
t=005
15 16 17 18
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98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 -10
-8
-6
-4
-2
0
2
4
6
8
10
10.0cm/s 5.0cm/s
t=005
15 16 17 18
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98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 -20
-15
-10
-5
0
5
10
15
20
10.0cm/s 5.0cm/s
t=005
sensitivity to initial adjustment
1/10 1/20 1/40
surface current with SSH (t=5d)
22
23
24
25
91 90 89 88 -20
-15
-10
-5
0
5
10
15
20
4.0cm/s 2.0cm/s
t=125
22
23
24
25
91 90 89 88 -20
-15
-10
-5
0
5
10
15
20
4.0cm/s 2.0cm/s
t=125
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23
24
25
91 90 89 88 -20
-15
-10
-5
0
5
10
15
20
4.0cm/s 2.0cm/s
t=125
1/10 1/20 1/40
sensitivity to propagation
surface current with SSH (t=125d)
7
sensitivity to trajectory
• Stepwise/continuous trajectory with low/high resolution• Resolution convergence: 1/20
−95 −94 −93 −92 −91 −90 −89 −88
21
21.5
22
22.5
23
23.5
24
x (oW)
y (o N
)
1/40o
1/20o
1/10o
1/5o
1/3o
−90 −89.8 −89.6 −89.4 −89.2 −89 −88.8 −88.6 −88.4 −88.2 −8822
22.2
22.4
22.6
22.8
23
23.2
23.4
23.6
23.8
24
x (oW)
y (o N
)
1/40o
1/20o
1/10o
1/5o
1/3o
trajectory for 1 yr 5d interval
• Faster propagation with high resolution (1/20 is 2 times faster than 1/3)
• Resolution convergence at 1/20
sensitivity to propagation speed
0 50 100 150 200 250 300 350 4000
100
200
300
400
500
600
700
day
dist
ance
(km
)
1/40o
1/20o
1/10o
1/5o
1/3o
0 5 10 15 20 25 30 35 40200
250
300
350
400
450
500
550
600
650
700
resolution (1/No)di
stan
ce (
km)
zonalmeridional
zonal (solid)meridional (dashed)
propagation distance distance for 1 yr
9
sensitivity to dissipation
• Slow dissipation with high resolution (1/20 dissipates ~20% slower than 1/10)
• Resolution convergence 1/20• Vorticity: oscillatory/continuous
dissipation with low/high resolution
0 50 100 150 200 250 300 350−0.2
−0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Day
ζ (1
0−5 s−
1 )
1/40o
1/20o
1/10o
1/5o
1/3o
0 50 100 150 200 250 300 350 4000
2
4
6
8
10
12
14
16
18
Day
ssh
(cm
)
1/40o
1/20o
1/10o
1/5o
1/3o
0 50 100 150 200 250 300 350 4000
20
40
60
80
100
120
140
t (day)
KE
(J
m−
2 )
1/40o
1/20o
1/10o
1/5o
1/3o
0 10 20 30 40 50 600.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.55
Day
|ζ| (
10−
5 s−1 )
1/40o
1/20o
1/10o
1/5o
KE
ssh
vorticity
pv=(ζ+f)/h
2. Eddy-topography interaction
11
• Cross-slope /alongslope translation before/after collision, slope jet (qualitatively consistent for >1/10)
• 1/40 well- resolved for filament/frontal eddies
20
21
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24
97 96 95 94 93 -10
-8
-6
-4
-2
0
2
4
6
8
10
10.0cm/s 5.0cm/s
t=180
20
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23
24
97 96 95 94 93
t=300
20
21
22
23
24
97 96 95 94 93
t=420
20
21
22
23
24
97 96 95 94 93 -10
-8
-6
-4
-2
0
2
4
6
8
10
10.0cm/s 5.0cm/s
t=180
20
21
22
23
24
97 96 95 94 93
t=300
20
21
22
23
24
97 96 95 94 93
t=420
20
21
22
23
24
97 96 95 94 93 -10
-8
-6
-4
-2
0
2
4
6
8
10
10.0cm/s 5.0cm/s
t=180
20
21
22
23
24
97 96 95 94 93
t=300
20
21
22
23
24
97 96 95 94 93
t=420
1/10
1/20
1/40
sensitivity to surface currentsurface currents (180d, 300d, 420d)
12
• Stronger subsurface cyclone for> 1/20
500
1000
1500
2000
2500
3000
2345
6
7
8
9
10
97W 96W 95W 94W
93.8W/22.4Nt=180
2345
6
7
8
9
10
97W 96W 95W 94W
95.5W/22.1Nt=300
-40
-30
-20
-10
0
10
20
30
40 2345
6
7
8
9
10
97W 96W 95W 94W
95.4W/21.3Nt=420
500
1000
1500
2000
2500
3000
2345
6
7
8
9
10
97W 96W 95W 94W
93.9W/22.3Nt=180
2345
6
7
8
9
10
97W 96W 95W 94W
95.6W/22.1Nt=300
-40
-30
-20
-10
0
10
20
30
40 2345
6
7
8
9
10
97W 96W 95W 94W
95.6W/21.1Nt=420
500
1000
1500
2000
2500
3000
2345
6
7
8
9
10
97W 96W 95W 94W
93.9W/22.2Nt=180
2345
6
7
8
9
10
97W 96W 95W 94W
95.5W/22.1Nt=300
-40
-30
-20
-10
0
10
20
30
40 2345
6
7
8
9
10
97W 96W 95W 94W
95.5W/21.0Nt=420
1/10
1/20
1/40
sensitivity to subsurface currentNS currents (180d, 300d, 420d)
100
200
300
400
500
600
700
2
3
4
5
6
97W 96W 95W 94W
93.8W/22.4Nt=180
2
3
4
5
6
97W 96W 95W 94W
95.5W/22.1Nt=300
-40
-30
-20
-10
0
10
20
30
40
2
3
4
5
6
97W 96W 95W 94W
95.4W/21.3Nt=420
100
200
300
400
500
600
700
2
3
4
5
6
97W 96W 95W 94W
93.9W/22.3Nt=180
2
3
4
5
6
97W 96W 95W 94W
95.6W/22.1Nt=300
-40
-30
-20
-10
0
10
20
30
40
2
3
4
5
6
97W 96W 95W 94W
95.6W/21.1Nt=420
100
200
300
400
500
600
700
2
3
4
5
6
97W 96W 95W 94W
93.9W/22.2Nt=180
2
3
4
5
6
97W 96W 95W 94W
95.5W/22.1Nt=300
-40
-30
-20
-10
0
10
20
30
40
2
3
4
5
6
97W 96W 95W 94W
95.5W/21.0Nt=420
• Strong deep cyclonic current (1/20, 1/40)
• 1/40 resolved better than 1/20 for deep cyclone
1/10
1/40
1/20
sensitivity to subsurface currentNS currents (180d, 300d, 420d)
14
sensitivity to collision/reflection
• 1st impinging depth is shallow with high resolution: 740m (1/20, 1/40), 820m (1/10)
• Shallowest point: topographic β effect max• Offshore turning point: topographic β effect balances planetary β effect • Smooth collision trajectory with high resolution• Low resolution suppresses cross-isobaths oscillation• Frequent collision with high resolution
250 300 350 400 450−1500
−1400
−1300
−1200
−1100
−1000
−900
−800
−700
−600
−500
Day
H (
m)
1/40o (topo)
1/20o (topo)
1/10o (topo)
−92.7 −92.6 −92.5 −92.4 −92.3 −92.2 −92.1 −92 −91.9 −91.8 −91.7
20.2
20.4
20.6
20.8
21
21.2
21.4
21.6
21.8
22
x (oW)
y (o N
)
1/40o (topo)
1/20o (topo)
1/10o (topo)
1
23
5
4
6
1 243
5
7
6
8
87
trajectory for 240-480d total depth of eddy center
15
sensitivity to eddy swirl currents
• strong dissipation/oscillation over topography; zonal/meridional oscillation • faster dissipation with lower resolution• 1/20 resolution convergence but smoothed pattern (following the mean of 1/40)• 1/40 stronger oscillation amplitude (more realistic)
0 50 100 150 200 250 300 350 400 4500
5
10
15
20
25
30
35
40
45
t (day)
u max
(cm
s−
1 )
layer 1−2
1/40o (topo)
1/20o (topo)
1/10o (topo)
0 50 100 150 200 250 300 350 400 4500
5
10
15
20
25
30
35
40
45
t (day)v m
ax (
cm s
−1 )
layer 1−2
1/40o (topo)
1/20o (topo)
1/10o (topo)
zonal meridional
16
• shelf break depth = 163m• stronger cross-shelf current core
speed, frequent collision with high resolution
250 300 350 400 450500
550
600
650
700
750
800
850
900
950
1000
−7
−6
−6 −6
−5
−5
−5
−5
−4
−4
−4−4
−3
−3
−3
−3
−3
−3
−2
−2
−2
−2
−2−2 −2
−1
−1
−1
−1
−1
−1
−1
−1
−1
0
0
0
0
0
0
0
0
0
0
0 0
0
0
00
0
0
0
0
0
0
0
0
0
00
11
1
1
1 1
1
1
1
22
2
2
2
2
2
3
3
3
3
3
3
3
3
4
4
4
4
4
5
5
55 5
6
6
6 67
7
8
8
9
1/20o (topo)
Day
y (k
m)
250 300 350 400 450500
550
600
650
700
750
800
850
900
950
1000
−9
−9
−8
−8
−7
−7
−6
−6
−6
−6
−5
−5
−5 −5
−5
−5
−4
−4
−4
−4
−4
−4
−3
−3
−3
−3
−3
−3
−2
−2
−2
−2
−2
−2
−2
−2
−2
−1
−1
−1
−1
−1
−1
−1
−1
−1
−1
−1
−1
−1
−1
−1
0
0
0
0
0
0
0
0
0
0
0
00
0
0
0
00
0
0
0
0
0
00
0
0
0
0
0
0
0
1
1
1
1
1
1 11
11
1
1
11
1
2
22
2
2
2
2
2
2
2
3
3
3
3
3
33
4
4
4
4
4
44
5
5
5
5
5
55
66
6 6
6
6
7
7 7
7
7
8
8
8
9
9
1/40o (topo)
Day
y (k
m)
250 300 350 400 450500
550
600
650
700
750
800
850
900
950
1000
−3−2
−1
−1
−1
−1
−1
0
0
0
00
0
0
0
0
0
0
0
0
0
0 0 01
1
11
2
223
34
4 56
1/10o (topo)
Day
y (k
m)
sensitivity to cross-shelf current
1 32
5
4
6
1
1 2
32
4
677
5
8
ubaro along the shelf break
17
sensitivity to shelf break jet
• Stronger/frequent shelf break jet with high resolution
250 300 350 400 450500
550
600
650
700
750
800
850
900
950
1000
−8
−6−6
−6
−6
−6
−6
−4
−4
−4
−4
−4
−4
−4
−4
−4
−4
−4
−4
−2−2
−2
−2
−2
−2
−2−2
−2
−2
−2
−2
−2
−2
−2
−2
0
0
0
0
0
0
0
0
0
0
00
0
0
00
2
2
2
2
2
2
2
2
4
4
4
4
4
4
4
6
6
6
6
6 6
6
8
8
8
8
88
888
10
10
10
10
1010
10
12
12
12
1212
12
14
1414
14
14
16
16
16
1616
18
18
18
18
18
20
20
2020
2020
22
22
24
24
1/40o (topo)
Day
y (k
m)
250 300 350 400 450500
550
600
650
700
750
800
850
900
950
1000
−6−6
−6
−6
−6
−4
−4
−4
−4
−4 −4
−4
−4
−2
−2
−2
−2
−2 −2
−2−2
−2−2
−2
−2
00
0
0
0
0
0
0
0
0
02
22
2
2
2
4
4
4
4
4
4
6
6
6
6
6
6
88
8
8 8
8
1010
10
10
10
10
10
12
12
12
12
12
12
1212
14
14
14
14
14
16
16
1616
16
18
18
18 18 18
20
20
22 2224
1/20o (topo)
Day
y (k
m)
250 300 350 400 450500
550
600
650
700
750
800
850
900
950
1000
−4
−4
−2
−2
−2
−2
−2
−2
−2
−2
0
0
0
0
0
0
0
0
2
2
2
2 2
4
44
4
4
6
6
6
8 8
8
10
1010
12
12
14
141618
1/10o (topo)
Day
y (k
m)
vbaro along the shelf break
18
• Larger on-shelf transport with higher resolution• Smaller off-slope transport with higher resolution
net shelf-slope-abyssal exchange
250 300 350 400 450
−0.05
0
0.051/40o (topo)
Day
U (
Sv)
250 300 350 400 450
−0.05
0
0.051/20o (topo)
U (
Sv)
250 300 350 400 450
−0.05
0
0.051/10o (topo)
U (
Sv)
150 200 250 300 350 400 450−2
−1
0
1
21/40o (topo)
Day
U (
Sv)
150 200 250 300 350 400 450−2
−1
0
1
21/20o (topo)
U (
Sv)
150 200 250 300 350 400 450−2
−1
0
1
21/10o (topo)
U (
Sv)
integrated ubaro along the shelf break integrated ubaro along the slope bottom(3000m)
19
• On flat bottom, stepwise propagation, oscillatory dissipation with low resolution– Qualitative agreement in propagation for >1/10– Resolution convergence at 1/20 according to propagation and
dissipation
• Eddy-topography interaction requires high resolution (>1/20)– Frequent/stronger collision, smoothed trajectory with high resolution– Low resolution suppresses cross-isobaths translation– Enhanced on-shelf, reduced off-slope transport with high resolution
Conclusions
20
Future works
27
28
29
30
89 88 87 86 -5
-4
-3
-2
-1
0
1
2
3
4
5
4.0cm/s 2.0cm/s
t=005
27
28
29
30
89 88 87 86
t=065
27
28
29
30
89 88 87 86
t=125
81 82 83 84 85 86 87 88 8920.5
21
21.5
22
22.5
23
23.5
24
x (oW)
y (o N
)
80km
40km
20km
0 50 100 150 200 250 300 350 40040
50
60
70
80
90
100
110
120
130
140
t (day)
KE
(J
m−
2 )
dragno drag
Inter-eddy interaction
Eddy size? Bottom drag?
21
Acknowledgments
• HYCOM consortium group : HYCOM model
• Dr. Wallcraft : HYCOM Utility, ARSC HPC
• SEED (Shelf to slope Energetics and Exchange Dynamics)