modeling china sea circulation: kuroshio-seas transporttezer/iwmo_2010/presentations/tuesday...118o...
TRANSCRIPT
Modeling China Sea Circulation: Kuroshio-Seas
transport
J. Gan
Collaborators: A. Cheung, Z. Liu and L. Liang
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Outline:
•General circulation and model-observation comparisons in CS
•Kuroshio-East China Sea Transport
•Discussion
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HK
<1km
<10km
South China Sea Basin
ContinentalShelf of SCS
Pearl RiverEstuary
HK
HK
<3km
HKUST China Sea Multi‐Scale Modeling System
120 121 122 123 124 125
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29
30
31
32
33
34
longitudela
titud
e
Δ=Δ
<3km <1km
ECS shelf
CJ Estuary
Shanghai
ShanHai
<10km
<7km
ROMS, Real-time nesting with external fluxes using an OBC (Gan and Allen, 2005), QuickSCAT wind and NCEP atmosphere fluxes
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SCS
ECS
Climatology Run
Direct simulation for 2009-2009
East China Sea
South China Sea
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Surface geostrophic velocityWinter (2007-2009)
W1
W2
W3
W1
W2
W3
Model Observation
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S1 S1
S2 S2
Surface geostrophic velocity
Summer (2007-2009)
Model Observation
7
winter
Modeled Observation
summer
(2007-2009)
W1
W2
W3
W1
W2
W3
S1
S2
S1
S2?
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Modeled total velocity sd
summerwinter
spring fall
W1
W2
W3
S1
S2
9
10
River inputRiver input
Atmosphere COAtmosphere CO22
sinkingsinking
Microbialrecycling
sedimentsCoupled physical-biogeochemical processes in estuary and coastal ocean play a significant role in global ocean carbon cycling.
zooplankton
phytoplankton
Boundary exchangeBoundary exchange
IntraIntra--system transfersystem transfer
Carbon poolCarbon pool
Biological pump compositionBiological pump composition
ReRe--suspensionsuspension
DICDIC
Euphonic layer
DOCDOC
POCPOC
POCPOC
Deep
Ocean
Coastal upward motion
Exchange with ocean
Biological pump
Terrestrial inputHigh biomassShallow waterFast sinking
AB
C
cs10.r
120 121 122 123 124 125 126 127 128 129 130 131 13223
24
25
26
27
28
29
30
31
32
33
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AVISO
120 121 122 123 124 125 126 127 128 129 130 131 13223
24
25
26
27
28
29
30
31
32
33
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vorticity<0vorticity>0
A: Exchange with Open Ocean
Observation
Model
2007-2009average
S
T
KECS
Q
P
11
Taiw
an
Taiw
an
Yangtze
2007 2007.5 2008 2008.5 2009 2009.5 20105
6
7
8
9
10
11
12 x 104
years
alon
g-ax
is tr
ansp
ort (
×104 m
2 /s)
AVISO
2007 2007.5 2008 2008.5 2009 2009.5 20105
6
7
8
9
10
11
12 x 104
years
alon
g-ax
is tr
ansp
ort (
m2 /s
)
cs10.9r
Observed
Model
Kur
oshi
o Su
rfac
e Fl
ux
Kur
oshi
o S
hore
war
d In
trus
ion
(Sur
face
)
5
0
5
10
ores
ide
boun
dary
tran
spor
t(×
104 m
2 /s)
5
0
5
10
ores
ide
boun
dary
tran
spor
t(×
104 m
2 /s)
Observed
Model
2007 2007.5 2008 2008.5 2009 2009.5 2010-3
-2
-1
0
1
2
3
4
5
6
years
diffe
renc
e of
alo
ng-a
xis
trans
port
(×10
4 m2 /s
)
Total - Geo
2007 2007.5 2008 2008.5 2009 2009.5 2010-15
-10
-5
0
5
10
15
years
diffe
renc
e of
cro
ss s
hore
side
bou
ndar
ytra
nspo
rt (×
104 m
2 /s)
Total - Geo
V-Vg
Model
U-Ug
Model
Surface Ekman Surface Ekman
shoreside
seaside
wintersummer winter
summer12
13
Taiw
an
China
Korea
Japan
seaward
T1
T2
T1
T2
T1-T2
Net volume change in ECS
Intrusion of Kuroshio
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Taiwan Strait
Tsushima Strait
Shoreward intrusion
Summer Winter
intrusion
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122 124 126 128 130-0.2
-0.1
0
0.1
0.2
shor
ewar
d ve
loci
ty(m
/s)
122 124 126 128 130-0.2
-0.1
0
0.1
0.2
shor
ewar
d ve
loci
ty(m
/s)
Observation Model
Shoreward intrusion
Shoreward intrusion
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T1
T2
Along T1 line
Along T2 line
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Taiwan Strait Mainland Taiwan Island
Summer
Winter
Pdownstream>Pupstream, intrusion occurs where isobaths are concave and Kuroshio turns anticyclonically.
P2
P1
isobath
P2>P119
Depth integrated velocity averaged from Dec. 2009 to Feb. 2009
temperature
salinity
PN
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118o 119o 120o 121o 122o 123o 124o 125o 126o 127o 128o 129o 22o
23o
24o
25o
26o
27o
28o
29o
30o
31o
32o
33o
DH01DH02
DH03DH04
DH05
DH11
DH12
DH13DH21
DH21a
DH22
DH23
DH24
DH25
DH26
DH27
DH27b
DH31a
DH31bDH32
DH33
DH34
DH35
DH36
DH37DH51DH51a
DH51b
DH51c
DH52a
DH53
DH54
KP00KP01KP01a
KP07aKP04
KP13KP13aKP13b
PN03
PN03bPN04PN05PN06PN07PN08PN0PN10
YZ09
YZ-12a
YZ-02YZE YZEa
KP10a
F16
TW03
E
N
Temperature
Front formed between coastal waters and Kuroshio
~300km
Observation
Model Observation
Model21
DH01DH02
DH03DH04
DH05
DH11
DH12
DH13DH21
DH21a
DH22
DH234
DH31a
DH31bDH32
DH33
DH34
DH35
DH3651
PN03
PN03bPN04PN05PN06PN07PN08PN0PN10
YZ09
YZ-12a
YZ-02YZE YZEa
Current structure dominated by sub‐tidal current
Edge of Kuroshio
Model Observation
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front front
Modeled MVP PN07 – PN04
density
Summer 2009
temperature
salinity
118o 119o 120o 121o 122o 123o 124o 125o 126o 127o 128o 129o 22o
23o
24o
25o
26o
27o
28o
29o
30o
31o
32o
33o
DH01DH02
DH03DH04
DH05
DH11
DH12
DH13DH21
DH21a
DH22
DH23
DH24
DH25
DH26
DH27
DH27b
DH31a
DH31bDH32
DH33
DH34
DH35
DH36
DH37DH51DH51a
DH51b
DH51c
DH52a
DH53
DH54
KP00KP01KP01a
KP07aKP04
KP13KP13aKP13b
PN03
PN03bPN04PN05PN06PN07PN08PN0PN10
YZ09
YZ-12a
YZ-02YZE YZEa
KP10a
F16
TW03
E
N
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NO3 at 200 m
Winter
Luzon StraitInter-annual variation of Luzon transport
Enhancing intrusion
El Nino?
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AGE.
NL.
DIFF.
n
Intrusive current at Luzon Strait Mean net normal PGF (>0, westward)
Kuroshio
Ageostrophicterm
Nonlinear advection term
Dynamics of Intrusion
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SSHA along 20 N as function of time
C: 0.35-0.47 m/s
SSHA>0, KU geostrophically weakened
Surface elevation along 20 N as function of time
and intrusion is enhanced.
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2007 2008 20092007 2008 2009
2007 2008 20092007 2008 2009 27
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Kuroshio transport in ECS
Transport doesn’t drop in ECS!X
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Summary
Validated China Sea circulation model shows highly time- and space-coeherent transport in the directions along and cross Kuroshio at the edge of China Sea.
accel:prsgrd:Coriolis: hadv:sstr: bstr:hvisc:
2007 2008 2009
90days filter
Relax of wind stress leads to decrease of meridional pressure gradient
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Winter Spring Summer Fall Annul
Taiwan Strait
0.61 2.24 3.03 0.56 1.6
TsushimaStrait
‐0.08 ‐1.38 ‐1.32 ‐0.64 ‐0.86
Shoreside 3.70 1.59 ‐0.07 0.39 1.4
NET 4.23 2.45 1.64 0.31 2.14
Seasonal and annual averages transport
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