Lecturer: Chia-Ping Chiang Data: March/19/2009
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Variations of the volume tra Variations of the volume tra nsport and vertical current nsport and vertical current structure in relation to the structure in relation to the path of the Kuroshio path of the Kuroshio Lecturer: Chia-Ping Chiang Lecturer: Chia-Ping Chiang Data: March/19/2009 Data: March/19/2009
description
Variations of the volume transport and vertical current structure in relation to the path of the Kuroshio. Lecturer: Chia-Ping Chiang Data: March/19/2009. Typical path of the Kuroshio. Large meander (LM) path Nonlarge meander (NLM) path － nearshore (nNLM) － offshore (oNLM) 6: Uragami - PowerPoint PPT Presentation
Transcript of Lecturer: Chia-Ping Chiang Data: March/19/2009
Variations of the volume transport and Variations of the volume transport and vertical current structure in relation to vertical current structure in relation to the path of the Kuroshiothe path of the Kuroshio
Lecturer: Chia-Ping ChiangLecturer: Chia-Ping Chiang
Data: March/19/2009Data: March/19/2009
Typical path of the KuroshioTypical path of the Kuroshio
Large meander (LM) pathLarge meander (LM) path
Nonlarge meander (NLM) pathNonlarge meander (NLM) path
－ － nearshore (nNLM)nearshore (nNLM)
－ － offshore (oNLM)offshore (oNLM)
6: Uragami6: Uragami
7: Kushimoto7: Kushimoto
Kawabe M. (2005), Kawabe M. (2005), Journal of Oceanography.
Occurrence of Typical pathsOccurrence of Typical paths
Path Type Time of Occurence
NLM (Non-Large Meander)
October 1963 - 7 August 1975 9 August 1980 – September 1981
LM(Large Meander)
10 July 1953 - December 1955 22 May 1959 - January 1963 8 August 1975 - 15 March 1980 October 1981 - May 1984 November 1986 - July 1988 October 1989 - January 1991 May 2004 – July 2004
MD(Meander-Damping)
January - May 1956 January – July 1963 16 March - 8 August 1980
Kawabe M. (1985),Kawabe M. (1985), Journal of the Oceanographical Society of Japan.
Kawabe M. (1995), Kawabe M. (1995), Journal of Physical Oceanography.
Cycle of the three typical pathsCycle of the three typical paths
Large meander (LM) pathLarge meander (LM) path
Nonlarge meander (NLM) pathNonlarge meander (NLM) path
－ － nearshore (nNLM)nearshore (nNLM)
－ － offshore (oNLM)offshore (oNLM)
Kawabe M. (1995), Kawabe M. (1995), Journal of Physical Oceanography.
Model Description ~ Model Description ~ DuDuo-grids o-grids PPacific acific OOcean cean MModelodel (DUPOM)(DUPOM)
Model Domain:Model Domain: NPB (NPB (NNorth orth PPacific acific BBasin) Domain ~ From 3asin) Domain ~ From 3
0°S to 60°N and from 150°E to 80°W with a 0°S to 60°N and from 150°E to 80°W with a grid resolution of grid resolution of 1/4°1/4°..
TAI Domain ~ From 0° to 50°N and from 100TAI Domain ~ From 0° to 50°N and from 100°E to 150°E with a grid resolution of °E to 150°E with a grid resolution of 1/8°1/8°..
The vertical resolution ~ linear-exponential strThe vertical resolution ~ linear-exponential stretched grid, etched grid, 26 layers26 layers, Z=, Z=6, 20, 36, 54, 75, 98, 126, 159, 198, 244, 298, 364, 442, 537, 652, 790, 958, 1161, 1408, 1709, 2075, 2520, 3063, 3725, 4532 m.
Both grids share the same vertical grid.Both grids share the same vertical grid. Varying latitudeVarying latitude and and uniform longitudeuniform longitude grid grid
(Mercator grid).(Mercator grid).
Bathymetry:Bathymetry: Interpolated from unfiltered ETOPO2 depth dInterpolated from unfiltered ETOPO2 depth d
ata ata Supplemented with NCOR’s 1-minute high acSupplemented with NCOR’s 1-minute high ac
curacy depth archive.curacy depth archive.
100oE 125oE 150oE 175oE 160oW 135oW 110oW 85oW 60oW
36oS
24oS
12oS
0o
12oN
24oN
36oN
48oN
60oN
1/8 1/81/4 1/4
North Pacific
South Pacific
Longitude
Lat
itu
de
(a) Domains under consideration
-5500
-5000
-4500
-4000
-3500
-3000
-2500
-2000
-1500
-1000
-500
Based on the 4Based on the 4thth order accurate, collocated order accurate, collocated Arakawa “a” grid DieCAST (Arakawa “a” grid DieCAST (DieDietrich/trich/CCeenter for nter for AAir ir SSea ea TTechnology) model.echnology) model.
The control volume equations include The control volume equations include fluxes of the conservation of fluxes of the conservation of momentummomentum, , heatheat and and saltsalt across control volume faces. across control volume faces.
Surface wind forcing:Surface wind forcing: Use interpolated monthly Hellerman and Rosentstein winds (Hellerman and RosUse interpolated monthly Hellerman and Rosentstein winds (Hellerman and Ros
enstein, 1983).enstein, 1983). Use Levitus’94 climatology (Levitus and Boyer, 1994) to initialize the model aUse Levitus’94 climatology (Levitus and Boyer, 1994) to initialize the model a
nd determine its surface sources of heat and fresh water.nd determine its surface sources of heat and fresh water.
Other details:Other details: The northern boundary is closed. The southern boundary condition (30°S) is sloThe northern boundary is closed. The southern boundary condition (30°S) is slo
w nudging toward climatology in a sponge layer. The bottom is insulated, with w nudging toward climatology in a sponge layer. The bottom is insulated, with non-slip conditions parameterized by a nonlinear bottom drag. non-slip conditions parameterized by a nonlinear bottom drag.
Sub-grid scale vertical mixing is parameterized by eddy diffusivity (for temperaSub-grid scale vertical mixing is parameterized by eddy diffusivity (for temperature and salinity) and viscosity (for momentum) using a modified Richardson nture and salinity) and viscosity (for momentum) using a modified Richardson number based approach based on Pacanowski and Philander.umber based approach based on Pacanowski and Philander.
Background lateral viscosity (diffusivity) is 20 m²/s in both domains. Background lateral viscosity (diffusivity) is 20 m²/s in both domains.
Model Description ~Model Description ~ DuDuo-grids o-grids PPacific acific OOcean cean MModelodel (DUPOM)(DUPOM)
Results and DiscussionResults and Discussion
PN-LinePN-LineTK-LineTK-LineASUKA-LineASUKA-Line
PN-LinePN-Line
PN: PN: PPollution ollution NNagasakiagasaki Location on earth: (126°E, 28.9°N) ~ Location on earth: (126°E, 28.9°N) ~
(128.25°E , 27.5°N)(128.25°E , 27.5°N) Depth: 0 ~ 1000 metersDepth: 0 ~ 1000 meters Features: Features: single stable current coresingle stable current core
and and volume transport around 25 Svvolume transport around 25 Sv (Note: 1 Sv[≡]10(Note: 1 Sv[≡]1066 m m33/sec)/sec)
Location in DUPOM: (123.9375°E, 3Location in DUPOM: (123.9375°E, 31.0°N) ~ (128.0625°E , 26.2°N)1.0°N) ~ (128.0625°E , 26.2°N)
J M M J S N J M M J S N J M M J S N-10
0
10
20
30
40
50
60
Time [Month]
Vol
um
e T
ran
spor
t [S
v]
(a) Volume Transport across PN lineTotal Volume TransportUpper LayerIntermediate LayerDeep Layer
The solid line denotes the geostrophic transport relative to 700db from the observation of Nagasaki Marine Observatory
The dash-dotted line denotes the model transport relative to 700 m.
PN-LinePN-Line
10
10
20
20
3040
50 50
607080
90
(b) Vertical Current Structure normal to PN line
Latitude ( N)
Dep
th (
m)
27.527.727.928.128.328.528.728.9
100
200
300
400
500
600
700
800
900
(Upper) (Upper) Geostrophic calculation with a reference level at 700 m.
(Lower) OGCM.(Lower) OGCM.
TK-LineTK-Line
TK: TK: TTookkara Straitara Strait Location on earth: (129.75°E, 28.5°Location on earth: (129.75°E, 28.5°
N) ~ (130.8°E , 30.25°N)N) ~ (130.8°E , 30.25°N) Depth: 0 ~ 1000 metersDepth: 0 ~ 1000 meters Features: Features: Two current coresTwo current cores and and volvol
ume transport around 26 Svume transport around 26 Sv
Location in DUPOM: (130.1875°E, 2Location in DUPOM: (130.1875°E, 28.6°N) ~ (130.1875°E , 30.1°N)8.6°N) ~ (130.1875°E , 30.1°N)
J M M J S N J M M J S N J M M J S N-5
0
5
10
15
20
25
30
35
40
45
Time [Month]
Vol
um
e T
ran
spor
t [S
v]
(a) Volume Transport across TK lineTotal Volume TransportUpper LayerIntermediate LayerBottom Layer
TK-LineTK-Line
TK: TK: TTookkara Straitara Strait Location on earth: (129.75°E, 28.5°Location on earth: (129.75°E, 28.5°
N) ~ (130.8°E , 30.25°N)N) ~ (130.8°E , 30.25°N) Depth: 0 ~ 1000 metersDepth: 0 ~ 1000 meters Features: Features: Two current coresTwo current cores and and volvol
ume transport around 26 Svume transport around 26 Sv
Location in DUPOM: (130.1875°E, 2Location in DUPOM: (130.1875°E, 28.6°N) ~ (130.1875°E , 30.1°N)8.6°N) ~ (130.1875°E , 30.1°N)
5
5
5
5
51010
10
10
10
10
15
1515
15
15
15
20
20
2020
20
25 25
25
25
25
25 30
30 30
30
30
30
3035
3535
35
35
35
3535
40
4040
45
45
50
50
(b) Vertical Current Structure normal to TK line
Latitude ( N)
Dep
th (
m)
28.628.82929.229.429.629.830
100
200
300
400
500
600
700
800
900
ASUKA-LineASUKA-Line
ASUKA: ASUKA GroupASUKA: ASUKA Group Location on earth: (133.0°E, 33.0°N) Location on earth: (133.0°E, 33.0°N)
~ (135.5°E , 26.0°N)~ (135.5°E , 26.0°N) Depth: 0 ~ 2000 metersDepth: 0 ~ 2000 meters Features: Features: A pair of opposite currentA pair of opposite current
ss and and volume transport 20~60 Svvolume transport 20~60 Sv
Location in DUPOM: (Location in DUPOM: (132.9375132.9375 °E, °E, 33.0°N) ~ (33.0°N) ~ (136.6875136.6875°E , 26.0°N)°E , 26.0°N)
J M M J S N J M M J S N J M M J S N-150
-100
-50
0
50
100
150
200
250
Time [Month]
Vol
um
e T
ran
spor
t [S
v]
(a) Volume Transport across ASUKA lineTotal Volume TransportUpper LayerIntermediate LayerDeep Layer
The solid line denotes the geostrophic transport relative to 700db from the observation of Nagasaki Marine Observatory
The dash-dotted line denotes the model transport relative to 700 m.
ASUKA-LineASUKA-Line
10
1010
1020
2020
3030
3040
4050 5060
(b) Vertical Current Structure normal to ASUKA line
Latitude ( N)
Dep
th (
m)
272829303132
500
1000
1500
2000
2500
3000
3500
4000
4500
(Upper) (Upper) Geostrophic calculation with a reference level at 2000 m.
(Lower) OGCM.(Lower) OGCM.
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