WESTERN AND EASTERN BOUNDARY CURRENTS
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Transcript of WESTERN AND EASTERN BOUNDARY CURRENTS
WESTERN AND EASTERN BOUNDARY CURRENTS
Schematic Model of Boundary Currents
Explanation of Western Intensification
Western Intensification from Beta effect
Coriolis constant
Coriolis changing with latitude
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Ocean Color
Low Productivity in Western Boundary Currents
- major pathway for heat, salt and nutrients transport to high latitudes- frontal processes of important ecological implications
General Origin and Path of Gulf Stream
Sea Surface Temperature image of the Gulf Stream, in yellow and orange. Data from the MODIS instrument on the Aqua satellite. Image provided by Norman Kuring, NASA/GSFC. (oceanmotion.org)
Complete View of the Gulf Stream
Poleward transport of heat
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Azy
uA
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wyu
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utu
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fVH
UWLUV
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y
x
xyx
U = 1 m/s, V = 0.1 m/s, W = 1x10-5 m/s, t = 4x105 s, Lx = 5x105 m, Ly =1x105 m, H = 500 m, f = 1x10-4 s-1, Ax = 10 m2/s, Az=1x10-3 m2/s
991157666 1041011041
101102101102105.2
xp
Along-stream Momentum Balance
Inertia, Coriolis, Pressure Gradient
zv
Azy
vA
yxv
Axy
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zv
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vxv
utv
zyx1
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VA
L
VA
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fUH
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U = 1 m/s, V = 0.1 m/s, W = 1x10-5 m/s, t = 4x105 s, Lx = 5x105 m, Ly =1x105 m, H = 500 m, f = 1x10-4 s-1, Ax = 10 m2/s, Az=1x10-3 m2/s
10101248777 1041011041
101102101102105.2
xp
Across-stream Momentum Balance
Coriolis and Pressure Gradient = Geostrophy
Gulf Stream Eddies
May 1997
Temperature cross-section of a cold-core ring in the Gulf Stream
Link to Gulf Stream Tutorial
KUROSHIO CURRENT
(Black Water)
Long-term mean geopotential anomaly (converted to meters) relative to 1000 db (Hasunuma and Yoshida, 1978)
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v
5101
x
54 101
10110
v
smv /1Ja
pan
Ko
rea
Ch
ina
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ilipp
ines
kmm
x 1001
Surface mean currents in the East China Sea derived from geopotential anomaly data from 1953-1984 (Qiu and Imasato, 1990).
Taiw
anChina
Korea
Japa
n
with respect to 700 db.
(Guo et al., 2003)
Velocity profile along the ASUKA line: Geostrophic calculation with a reference level at 2000 m in the deep area and at the bottom in the shallow area (S. Imawaki 1995) Contour interval is 0.1 m/s; shaded areas denote negative values.
Kuroshio path in 2000 (from the Bulletin of Oceanic Conditions, published by the Japanese Coast Guard)
EASTERN BOUNDARY CURRENTS
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v
7104
5002.0
kmm
x 7
4104
101
10
v smv /04.0
WeakWinds
StrongWinds
PF = Polar Flow
CJ = Coastal Jet
GF = Geostrophic Flow
(From Tomczak)