Upwelling, downwelling, and cross-shelf transport of bivalve
EVAT 554 OCEAN-ATMOSPHERE DYNAMICS UPWELING AND DOWNWELLING; EKMAN TRANSPORT LECTURE 14...
17
EVAT 554 OCEAN-ATMOSPHERE DYNAMICS UPWELING AND DOWNWELLING; EKMAN TRANSPORT LECTURE 14 (Reference: Peixoto & Oort, Chapter 8,10)
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Windstress and Circulation in the Upper Ocean Northern Hemisphere take H=2D E Coastal Downwelling
Transcript of EVAT 554 OCEAN-ATMOSPHERE DYNAMICS UPWELING AND DOWNWELLING; EKMAN TRANSPORT LECTURE 14...
EVAT 554OCEAN-ATMOSPHERE
DYNAMICS
UPWELING AND DOWNWELLING; EKMAN TRANSPORT
LECTURE 14
(Reference: Peixoto & Oort, Chapter 8,10)
Windstress and Circulation in the Upper Ocean
)/()2( 00 EDfV
fV
DE /2
Northern Hemisphere
take H=2DE
Mean transport is at right angles to surface wind (to the right in Northern Hemisphere)
This transport occurs in a boundary layer of width fD
VE /2
Below this boundary layer we will generally have geostrophic flow...
)0,0(1xyf
M kτ ˆ10
f
Windstress and Circulation in the Upper Ocean
)/()2( 00 EDfV
fV
DE /2
Northern Hemisphere
take H=2DE
)0,0(1xyf
M kτ ˆ10
f
Coastal Downwelling
fy
xM 0
Windstress and Circulation in the Upper Ocean
)/()2( 00 EDfV
fV
DE /2
Northern Hemisphere
take H=2DE
)0,0(1xyf
M kτ ˆ10
f
Coastal Upwelling
fy
xM 0
Windstress and Circulation in the Upper Ocean
)/()2( 00 EDfV
fV
DE /2
Northern Hemisphere
take H=2DE
)0,0(1xyf
M kτ ˆ10
f
SUMMER COASTAL UPWELLING ALONG CALIFORNIA COAST
fy
xM 0
Windstress and Circulation in the Upper Ocean
)/()2( 00 EDfV
fV
DE /2)0,0(1
xyfM kτ ˆ1
0f
SUMMER COASTAL UPWELLING ALONG CALIFORNIA COAST
fy
xM 0
SEA SURFACE TEMPERATURES
Windstress and Circulation in the Upper Ocean
)/()2( 00 EDfV
fV
DE /2
Northern Hemisphere
take H=2DE
)0,0(1xyf
M kτ ˆ10
f
fxxxM y0
fx
yfx
yyyM
00
Associated with a horizontal divergence of mass within the Ekman layer
fx
yfxy 00
)(
0
kf
τ
yyM
xxM
M
Windstress and Circulation in the Upper Ocean
Northern Hemisphere
take H=2DE
Associated with a horizontal divergence of mass within the Ekman layer
fx
yfxy 00
yyM
xxM
M
But by continuity this horizontal divergence must be replaced at the base of the Ekman layer,
)(
0)(k
E fHzw
τ
)(
01)(k
E fHzw
τ
Ekman Pumping
fxxxM y0
fx
yfx
yyyM
00
)(
0
kf
τ
Windstress and Circulation in the Upper Ocean
JJA
Dynamic Topography
Surface Windstress
Ekman Transport piles up water in the
subtropics!
Surface Windstress
Windstress and Circulation in the Upper Ocean
DJF JJA
0y0x
Note the relative amplitudes of variation with latitude!
Windstress and Circulation in the Upper Ocean
0x
Windstress and Circulation in the Upper Ocean
0x
fxyM 0
Windstress and Circulation in the Upper Ocean
0x
fx
yfHzwE
011)( 0
τ
Windstress and Circulation in the Upper Ocean
0x
Equatorial Upwelling!f changes sign at the equator
fx
yHzwE
01)(
Windstress and Circulation in the Upper Ocean
Equatorial Upwelling!
||0
fx
||0
fx
f
xyM 0
Within Ekman layer
f changes sign at the equator
fx
yHzwE
01)(
El Nino vs. La Nina
equatorial upwelling
El Nino vs. La Nina
coastal upwelling
