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Weekly result Eda 20100122 Heat and mass balance in GOM 5years runs with and without wind from the same IC.
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Heat transport Z=0m Z=-100m Z=-300m wind nowind
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Today’s topic The wind case shows different circulation and heat transport. Circulation affect eddy’s track and speed? (p11-p13) The higher heat in western Gulf may come from shelf and eddy. South of the eddy has higher heat, this may relate to downfront wind effect. (p5-p10) If the eddies dump heat in the western gulf result in higher OHC. (p4) Mass balance concludes from a simple assumption. (p14-17)
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Eddy dumps the heat, the near coast downwelling also result in higher OHC. windnowind Smooth (7points) vertical velocity at z=-100m OHC windnowind
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90w 5years mean T U PV Wind Nowind Wind- nowind downfront upfront downfront upfront
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90w mean, with eddy pass by T U PV Wind Nowind Wind- nowind downfront upfront
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Summary for upper 2 pages The deeper isotherm is contributed from the wind. The asymmetries in isotherms & PV’s about the eddy- center @26N are due to downfront to the south and upfront to the north. The downfront effect induces the instability and mixing, resulting in the deeper isotherm and near positive PV. The higher heat energy has been transferred to the western Gulf. Downwelling at the northern shelf is due to the upfront wind, the warmer water is also carried to the west.
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Along 3500m isobath Find the grids between 3300~3500m High energy had been transferred in wind case South of the eddy has higher heat transport downfront effect?
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Along isobath 5yrs mean T W PV Wind Nowind Wind- nowind
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Summary for upper 2 pages West of the section represents the situation when the eddy settles down, east of the section is the passage of the eddy. In wind case, downward motion is strong in the near surface layer deepens the isotherm. The PV is smaller (close to positive). This is similar as 90W may contributed from downfront wind.
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Find eddy propagates direction and speed EL=0.2m EL=0.3m wind nowind Define mean track
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Along track EL Zoom in one event (time is close to each other) to calculate eddy propagate speed nowind wind Speed (to the west): Wind: 334km/53days=7.3cm/s Nowind: 211km/28days=8.7cm/s Note: wind and nowind are based on different tracks in order to catch the eddies.
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Summary for upper 2 pages Wind: The large EL can propagate further westward. (see EL=0.3m) It means the eddy is larger or it dissipates slower. Eddy tends to move more southward than nowind, because of the nonlinear self advection (Smith and O’brien,1983). Eddy westward propagate speed is slower than nowind case because of the eastward background flow. Note: big eddy supposes to propagate faster because c=- βR d 2
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Mass balance The Gulf is closed, so the mass has to go somewhere after eddy shedding, either goes out from Florida strait or Yucatan channel. Hypothesis: The local wind changes the circulation, showing the strong westward flow in the shelf, so the Florida return flow may weaken; as a result, the Yucatan outflow is strengthened. Q q QyQy QfQf Q eddy Wind
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Mass balance Q q QyQy QfQf Q eddy Nowind Q q QyQy QfQf Q eddy Wind Q=30.58Sv Q y =+6.91Sv For Gulf Control Vol: Q-Q y =q+Q f =23.67Sv Q=33.19Sv Q y =+9.23Sv For Gulf Control Vol: Q-Q y =q+Q f =23.96Sv For EG Control Vol: Q-q=Q eddy =Q y +Q f is about the same in wind and no wind! (Eddy in wind is larger but moves slower and in nowind is smaller but moves faster ) EG Control Volume
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Q eddy Q eddy is eddy’s transport=∫∫udydz depth is about the same in wind and no wind~800m y length comes from eddy’s size, and we have u already(p12) Eddy size: find the el>0.1m (exclude LC and shelf region), area=sum(dx*dy) √area~y length Wind:210km Nowind:175km Qeddy_wind=210km*800m* 7.3cm/s=12.26Sv Qeddy_nowind=175km*800 m*8.7cm/s=12.18Sv
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t1 t0 t2
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Since Q eddy is about the same, and Q y is larger, so Q f is smaller in wind case. Q eddy = Q y + Q f Wind: 12.26=9.23+3.03 Nowind: 12.18=6.91+5.27 The hypothesis is valid. Summary for mass balance
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N Wind Volume transportHeat flux 800m to bottom stream function
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N Wind Volume transportHeat flux Surface to 800m stream function
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C Wind Volume transportHeat flux Surface to 800m stream function
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N Wind Volume transportHeat flux Surface to bottom stream function
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C Wind Volume transportHeat flux Surface to bottom stream function
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TrWBC Alon(*, ~24N) WBC ~6 Sv?
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Surface to 800m stream function WindNo Wind
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Figures for Papers In notes: Fig.1.2 means Fig.2 of paper#1 Fig.2.5 means Fig.5 of paper#2
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Q q QyQy QfQf Q eddy Q q QyQy QfQf (A) No Wind(B) Wind
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(A) Quiescent period Bottom Loop CurrentRing (B) Incipient shedding(C) Ring crosses 90W Upper Layer Lower Layer Upper Layer Lower Layer Upper Layer Lower Layer 90W Yucatan inflow Yucatan outflow
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(A) Loop Current expands Bottom Loop CurrentRing (B) Incipient shedding(C) Ring crosses 90W Upper Layer Lower Layer Upper Layer Lower Layer Upper Layer Lower Layer 90W Yucatan inflow Yucatan outflow
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(A) Loop Current expands Bottom Loop CurrentRing (B) Incipient shedding(C) Ring passes 90W Upper Layer Lower Layer Upper Layer Lower Layer Upper Layer Lower Layer 90W
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(A) Loop Current expands Bottom Loop CurrentRing (B) Incipient shedding(C) Ring passes 90W Upper Layer Lower Layer Upper Layer Lower Layer Upper Layer Lower Layer
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No Wind U90W_L=0.039 U90W_U=-0.035 WWG 0.196 WEG -0.557 MEANS:
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Q q QyQy QfQf Q eddy Nowind
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Q q QyQy QfQf Q eddy Nowind Q q QyQy QfQf Q eddy Wind
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Q q QyQy QfQf Q eddy Nowind Q q QyQy QfQf Q eddy Wind
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Q q QyQy QfQf Q eddy Nowind Q q QyQy QfQf Q eddy Wind
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