Weekly result Eda Heat and mass balance in GOM 5years runs with and without wind from the same IC.

Heat transport Z=0m Z=-100m Z=-300m wind nowind

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)

Eddy dumps the heat, the near coast downwelling also result in higher OHC. windnowind Smooth (7points) vertical velocity at z=-100m OHC windnowind

90w 5years mean T U PV Wind Nowind Wind- nowind downfront upfront downfront upfront

90w mean, with eddy pass by T U PV Wind Nowind Wind- nowind downfront upfront

Summary for upper 2 pages The deeper isotherm is contributed from the wind. The asymmetries in isotherms & PV’s about the eddy- 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.

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?

Along isobath 5yrs mean T W PV Wind Nowind Wind- nowind

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.

Find eddy propagates direction and speed EL=0.2m EL=0.3m wind nowind Define mean track

Along track EL Enlarge 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.

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 there is a eastward flow south of northern basin. (see p.3 up-left figure) Eddy westward propagate speed is slower than nowind case.

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

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

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

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= Nowind: 12.18= The hypothesis is valid. Summary for mass balance