上层海流对台风的反应

1、Upper Ocean Response to a hurricane (James F.Price 1981)Zhu ShunliPukyong National University1. Introduction2. Review of observations3. A model of the upper ocean response4. Specification of the EB-10/Eloise case5. Overview of the response6. Comparison of the model solution with the EB-10 data7 Nume

2、rical experiments8. ConclusionQuestion1.What is the reason for SST response to a hurricane and rightward bias?2. How does the response depend upon such factors as the hurricane translation speed, the ocean initial condition, etc.?3. What role do nonlocal dynamics play in the upper ocean response4. I

3、s there evidence that air-sea transfer coefficients increase significantly under hurricane conditions?a. Hydrographic surveysb. Buoy/hurricane encountersa. Hydrographic surveys)36()27(10STeWhVth)(111eWhVth-)(122)(333hVthEntrainment velocity We0 1e1111hhTWTVQtT111111hSWSVhFStSeThe heat flux Q=Qs+QL +

4、 R is the sum of sensible , latent and radiative Heat exchange across the sea surface F is the mass flux, equal to evaporation minus precipitationThe term TWe is called the entrainment heat flux and is the bulk Representation of the turbulent heat flux zTWeTVtT2222zSWeSVtS2222zT/2is understood to be

5、 vertical gradient of T within layer 21111111hVWePVVhVftV22222PVVVftV33333PVVVftVWhere f is the Coriolis parameter times the vertical unit vector, is wind stress,P is the hydrostatic pressure perturbation01332211/)21(1hhhhgP03321/)21(2hhgP033/213hgP)(1110STAnd in the lower layers )(2212hhz)(33213hhh

6、zBSSTTUCQQs)(1010KqqUCQssQL)(1010Density of air divided by density of seawaterQCBulk transfer coefficient,=1.3*10-310UWind speed at 10m heightB heat capacity of air divided by heat capacity of seaweater q10,ss specific humidity at 10m height, and at the sea surface assuming satuation at the sea surf

7、ace temperatureK latent heat of vaporation divided by the heat capacity of seawaterWind stress :Where the drag coefficient1010UUCD31010)069.073.0(UCDVWEe44105vR0, if Rv1,If Rv1201/VhgRvis a bulk Richardson number Parameterize entrainmentlThe time step t = x/mUH ,Where m is the smallest Integer that

8、gives t 2*103s lThe ocean is moved down the grid one row after everym steps and the first row of the grid points is updated with the ocean initial condition.lSpace derivative are estimated with a second-order centered Form, and time-stepping is carried out using the three-time-level ,two-step, leapf

9、rog trapezoidal method. A check of the entrainment calculations 2/12/12/1/RnRWevComparing with the quasi-steady entrainment Where n=1/2 for a linearly straitified fluid , and n=1 for a two-layer stratified fluid, Where R=(gh)/(p0) is the external Richardson Number。Specification on the EB-10/Eloise c

10、asea. Ocean initial conditionb. Model hurricanethe ML transports computed from a local momentum balance :1111)(hVfthVRightward biasFig 15b The SST response shown as the change in sea surface temperature Fig 23 a Observed and predicted sea surface temperature for the EB-10/EloiseReason: the y-component of velocity in the ML combined with the strong y-gradients in Fig 18bPumping & Fig 19bUpwelling below the base of the ML