[MITgcm-support] dissipation and diffusion rates

[Yangxin He]

Hi there,


I am currently running a simple oceanic internal wave simulation. I have implemented Smagorinsky for horizontal viscosity, pp81 for the vertical viscosity and diffusion. I have the horizontal diffusion set to 0. Part of my data file is attached in the end.

I would like to output dissipation/diffusion rates using the diagnostic package. I know I should have Um_Diss, Vm_Diss and Wm_Diss. This way my dissipation rate for the kinetic energy will be

Kt=U*(Um_Diss)+V*(Vm_Diss)+W*(Wm_Diss).

pp81 can only be used if implicitViscosity and implicitDiffusion are on. Few questions here

1) From reading some of the previous posts, I got the impression that if implicitViscosity is on, I need to add more terms to my expression of Kt. Why?


2) If 1) is true, I will need 'VISrE_Um', 'VISrI_Um', 'VISrE_Vm' and ''VISrI_Vm'', but their units are 'm^4/s^2' instead of 'm/s^2'. How do I understand this? and how can I add them to Kt?


3) For the diffusion rate of the density equation, I will need both 'DFrE_TH' and 'DFrI_TH'? Their units are degC.m^3/s, but I am expecting degC/s. Does this need some scaling? or my understanding is not quite right?


 viscAz=1.E-5,

 viscAh=0.,

 no_slip_sides=.FALSE.,

 no_slip_bottom=.FALSE.,

 diffKhT=0.,

 diffKzT=1.E-5,

#new parameters for smag

 viscC2Smag=2.0,

# viscC4Smag=1.0,

 f0=6.5E-5,

 beta=0.,

 eosType='LINEAR',

 tAlpha=2.E-4,

 sBeta =0.,

 rhonil=1028.0,

 rhoConst=1028.0,

 gravity=9.81,

 rigidLid=.TRUE.,

 implicitFreeSurface=.FALSE.,

# exactConserv=.TRUE.

 nonHydrostatic=.FALSE.,

# minimum cell fraction. This reduces steppiness from Jody

 hFacMin=0.1,

# implicSurfPress=0.5,

# implicDiv2DFlow=0.5,

# nonlinFreeSurf=3,

# hFacInf=0.2,

# hFacSup=1.8,

#- not safe to use globalFiles in multi-processors runs

 globalFiles=.TRUE.,

 readBinaryPrec=64,

 writeBinaryPrec=64,

 writeStatePrec=64,

 saltStepping=.FALSE.,

#parameters for pp81

 implicitDiffusion=.TRUE.,

 implicitViscosity=.TRUE.,

#change advection shceme

 tempAdvScheme=33,

 staggerTimeStep=.TRUE.,

 &



Thanks


Yangxin


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