[MITgcm-support] Vorticity balance

[Marco Reale]

Dear MITGCM users,

my name is Marco and I’m a ph.student at University of Trieste.Presently I’m working using MITGCM outputs on an estimation of vorticity balance for a basin trying to compute the different terms of vorticity balance (Stretching , lateral dissipation, Baroclinicity term and advection of vorticity) starting from the data available from the model such as Relative vorticity (momVort3), U and V (zonal and meridional momentum) , Horizontal divergence of velocity field (momHdiv) and Um_dPHdx and   Vm_dPHdx  (as components of Hydrostatic pressure gradient divided by rho ).

I estimated relative vorticity using the same approach of model and U and V data and the results looks fine.But I’m faced some troubles in the computations of the others terms.have you any suggestions about the numerical schemes to be employed in the computations or to estimate different terms?

For your knowledge :

a) I’m estimating the stretching terms of vorticity equations as  momVort3*momHdiv.
b) I’m estimating the diffusion of vorticity( muh*del^2Z3) using a simple backward second order scheme in the form [Z3(i-2)-2*Z3(i-1)+Z3(i)]/DXC(i,j)^2 and multiplying it for visc_Ah(muh)=400;
c) I’m estimating the curl X (gradP/rho) using  Um_dPHdx and   Vm_dPHdx as component and applying the formula already employed with momVort3
d) finally I’m estimated the advection of vorticity using the formula  0.25*[HFacW(i,j,iz)*DYG(i,j)*Level(iz)*U(i,j,iz,t)+HFacW(i+1,j,iz)*DYG(i+1,j)*Level(iz)*U(i+1,j,iz,t)]*(Z3(i,j,iz,t)+Z3(i+1,j,iz,t)) and 0.25[HFacS(i,j,iz)*DXG(i,j)*Level(iz)*V(i,j,iz,t)+HFacS(i,j+1,iz)*DXG(i,j+1)*Level(iz)*V(i,j+1,iz,t)]*(Zeta3(i,j,iz,t)+Z3(i+1,j,iz,t))

The sum of all these term doesn’t give the original value of Z3 and neither approximates the original values.Anyone of you has faced this kind of computations?Do you think I should do the balance including also vertical velocity (w)?Any suggestions?

Best Regards

Marco


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