[MITgcm-support] Diagnostics & temperature transport equation
Krishnakumar Rajagopalan
krishna_raj_2010 at yahoo.com
Mon Jul 11 17:53:29 EDT 2011
Hi All,
I am (re)calculating theta in the temperature transport equation ( equation 2.166 of manual) implemented in gad_calc_rhs.F using the diagnostics ( advective & diffusive fluxes of potential temperature and transports) and i am ending up with a difference between the instantaneous theta calculated by the MITgcm solver and theta recalculated using the diagnostics. I am unable to figure out the mistake I am making with the diagnostics. Any help is most welcome.
The tutorial is : tutorial_global_oce_latlon ( global ocean simulation at 4deg resolution with GMREDI scheme). I am focusing on the second layer. Thus there is no external forcing.
I am using this bit of fortran code from gad_calc_rhs.F as a guide to calculate gTracer :
//////////////////////////////////////////////////////////////////////
gTracer(i,j,k,bi,bj)=gTracer(i,j,k,bi,bj)
& -_recip_hFacC(i,j,k,bi,bj)*recip_drF(k)
& *recip_rA(i,j,bi,bj)*recip_deepFac2C(k)*recip_rhoFacC(k)
& *( (fZon(i+1,j)-fZon(i,j))
& +(fMer(i,j+1)-fMer(i,j))
& +(fVerT(i,j,kDown)-fVerT(i,j,kUp))*rkSign
& -localT(i,j)*( (uTrans(i+1,j)-uTrans(i,j))
& +(vTrans(i,j+1)-vTrans(i,j))
& +(rTransKp1(i,j)-rTrans(i,j))*rAdvFac
& )*advFac
& )
///////////////////////////////////////////////////////////////
fZon=ADVx_TH + DFxE_TH ; from 2nd layer 2
fMer=ADVy_TH + DFyE_TH; from 2nd layer 2
fVerT(i,j,kDown)=ADVr_TH+DFrE_TH from bottom of 2nd layer
fVerT(i,j,kUp) =ADVr_TH+DFrE_TH from top of 2nd layer
For the transports, i multiply the velocity diagnostics with the respective area (The transport terms play only a small role). All diagnostics are averaged montly. So the change in theta after 1month is gTracer*1month (in seconds) with the gTracer calculated from averaged diagnostics. But this value (change in theta) is different when I calculate with instantaneous theta output by the solver.
My data.diagnostics file, say for, for ADVr_TH averaged for 1 month is here :
&diagnostics_list
frequency(1) = 2592000,
fields(1,1)= 'ADVr_TH',
filename(1) = 'flux',
&
Thanks in advance
Krishnakumar
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