Discussion of how to use ROMS on different regional and basin scale applications.

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lmkli
Posts: 23
Joined: Wed Aug 02, 2006 1:21 pm
Location: TAMU

Hello,

Is dqdt in set_vbc.F same as dQdSST in forcing file?
stflx(i,j,itemp)=stflx(i,j,itemp)+ &
& dqdt(i,j)*(t(i,j,N(ng),nrhs,itemp)-sst(i,j))
If so, the unit of stflx is "degC m/s", while the unit of dQdSST is "Watts meter-2 Celsius-1".
It seems the units of both sides of the equation are not matching.

If not, what's the relationship between them?

meiw
Posts: 8
Joined: Fri Oct 12, 2007 5:59 pm
Location: University of California, Irvine

I think they are the same. When you set the value of dqdt in "ana_sst.h", you need to divide it by (rho0*Cp), and then the unit of dqdt is m/s.

chimera.u
Posts: 4
Joined: Mon Nov 10, 2008 8:44 pm
Location: IOCAS, TAMU

In my ana_sst.h
!-----------------------------------------------------------------------
! Set sea surface temperature (Celsius) and heat flux sensitivity to
! SST (Watts/m2).
!-----------------------------------------------------------------------
!
DO j=JstrR,JendR
DO i=IstrR,IendR
sst(i,j)=???
dqdt(i,j)=???
END DO
END DO
ana_sst.h: no values provided for sst and dqdt.
and
! expressions. The forcing dQdSTT is usually computed in units of !
! (Watts/m2/degC). It needs to be scaled to (m/s) by dividing by !
! rho0*Cp.
so easy to miss it..., what's the consequence if just keep it the way as dqdt(i,j)=???.... during the compiling there is no warning

lmkli
Posts: 23
Joined: Wed Aug 02, 2006 1:21 pm
Location: TAMU

meiw wrote:I think they are the same. When you set the value of dqdt in "ana_sst.h", you need to divide it by (rho0*Cp), and then the unit of dqdt is m/s.
Do I need to divide dQdSST by (rho0*Cp) when I am preparing the forcing file?

In the varinfo.dat:
'dQdSST' ! Input
'surface net heat flux sensitivity to SST'
'watt meter-2 Celsius-1' ! Input: [Watt/m2]
'dQdSST, scalar, series' ! [Celsius m/s]
'sst_time'
'iddQdT'
'r2dvar'
1.0d0
I think it suggests that I don't need to divide it by (rho0*Cp) when I prepare dQdSST

meiw
Posts: 8
Joined: Fri Oct 12, 2007 5:59 pm
Location: University of California, Irvine

chimera.u wrote:In my ana_sst.h
!-----------------------------------------------------------------------
! Set sea surface temperature (Celsius) and heat flux sensitivity to
! SST (Watts/m2).
!-----------------------------------------------------------------------
!
DO j=JstrR,JendR
DO i=IstrR,IendR
sst(i,j)=???
dqdt(i,j)=???
END DO
END DO
ana_sst.h: no values provided for sst and dqdt.
and
! expressions. The forcing dQdSTT is usually computed in units of !
! (Watts/m2/degC). It needs to be scaled to (m/s) by dividing by !
! rho0*Cp.
so easy to miss it..., what's the consequence if just keep it the way as dqdt(i,j)=???.... during the compiling there is no warning
I think this depends on whether "QCORRECTION" is defined in your header file or not.

meiw
Posts: 8
Joined: Fri Oct 12, 2007 5:59 pm
Location: University of California, Irvine

lmkli wrote:
meiw wrote:I think they are the same. When you set the value of dqdt in "ana_sst.h", you need to divide it by (rho0*Cp), and then the unit of dqdt is m/s.
Do I need to divide dQdSST by (rho0*Cp) when I am preparing the forcing file?

In the varinfo.dat:
'dQdSST' ! Input
'surface net heat flux sensitivity to SST'
'watt meter-2 Celsius-1' ! Input: [Watt/m2]
'dQdSST, scalar, series' ! [Celsius m/s]
'sst_time'
'iddQdT'
'r2dvar'
1.0d0
I think it suggests that I don't need to divide it by (rho0*Cp) when I prepare dQdSST
I think you still need to divide it by (rho0*Cp) in your forcing file. Actually, it is easy to check whether this is right or not since (rho0*Cp) is a very big number. You can run and compare two experiments: one with dqdt divided by (rho0*Cp) and the other without.