Add a passive tracer to the model which has run for one year

[Yomi]

Hi, all,
I want to add a passive tracer to the model which has run for one year in order to minimize the influence of initial conditions ( especially in temperature and salinity), I would like to follow these steps:

STEP 1: undef T_PASSIVE and define PERFECT_RESTART in the cpp file
NPT=0 in the ocean.in file
Run the model for one year, and I will get a restart.nc file.

STEP 2: define T_PASSIVE in the cpp file
NPT=1 and modify the NPT related items in the ocean.in file
Add a variable dye_01 in the restart.nc file
Run the model with the restart.nc as initial file

Am I right?
Many thanks in advance.

[kate]

Yes, that sounds OK. You might also have to add a boundary condition for it - at the very least setting LBC for it. Try it and see what happens!

[Yomi]

Yes, that sounds OK. You might also have to add a boundary condition for it - at the very least setting LBC for it. Try it and see what happens!

Thanks very much! But is a boundary condition indispensable? I only focus on how decay happens in the initial dye_01 field.

[lanerolle]

Do not forget:

ANA_SPFLUX
ANA_BPFLUX

if you do not have ocean surface or ocean bottom passive tracer fluxes.

Also, be careful to either bring-in or not bring-in passive tracers into the computation via rivers/point sources. This can be controlled by the parameters in ocean.in

[m.hadfield]

A couple more comments:

If the initial dye field is simple, you can set it with ana_passive.h. Just #define ANA_PASSIVE in the header file, set DSTART in the input file to the time at which
you want the dye introduced and set NRREC to 0. You will not get a perfect restart in this case: the model will treat the restart as the beginning of a new simulation, but this may not matter.

Depending on the initial dye field, you may be able to use with un-nudged radiative boundary conditions, which do not require dye data in the boundary files.

[Yomi]

A couple more comments:

If the initial dye field is simple, you can set it with ana_passive.h. Just #define ANA_PASSIVE in the header file, set DSTART in the input file to the time at which
you want the dye introduced and set NRREC to 0. You will not get a perfect restart in this case: the model will treat the restart as the beginning of a new simulation, but this may not matter.

Depending on the initial dye field, you may be able to use with un-nudged radiative boundary conditions, which do not require dye data in the boundary files.

Thanks! Your suggestion works! If I set NRREC to -1, dye_01 is also needed in the latest history file, which will result in an immediate blow up. Setting NRREC to 0 is a good choice.