add passive tracer

[xrhuang]

Hi,
I want to add passive tracer in ROMS.
Anyone can tell me how to do it ?
Especially, how to make the initial file of passive tracer.
Many thanks.

[kate]

First, you turn on T_PASSIVE and set NPT in roms.in. For the initial conditions, ANA_PASSIVE can be used, otherwise you'll have to put the initial conditions into a netcdf file. I've usually initialized with zero via ANA_PASSIVE, then used sources to introduce the passive dye locally. What is your strategy going to be?

[xrhuang]

Thank you Kate.
I have turned on T_PASSIVE and set NPT =1. And I add dye_01 into the initial file.
Then, I run the model, but get the error message:
unable to find requested variable: dye_01_sflux
How can I figure it out?

[kate]

You need these as well:

Code: Select all

# define ANA_BPFLUX        /* analytical bottom passive tracers fluxes */
# define ANA_SPFLUX

unless you want the top and bottom tracer fluxes to be non-zero.

[wilkin]

There is an FAQ
https://www.myroms.org/wiki/Frequently_ ... tracers.3F
and also guidance on what to do if you want passive tracers in your rivers
https://www.myroms.org/wiki/River_Runoff

[xrhuang]

Thank you, Kate and Wilkin. It works.
I am not sure whether this result present the concentration of dye or not?
How can I do if I want to simulate only the Lagrange motion of particles, rather than the diffusion of the dye concentration?

[kate]

The FLOATS option is a whole different can of worms. Is that what you want? Online or offline?

[xrhuang]

Online
How to use FLOATS option?

[kate]

I see the wiki page on FLOATS is still empty. There is probably something about floats in the manual, though.

[wilkin]

Read the GLOSSARY at the end of one of the floats files, e.g. floats_upwelling.in, in the External directory. It is quite comprehensive.