Chemical Tracers

[GraceMaze]

I have been using ROMS for a little over a year now, but so far I have strictly been concerned with how the water column reacts and where the water moves to. I have taken on a new project and I am trying to add chemical tracers into my program. Specifically I am trying to look at how 4 different isotopes of Radium are distributed. I sadly have no idea where to start. I have my basic model set up I just do not know how to turn on the chemical tracers and if I can specify a specific decay rate. Any help would be greatly appreciated.
Thank you.

[ocecept]

You can use passive/inert tracers, but I'm not sure about the decay rate.


Reading the following posts will help:

viewtopic.php?f=4&t=789&hilit=passive

viewtopic.php?f=14&t=1051&hilit=passive


Cheers

Carlos

[csherwood]

Passive tracers will work fine if all of the isotopes have the same initial age and are not decay products of other isotopes you are modeling. If that is the case, you can decay them all after the ROMS run during post processing.

[crowley]

I did this for pesticide concentrations some time back. They were just passive tracers and I added a bit of code to step3d_t.F to handle the decay. My situation was a little more complicated than Radium would be (increased decay rate in daylight), but it was actually pretty straightforward.

[GraceMaze]

Thank you all for your responses. I have a better understanding but I still have a few questions.
I have defined T_PASSIVE, ANA_PASSIVE, and ANA_INITIAL and I have set NPT=4 (I am using 4 different isotopes), but how do I set up the initial concentrations?

I am trying to set each isotope with an initial concentration that varies with depth and distance from the coast line. After the initial moment I want the isotopes to begin to decay, but I would also like to have several sources that deposit a set concentration into the system at the coast.