roms river temperature problem

[xmuliuy]

Hi,
I'm running a case on a estuary with river runoff input.Let the Logical switch of point sources temperature 'LtracerSrc' to False.
But the temperature of the zone where point sources located decrease along the model run,and the low temperature water along the river flows downward .
After several days,the model Blowing up.
Like the figure show.

Hopes for your help.
thanks.

[kate]

You have to set those LtracerSrc to True and provide tracer values for the incoming river flow. Otherwise you have a "downwind" advection scheme, known to be unstable. The only time it makes sense to turn LtracerSrc to False is on outflow from the domain (which could argue for LtracerSrc to be on for some sources, off for others).

[xmuliuy]

Thank you kate.
here is my TS advection option:
TS_C4HADVECTION Fourth-order centered horizontal advection of tracers.
TS_C4VADVECTION Fourth-order centered vertical advection of tracers.
Is this option unstable?
How about set TS advection option to TS_MPDATA ?
Or other option you recommend.

[kate]

Did you set LtracerSrc to true or are you trying to find a way to avoid it?

[xmuliuy]

Kate,
Thanks for your reply.

Yes,I try to avoid set LtracerSrc to True.
Once Ltracersrc is True,I should specified a river_temp value for my river,and it make the temp structure of the estuary strange and obviously wrong,so... i try to let the model compute itself to get a result.

[m.hadfield]

You have to set those LtracerSrc to True and provide tracer values for the incoming river flow. Otherwise you have a "downwind" advection scheme, known to be unstable. The only time it makes sense to turn LtracerSrc to False is on outflow from the domain (which could argue for LtracerSrc to be on for some sources, off for others).

That's odd. I have done quite a few simulations with rivers recently and have invariably set LtracerSrc to "F T" (false for temperature, true for salt). They all seem to have worked fine, once I have sorted out little details like getting the river in the right location relative to the land mask, the flow in the right direction, etc.

[xmuliuy]

thank you m.hadfield,
When I choose the wrong location and direction of the river,the model will blowing up soon .

when you set Ltracersrc to false,what is your TS advection scheme ?

[m.hadfield]

When you set LtracerSrc to false, what is your TS advection scheme?

Sometimes TS_U3HADVECTION, sometimes TS_MPDATA, but I may have to back down on my reassurances about LtracerSrc = F.

As I said, I've used this setting before now with no problems I have been aware of, but right I'm now looking at a simulation where I'm injecting a series of tracers (via additional code in step3d_t.F) into a grid cell that is adjacent to a river point source, and I have LtracerSrc set to false on all the tracers. One of the tracers is going very negative after 30 days of the simulation, and I wonder if this is the problem Kate refers to.