about nudging problem (TCLM_NUDGING)

[jschoi]

Hello dear,

I have using TCLM_NUDGING of CPP option to decrease between climatology and simulation.
Nudging area is limit at northern part of my domain. i.e. I using nudging only northern part.
Climatology data is WOA09.

By the way, my problems are two.

First is phenomenon which low salinity don't entered in my model western boundary.
As a result, my model has simulating wrong salinity in all domain.

Second, I ran two models all the same, forcing, river, tide, climatology, etc .. only differ output path.
Nevertheless, one and the other model differ result so little.
I think that spread is occurred by non-linear term
But if model is used TCLM_NUDGING, result is the more differ .. so many many many .. before no TCLM_NUDGING.

If known's these problems, I need to help you.
Always feel to thank everyone in here.

[kate]

I think a few pictures would help us understand what you are saying. I think you have two issues:

1. Not enough fresh water inflow - from a river? from an open boundary? Is the low salinity in WOA?

2. You made a small change and the results are wildly different. Right? That's not a surprise with a non-linear system like this. I'm not sure what your point about the nudging is, but TCLM_NUDGING shows that you are not using the newest code since that option has been changed into a run-time logical instead of a compile-time flag.

[jschoi]

I think a few pictures would help us understand what you are saying. I think you have two issues:

1. Not enough fresh water inflow - from a river? from an open boundary? Is the low salinity in WOA?

2. You made a small change and the results are wildly different. Right? That's not a surprise with a non-linear system like this. I'm not sure what your point about the nudging is, but TCLM_NUDGING shows that you are not using the newest code since that option has been changed into a run-time logical instead of a compile-time flag.

1. open boundary data is low salinity in western part (left-bottom in figure). However, don't entered low salinity to my model.
WOA09 is also low salinity. If WOA09 is high salinity, I used nudging only northern part.

2. EX1 model and EX2 model are no nudging model. EX1 and EX2 are all the same.
EX3 model and EX4 model are nudging model. EX3 and EX4 are all the same.

To differ is so small between EX1 and EX2. It is allow range by non-linear system.
But To differ is large between EX3 and EX4. This experiment result shows difference perfectly.

figure 1 is no nudging model at 1-m depth in June (EX1).
figure 2 is nudging model at 1-m depth in June (EX3).
figure 3 is nudging model at 1-m depth in June (EX4).
figure 4 is nested WOA09 at surface layer in June.
figure 5 is nudging area (nudging area is used only northern and eastern part, Ignore 1 value of interior.

p.s : I have used ROMS v3.4

[kate]

I don't think 3 and 4 are so very different.

How did you get the fresh water in without the nudging? Are you sure the interior nudging is off in 3 and 4? It looks like it's nudging towards salty water.

[jschoi]

I don't think 3 and 4 are so very different.

How did you get the fresh water in without the nudging? Are you sure the interior nudging is off in 3 and 4? It looks like it's nudging towards salty water.

I don't understand what you say 3 and 4.
3 and 4 are figure number? or EX number?

If figure number, maybe I seems to confuse you because of figure order. sorry.
I uploaded figure in regular order but it reversed.
Anyway, In other words,
Fig. 5 (nudging area)
Fig. 4 (WOA09)
Fig. 3 (Nudging : EX4)
Fig. 2 (Nudging : EX3)
Fig. 1 (No nudging : EX1)

If EX number, I think EX3 and EX4 are so different. you don't agree this.
Horizontally averaged RMSE between EX1 and EX2 is 0.0254
However, Horizontally averaged RMSE between EX3 and EX3 is 0.083. In addition, current is changed too.

My problems are two.
Low salinity don't entered.
When use nudging, model which all the same is shown to differ result than don't used nudging.

Thank you for your interest.

[kate]

Sorry, I meant experiments 3 and 4. How did their setups differ?

So, we can't answer all your questions. You're the one who has to dig in and find out what's going on with your fresh water. Does your supercomputer center support an interactive debugger? Maybe it's time to learn how to use it. Or learn to use print statements. You are comfortable with the plotting at least. ROMS has the DIAGNOSTICS options - maybe give that a whirl to track salt changes and where they are coming from.

[jschoi]

Sorry, I meant experiments 3 and 4. How did their setups differ?

So, we can't answer all your questions. You're the one who has to dig in and find out what's going on with your fresh water. Does your supercomputer center support an interactive debugger? Maybe it's time to learn how to use it. Or learn to use print statements. You are comfortable with the plotting at least. ROMS has the DIAGNOSTICS options - maybe give that a whirl to track salt changes and where they are coming from.

EX3 and EX4 is all the same. only differ output path.

It seems that I have to study about source code with DIAGNOSTIC or supercomputer.
One more time, thank you for your interest.