Ocean Modeling Discussion

ROMS/TOMS

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PostPosted: Wed Feb 18, 2015 5:30 pm 
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Location: North Carolina State University
Hi,

I was running LTRANS and came across the problem of "jumped over a u element" or "jumped over a v element" problem (error info listed below)

" Previous Location:
x: -7221945.47253313 y: 2073598.67415 247
lon: -64.8772335292822 lat: 18.3081033479963

Current Location:
x: -7221948.21037701 y: 2073618.07464950
lon: -64.8772581242805 lat: 18.3082688073524

The Program Cannot Continue and Will Terminate

Any suggestions how to overcome this problem?
Thanks.


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PostPosted: Wed Feb 18, 2015 5:44 pm 
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Location: IMS/UAF, USA
I haven't run LTRANS, but perhaps it's complaining that the time-step is too long? It probably has the same sort of CFL condition as the ROMS model.


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PostPosted: Thu Feb 19, 2015 5:37 am 
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Joined: Mon Apr 15, 2013 7:05 pm
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Location: umces
fanqing wrote:
Hi,

I was running LTRANS and came across the problem of "jumped over a u element" or "jumped over a v element" problem (error info listed below)

" Previous Location:
x: -7221945.47253313 y: 2073598.67415 247
lon: -64.8772335292822 lat: 18.3081033479963

Current Location:
x: -7221948.21037701 y: 2073618.07464950
lon: -64.8772581242805 lat: 18.3082688073524

The Program Cannot Continue and Will Terminate

Any suggestions how to overcome this problem?
Thanks.


Decrease the internal timestep in LTRANS.data. The variable name is idt.


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PostPosted: Thu Feb 19, 2015 6:33 pm 
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Location: North Carolina State University
Yes, changing the time step seems to have solved the problem. Thanks!


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PostPosted: Thu Feb 19, 2015 6:34 pm 
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Location: North Carolina State University
Is there a recommended idt value, maybe depending on the spatial resolution?


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PostPosted: Fri Feb 20, 2015 5:39 am 
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fanqing wrote:
Is there a recommended idt value, maybe depending on the spatial resolution?


Yes, the value is highly dependent on the spatial resolution and the particle velocities.

The model will not allow a particle to move through a gridcell without being effected by its properties, so smaller gridcells and larger velocities require smaller idt values.


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PostPosted: Thu Mar 05, 2015 5:12 pm 
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Location: North Carolina State University
Can LTRANS be used to simulate oil spill trajectory and fate?

Thanks,
Fanqi


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PostPosted: Thu Mar 05, 2015 6:28 pm 
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LTRANS was designed for tracking biological critters within the ocean. You could probably use it to track surface objects, but I doubt it has the oil weathering processes or the effect of winds on oil.

One could of course add them since the source is out there.


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PostPosted: Thu Mar 05, 2015 6:46 pm 
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I just found it was used for this purpose:
http://omgrhe.meas.ncsu.edu/RHE/Northet ... npress.pdf


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PostPosted: Fri Mar 06, 2015 6:35 am 
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fanqing wrote:
Can LTRANS be used to simulate oil spill trajectory and fate?

Thanks,
Fanqi


Yes, actually it can!

We have not released this code to the public yet, but I believe some others have independently done so. Keep on the look out for LTRANS 3.0!


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