WRF and ROMS

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jivica
Posts: 130
Joined: Mon May 05, 2003 2:41 pm
Location: The University of Western Australia, Perth, Australia

WRF and ROMS

#1 Post by jivica » Mon Oct 15, 2007 6:46 am

Dear community,
I am running WRF as forcing counterpart for ROMS and I am wondering what are impressions of any of you in the same business...
I have question about forcing variables for ROMS, what do you use (some .m scripts?) for computing (or better saying preparing) forcing fields like relative humidity, rainfall rate, cloud fraction ...
do you trim WRF output file that can be quite large... to save only important variables for forcing ROMS?...
Thanks in advance
Ivica

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kate
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Location: IMS/UAF, USA

#2 Post by kate » Mon Oct 15, 2007 5:04 pm

The WRF output is likely 3-D and you would only need surface fields for ROMS. Do you have the WRF grid as exactly the same as the ROMS grid? WRF wants its grids to be rectangular on a conformal projection and ROMS can use the same grids. It would save you a nasty interpolation step.

The atmospheric fields I'm using are global, on a uniform lat,lon grid. ROMS can do the interpolation internally for such a case, but not for the WRF grid case.

If you have the same grid, you also have the option of running them as a coupled system. Ask John Warner about that one.

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jivica
Posts: 130
Joined: Mon May 05, 2003 2:41 pm
Location: The University of Western Australia, Perth, Australia

Well...

#3 Post by jivica » Tue Oct 16, 2007 7:00 am

Hej Kate (If you do not recall I'm the one with funny shirt at Gordon RC :D ),
I am not able to run the same grids for WRF and ROMS, I use NCEP GFS 0.5deg for init of WRF at 20km and than I use nest to my domain at 5km and this is CPU disaster (on my hand made cluster) ... I can not afford it to run the WRF at 2km as I do run ROMS :cry: ... I am asking if you have some scripts (perl, .m?) that can use WRF 3D output to get 2D ROMS frc variables like RH, CF, Rain that I do not have to write and save me some time..
I'll do interpolation once and think it is not so bad/hard, I do not run model in real time /forecast...

Thanks
IVica

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kate
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Location: IMS/UAF, USA

#4 Post by kate » Tue Oct 16, 2007 6:21 pm

Sure, I remember you and the T-shirts, Ivica. :)

I have some .m files, but I didn't write them and I haven't used them recently. It's so old it uses the mexcdf interface.

Consider these two cases:
Image
In the top one, the black (WRF) grid is aligned with some x,y coordinate system. If you know the red (ROMS) grid in the same coordinate system, you can do a bilinear interpolation quite easily. In the bottom one, it's a lot less simple to do a bilinear interpolation so we usually end up doing something much more computationally challenging, perhaps treating the black grid as randomly spaced points.

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