Regridding and using WRF outputs as forcing data

[Mirce]

Hello all,

I am planning to use WRF outputs as forcings for WRF-Hydro, however, I will need to regrid them to get a higher resolution and make them match with my domain.

To do this regridding, I am planning to regrid only the variables that WRF-Hydro requires but I am still doubting about the following:

1) Is it ok to only regrid the required variables?

2) Can I use the same weight file to regrid them all?

3) What variables does WRF-Hydro read from the WRF files?. For this question, I attach to this message a table with the ones I think WRF-Hydro is using.

I will appreciate any help about this!.

Thanks!

Mirce.

[Dani]

Hi Mirce,

From what I understood in using the WRF, the first step would be generating your domain, your GEOGRID file. You could nest the domain for a finer-resolution model run. Assuming you've used the used the finer-resolution domain for your model runs, then it should have produced wrfout at the same resolution. So if you've used the finer-resolution domain (GEOGRDI File) and the resulting WRF output, you should be able to use them directly as inputs for the WRF-Hydro. Just change the FORC_TYP according to your forcings. Also, there should be a grid indicator with your WRF output files (ei.wrfout_d0x_2015_) as well as your GEOGRID file (ei. geo_em_d0x.nc). This should at least let you check if you've used matching resolution. 

For the meteorological forcing data required for the WRF-Hydro model, there should be a detailed description of it in the WRF-Hydro Technical Description found in the website.

Please do correct me if I'm wrong everyone.

Cheers,
Dani

[Mirce]

Hi Dani,

Thank you very much for the answer and advice about this!. I am planning to use some WRF outputs that I already got from a run I made before, so the domains don't match perfectly.

Thanks also for your advice about how to run with WRF forcings, I will follow it and I will check again the online technical description and user guides as you suggested me.

Cheers!,

Mirce.

[Katelyn FitzGerald]

Hi Mirce,

Answers below:

1) Is it ok to only regrid the required variables?

Yes, with a bit of a caveat (see answer to #3).

2) Can I use the same weight file to regrid them all?

Yes, as long as you are using the same regridding method for all variables (e.g. bilinear).  Otherwise, you will need one weight file for each method.

3) What variables does WRF-Hydro read from the WRF files?. For this question, I attach to this message a table with the ones I think WRF-Hydro is using.

This will depend upon what forcing option (for WRF-Hydro) you use.  If you're already planning on regridding the WRF output files, I would recommend writing them to the HRLDAS style forcing files.  If you choose to do this, the variable mapping in your attachment should work well.  You'll just want to make sure you double check the units, variable names, and format the filenames correctly.  If you're using the WRF output forcing option for WRF-Hydro, you may need to keep a few more variables related to vegetation that WRF-Hydro can optionally use.  You can find what variables are read in here: https://github.com/NCAR/wrf_hydro_nwm_public/blob/master/trunk/NDHMS/Routing/module_lsm_forcing.F

Hope this helps! 

Best,

Katelyn

[Mirce]

Hi Katelyn!,

Thank you very much for the response and guide about this, it helps me a lot!. 

I will think carefully about what forcing option I want to use for the test, in any case, I will try to adapt one of the regridding scripts you give us as examples in the web page.

Thanks a lot again!.

Cheers,

Mirce.

[Somaye Imani]

Hi Mirce,

I am planning to regridding the output of WRF for a small domain of WRF-Hydro. 

I wonder whether you could select the best regridding script?  would you mind sharing your experience with me in this subject?

Thanks,

Somaye

[Molly McAllister]

Hi Somaye, 

We have just published WRF output regridding scripts. You can find them here https://ral.ucar.edu/projects/wrf_hydro/regridding-scripts. 
Note: Do not download them on a Windows machine as they will not work. 
Best regards,

Molly

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[Mirce]

Hi Somaye, 

I think there is nothing extra I could contribute to this.
I am glad there are scripts available on the page!

Thanks,

Mirce

[Somaye Imani]

Hi  Molly  and  Mirce ,   

I appreciate your help so much.

Thanks,

Somaye