MPAS tutorial questions about ungrid and SST data

[ajrosales]

Hello everyone,

I would like to ask you some questions about the MPAS tutorial.

1. In the installation of the MPAS model, is it possible to find the ungrib program or is it necessary to install the WRF model previously to get the ungrib program?

2. Where is the resource of the SST data input? Should I use ungrib with the SST datasets or not?

Thanks for your time,

Alan

 

[Ming Chen]

Alan,

Please see my answers below to you questions:

(1) Starting from WPSV4.3, a configure option, --nowrf, has been added to allow for configuration of the WPS without reference to a compiled WRF model. if you only need the ungrib component of the WPS, you can compile WPS with this option.

(2) Most of the reanalysis products like GFS, ERA5 etc include SST. When you run ungrib to extract variables from the reanalysis data, SST will be included in the intermediate file.

Hope this is helpful for you.

 

[zhangwei20d]

Alan,

Please see my answers below to you questions:

(1) Starting from WPSV4.3, a configure option, --nowrf, has been added to allow for configuration of the WPS without reference to a compiled WRF model. if you only need the ungrib component of the WPS, you can compile WPS with this option.

(2) Most of the reanalysis products like GFS, ERA5 etc include SST. When you run ungrib to extract variables from the reanalysis data, SST will be included in the intermediate file.

Hope this is helpful for you.

Dear Chen,

I have a question regarding the MPAS tutorial (MPAS Tutorial — Practice Session Guide) related to the generation of the sfc_update.nc file. Are the SST* files used for this purpose sourced from ERA5 data?

Additionally, could you please provide guidance on how to generate similar SST* files?

Thank you for your time and assistance.

Wei

 

[Ming Chen]

Hi, Wei,

The website you posted is pretty old. Please see the latest website for MPAS practice:

MPAS Tutorial — Practice Session Guide

The SST files we use for tutorial is from a different SST products (possibly from NOAA OI SST datasets).

To produce SST files for MPAS surface update, you only need to run ungrib.exe to process your global SST data. The method is same as that for producing intermediate file.

 

[ajrosales]

Dear Ming Chen,

Thank you for your reply.

I have another question. As you mentioned, most reanalysis products, such as GFS and ERA5, include SST. So, when this happens, how can we generate the file "x1.10242.sfc_update.nc" if the variable SST is included in the file "x1.10242.init.nc", which is generated one step before "x1.10242.init.nc" according to the MPAS tutorial?

Best,

Alan

 

[Ming Chen]

Alan,

To produce "x1.10242.sfc_update.nc", you need to extract SST from intermediate files and NOT from "x1.10242.init.nc".

Note that "x1.10242.init.nc" only contains data at the initial time ( a single time) of model integration. "x1.10242.sfc_update.nc" contains multiple times of SST etc.

Hope I answer your question. Please let me know if you have more questions.

 

[ajrosales]

Dear Ming Chen,

Thank you for your reply.

I am changing some parameters in the namelist.atmosphere following the MPAS tutorial, but I notice that there is no parameter called "config_len_disp =", and I am using MPAS version 8.2.2. Is it normal? Because when I compiled the MPAS model, I didn't have any error messages.

And my other question is how to determine the values of the parameters config_dt and config_len_disp if my experimental simulation is set up for a 480-km mesh.

Best,

Alan

 

[Ming Chen]

Alan,

config_len_disp is an important option that must be set. It should be the minimum mesh size in unit of meter.

For 480km mesh, config_len_disp = 480000, and the maximum config_dt = 2880 (i.e., 480 x 6). It can be smaller than 2880 but should not be larger than 2880.

Ming