Questions about irr_ph of irrigation module in WRF-Noah

[Han Lubin]

Hello everyone,

I am new to the WRF irrigation module, and I have some confusion about the irrigation settings in the Noah LSM. In the WRF user guide's section on Surface Irrigation Parameterization, it is mentioned that "irr_ph" regulates the spatial activation of irrigation (with irr_freq >1), particularly determining whether it is activated for all domains on the same day (irr_ph = 0). My understanding is that irr_ph=0 means that irrigation will be applied as long as there is a non-zero value for the irrigation area fraction.

So, I have the following questions:
1. irr_ph=1: The activation field is defined as a function of (i, j, IRRIGATION). Does this mean that I can specify which grid within the domain will be irrigated, rather than all irrigated grids? If so, how can I specify this?
2. irr_ph=2: The activation field is created using the Fortran RANDOM function. Does this mean that the grids where irrigation occurs are selected randomly?
3. Both the WRF user guide's Surface Irrigation Parameterization section and the WRF's README.namelist mention irr_ph=0, 1, and 2, but in the WRF user guide's namelist variable section, only irr_ph=0 and 1 are described. Can irr_ph=2 be also used?
4. If I want to specify when and how much water is applied to any irrigated grid within the domain, is it correct to assume that the current version of WRF does not fully support my needs? Would I need to modify the code myself to achieve my research objectives?

Thank you for your reply!

 

[Ming Chen]

Hello everyone,

I am new to the WRF irrigation module, and I have some confusion about the irrigation settings in the Noah LSM. In the WRF user guide's section on Surface Irrigation Parameterization, it is mentioned that "irr_ph" regulates the spatial activation of irrigation (with irr_freq >1), particularly determining whether it is activated for all domains on the same day (irr_ph = 0). My understanding is that irr_ph=0 means that irrigation will be applied as long as there is a non-zero value for the irrigation area fraction.

So, I have the following questions:
1. irr_ph=1: The activation field is defined as a function of (i, j, IRRIGATION). Does this mean that I can specify which grid within the domain will be irrigated, rather than all irrigated grids? If so, how can I specify this?

I am not sure ...

2. irr_ph=2: The activation field is created using the Fortran RANDOM function. Does this mean that the grids where irrigation occurs are selected randomly?

yes you are correct

3. Both the WRF user guide's Surface Irrigation Parameterization section and the WRF's README.namelist mention irr_ph=0, 1, and 2, but in the WRF user guide's namelist variable section, only irr_ph=0 and 1 are described. Can irr_ph=2 be also used?

irr_ph=2 can be used.

4. If I want to specify when and how much water is applied to any irrigated grid within the domain, is it correct to assume that the current version of WRF does not fully support my needs? Would I need to modify the code myself to achieve my research objectives?

I believe WRF doesn't have such capabilities, Yes you need to modify the codes.

Please see Three new surface irrigation parameterizations by arjanna · Pull Request #980 · wrf-model/WRF and hope you can find some helpful information there.

Thank you for your reply!

 

[Han Lubin]

Hi, Ming

Thank you very much for your response! I have a few more questions that I would like to ask:

1. If I modify the WRF code, even if it's just adjusting one parameter, do I need to recompile both WRF and WPS?
2. To familiarize myself more quickly with the code and start making modifications, do you have any experiences or resources that you could recommend?

Thank you in advance, and I look forward to your reply!

 

[Ming Chen]

Hi, Ming

Thank you very much for your response! I have a few more questions that I would like to ask:

1. If I modify the WRF code, even if it's just adjusting one parameter, do I need to recompile both WRF and WPS?

If you change anything in Registry, you will need to do ./clean -a and recompile all the codes.
If you only change Fortran codes, you only need to type ./compile em_real under top WRF directory. In this case only the changed code will be recompiled.

2. To familiarize myself more quickly with the code and start making modifications, do you have any experiences or resources that you could recommend?

I guess you can contact the developer for help. Cenlin (cenlinhe@ucar.edu) is our expert on land model.

Thank you in advance, and I look forward to your reply!

 

[Han Lubin]

Thank you so much for your suggestions! Have a good day!