GREENFRAC

[ghuan]

I want to examine the impact of changes in vegetation cover on the study area, so I replaced the GREENFRAC parameter in geo_em_d03. I have confirmed that the replacement was successful and that there is a significant difference compared to the default values, as shown in the figure below.


After replacing the parameter, I re-ran metgrid, real, and wrf. However, the results from the two simulations are exactly the same (using T2 as an example). I would like to know how to ensure that the modified GREENFRAC actually takes effect. My namelist file is as follows.

 

[haiqingsong]

I want to examine the impact of changes in vegetation cover on the study area, so I replaced the GREENFRAC parameter in geo_em_d03. I have confirmed that the replacement was successful and that there is a significant difference compared to the default values, as shown in the figure below.
View attachment 17998
View attachment 17999
After replacing the parameter, I re-ran metgrid, real, and wrf. However, the results from the two simulations are exactly the same (using T2 as an example). I would like to know how to ensure that the modified GREENFRAC actually takes effect. My namelist file is as follows.

what is your dynamic vegetation option？

 

[ghuan]

what is your dynamic vegetation option？

I don't quite understand what you mean by dynamic vegetation option. Can you be more specific? For example, in which file is the parameter you mentioned related to?

 

[kwerner]

The dynamic vegetation option (dveg) is specific to the NoahMP LSM, but @ghuan is using the Noah option.

I believe the issue is related to the fact that different physics options use specific lookup tables to get certain values. For e.g., the Noah LSM uses the VEGPARM.TBL (from run/ or test/em_real/) to calculate VEGFRA values (and VEGFRA in WRF corresponds to GREENFRAC in WPS).