How to fix the short wave radiation in the simulation process

[chenwenjiang]

Hi all,

I am a new user of WRF and I am trying to run Version 3.7 for 720 hours (30 days). The horizontal domain used for the simulations is composed of 2 nested domains. The control experiment has been simulated successfully.

I want to know how to modify the source code so that the short wave radiation in the simulation process can be fixed, so as to eliminate the monthly variation (each grid point is a different value, but does not change with time). That is, the short wave radiation read at each integration time is the same. It seems to have something to do with local time.

Any ideas or tips on how to resolve this would be great.

Thank you in advance.
wenjiang

 

[Ming Chen]

Weijiang,
If I understand correctly, you want to specify fixed values of shortwave radiation to exclude diurnal and daily variation. If this correct?
If so, you may simply specify the values you want to those variables calculated in radiation scheme. Let's take RRTMG as an example.
SUBROUTINE RRTMG_SWRAD (phys/module_ra_rrtmg_sw.F) is the scheme for RRTMG shortwave radiation. You may simply set all those variables calculated in this scheme to the values you want at the end of the code (approximately after " call rrtmg_sw".) You can actually skip the calculation and let the code go directly to where you specify the values.
However, please be cautious that this procedure may lead to model failure due to the unreasonable physics.

 

[chenwenjiang]

Weijiang,
If I understand correctly, you want to specify fixed values of shortwave radiation to exclude diurnal and daily variation. Is this correct?
If so, you may simply specify the values you want to those variables calculated in radiation scheme. Let's take RRTMG as an example.
SUBROUTINE RRTMG_SWRAD (phys/module_ra_rrtmg_sw.F) is the scheme for RRTMG shortwave radiation. You may simply set all those variables calculated in this scheme to the values you want at the end of the code (approximately after " call rrtmg_sw".) You can actually skip the calculation and let the code go directly to where you specify the values.
However, please be cautious that this procedure may lead to model failure due to the unreasonable physics.

Thank you very much for your answer! It's very helpful to me. According to your suggestion, my question has changed. I hope the short wave radiation has daily variation but no monthly variation, that is, the simulated 30 days, and the short wave radiation of each day is the same as that of the first day. This may not cause the simulation process to fail. In this case, how to set it?

 

[Ming Chen]

Hi,
In phys/module_radiation_driver.F, you can find the SUBROUTINE "pre_radiation_driver", which specifies parameters related to radiation including shortwave radiation. The two important parameters related to your case are "julian" and "time". You may set these two variables to values corresponding to that in your first day of simulation, then you will have shortwave radiation that has diurnal cycle but not includes daily variation within the month.

 

[chenwenjiang]

Hi,
In phys/module_radiation_driver.F, you can find the SUBROUTINE "pre_radiation_driver", which specifies parameters related to radiation including shortwave radiation. The two important parameters related to your case are "julian" and "time". You may set these two variables to values corresponding to that in your first day of simulation, then you will have shortwave radiation that has diurnal cycle but not includes daily variation within the month.

Thank you very much!!! I'll try.