How to set up WRF water vapor sensitivity test

[WENSHUO HUANG]

Dear WRF&MPAS experts,
I would like to use WRF to do several sensitivity tests on water vapor, such as modifying the water vapor content of a certain area, and now I have two questions:
1. What files and variables should be modified for the water vapor test? The RH in met_em* files or the QVAPOR in wrfbyd and wrfinput? or both is ok? (As met_em files would be used to regenerate the initial boundary field)
2. Is it appropriate to modify the water vapor variables in this way. For soil moisture and SST, which are assumed to be independent external forcing for atmosphere. I think it is fine to modify a single variable, but for non-independent processes inside the atmosphere, is it necessary to modify variables such as temperature and pressure to match the change in water vapor. Or is it okay to modify only the water vapor, as long as the spin-up time is long enough to make the system adaptively stable?
Thanks for you help!

 

[Ming Chen]

Please see my answers below:

1. What files and variables should be modified for the water vapor test? The RH in met_em* files or the QVAPOR in wrfbyd and wrfinput? or both is ok? (As met_em files would be used to regenerate the initial boundary field)

I would suggest to modify RH in met_em files. This will give you consistent changes in wrfint and wrfbdy files after you run REAL program.

2. Is it appropriate to modify the water vapor variables in this way. For soil moisture and SST, which are assumed to be independent external forcing for atmosphere. I think it is fine to modify a single variable, but for non-independent processes inside the atmosphere, is it necessary to modify variables such as temperature and pressure to match the change in water vapor. Or is it okay to modify only the water vapor, as long as the spin-up time is long enough to make the system adaptively stable?

I don't think you need to modify T and P. Once the model starts, it will quickly adjust in response to changes in QVAPOR. I suppose this is what you expect from the 'sensitivity experiment' .

 

[WENSHUO HUANG]

Please see my answers below:

1. What files and variables should be modified for the water vapor test? The RH in met_em* files or the QVAPOR in wrfbyd and wrfinput? or both is ok? (As met_em files would be used to regenerate the initial boundary field)

I would suggest to modify RH in met_em files. This will give you consistent changes in wrfint and wrfbdy files after you run REAL program.

2. Is it appropriate to modify the water vapor variables in this way. For soil moisture and SST, which are assumed to be independent external forcing for atmosphere. I think it is fine to modify a single variable, but for non-independent processes inside the atmosphere, is it necessary to modify variables such as temperature and pressure to match the change in water vapor. Or is it okay to modify only the water vapor, as long as the spin-up time is long enough to make the system adaptively stable?

I don't think you need to modify T and P. Once the model starts, it will quickly adjust in response to changes in QVAPOR. I suppose this is what you expect from the 'sensitivity experiment' .

Thank you for your help! I will try it!