Injecting moisture at a specific grid point throughout a WRF run

[vaakos]

Hello,

I would like to investigate the effects of continuously injecting moisture into the atmosphere at the surface at a specific grid point during a multi-day mesoscale WRF simulation. The moisture should be added throughout the entire run (e.g., at every time step or hourly), not just at initialization. It is also important that the added moisture is fully incorporated into the model's dynamics and physics.

Initially, I considered simply increasing the latent heat flux (LH), but I’m not sure if that would achieve the desired effect.

Are there any guidelines or recommended methods for implementing this? Any advice or experience with similar modifications would be greatly appreciated.

Many thanks in advance,
Akos

 

[vaakos]

As an update: I might have found a way to do this. I believe I should include the moisture source in the specific grid cell by adding it to QFX (the upward moisture flux at the surface, in kg/m^2/s).

Since I'm using the Unified Noah LSM (WRF v4.7.0), I need to modify the module_sf_noahdrv.F file.

Specifically, after line 1259:

QFX(I,J) = ETA_KINEMATIC

I would add something like:

IF (I == isource .AND. J == jsource) THEN
QFX(I,J) = QFX(I,J) + qfx_add
END IF

However, it's unclear whether I need to insert this modification after every occurrence of the line QFX(I,J) = ETA_KINEMATIC, or if it's sufficient to do so only after the first (since this line appears multiple times in the code).

Any expert insights or confirmation would be greatly appreciated.

Akos