Relationship of 2-meter variables to model layer variables

[clayblankenship]

I just sent this to wrfhelp, but maybe someone here can point me in the right direction.

I am running WRF ARW 2.2 coupled with LIS (the Land Information System) as well as uncoupled (Noah land surface scheme) and I am trying to figure out what is going wrong with my coupled runs. The 2m humidity jumps dramatically to 100% after 5 minutes in the coupled run, but this does not show up in the model level (3d) humidity fields. I would like to know how the 2m fields (T and q) are related to the model-level fields.

1) Do the surface/2m fields affect the model-level fields?
2) Is WRF just passing along surface values from the land surface model to the output without using them in any other way?
3) Are the surface fields that WRF passes back to the land surface model derived from the level fields?

Thanks for any information you can provide, or any resources you can point me to that explain the flow of data in WRF. I understand what happens on the LIS side, but not on the WRF side.

Clay Blankenship (clay.b.blankenship@nasa.gov)
USRA
NASA-MSFC National Space Science and Technology Center
Huntsville, AL

[jimmyc]

The 2 meter variables are derived I believe. You will have to check out the code (module_sf_sfcdiags.F) that does the diagnostics for the surface layer. As far as I know the fluxes are used along with the lowest model level and surface data to get at these quantities.

I suppose it is possible that your input data is not matching well with the land surface information. There could any number of things at play here. How you specify TSK, CQS2, or CHS2 should matter given those IF statements.

[clayblankenship]

OK, I'm trying to follow all the variables. One more question: do the 4 layers of soil moisture and temperature (smois and tslb) get used outside the LSM (other than for output)? In other words, does it matter what units these are in if I am exporting them from LIS?

Clay

[clayblankenship]

To answer my own question, I got this from wrfhelp:

The 4 layer soil moisture and temp data are not used anywhere else in
the model. They are computed in LSM and output.
wrfhelp