I would like to ask experts, where is the calculation formula of vegetation stomatal resistance (rs) used to calculate the surface latent heat flux?

[zqzq]

Dear all，
I tried to reduce the value of vegetation stomatal resistance to determine the sensitivity of the near-surface latent heat flux to it，But I found rssun and rsshade in the folder (CanopyFluxesMod.F90), but I did not find their calculation formulas, so I could not enlarge or reduce their values to realize the sensitivity of the near-surface latent heat flux to them. test.I implore the help of experts.

 

[oleson]

My advice would be to read Chapter 2.9 of the technical note on stomatal resistance and photosynthesis. Stomatal conductance in CLM5 is based on the Medlyn model (Equation 2.9.1). There are a number of free/tunable parameters that are used in the stomatal conductance calculation, for example, g1, which is a plant functional type dependent parameter (Table 2.9.1) and can be found on the parameter file (medlyn slope).

 

[zqzq]

My advice would be to read Chapter 2.9 of the technical note on stomatal resistance and photosynthesis. Stomatal conductance in CLM5 is based on the Medlyn model (Equation 2.9.1). There are a number of free/tunable parameters that are used in the stomatal conductance calculation, for example, g1, which is a plant functional type dependent parameter (Table 2.9.1) and can be found on the parameter file (medlyn slope).

Thank you for your reply. I read the code of the program. Why are there two stomatal impedances? (Rs_sun and re_z_sun)

 

[oleson]

I don't see re_z_sun, but perhaps you mean rs_z_sun. The rs_z_sun refers to sunlit stomatal resistance for a specific layer in the vegetated canopy. There was some infrastructure put in to support a multi-layer canopy at some point but it is no longer functional or supported. So the extra dimension in that variable is always equal to 1.