The sunlit and shaded component in CTSM

[Wenge99]

I have a specific question about Eqn 2.3.21 - radiation absorption by vegetation. Is the solution for the whole canopy layer or is it for each layer within a whole canopy?
Here is the link: 2.3. Surface Albedos — ctsm release-clm5.0 documentation
Anyone has the reference of the two stream solution of canopy radiative transfer theory for a finite canopy layer?

If Eqn 2.3.21 is for the whole canopy, then the light absorption by the sunlit and shaded vegetation is for the whole canopy only (Eqns 2.3.23-24).
I am interested in light absorption by the sunlit and shaded vegetation for each layer within a whole canopy. For a multilayer canopy, I see that the code has the derivatives of fabs: d_fabd, d_fabd_sun and d_fabd_sha. But if fabs is the whole canopy, can you still take the derivative of fabd (light absorption by the whole canopy)?

 

[oleson]

Eqn 2.3.21 describes radiation absorbed by vegetation for the whole canopy.
For a multi-layer canopy these references might be useful:

Bonan G.B., M. Williams, R.A. Fisher, and K.W. Oleson, 2014: Modeling stomatal conductance in the earth system: linking leaf water-use efficiency and water transport along the soil-plant-atmosphere continuum, Geosci. Model Dev., 7, 2193-2222, DOI:10.5194/gmd-7-2193-2014.

Bonan, G.B., E.G. Patton, I.N. Harman, K.W. Oleson, J.J. Finnigan, Y. Lu, and E.A. Burakowski, 2018: Modeling canopy-induced turbulence in the Earth system: a unified parameterization of turbulent exchange within plant canopies and the roughness sublayer (CLM-ml v0), Geosci. Model Dev., 11, 1467-1496, doi:10.5194/gmd-11-1467-2018.

 

[Wenge99]

Thanks, Keith. Bonan et al. 2018 paper states that "radiative transfer in the visible and near-infrared wavebands is calculated from the two-stream approximation with the absorbed solar radiation partitioned into direct beam, scattered direct beam, and diffuse radiation for sunlit and shaded leaves in relation to cumulative plant area index as in Dai et al. (2004)." Where can I find the code used in the paper?

 

[oleson]

I believe you can find it here:

GitHub - gbonan/CLM-ml_v0: CLM-ml_v0 canopy flux code

CLM-ml_v0 canopy flux code. Contribute to gbonan/CLM-ml_v0 development by creating an account on GitHub.

github.com

There also seems to be a "v1" here:

GitHub - gbonan/CLM-ml_v1: CLM-ml_v1 source code

CLM-ml_v1 source code. Contribute to gbonan/CLM-ml_v1 development by creating an account on GitHub.

github.com

 

[Wenge99]

Keith, thank you for the information. I was able to solve my problem with your help.