Computing the effective LAI as seen by SW radiation (cbl_lai_eff.F90)

penguian commented 4 years ago

keyword_nogit owner:jxs599@nci.org.au resolution_fixed type_JAC readiness | by srb001@csiro.au

In JAC, the surface albedo is required before CABLE has more generally been initialized. HOWEVER, CABLE does not require initialization beyond a few veg and soil parameters - So long as we move to accessing whether a cell is sunlit or not given the zenith angle.

To calculate the surface albedo CABLE needds to compute the canopy reflectivity for which it needs to know the effective LAI, i.e. the LAI that may actually be seen by SW radiation, IF the canopy is covered in snow. This calculation has been extracted from the model so that it can be specifically called in isolation: cbl_lai_eff.F90

in contrast to the previous scenario where it was embedded in a subroutine which DOES require CABLE to be properly initialised - with forcing that does not even exist at the stage where surface albedo is required.

In order to calculate the effective LAI CABLE needs to know the height of the canopy above snow. This calculation has been extracted from the model so that it can be specifically called in isolation: cbl_hgtAbove_snow.F90

In order to calculate the effective LAI, clearly CABLE needs to know the height of the canopy and the LAI of the PFT at that cell. This calculation has been extracted from the model so that it can be specifically called in isolation: cbl_LAI_canopy_height.F90 In the JAC version of CABLE, we get the LAI and canopy height from UM I/O spatial maps. In the interface we limit these values.However it is not even clear any longer if this is actually needed.

Issue migrated from trac:263 at 2023-11-27 11:34:00 +1100

penguian commented 4 years ago

@jxs599@nci.org.au changed milestone from 2. Submission to 6. Report