I just looked at the
EXTPAR
source code. As far as I understand now I have misinterpreted the sentence
Values that depend on the plant cover, such as
PLCOV
MX,
PLCOV
MN,
LAI
MN,
LAI
MX, RS
MIN
,
FOR
E,
FOR
D,
ROOTDP
and z0, are weighted with the plant cover maximum in addition to the pixel area.
This seems to hold only for
GLOBECOVER
and there is a general maximum plant cover in a grid cell defined for this. I mixed it up with the actual plant cover which is a different thing. Therefore I think you are right and for_e and for_d are fractions of the total grid cell and thus the long_names are OK.
From this the equation for zsnow_alb is clear now and it fits to your example for vegetation fraction of 0.8, for_e = 0.4, for_d = 0.3 and veg_low = 0.1.
What the equation for also concerns I can only suspect that the programmer assumed that the fractions for for_e and for_d hold also for the vegetation part not just for the whole grid cell.
Would the following be more appropriate?
zalso(i,j)= zsnow*zsnow_alb + &
(1._ireals-zsnow)* &
(for_e(i,j)*0.10_ireals + &
for_d(i,j)*0.15_ireals + &
(zvege-for_e(i,j)-for_d(i,j))*0.20_ireals+ &
(1._ireals-zvege)*zalso(i,j))
What do you think?
Anyway, at the end the meaning can only be revealed by the programmer (whom I do not know).
I just looked at the EXTPAR source code. As far as I understand now I have misinterpreted the sentence
Values that depend on the plant cover, such as PLCOV MX, PLCOV MN, LAI MN, LAI MX, RS MIN , FOR E, FOR D, ROOTDP and z0, are weighted with the plant cover maximum in addition to the pixel area.
This seems to hold only for GLOBECOVER and there is a general maximum plant cover in a grid cell defined for this. I mixed it up with the actual plant cover which is a different thing. Therefore I think you are right and for_e and for_d are fractions of the total grid cell and thus the long_names are OK.
From this the equation for zsnow_alb is clear now and it fits to your example for vegetation fraction of 0.8, for_e = 0.4, for_d = 0.3 and veg_low = 0.1.
What the equation for also concerns I can only suspect that the programmer assumed that the fractions for for_e and for_d hold also for the vegetation part not just for the whole grid cell.
Would the following be more appropriate?
zalso(i,j)= zsnow*zsnow_alb + & (1._ireals-zsnow)* & (for_e(i,j)*0.10_ireals + & for_d(i,j)*0.15_ireals + & (zvege-for_e(i,j)-for_d(i,j))*0.20_ireals+ & (1._ireals-zvege)*zalso(i,j))What do you think?
Anyway, at the end the meaning can only be revealed by the programmer (whom I do not know).