In the
EXTPAR
v4.0 documentation on page 19 it reads:
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 would mean that
FOR
_D and
FOR
_E are relative to plant cover fraction. In that case the vegetation part of the cell is
veg_part = for_e+for_d+veg_low
where veg_low stands for low vegetation which has a snow free albedo of 0.20 in your first equation
For the snow albedo the equation would be then
zsnow_alb = zsalb_snow*(1._ireals-for_e(i,j)-for_d(i,j)-veg_low(i,j)) &
+ csalb_snow_fe * for_e(i,j) &
+ csalb_snow_fd * for_d(i,j)
+ csalb_snow_veg_low * veg_low(i,j)
In CCLM it is assumed that low vegetation has the same snow albedo as bare soil. Therefore zsalb_snow=csalb_snow_veg_low. With this assumption you get
zsnow_alb = zsalb_snow*(1._ireals-for_e(i,j)-for_d(i,j)) &
+ csalb_snow_fe * for_e(i,j) &
+ csalb_snow_fd * for_d(i,j)
which is your second equation.
Maybe one should define the long names in the output files more precisely:
In the
EXTPAR
output files
long_name = “Fraction of deciduous forest”
should be better defined as e.g.
long_name = “Fraction of deciduous forest of maximum plant cover”
and in the
CCLM
output files
long_name = “ground fraction covered by deciduous forest”
should be better defined as e.g.
long_name = “ground fraction covered by deciduous forest weighted by maximum plant cover”
In the EXTPAR v4.0 documentation on page 19 it reads:
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 would mean that FOR _D and FOR _E are relative to plant cover fraction. In that case the vegetation part of the cell is veg_part = for_e+for_d+veg_low
where veg_low stands for low vegetation which has a snow free albedo of 0.20 in your first equation
For the snow albedo the equation would be then
zsnow_alb = zsalb_snow*(1._ireals-for_e(i,j)-for_d(i,j)-veg_low(i,j)) & + csalb_snow_fe * for_e(i,j) & + csalb_snow_fd * for_d(i,j) + csalb_snow_veg_low * veg_low(i,j)In CCLM it is assumed that low vegetation has the same snow albedo as bare soil. Therefore zsalb_snow=csalb_snow_veg_low. With this assumption you get
zsnow_alb = zsalb_snow*(1._ireals-for_e(i,j)-for_d(i,j)) & + csalb_snow_fe * for_e(i,j) & + csalb_snow_fd * for_d(i,j)which is your second equation.
Maybe one should define the long names in the output files more precisely:
In the EXTPAR output files
long_name = “Fraction of deciduous forest”
should be better defined as e.g.
long_name = “Fraction of deciduous forest of maximum plant cover”
and in the CCLM output files
long_name = “ground fraction covered by deciduous forest”
should be better defined as e.g.
long_name = “ground fraction covered by deciduous forest weighted by maximum plant cover”