3. Global Terrestrial Gross and Net Primary Productivity from the Earth Observing System
51
1. average 24-hour daily temperature eC),
2. daily 24-hour minimum temperature eC),
3. actual vapor pressure (derived from DAO specific humidity, in Pa units), and
4. incident shortwave solar radiation (MJ m -2 per
3-hr timestep).
These surface weather "observations" are then used
in the final computation of the NPP algorithm by
the EOS data system.
Final NPP Algorithm
Daily Estimation of GPP
The following steps are performed to calculate each
day's intermediate GPP, subtract maintenance respiration (GPP - Rm), and accumulate NPP variables (Fig. 3.3).
1. A PAR conversion efficiency (6) is first extracted from the global BPLUT in Table 3.1 for
the appropriate pixel. This retrieved 6max applied
to a maximum value established for each vegetation (biome) type is attenuated by two controls. These controls are
a. stomatal closure due to cold night temperature (TMIN) and
b. stomatal control due to daytime vapor pressure deficit (VPD).
2. The simple daily GPP for the model day is then
calculated as a function of net incident shortwave radiation, FPAR, and 6.
3. The daily maintenance respiration "costs" are
then estimated, using a QIO function from a 20
D
e
base temperature. Next we calculate a cumulative daily term for estimating annual NPP:
4. To incrementally build the annual NPP term, we
maintain a series of daily terms for each pixel,
calculating the annual growth (for live wood,
leaf, and roots), to appropriately take plant and
root respiration into account.
The two parameters for TMIN and the two parameters for VPD are used to calculate two scalars
that attenuate 6 max to produce the final 6 used to
-------------------------------------------------------------------------------I
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I
I
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I
I
I
I
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I
I
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I
I
Photosynthesis
GPP
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
~----------------------------------------------------------------------- -------,
MOD·17
Daily NPP*
*does not include growth respiration or
live wood maintenance resplrallon costs
Maintenance Respiration
MR
I
I
-------,
- - - - - - - - - - - - - I
r---~--~
I
MR
Daily:
mass
index
NPP*
I
I
I
I
I
I
Daily Outputs
I
~----------------------- ______ I
FIGURE 3.3. Logical and data flow diagram for the daily NPP algorithm.
51
1. average 24-hour daily temperature eC),
2. daily 24-hour minimum temperature eC),
3. actual vapor pressure (derived from DAO specific humidity, in Pa units), and
4. incident shortwave solar radiation (MJ m -2 per
3-hr timestep).
These surface weather "observations" are then used
in the final computation of the NPP algorithm by
the EOS data system.
Final NPP Algorithm
Daily Estimation of GPP
The following steps are performed to calculate each
day's intermediate GPP, subtract maintenance respiration (GPP - Rm), and accumulate NPP variables (Fig. 3.3).
1. A PAR conversion efficiency (6) is first extracted from the global BPLUT in Table 3.1 for
the appropriate pixel. This retrieved 6max applied
to a maximum value established for each vegetation (biome) type is attenuated by two controls. These controls are
a. stomatal closure due to cold night temperature (TMIN) and
b. stomatal control due to daytime vapor pressure deficit (VPD).
2. The simple daily GPP for the model day is then
calculated as a function of net incident shortwave radiation, FPAR, and 6.
3. The daily maintenance respiration "costs" are
then estimated, using a QIO function from a 20
D
e
base temperature. Next we calculate a cumulative daily term for estimating annual NPP:
4. To incrementally build the annual NPP term, we
maintain a series of daily terms for each pixel,
calculating the annual growth (for live wood,
leaf, and roots), to appropriately take plant and
root respiration into account.
The two parameters for TMIN and the two parameters for VPD are used to calculate two scalars
that attenuate 6 max to produce the final 6 used to
-------------------------------------------------------------------------------I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Photosynthesis
GPP
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
~----------------------------------------------------------------------- -------,
MOD·17
Daily NPP*
*does not include growth respiration or
live wood maintenance resplrallon costs
Maintenance Respiration
MR
I
I
-------,
- - - - - - - - - - - - - I
r---~--~
I
MR
Daily:
mass
index
NPP*
I
I
I
I
I
I
Daily Outputs
I
~----------------------- ______ I
FIGURE 3.3. Logical and data flow diagram for the daily NPP algorithm.