139 | | When sow is present in a pixel, all snow is assumed to reach the ground and the background albedo and the snow albedo (calculated as a function of snow age) are weighted according to their cover fractions (see Background albedo). |
140 | | |
141 | | === Allocation === |
142 | | ORCHIDEE-CN-CAN uses the allometric allocation as developed in OCN. In ORCHIDEE-CAN the approach was adjusted to work for more than one diameter class. Since it was developed this allocation has been used in ORCHIDEE-CN, and ORCHIDEE-CNP. In those branches only a single diameter class was used. Except for the way the reserves and labile pools are calculated, the allocation scheme is identical between all aforementioned versions. The model is, however, very sensitive to the way the reserves and labile pools are calculated. The allocation makes use of a labile pool for which the activity is calculated based on the temperature. As such the model addresses the sink/source discussion initiated by Körner. Whereas this approach resulted in an acceptable interannual variability in for example NPP in ORCHIDEE-CAN, adding N seems to have dampen the interannual variability too much. This dampening was observed in ORCHIDEE-CN and ORCHIDEE-CN-CAN. IN ORCHIDEE-CNP this temperature relationship was removed because the interannual variability became unrealistic. |
143 | | |
144 | | ORCHIDEE-CN-CAN calculates the number of individuals and uses this as a criterion to initiate a stand replacing disturbance. This approach, guided by the self-thinning relationship, avoids the need for a stand-level turnover time. ORCHIDEE-CN, and ORCHIDEE-CNP still make use of stand-level turnover. |
145 | | |
146 | | There are no options to revert to the allocation based on resource limitation. All references and parameters for allocation based on resource limitation have been removed from the code (those that were overlloked can be removed). Allometric allocation makes use of the following PFT-specific parameters: '''sla''', '''tau_root''', '''tau_leaf''', '''tau_sap''', '''pipe_density''', '''tree_ff''', '''pipe_tune_x''', '''k_latosa_max''', and '''k_latosa_min'''. In addition to this set of parameters that mainly describe the allometric relationships and the longevity of the different tissues, the calculation of the allocation coefficients makes use PFT-specific tissue conductivities, i.e., '''k_sap''', '''k_root''', and '''k_leaf''' (see also plant water stress). As such there is a functional link between C and N-allocation and the hydraulic architecture of a plant. Details on the parameters can be found in the SI of Naudts et al 2015 in GMD or in src_parameters/constantes_mtc.f90. |
147 | | |
148 | | === Background albedo === |
| 139 | When sow is present in a pixel, all snow is assumed to reach the ground and the background albedo and the snow albedo (calculated as a function of snow age) are weighted according to their cover fractions (see Background albedo). |
| 140 | |
| 141 | === Albedo (background) === |
| 145 | |
| 146 | === Albedo (snow) === |
| 147 | The snow albedo could be either prescribed (in condveg_init.f90) or calculated following Chalita and Treut (1994) '''do_new_snow_albedo = n ''' or calculated following CLM3 '''do_new_snow_albedo = y'''. The difference between the latter two methods has not been tested yet. The CLM method was added to CN-CAN, the Chalita and Treut method was added in parallel to the runk. When merging both versions we ended up with two options. |
| 148 | |
| 149 | === Allocation === |
| 150 | ORCHIDEE-CN-CAN uses the allometric allocation as developed in OCN. In ORCHIDEE-CAN the approach was adjusted to work for more than one diameter class. Since it was developed this allocation has been used in ORCHIDEE-CN, and ORCHIDEE-CNP. In those branches only a single diameter class was used. Except for the way the reserves and labile pools are calculated, the allocation scheme is identical between all aforementioned versions. The model is, however, very sensitive to the way the reserves and labile pools are calculated. The allocation makes use of a labile pool for which the activity is calculated based on the temperature. As such the model addresses the sink/source discussion initiated by Körner. Whereas this approach resulted in an acceptable interannual variability in for example NPP in ORCHIDEE-CAN, adding N seems to have dampen the interannual variability too much. This dampening was observed in ORCHIDEE-CN and ORCHIDEE-CN-CAN. IN ORCHIDEE-CNP this temperature relationship was removed because the interannual variability became unrealistic. |
| 151 | |
| 152 | ORCHIDEE-CN-CAN calculates the number of individuals and uses this as a criterion to initiate a stand replacing disturbance. This approach, guided by the self-thinning relationship, avoids the need for a stand-level turnover time. ORCHIDEE-CN, and ORCHIDEE-CNP still make use of stand-level turnover. |
| 153 | |
| 154 | There are no options to revert to the allocation based on resource limitation. All references and parameters for allocation based on resource limitation have been removed from the code (those that were overlloked can be removed). Allometric allocation makes use of the following PFT-specific parameters: '''sla''', '''tau_root''', '''tau_leaf''', '''tau_sap''', '''pipe_density''', '''tree_ff''', '''pipe_tune_x''', '''k_latosa_max''', and '''k_latosa_min'''. In addition to this set of parameters that mainly describe the allometric relationships and the longevity of the different tissues, the calculation of the allocation coefficients makes use PFT-specific tissue conductivities, i.e., '''k_sap''', '''k_root''', and '''k_leaf''' (see also plant water stress). As such there is a functional link between C and N-allocation and the hydraulic architecture of a plant. Details on the parameters can be found in the SI of Naudts et al 2015 in GMD or in src_parameters/constantes_mtc.f90. |