- Equilibrium run:
- Initial Conditions:
These don't really matter for the Abiotic Equilibrium run. That is,
the final steady-state distributions for DIC and DIC14 do not depend
on the initial conditions because exchange with the atmosphere will
ultimately determine their final steady-state inventories. However, a
judicious choice of initial conditions can reduce the integration time
required to reach steady-state. Unfortunately, initial conditions
must be quite close indeed to the steady-state solution if there is to
be a significant reduction in computing time. The choice of initial
conditions is left to the discretion of each of the modeling groups.
For initial debugging, groups may prefer to initialize DIC14 to the
same 3-D field as used for DIC. That way the only difference between
the two tracers is driven by radioactive decay.
- Duration:
The Equilibrium run for abiotic DIC and DIC14 should be
continued until at least both the following criteria are reached:
- For DIC, we recommend that
the globally integrated air-sea flux should be less than 0.01
Pg C/yr
- For C-14, we recommend that
98% of the ocean volume should have a drift of less than
0.001 permil/year (Aumont et al., 1998, p. 105). In terms of C-14
age, this drift is equivalent to a change of 8.27 yr per 1000 years of
simulation.
For most models, these criteria can be reached only after integrations of
at least few thousand model years.
- Historical run:
- Initial Conditions:
The historical abiotic simulation
for both DIC and DIC14 will be initialized with final output (on
Dec. 31) from the Equilibrium run or "steady-state" simulation.
- Duration:
The historical simulation will begin at the beginning of 1765 (Jan
1, i.e., 1765.0). The anthropogenic simulation will be continued
until the year 2000.0.
- CO2:
Until 1990.5, pCO2atm will follow the
splco2.dat; then from
1990.5 to 2000.0, the atmosphere will follow IPCC scenario S650 in
stab.dat.
- C-14:
Atmospheric D14Catm will follow values in
c14nth.dat,
c14equ.dat, and
c14sth.dat (for 90S-20S,
20S-20N, and 20N-90N, respectively) until 2000.0. For lack of data,
atmospheric C-14 between 1995.5 and 2000.0 is held constant at 107
permil.
- Future runs (DIC only):
- Future run CIS92A:
- Initial Conditions:
3-D DIC field, 2-D Cumulative Fluxes and 2-D Cumulative Virtual
Flux fields to be initialized with output from the
Historical run at 1990.0
- Duration:
to be continued using atmospheric CO2 from IPCC Scenario CIS92A
until the year 2100.0
- Future run S650:
- Initial Conditions:
3-D DIC field, 2-D Cumulative Fluxes and 2-D Cumulative Virtual
Flux fields to be initialized with output from the
Historical run at 1990.0
- Duration:
to be continued using atmospheric CO2 from IPCC Scenario S650
until the year 2300.0
- Pulse input response function (DIC only):
- Initial Conditions:
Ocean DIC is to be initialized with final output from the
Equilibrium run; Atmospheric CO2 is to be doubled (556 ppm, where
1 ppm = 2.123 Pg C) at t=0, and then be controlled only via
air-sea fluxes. Thus the model is then to be run in forward mode
(atmospheric CO2 is calculated). The Injection HOWTO describes other
forward simulations in more detail.
- Duration:
The total integration will be for 1000 years (1765.0 - 2765.0).
- Control Runs
- Historical Control (DIC and DIC14); and
Future Control (DIC only)/:
-
Initial Conditions: Ocean DIC is to be initialized
with final output from the Equilibrium run; Atmospheric CO2 and
C-14 are to be held at preindustrial conditions (278 ppm, 0
permil) throughout the duration of the simulation.
-
Duration: The total integration for DIC will be for 535
years (1765.0 - 2300.0). However the integration including DIC14 is
only necessary for the first 235 years (Historical Control
run 1765.0 - 2000.0).
-
Historical-Future transistion:
If run separately, the Future Control run should
be initialized with the 3-D DIC fields AND the 2-D Cumulative Fluxes
(i.e., both air-sea gas cumulative flux and virtual cumulative flux)
from the last time step of 1999 (end of Historical Control
run).
- Pulse Control (DIC only):
- Initial Conditions:
Ocean DIC is to be initialized with final output from the
Equilibrium run; Atmospheric CO2 is to be initialized with the quantity
of CO2 equivalent to 278 ppm
(1 ppm = 2.123 Pg C) at t=0, and then be controlled only via
air-sea fluxes. Thus the model is to be run in forward mode
(atmospheric CO2 is calculated). The Injection HOWTO describes other
forward simulations in more detail.
- Duration:
The total integration will be for 1000 years (the equivalent of
1765.0 - 2765.0).
There are no Future or Pulse simulations for DIC14.