Geoscience Reference
In-Depth Information
325
DJF
300
275
250
225
90 80
60
40
20
Eq
20
40
60
80 90
S
N
Latitude
325
JJA
300
275
Figure 8.3
Comparison of zonally averaged
surface temperatures for December to February
(above) and June to August (below) as simulated
by the AMIP models compared with observations
(bold line). The shaded band shows the range of
results for 17 AMIP models.
Source
: AMIP website.
250
225
90 80
60
40
20
Eq
20
40
60
80 90
S
N
Latitude
B MODEL SIMULATIONS
anthropogenic effects as increased atmospheric CO
2
occur.
2
Storage times
. For each compartment of the atmos-
phere and ocean subsystems these are the average
times taken for an input of thermal energy to diffuse
and mix within the compartment. For the earth
subsystem, the average times are those required for
inputs of water to move through each compartment.
1 GCMs
Climate model simulations are used to examine possible
future climates by simulating plausible scenarios (e.g.
increasing atmospheric CO
2
, tropical deforestation) into
the future using representations of inputs (i.e. forcings),
storage between components of the climate system and
and transfers between components (see Figure 8.4
and Chapter 11). The periods of time shown in Figure
8.4 refer to:
Model simulations can be performed in several
different ways. A common procedure is to analyse the
model's sensitivity to a specified change in a single
variable. This may involve changes in external forcing
(increased/decreased solar radiation, atmospheric
CO
2
concentrations, or a volcanic dust layer), surface
boundary conditions (orography, land surface albedo,
continental ice sheets) or in the model physics
(modifying the convective scheme or the treatment of
biosphere exchanges). In these simulations, the model
1
Forcing times
. The characteristic timespans over
which natural and anthropogenic changes of
input occur. In the case of the former, these can be
periods of solar radiation cycles or the effect of
volcanism and in the case of the latter the average
time interval over which significant changes of such
