d. Equilibrium State: Meridional Energy Transport
Figures 1(a) and 2(a) show the meridional transport of dry static
energy, cpT + gz, and latent heat, Lq,
respectively. The distribution of dry static energy transport
reveals sharp peaks near 10° latitude north and south (Fig
1a). This result can be explained by the fact that the energy
transport at latitudes higher than 10° is significantly smaller in
the modeled atmosphere than in the actual Earth's atmosphere
(Masuda, 1994). In particular, the amount of energy transported by
disturbances at mid- to high latitudes is approximately one third of
that on the Earth. It can be presumed that this shortcoming of the
model result arose from an inaccurate simulation of baroclinic
instabilities. Confirmation of this presumption requires
high-resolution calculations and is left as a topic for future
research.
Regarding the latent heat transport (Figure 2(a)), its peaks exist
around 20° and 40° latitude north and south. The peaks in the
low-latitude regions represent water vapor converging into the
equator, which is similar to a trend observed on the actual
Earth. Furthermore, each of the peak values of latent heat transport
obtained from the model is approximately the same as that observed
on the Earth.
When filtering and a damping layer are implemented, the amount of
transported dry static energy in the region of the Hadley
circulation decreases significantly (Figure 1(b)). In addition, the
amount of equatorward transport of latent heat also decreases in the
tropics (Figure 2(b)), creating gentle mountain-shaped patterns in
the meridional direction. It can be presumed that these deficiencies
are caused by the weakening of the Hadley circulation as described
previously.
(a)  |
(b)  |
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Figure 1: Distribution of the meridional transport
of dry static energy (W). (a) With no filtering and with a single
damping layer. (b) Experiment S1380 (filtering included in all
layers, seven damping layers). Red: total transport. Blue: transport
by the mean meridional circulations. Green: transport by stationary
disturbances. Light brown: transport by transient disturbances. The
value of solar constant used for these model runs is S =1380 W/m2.
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(a)  |
(b)  |
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Figure 2: Distribution of the meridional transport
of latent heat energy (W). (a) With no filtering and with a single
damping layer. (b) Experiment S1380 (filtering included in all
layers, seven damping layers). Red: total transport. Blue: transport
by the mean meridional circulations. Green: transport by stationary
disturbances. Light brown: transport by transient disturbances. The
value of solar constant used for these model runs is S=1380 W/m2.
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