Development of a Cloud Convection Model for Jupiter's Atmosphere
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Fig. 3.5
shows the vertical profile
of time and horizontal mean static stability
*N*^{2} (square of buoyancy frequency
*N*).
There is a distinct maximum of
*N*^{2} at the H_{2}O condensation
level.
Although the peak magnitude of *N*^{2}
is roughly 1/3 of that expected by
the one-dimensional thermodynamic equilibrium model
(See Appendix G),
it can be regarded to be large enough
to explain why the H_{2}O
condensation level acts as both a compositional and a dynamical boundary
as shown in Section 3.2 .
Fig. 3.5 also shows the contributions of the vertical gradient
of mean molecular weight (mixing ratio of condensible components)
and that of temperature (latent heat release)
to the value of *N*^{2}.
The value of
*N*^{2} is determined mainly by the decrease
in the mean molecular weight;
the contribution from temperature variation is relatively small.

The maximum values of *N*^{2} at
the NH_{4}SH reaction level and the
NH_{3} condensation level are about 1/15 and 1/5 times
as large as that at the H_{2}O condensation level,
respectively.
These ratios are obviously smaller than those obtained by
the one-dimensional thermodynamic equilibrium model
(see Appendix G),
which estimates the ratios as 1/4 and 1/3, respectively.
The magnitudes of these peaks are not quite large,
of the order of 10^{-6}s^{-1}.
The reason for these weaker stabilities is that steep decreases of the
mixing ratios of H_{2}S and NH_{3} vapor
as those observed in the one-dimensional thermodynamic equilibrium
calculation do not develop around the NH_{3}
condensation and NH_{4}SH production levels (see
Fig. 3.3).
It is considered that,
since the values of *N*^{2} do not grow enough,
those condensation and reaction levels do not act as
a compositional and/or a dynamical boundary.

Figure 3.5:
Vertical profiles of time and horizontal mean static stability
*N*^{2} (black line). Red and blue lines indicate the
contribution from temperature gradient and that from molecular
weight gradient, respectively.

Development of a Cloud Convection Model for Jupiter's Atmosphere
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