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3.d. Intensity of the convection (1)
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Figure 7:
Vertical profile of horizontal mean potential temperature below 1 km hight
at LT=14:00 in dust-free case.
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The wind velocity associated with the km-size convection can be
estimated by using the equation (1).
In this section, we consider how the potential temperature deviation
of ascending convective plume
( )
can be estimated.
The convective plume associated with the km-size thermal convection
is generated by convective instability in the thermal boundary layer
(see Figure 4 (upper left)).
Therefore, it is considered that the potential temperature deviation
of convective plume is corresponds to potential temperature
difference in the thermal boundary layer.
Figure 7 shows the vertical profile of
horizontal mean potential temperature below 1 km hight in daytime.
The thermal boundary layer where the vertical gradient of horizontal
mean potential temperature is negative can be divided two regions.
One is "conduction layer" which is located
below about 50 m hight.
In this region, the heating due to turbulent diffusion is comparable
to radiative heating (Figure 3d)
and the horizontal mean potential temperature increases linearly
toward the grand surface.
The other is "transition layer"
which is located
between the conduction layer and about 400 m hight
where the vertical gradient of horizontal mean potential temperature
is relatively moderate.
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