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3.a. Diurnal Changes of Horizontal Mean Fields
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Figure 3a
shows the diurnal changes of horizontal mean temperature and potential
temperature for the dust-free case. During the daytime, a layer where
potential temperature is vertically uniform is present. This region is
where convective flux is dominant during heat transport; hereafter, we
refer to this layer as the convection layer. The height of the
convection layer increases rapidly as the inversion layer, which forms
during the nighttime, diminishes; it reaches a maximum height of
approximately 10 km at 16:00 LT. Near the surface, a thermal boundary
layer characterized by an unstable potential temperature profile is
present. During the night, an intense inversion layer developed below
2 km, which was due to infrared radiative cooling. In the stably
stratified region above 10 km (hereafter, referred to as the
stratosphere), the diurnal variation of the horizontal mean potential
temperature is about 2 K. The increase of stratospheric temperature
during the daytime is caused by near infrared radiative heating of
CO2.
As shown in Figure 3a , the depth of
the convection layer in daytime is about 1 km larger than that
obtained by the 1D model used
by Pollack et al. (1979)
under the same seasonal and latitudinal conditions. This difference is
caused by an explicit representation of the penetration of convective
plumes into the stratosphere. At nighttime, the vertical profile of
horizontal mean temperature coincides with that of
Pollack et al. (1979).
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Figure 3a:
Vertical profiles of horizontal mean temperature (left panel) and
potential temperature (right panel) for the dust-free case. Profiles
are shown every 4 hours from 8:00 LT on day 6.
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The other results of diurnal changes in mean fields.
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