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3.a.iii. Atmospheric heating
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Figure 3d:
Diurnal change of the
horizontal and time mean vertical profiles of
atmospheric heating rate (K/day) for potential temperature
of the dust-free case.
Orange line denotes convective heating,
red line denotes infrared radiative heating,
blue line denotes solar radiative heating,
green line denotes turbulent diffusion of potential
temperature, and
light purple line denotes
heating due to turbulent dissipation, respectively.
Lower panel shows the magnified profiles of
the lower altitudes below 1 km height of
upper panel.
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Figure 3d shows the horizontal and time
mean vertical profiles of atmospheric heating
rate for potential temperature.
Radiative heating in daytime increases exponentially
below about 2 km height toward the ground surface.
This is caused by CO2
absorption of infrared radiation emitted mainly
from the ground surface.
The radiative heating
which is roughly uniform vertically
above about 4 km height
is caused by
CO2 absorption
of near infrared radiation
In the layer near the surface,
there appear
heating due to diffusion of sensible heat
supplied from the ground surface
and heating due to kinetic energy dissipation.
The magnitude of diffusive heating at the lowest level
is comparable with that of radiative heating.
Heating due to convection is negative near the ground
surface, positive in the convective layer, and
negative again in the upper stable layer where
convective plumes penetrate.
The magnitude of convective heating reaches
about 100 K/day in the morning when the convective layer
thickness is small, and from 20 to 40 K/day in the
afternoon when the layer thickness is large.
The depth of the convective cooling layer near the ground
surface is about 400 m, where the thermal boundary layer
is included.
The vertical profile of infrared radiative cooling
during nighttime
is similar to that during daytime but with opposite sign.
The magnitude of infrared radiative cooling
gradually becomes small as the inversion layer
develops below the altitude of 2 km.
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