3. Results: dust-free case up previous next
3.a. Diurnal change of horizontal mean fields

Figure 3a shows the diurnal changes of horizontal mean temperature and potential temperature of the dust-free case. In the daytime, there appears a layer where potential temperature is vertically uniform. This is the region where convective flux is dominant in the heat transport; hereafter, we refer to this layer as the convection layer. The height of the convection layer increases rapidly as the extinction of the inversion layer which forms during the nighttime; it reaches the maximum height of about 10 km at LT = 16:00. Near the ground surface, there appears a thermal boundary layer characterized by the unstable potential temperature profile. During the night, an intense inversion layer develops below the height of 2 km, which is produced by infrared radiative cooling. In the stably stratified region above the height of 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 in the daytime is caused by near infrared radiative heating of CO2.

The depth of the convection layer in daytime shown in Figure 3a is about 1 km larger than that of the 1D model obtained by Pollack et al.(1979) under the same seasonal and latitudinal conditions. This difference is caused by the explicit representation of the penetration of convective plumes to the stratosphere. At nighttime, the vertical profile of horizontal mean temperature coincide with that of Pollack et al. (1979).

Figure 3a: Time development of the vertical profiles of horizontal mean temperature (left panel) and potential temperature (right panel) of the dust-free case. Profiles are for every 4 hours from LT = 8:00 of the sixth day.


Diurnal change of other horizontal mean fields:


A numerical simulation of thermal convection in the Martian lower atmosphere.
Odaka, Nakajima, Ishiwatari, Hayashi,   Nagare Multimedia 2001
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