|
4.c. Circulation structure of convection
|
Figure 13 shows the circulation structure of
thermal convection of the 6th day in dusty case.
The thermal convection in the Martian lower atmosphere under dusty
condition is km-size convection; the maximum vertical and
horizontal scales of convective cells are 5 km and 2 to 3 km,
respectively.
The potential temperature deviation of convective plume is 1 to 2 K,
which value is smaller than that in dust-free case
(Figure 4 (left upper)).
The values of vertical wind velocity is 10 ˜ 15
msec-1 and that of horizontal wind velocity
is 10 msec-1 in day time.
These values are smaller than those in dust-free case, respectively.
The ratio of updraft width to downdraft width, features of convective
plume and mixing in convection layer are similar to those observed in
dust-free case.
The relatively small wind velocity is caused by decreasing of depth
of convection layer and potential temperature deviation of
convective plume, which results in decreasing of work done by
ascending convective plume.
The depth of convection layer h and potential temperature
deviation of convective plume Δθ are one half of
those in dust-free case, respectively.
Therefore, the wind velocity estimated by using (1) is also one half of that in dust
free case (˜ 10 msec-1).
The potential temperature deviation of convective plume can be estimated
by using (5);
the detail estimation is shown here.
| 
