Cloud Statistics from Calipso Lidar Data for the ... - espace-tum.de

Chapter 6. Cloud flatness occurrence 60
events are located mainly above oceans and especially in front of the western coast of
all continents (e.g. West Coast of North America, South America, Europe, Africa and
Australia). The general maritime dominance is related to the typically smooth shape of
the maritime boundary layer.
(a)
60°N
30°N
0°
30°S
60°S
180° 135°W 90°W 45°W 0° 45°E 90°E 135°E
180°
0 1 2 3 4 5 6 7 8
(b)
(c)
Height [km]
8
7
6
5
4
3
2
1
0
0 1000 2000 3000 4000 5000
Number of events
Height [km]
8
7
6
5
4
3
2
1
0
-82 -60 -30 0 30 60 82
Latitude
80
72
64
56
48
40
32
24
16
8
0
Figure 26: Global cloud top flatness events computed for 2007 and a partly overlapping
search window of 200 km and a 50 km consecutive or partly broken cloud within
the search window, while the vertical variation does not exceed ± 15 m. The global
distribution of flat cloud tops and their respective maximum height is shown on a 1 ◦
x 1 ◦ grid (a). The height of such events is color-coded. (b) represents the top height
histogram of all events, while (c) shows the latitude averaged cloud top flatness height
distribution in number of events. Once again, the oversampling at high latitudes is
evident.
Generally, the top height of cloud flatness occurrence is related to cloud cover which
is discussed further in Chapter 7. Not surprisingly the accumulation of events in the
northern hemisphere between 50 ◦ N and 70 ◦ N, as well as in the southern hemisphere
between 50 ◦ S and 70 ◦ S is based on the overall cloudiness in these latitude bands as