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

Chapter 5. Cloud free statistics 54
(a)
60°N
30°N
0°
3600
3200
2800
2400
2000
1600
30°S
60°S
180° 135°W 90°W 45°W 0° 45°E 90°E 135°E
180°
(b)
(c)
1200
800
400
0
1000
4000
Mean cloud gap length [km]
100
10
1
Global mean cloudless fraction 40.5 %
Global mean cloud gap length 7.41 km
0.0 0.2 0.4 0.6 0.8 1.0
Mean cloudless fraction
(d)
Total number of measurements
1000
100
250 measurements 98.9 %
500 measurements 82.2 %
1000 measurements 34.2 %
10
0.0 0.2 0.4 0.6 0.8 1.0
Mean cloudless fraction
60°N
30°N
0°
30°S
60°S
50
45
40
35
30
25
20
15
10
5
180° 135°W 90°W 45°W 0° 45°E 90°E 135°E
180°
Figure 23: Total number (a) and their respective mean length (b) of cloud gaps
for the complete data set of 2007 on a 2 ◦ x 2 ◦ grid. As shown in (a) the amount
of pure cloud gaps dominates over the tropic and subtropic ocean regions, while the
mean cloud gap length in km (d) has its maximum above the global deserts and high
mountain ranges. To support this statement, (b), on the one hand shows that for a
high cloudless fraction, the mean cloud gap length rises, but on the other hand very
few measurements are available for regions with a high cloudless fraction (c).