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The inter-comparison of SCIAMACHY and radar cloud top heights Alexander A. Kokhanovsky(1), C. Naud(2), A. Devasthale(3) (1)Institute of Remote Sensing, Bremen University Bremen, Germany (2) NASA GISS, New York, USA (3) Max Planck Institute for Meteorology, Hamburg, Germany - PowerPoint PPT Presentation
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The inter-comparison of SCIAMACHY and radar cloud top
heights
Alexander A. Kokhanovsky(1), C. Naud(2), A. Devasthale(3)
(1)Institute of Remote Sensing, Bremen UniversityBremen, Germany
(2) NASA GISS, New York, USA(3) Max Planck Institute for Meteorology, Hamburg, Germany
CONTENTS
1. Rationale
2. Cloud retrievals using SACURA: the accuracy of the forward model
3. Inter-comparison study
4. Conclusions
Rationale: The validation of satellite-derived cloud top heights is needed to establish
the accuracy of a given technique for the CTH determination. This can be done
either using highly accurate lidar or radar systems in space or on ground.
CLOUD RETRIEVALS USING SACURA: THE ACCURACY OF
THE FORWARD MODEL and the physical principles behind
retrievals
The cloud optical thickness determination: the physical principle
0.65 m ,2003Kokhanovsky and Rozanov
Symbols-SCIATRAN
The effective radius determination from a satellite ,2003Kokhanovsky and Rozanov 1.55 m
The cloud top height determination from a satellite The physical principle behind the retrieval
0250 , 5, 60l m
Preliminary results !
Teh cloud geometrical thickness/bottom height determination from a satellite
0 5.5 , =20, 60h km
Inter-comparisons
36.6N; 97.5W
Radar: 35-GHz Millimeter wave Cloud Radar
36.6N; 97.5W
ARM (USA):
25min 0.5deg
Low clouds
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00
500
1000
1500
2000
2500
3000
10.03.2003
CT
H, m
CF
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00
500
1000
1500
2000
2500
3000
28.03.2003
CT
H, m
CF
scia scia
CF CFradar
Low clouds
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00
500
1000
1500
2000
2500
3000
22.05.2007
CT
H, m
CF
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00
500
1000
1500
2000
2500
3000
06.11.2003
CTH
, m
CFCF CF
scia scia
radar
High Clouds
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00
2000
4000
6000
8000
10000
12000
14000
04.06.2003
CT
H, m
CF
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00
2000
4000
6000
8000
10000
12000
14000
12.11.2003
CT
H, m
CF
High Clouds
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00
2000
4000
6000
8000
10000
12000
14000
22.11.2004
CT
H, m
CF0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0
2000
4000
6000
8000
10000
12000
14000
31.10.2003
CT
H, m
CF
The inter-comparisons of CTHs derived using SCIAMACHY,
MODIS, and MERIS
0 2 4 6 8 10 12 14 160
2
4
6
8
10
12
14
16
C
TH
, km
(sa
telli
te)
CTH, km (radar)
SACURA/SCIAMACHY ESA/MERIS NASA/MODIS
radar
satellite
Date(d/m/year) Radar SCIA MERIS MODIS
10/03/2003 1.73 1.46 2.21 1.37
28/03/2003 2.04 1.45 2.01 2.91
22/05/2003 1.73 1.45 2.50 2.09
06/11/2003 1.32 1.44 1.71 -
16/11/2003 1.37 1.45 0.73 -
10/06/2004 1.86 2.30 1.61 -
26/ 04/2007 1.46 1.45 3.12 -
Table 2. Cloud top heights (in km) of high-level clouds derived from radar and satellite data
Date(d/m/year) Radar SCIA MERIS MODIS
17/04/2003 11.66 14.54 5.31 -
15/05/2003 11.54 9.35 5.20 10.39
04/06/2003 10.60 12.31 5.10 -
31/10/2003 13.20 11.87 6.61 11.32
12/11/2003 9.56 9.82 6.92 8.35
13/11/2003 10.64 8.09 6.91 9.51
22/11/2004 11.04 8.27 6.64 -
Table 1. Cloud top heights (in km) of low-level clouds derived
from radar and satellite data
Statistical data: average CTH (km)Radar SCIA MERIS MODIS
Low-level clouds
1.64 1.57 1.98 2.12
High-level clouds
10.46 10.0 6.10 9.89
Conclusions
• The max error of the cloud top height retrievals for low clouds (below 2km) is in the range [-0.5km; 0.5km]
• The max error for high clouds(10-12km) is in the range [-3km;+3km].
Acknowledgements
J. P. BurrowsW. von Hoyningen-Huene
V. V. Rozanov, H. Bovensmann, M. Vountas, W. Lotz
ESA, DLR