The retrieval of the LWC in water clouds: the comparison of Frisch and RadarLidar techniques

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The retrieval of the LWC in water cloudsthe
comparison of Frisch and Radar-Lidar techniques
Third Progress Meeting24-25 April 2003 ,
Reading

• O. A. Krasnov and H. W. J. Russchenberg
• International Research Centre for
  Telecommunications-transmission and Radar,
• Faculty of Information Technology and Systems,
  Delft University of Technology,
• Mekelweg 4, 2628 CD Delft, The Netherlands.
• Ph. 31 15 2787544, Fax [phone]
• E-mail o.krasnov_at_irctr.tudelft.nl,
  h.w.j.russchenberg_at_irctr.tudelft.nl

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The Radar, Lidar, and Radiometer datasetfrom the
Baltex Bridge Cloud (BBC) campaign August 1-
September 30, 2001, Cabauw, NL

• Radar Reflectivity from the 95 GHz Radar MIRACLE
  (GKSS)
• Lidar Backscattering Coefficient from the CT75K
  Lidar Ceilometer (KNMI)
• Liquid Water Path from the 22 channel MICCY
  (UBonn)
• All data were presented in equal time-height grid
  with time interval 30 sec and height interval 30
  m.

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The relation between in-situ Effective Radius
and Radar Reflectivity to Lidar Extinction Ratio
for different field campaigns.
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Application of the relation for
the identification of the Z-LWC relationship
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Case study August 28, 2001, Cabauw, NL,
10.12-11.20 The profiles of measured variables
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Case study August 28, 2001, Cabauw, NL,
10.12-11.20 The profiles of Optical Extinction
and Radar-Lidar Ratio
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Case study August 28, 2001, Cabauw, NL,
10.12-11.20 The Resulting Classification Map
(radar and lidar data)
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Case study August 28, 2001, Cabauw, NL,
10.12-11.20 Retrieval Results (classification
using radar and lidar data)
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Frischs algorithm

• log-normal drop size distribution
• concentration and distribution width are
  constant in the cloud

From radiometers LWP and radar reflectivity
profile
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Case study August 28, 2001, Cabauw, NL,
10.12-11.20 Retrieval Results for Frischs
algorithm
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Case study August 28, 2001, Cabauw, NL,
10.12-11.20 Histogram of Differences in
Retrieval Results for the Frischs and the
Radar-Lidar algorithm
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Difference between LWC that retrieved using
Frisch method and retrieved from radar-to-lidar
ratio
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Case study August 28, 2001, Cabauw, NL,
10.12-11.20 Representation results on the Z-LWC
plane
Frischs fittings
Log-Normal DSDN1000 - 2000 cm-3, s
0.8N1000 - 2000 cm-3, s 0.1
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Case cloud without drizzle
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Case study September 23, 2001, Cabauw, NL,
8.00-10.00 The profiles of measured variables
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Case study September 23, 2001, Cabauw, NL,
8.00-10.00 The profiles of measured variables
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Case study September 23, 2001, Cabauw, NL,
8.00-10.00 The profiles of optical extinction
and Radar-Liadr Ratio
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Case study September 23, 2001, Cabauw, NL,
8.00-10.00 The Classification Map (Radar-Lidar,
threshold -35 and -25 dB)
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Case study September 23, 2001, Cabauw, NL,
8.00-10.00 The Resulting Classification Map
(radar and lidar data)
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Atlas Z-LWC relationship
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Case study September 23, 2001, Cabauw, NL,
8.00-10.00 The results of Frischs algorithm
application
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Conclusions

• The Frischs technique produce much more water
• It does not recognize the presence of in-cloud
  drizzle
• For the log-normal model Frischs fitting of
  Z-LWC relationships shows huge, non-realistic
  concentrations