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Second Progress Meeting 21-22 October 2002, KNMI. Water cloud retrievals. 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,

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water cloud retrievals

Second Progress Meeting21-22 October 2002, KNMI

Water cloud retrievals

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: +31 15 2784046

E-mail: [email protected], : [email protected]

slide3

The correlation between and as

  • function of for different types of function .

Threshold value for drizzle definition:

Rmin = 17…20 mm

slide4

, dB

drops

Z

/

drizzle

m

CLARE’98,

R

=20

m

Z

threshold

The dependence between the ratio of drizzle to droplets reflectivities versus the ratio of drizzle to droplets LWCs

The CLARE\'98 campaign data

slide5

, dB

, dB

drops

drops

Z

Z

/

/

drizzle

drizzle

Z

m

Z

m

CLARE’98,

CLARE’98,

R

R

=20

=20

m

m

threshold

threshold

The dependence of the ratio of drizzle reflectivity to droplets reflectivity

versus the total radar reflectivity

versus the Z/a ratio

(a)

(b)

The CLARE\'98 campaign data

slide6

The relation between “in-situ” Effective Radius and Radar Reflectivity to Lidar Extinction Ratio for different field campaigns.

slide7

log10(LWCdrizzle, g/m3)

The dependence of the LWC in drizzle fraction versus the Z/a ratio.

Cloud without drizzle

Cloud with heavy drizzle

Cloud with light drizzleLWC < 0.05 g/m3

The CLARE\'98 campaign data

slide8
Radar + Lidar data:LWC retrieval algorithm,based on the classification of the cloud’s cells into three classes:
  • cloud without drizzle,
  • cloud with light drizzle,
  • cloud with heavy drizzle
slide9

Application of the relation for the identification

of the Z-LWC relationship

slide10

The algorithm for the water cloud LWC retrieval from simultaneous radar and lidar measurements

Re-scaling data to common grid

Zlidar(h) => a (h)

  • Cloud classification map for
  • 7 classes k(h):
      • 0 - no cloud;
      • 1 - Z /a not available, Z < Z1 ;
      • 2 - Z /a not available, Z1 <Z < Z2 ;
      • 3 - Z /a not available, Z2 <Z ;
      • 4 - Z /a < Q1;
      • 5 - Q1 < Z /a < Q2;
      • 6 - Q2 < Z /a.

Zradar(h) / a (h)

LWC = Ak ZBk

LWPZ = S LWCiD hi

LWPRM = ? = LWPZ

slide11
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.

slide13
Case study: August 04, 2001, Cabauw, NL, 9:30-10:30 The profiles of Optical Extinction and Radar-Lidar Ratio
slide14

The comparison of the Z-Z/arelations calculated from in-situ measured DSD and from simultaneous radar and lidar data

slide15
Case study: August 04, 2001, Cabauw, NL, 9:30-10:30 The Resulting Classification Map (radar and lidar data)
slide16
Case study: August 04, 2001, Cabauw, NL, 9:30-10:30Retrieval Results (classification using radar and lidar data)
case study august 04 2001 cabauw nl 9 30 10 30 the resulting classification map only radar data
Case study: August 04, 2001, Cabauw, NL, 9:30-10:30The Resulting Classification Map (only radar data)
case study august 04 2001 cabauw nl 9 30 10 30 retrieval results classification using radar data
Case study: August 04, 2001, Cabauw, NL, 9:30-10:30Retrieval Results (classification using radar data)
frisch s algorithm
Frisch’s algorithm
  • log-normal drop size distribution
  • concentration and distribution width are equal to constant values

From radiometer’s LWP and radar reflectivity profile:

slide20

09:30-10:30, 04.08.2002, Cabauw, BBC-campaign

The solution of the Frisch equation

difference between lwc that retrieved using frisch method and retrieved from radar to lidar ratio
Difference between LWC that retrieved using Frisch method and retrieved from radar-to-lidar ratio
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