CSIP & COPS workshop 2009 Tuesday, October 27 th

IRCTR - International Research Centre for Telecommunication and Radar

AATTMMOOSS

Ice crystals properties retrieval within ice and mixed-phase clouds

using the Doppler polarimetric radar TARA.

CSIP & COPS workshop 2009Tuesday, October 27th

Y. Dufournet , C.M.H Unal, S. Placidi

H.W.J Russchenberg


AATTMMOOSS

DelftUniversity ofTechnology

2

COPS status – TU Delft

Outlines :

Cloud microphysical Retrieval principle

Case study and main use of COPS facilities

transmitter

receiver

H HV V

TARA

12 m

FMCW radar TARA

- Located on Supersite H (Hornisgrinde)

- measurements performed within:

ice or mixed-phase cloud (only the ice phase)

Precipitation

(3.3 GHz – 10 cm)


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Spectral polarimetric parameter - Principle

Particles with different size, habit, orientation

≠ fall velocities, particle axis ratio

0velocity

Spectral reflectivity

DRsZ

VVsZHHsZ

Doppler effect

Polarimetric behaviorra

dar

+Spectral polarimetric

parameters

( )( )

( )HH

DRVV

sZ vsZ v

sZ v

Isolate different

group of particles


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Microphysical retrieval : resulting parameters

hei

ght

time

Polarimetric information

Doppler information

Radar cell

Numb. of particles types

Particle orientation

Particle habits

PSD for each particle type

radial wind, spectral broadening

Assumption based

Retrieved Parameters

)(vsZHH

)(vsZVV

)(, vsL hDR

, ( )DR vsL v

)(vsZDR

( )cos v

Forward model

Detailed microphysical analysis


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Measurement at a microphysical mode– 21/07/07

-40 -30 -20 -10 0 10 20 30 40

15:39:03 15:51:19 16:03:36 16:15:52 16:28:09 16:40:26

1

529

1057

1585

2113

2641

3169

3697

4225

4753

5281

time

height (m)

Reflectivity [dB] MB VV

Profiles

Ran

ge b

in

box boundaries: x1= 1618 / x2= 2391y1= 491 / y2= 198

1 241 481 721 961 1201 1441 1681 1921 21611

50

99

148

197

246

295

344

393

442

491

Precipitation

Ice or mixed-phase cloud

Melting layer

Drizzle

Boundary layer top

Retrieval zone

time

heig

ht

Based on a retrieval technique !


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Retrieval orientation and particle habit

simplified particle categorization

50 100 150

10

20

30

40

50

60

70

no data

dominantpristine

dominantaggregates

aggregates

-40 -30 -20 -10 0 10 20 30 40

15:39:03 15:51:19 16:03:36 16:15:52 16:28:09 16:40:26

1

529

1057

1585

2113

2641

3169

3697

4225

4753

5281

time

height (m)


Profiles

Ran

ge b

in


1 241 481 721 961 1201 1441 1681 1921 21611

50

99

148

197

246

295

344

393

442

491

plates

dendrites

simplified orientation categorization

1700 1800 1900 2000 2100 2200 2300200

250

300

350

400

450

No data

no orient.

verticalmainly

horizont.mainlyMainlyhorizontal

Mainlyvertical

No orientation

No data

Horizontally aligned plates (+ dendrites) and few aggregates

Vertically aligned plates (+ dendrites) and few aggregates

Strong aggregation

Mainly aggregates and few plates

orientation

habits


50 100 150

10

20

30

40

50

60

70

no data

dominantpristine

dominantaggregates

aggregates


50 100 150

10

20

30

40

50

60

70

no data

dominantpristine

dominantaggregates

aggregates


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Comparison particle habits

-50 -40 -30 -20 -10 0 10 200

2000

4000

6000

8000

10000

12000

dry temperature (°C)

alt

itu

de

(m

)

M site - radiosonde 21/07/07 - 18:02

Radiosonde launch

ATR 42 flight

Plate production region

Cloud top region

PMS 2D-C probes images


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50 100 150

10

20

30

40

50

60

70

no data

dominantpristine

dominantaggregates

aggregates

Retrieval PSD and ambient wind

2.5 3 3.5 43000

3500

4000

4500

5000

5500

6000

6500

median volume diameter for aggregates (mm)

altitu

de ab

ove s

ea le

vel (m

)

D0 agg. retrieval

agg.plates + agg.

D0 agg.

0.31 0.32 0.33 0.34 0.35 0.36 0.37 0.38 0.39 0.44800

5000

5200

5400

5600

5800

6000

6200

median volume diameter (mm)

altitu

de

ab

ove

se

a le

ve

l (m

)

D0 pla.

102

103

104

105

3000

3500

4000

4500

5000

5500

6000

6500

number of aggregates

altitd

ue ab

ove s

ea le

vel (m

)

agg.

plates + agg.

Nt agg.

1500 2000 2500 3000 3500 40004800

5000

5200

5400

5600

5800

6000

6200

number of particles

altitu

de

ab

ove

se

a le

ve

l (m

)

Nt pla.

Vertical ambiant wind

Obtained from modified gamma distribution

Wind shear

Convergence zone

v0


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Comparison PSD

ATR 42 retrieved

IWC

Nt

Good agreement


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Cloud processes – possible explanation

m.s-1

Mean vertical Doppler velocity from TARA

Pristine ice prod.

aggregation

Orographic enhancement

Strong updraft

blocking area

Only agg. precipitate

Plates fully blocked

vTARA = vparticles


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Main achievements using COPS data set

• microphysical retrieval: promising results on the cloud observation processes assumptions tested and improved leading to good agreements when compared with other instruments

• 3D wind measurements: corrected and assessed with radiosondes measurements within optically thick clouds and precipitation

Conclusion

What is next ?

- Processing the remaining days

- Full Assessment and validation of the microphysical retrieval


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EarthCARE SIMulator - ECSIM

Earth Cloud Aerosols Radiaton Explorer by ESALaunch date: 2013

EarthCARE mission end2end SIMulator – ECSIM Simulate all the 4 EarthCARE instruments and the satellite platform

Model Atmosphere

Model Atmosphere

Forward Models

Forward Models

Syntheticobservations

Syntheticobservations

Space-borne radar and lidar Ground-based / aircraft radar and lidar

Satellite imager and broadband radiometer

(Courtesy of Simone Placidi)

cloud scene creation ( PSD, reff, shape

parameter, surface properties, cloud/aerosol

information…) input from LES models, fractal cloud

generator


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Validation – assessment with ECSIM

Microphysical data retrieved

Comparison with COPS

instrumentation

(Courtesy of Simone Placidi)

Optical Depth of original scene

Simulated 94 GHz Radar Reflectivity (ground)

Synthetic observations


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Thank you!


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Heig

ht [m

]

Reflectivity [dBZ] EL=75 deg. D20070703

11.55 11.6 11.65 11.7 11.75 11.8 11.85

2000

4000

6000

-40

-20

0

20

40

Heig

ht [m

]

Horizontal wind speed [m s-1] D20070703

11.55 11.6 11.65 11.7 11.75 11.8 11.85

2000

4000

6000

10

20

30

Decimal time UTC [hours]

Heig

ht [m

]Horizontal wind direction [deg.] related to North D20070703

11.55 11.6 11.65 11.7 11.75 11.8 11.85

2000

4000

6000

150

200

250

300

Example horizontal particle motion (COPS)

Wind shear at 4000 m

10 days processed

(Courtesy Christine Unal)

21 min averaged

Observation of 3D particle motion at high resolution within ice/mixed-phase clouds and precipitation


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EarthCARE SIMulator

INPUT OUTPUTSIMULATIONS

Cloud scene- Scene dimensions

- Atmospheric properties

- Surface properties

- Clouds/aerosols info

- Scattering regions

- ext, LWC, Reff

- Gamma / log-normal distribution

- shape parameter

- min/max value of Reff for DSD

- From LES, CRM, fractal cloud generator

Outputs- Radar Reflectivity

- Lidar return/ extinction/ backscatter

- COT - Reff – LWP

- Fluxes

Forward/Instruments models- ground

- Radar (5GHz, 32Ghz, 94 GHz)

- Lidar (0.353 nm)

- Space:

- Radar

- Lidar

- Multi Spectral Imager

- Broadband radiometer


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Radar measurement from TARAtransmitter

receiver

H HV V

Doppler and Polarimetric capabilities:

- transmit and receive horizontally (H) or vertically (V) change of the polarization state every 1ms: HH HV VV

-Antennas at 45° improve the polarimetric contrast

Other requirements for cloud observation:

- High resolution 15 m range resolution

1 profile every 1.5 s

- For mixed-phase clouds : at 3.3 Ghz, reflectivity of supercooled water droplets below the noise level – direct measurement of the ice crystals!

TARA: Transportable Atmospheric RAdar

(FMCW – S band)

12 m)(vsZHH )(vsZVV )(, vsL hDR

, ( )DR vsL v)(vsZDR

Spectral polarimetric parameter

( )cos v


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-40 -30 -20 -10 0 10 20 30 40

15:39:03 15:51:19 16:03:36 16:15:52 16:28:09 16:40:26

1

529

1057

1585

2113

2641

3169

3697

4225

4753

5281

time

height (m)


Profiles

Ran

ge b

in


1 241 481 721 961 1201 1441 1681 1921 21611

50

99

148

197

246

295

344

393

442

491

Case study – 21/07/2007 (COPS – EUFAR)

France

Convective and Orographically-induced Precipitation Study

Precipitation

Ice or mixed-phase cloud

Melting layer

Drizzle

Meteorological situation:

Frontal activities and mesoscale convective system development with orographic inhancement

Boundary layer top

Retrieval zoneHornisgrindeBlack Forest


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Measurement type overview h

eig

ht

time


Doppler information

Radar cell

-3 -2.5 -2 -1.5 -1 -0.5-15

-10

-5

0

sZhh

[dB

]

optimization result: 2382 / 394

-3 -2.5 -2 -1.5 -1 -0.5-0.5

0

0.5

1

1.5

sZdr

[dB

]

vertical velocity m/s

D0agg = 3.75 [mm]

Nwagg = 363 [mm-1m-3]

0 = 0.55 [ms-1]

v0 = 0.94 [ms-1]

IWC = 0.022 [g.m-3]Nt = 371 [particles]shape factor = 0

Microphysical model

Simulated sZDR(v) + sZHH(v)



Particle habits

Least square fit algorithm

Signal improvement



Velocity

Assumption based

Particle motion

Cloud microphysical retrieval

Mean Doppler velocity

Doppler width

)(vsZHH

)(vsZVV

)(, vsL hDR

, ( )DR vsL v

)(vsZDR

( )cos v

)(vsZDR

)(vsZHH


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Type of measurements h

eig

ht

time


Doppler information

Radar cell



Particle habits



Assumption based

Wind mode : moment computation from 3 beams

Microphysical mode : retrieval

Mean Doppler velocity

Doppler width

)(vsZHH

)(vsZVV

)(, vsL hDR

, ( )DR vsL v

)(vsZDR

( )cos v

Particle fall velocity, horizontal wind speed and direction

CSIP & COPS workshop 2009 Tuesday, October 27 th

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