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IRCTR: International Research Centre for Telecommunications and Radar Evaluation of particle shape and orientation within ice clouds using the S- band Doppler Polarimetric radar Tara – supersite H. COPS workshop – October 28th Y.Dufournet, H. Russchenberg

COPS workshop – October 28th

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Evaluation of particle shape and orientation within ice clouds using the S-band Doppler Polarimetric radar Tara – supersite H. Y.Dufournet, H. Russchenberg. COPS workshop – October 28th. Radar Tara : characteristics. FMCW S-band radar (3.3 GHz) - PowerPoint PPT Presentation

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IRCTR: International Research Centre for Telecommunications and Radar

Evaluation of particle shape and orientation within ice clouds using the S-band Doppler Polarimetric radar Tara – supersite H.

COPS workshop – October 28th

Y.Dufournet, H. Russchenberg

Radar Tara : characteristics

transmitter

receiver

H HV V

-FMCW S-band radar (3.3 GHz)

- Doppler and Polarimetric capabilities : vertical and horizontal reception and transmission performed in sequences

Ice and mixed-phase cloud measurement + precipitation measurement

Wind mode

- antennas: 75 degrees

- Polarimetry: VV VH HH OB1 OB2 (3 beams)

- time res.: ~ 3 s

- min range res.: 15 m

- max altitude: ~13 km

microphysical mode

- antennas: 45 degrees

- Polarimetry: VV VH HH (1 beam)

- time res.: ~ 3 s

- min range res.: 15 m

- max altitude: ~ 7 km

Tara within COPS airport

( www.cops2007.de )

• Period: July and August

• Placed in Hornisgrinde

• 264 measurements (310 hours of raw data)

• Orientation: 116° N (towards ARM site)

• measurements mode : mainly wind mode + 8 days in microphysical mode

Radar direction

Microphysic and radar measurements ?

dvvsZ

dvvsZdvvsZ

VV

HHDR )(

)()(

dvvsZHH )(

0velocity

Spectral reflectivity

DRsZ

VVsZHHsZ

Spectral polarimetric measurements

• particle orientation

• particle shape

• PSD (obtain from a microphysical model, not discussed in this presentation)

Microphysical characteristics of ice particles:

10

11

121416

15 13

Mono-modal

Bi-modal

sZdr categorization Built using large data set

Mono-modal

Bi-modal

category num > 10

Horizontal alignment

Category numb < 9

Vertical alignment

Category numb = 0

Not classified

Category numb = -2

Not good enough

sLDR < - 15 dB

sρ > 0.97

sZvv > -20 dBZ

0

0

0 0

00

0

00

1st case: 21/07/07 (SOP 2 – EUFAR related)

Boundary layer echo

drizzle

Melting layer

rainfall

Ice and mixed-phase cloud

Frontal activities and mesoscale convective system development

1750 1800 1850 1900 1950

300

320

340

360

380

400

420

440

Horizontal alignment

Vertical alignment

Not classified

sZdr simplified categorization

21/07 – statistical interpretation (whole box)

Mostly horizontally aligned particles

-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

Not classified (aggregates)

Plates and dentrites formation region

Hypothesis: presence of aggregates and plates or dentrites with preferred horizontal alignment

-2 0 2 4 6 8 10 12 14 160

50

100

150

200

250

Category number

0 20 40 60 80300

320

340

360

380

400

420

440

relative proportion (in %)

rang

e bi

n

-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= 1750 / x2= 1988y1= 446 / y2= 295

1 241 481 721 961 1201 1441 1681 1921 21611

50

99

148

197

246

295

344

393

442

491

21/07 : vertical cloud structure

From 2D-C probe (ATR42)

www.safire.fr and www.eufar.net

0 10 20 30 40 50 60-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8process res= 6possible averaged numb= 7

shape numb: 16p2= -0.18278

34 36 38 40 42 44 46 480.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3process res= 1possible averaged numb= 2

shape numb: 11p2= -25.8417

0 5 10 15 20 25 30 35 40 45 50-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5process res= 5possible averaged numb= 3

shape numb: 0p2= -0.17465

From the radar (sZdr)

velocity

sZd

r

monomodal plates

bimodal plates

aggregates alone

Riming and diffusional growth

aggregation

2nd case: 11/07/07

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

13:22:51 13:40:43 13:58:35 14:16:27 14:34:19 14:52:11

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= 1452 / x2= 1694y1= 297 / y2= 149

1 241 481 721 961 12011441168119212161240126412881312133611

50

99

148

197

246

295

344

393

442

491

145314751497151915411563158516071629165116731695150

164

178

192

206

220

234

248

262

276

290

-5 0 5

14:00:0314:00:5614:01:4914:02:4214:03:3514:04:2814:05:2114:06:14

1767

1919

2071

2223

2375

2527

2679

2831

2983

3135

time

height (m)

Mean particle velocity (m.s-1)

Showers events

145314751497151915411563158516071629165116731695150

164

178

192

206

220

234

248

262

276

290

0 1 2 3

14:00:0314:00:5614:01:4914:02:4214:03:3514:04:2814:05:2114:06:14

1767

1919

2071

2223

2375

2527

2679

2831

2983

3135

Doppler width (m.s-1)

A lot of turbulence processing not optimum yet

11/07 – statistical interpretation (whole box)

-60 -40 -20 0 200

2000

4000

6000

8000

10000

12000

14000M site - radiosonde 11/07/07 - 11:31

dry temperature (°C)

alt

itu

de

(m

)

Columns formation region

-2 0 2 4 6 8 10 12 14 160

100

200

300

400

500

600

Mostly vertically aligned particles

Not classified (aggregates)

Hypothesis: presence of aggregates and columns with preferred vertical alignment

Category number

Conclusion

• This new retrieval of particle shape and orientation seems feasible within ice and mixed-phase clouds but more study has to be carry out

• 8 days will be processed within COPS using such technique:

- 27/06 - 11/07- 21/07 - 09/08- 17/08 - 21/08 & 22/08- 28/08