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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