thomas.boerner@dlr.de, slide 1German Aerospace Center Microwaves and Radar Institute

Methodology for obtaining physical parameters from fully polarimetric

coherent weather radar data: A first approach to unsupervised

Entropy-Alpha-classification

Dr. Thomas BörnerDLR Oberpfaffenhofen

Microwaves and Radar InstituteD-82234 Weßling

thomas.boerner@dlr.de, slide 2German Aerospace Center Microwaves and Radar Institute

Outline

• Introduction to the H- decomposition theorem• Classification scheme• Analysis and interpretation of the polarimetric time

series data set• Conclusions• Future activities

thomas.boerner@dlr.de, slide 3German Aerospace Center Microwaves and Radar Institute

Decomposing the Scattering Matrix

yyyx

xyxxL SS

SSS TyyxyxxL SSSs 23

0

0

01

10

10

01

10

01

i

idcba

baidc

idcbaS

TxyyyxxyyxxLP SSSSSss 22

1

020

101

101

2

133

thomas.boerner@dlr.de, slide 4German Aerospace Center Microwaves and Radar Institute

Entropy H and angle

3

1

*

*

3

2

1

3

2

1

321*33

00

00

00

|||

|||

i

Tiii

T

TPP ww

w

w

w

wwwssC

.wherelog3

1

3

13

jj

ii

iii PPPH

3

1iiiP

sinsin

cossin

cos

with33i

iPP

e

ewwss

thomas.boerner@dlr.de, slide 5German Aerospace Center Microwaves and Radar Institute

What does tell us?

= 0 = 90 = 45

thomas.boerner@dlr.de, slide 6German Aerospace Center Microwaves and Radar Institute

H- feasible area

thomas.boerner@dlr.de, slide 7German Aerospace Center Microwaves and Radar Institute

“Classic” Products

Zyy [dBZ] ZDR [dB]

thomas.boerner@dlr.de, slide 8German Aerospace Center Microwaves and Radar Institute

Extracted Products

Entropy H angle [deg]

thomas.boerner@dlr.de, slide 9German Aerospace Center Microwaves and Radar Institute

Populated H- plane

thomas.boerner@dlr.de, slide 10German Aerospace Center Microwaves and Radar Institute

Zyy and Classification

Zyy [dBZ] Classes

thomas.boerner@dlr.de, slide 11German Aerospace Center Microwaves and Radar Institute

15 consecutive PPI Sector Scans

Zyy [dBZ] Classes

thomas.boerner@dlr.de, slide 12German Aerospace Center Microwaves and Radar Institute

Is there a Z-H relation?

thomas.boerner@dlr.de, slide 13German Aerospace Center Microwaves and Radar Institute

Is there a Z- relation?

thomas.boerner@dlr.de, slide 14German Aerospace Center Microwaves and Radar Institute

Conclusions

• It has been shown that it is possible to apply the H- decomposition to polarimetric weather radar data and to retrieve meaningful results.

• The classification provides knowledge about different types of scatterers without having to access empirical a-priori knowledge.

• Proper interpretation of PPI scans is difficult, because it is unclear what the radar beam is actually scanning.

• Regions with ground clutter can be easily detected, which might help to enhance clutter filtering.

thomas.boerner@dlr.de, slide 15German Aerospace Center Microwaves and Radar Institute

Future Activities

• Analyse RHI scans: different layers are easier to distinguish enhance the classification scheme!

• Compare results with other sources of information about particles, preferably simultaneously collected.

• Compare results with other classification methods.

• Use additional parameters as 1 or the anisotropy to refine the classification scheme.