ECE/METR6613

Title: Weather Radar Polarimetry

(Wave Interactions with Geophysical Media)

Class: 2:00-2:50 MWF, NWC 5930

Office hrs: 3:00-4:00 MW

Instructor: Guifu Zhang, guzhang1@ou.edu

NWC4620, 325-3507

Students: David Bonine, Petar Bukovcic, Lei Lei,

Yinguang Li, Sean Luchs, Jeffrey Snyder, Matt

Vandenbroeke, Charlotte Wainwright

Text book/References

• Text bookR. J. Doviak and D. S. Zrnic: Doppler Radar and Weather

Observations, 2006, 1993, 1984

• Reference books1. Akira Ishimaru: Wave Propagation and Scattering in Random

Media, 1997, 1978

2. V. N. Bringi and V. Chandrasekar: Polarimetric Doppler

Weather Radar: Principle and applications, 2001

3. C.E. Bohren and D.R. Huffman: Absorption and scattering of

light by small particles, 1983

4. H.C. van de Hulst: Light Scattering by Small Particles, 1981,

1957

History of Weather Radar

• Radar: radio detecting and ranging of objects

– Developed for aircraft detection (30s ~ 40s)

• History of weather radar development [Doviak & Zrnic,

1984 & 1993]

– Radar meteorology (40s)

– Reflectivity, Doppler velocity (40s ~ 50s)

– Polarimetry (70s ~ present)

– Phased array radar technique

• Differential reflectivity: ZDR ( late 70s)

• Other observables: KDP, LDR, !hv …. (80s ~ 90s)

• A matured technique

– Research radars (KOUN, S-pol, Chill)

– Network of polarization weather radars: WSR-88Ds, CASA

• Potential for cloud microphysics studies

Radar PolarimetryTo obtain information through measurements of polarization signatures

Accurate Quantification Possible

• Conception of detection needs to be extended to quantification

• Agreement between radar and in-situ measurements although

there is a 108 difference in sampling volume

Objective

Why do we offer this course?

Polarimetric weather radar data available

national/world-wide in next a few years

• Principles and techniques

• Improving data quality

• Interpretation of radar data

• Weather quantification

• Microphysical parameterization

• Data assimilation

Do you need this class?

• When is valid Z = <D6>?

• What are polarimetric radar variables?

• How to calculate radar variables when

Rayleigh scattering is not valid, complex

composition and shape?

• How to link polarimetric radar measurements

to weather phenomena?

• How to improve polarimetric radar

measurements

• How to use polarimetric radar data in

weather quantification and forecast

Course content

Ch. 1: characterization of geophysical

media

• Statistical/physical properties

• Electromagnetic properties

Ch. 2: Wave scattering by a single particle

• Scattering amplitude/cross section for

spherical/non-spherical paricle

• Rayleigh, Born, Mie theory, T-matrix

Content (continued)

Ch. 3: Scattering and propagation in media filled with

distributed particles

• Transmission matrix

• Attenuation/differential attenuation

• Phase/differential phase

• Covariance matrix

• Space/time/frequency correlation

Content (continued)

Ch. 4: Polarimetric signatures of hydrometers and

measurement

• Rain, snow, hail, melting

• clutter, noise …

• moment estimation

• correlation/spectrum estimation

• sampling errors

• optimal estimation

Content (continued)

Ch. 5: Applications in weather quantification and forecast

(partially taught by Dr. Ryzhkov)

• Fuzzy logic method for hydrometer classification

• Quantitative precipitation estimation (QPE)

• DSD retrieval

• Attenuation correction

• Model parameterization and initialization

Course structure

Hydrometeor

Characterization

Scattering by a

single particle

Scattering by a

collection of particles

Applications in weather observation,

quantification and forecast

Polarimetric signatures and

radar measurements