Post on 24-Feb-2022
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