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  • Author or Editor: Dusan Zrnic x
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Dušan S. Zrnić

This is a version of a speech presented at the 27th Conference on Radar Meteorology. Relative advantages of polarimetry are contrasted with the advantages accrued by the introduction of radar into meteorology and by the addition of Doppler measurements. A description of present interests as perceived by the author follows, and possible future trends are suggested.

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Dusan S. Zrnic
and
Alexander V. Ryzhkov

This paper is an overview of weather radar polarimetry emphasizing surveillance applications. The following potential benefits to operations are identified: improvement of quantitative precipitation measurements, discrimination of hail from rain with possible determination of sizes, identification of precipitation in winter storms, identification of electrically active storms, and distinction of biological scatterers (birds vs insects). Success in rainfall measurements is attributed to unique properties of differential phase. Referrals to fields of various polarimetric variables illustrate the signatures associated with different phenomena. It is argued that classifying hydrometeors is a necessary step prior to proper quantification of the water substance. The promise of polarimetry to accomplish classification is illustrated with an application to a hailstorm.

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Anthony J. Illingworth
and
Dusan Zrnic

A workshop on weather radar polarimetry for research and operational applications was held on 22 and 23 February 1994 at the National Center for Atmospheric Research. Polarization radar can provide estimates of the shapes, sizes, phase, and fall orientations of hydrometeors. This information can be used to remove some of the ambiguities present when only the reflectivity is measured. The morning of 22 February was devoted to 16 short presentations highlighting recent advances in polarimetric radar. The afternoon was dedicated to four discussion sessions that further developed important topics. On the following day, plans for the upgrading and development of the existing NCAR polarization radar capability were presented and debated. The workshop resulted in four recommendations: three of which proposed specific field measurement programs to quantify the potential improvements provided by the polarization techniques.

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Pravas R. Mahapatra
,
Richard J. Doviak
, and
Dusan S. Zrnić

A detailed and unique multisensor observation of an undular bore is presented. The data include those from rawinsonde, satellite, two Doppler radars, and a tall instrumented tower. Noteworthy are Doppler radar images that resolve the wave's characteristics and capture a good part of its spatial extent. The basic parameters of the wave train are established from the observations.

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Alexander V. Ryzhkov
,
Terry J. Schuur
,
Donald W. Burgess
,
Pamela L. Heinselman
,
Scott E. Giangrande
, and
Dusan S. Zrnic

As part of the evolution and future enhancement of the Next Generation Weather Radars (NEXRAD), the National Severe Storms Laboratory recently upgraded the KOUN Weather Surveillance Radar-1988 Doppler (WSR-88D) to include a polarimetric capability. The proof of concept was tested in central Oklahoma during a 1-yr demonstration project referred to as the Joint Polarization Experiment (JPOLE). This paper presents an overview of polarimetric algorithms for rainfall estimation and hydrometeor classification and their performance during JPOLE. The quality of rainfall measurements is validated on a large dataset from the Oklahoma Mesonet and Agricultural Research Service Micronet rain gauge networks. The comparison demonstrates that polarimetric rainfall estimates are often dramatically superior to those provided by conventional rainfall algorithms. Using a synthetic R(Z, K DP, Z DR) polarimetric rainfall relation, rms errors are reduced by a factor of 1.7 for point measurements and 3.7 for areal estimates [when compared to results from a conventional R(Z) relation]. Radar data quality improvement, hail identification, rain/snow discrimination, and polarimetric tornado detection are also illustrated for selected events.

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Robert Palmer
,
David Bodine
,
Pavlos Kollias
,
David Schvartzman
,
Dusan Zrnić
,
Pierre Kirstetter
,
Guifu Zhang
,
Tian-You Yu
,
Matthew Kumjian
,
Boonleng Cheong
,
Scott Collis
,
Stephen Frasier
,
Caleb Fulton
,
Kurt Hondl
,
James Kurdzo
,
Tomoo Ushio
,
Angela Rowe
,
Jorge Salazar-Cerrenˉo
,
Sebastián Torres
,
Mark Weber
, and
Mark Yeary

Abstract

The scientific community has expressed interest in the potential of phased array radars (PARs) to observe the atmosphere with finer spatial and temporal scales. Although convergence has occurred between the meteorological and engineering communities, the need exists to increase access of PAR to meteorologists. Here, we facilitate these interdisciplinary efforts in the field of ground-based PARs for atmospheric studies. We cover high-level technical concepts and terminology for PARs as applied to studies of the atmosphere. A historical perspective is provided as context along with an overview of PAR system architectures, technical challenges, and opportunities. Envisioned scan strategies are summarized because they are distinct from traditional mechanically scanned radars and are the most advantageous for high-resolution studies of the atmosphere. Open access to PAR data is emphasized as a mechanism to educate the future generation of atmospheric scientists. Finally, a vision for the future of operational networks, research facilities, and expansion into complementary radar wavelengths is provided.

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Robert Palmer
,
David Whelan
,
David Bodine
,
Pierre Kirstetter
,
Matthew Kumjian
,
Justin Metcalf
,
Mark Yeary
,
Tian-You Yu
,
Ramesh Rao
,
John Cho
,
David Draper
,
Stephen Durden
,
Stephen English
,
Pavlos Kollias
,
Karen Kosiba
,
Masakazu Wada
,
Joshua Wurman
,
William Blackwell
,
Howard Bluestein
,
Scott Collis
,
Jordan Gerth
,
Aaron Tuttle
,
Xuguang Wang
, and
Dusan Zrnić
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Mark Weber
,
Kurt Hondl
,
Nusrat Yussouf
,
Youngsun Jung
,
Derek Stratman
,
Bryan Putnam
,
Xuguang Wang
,
Terry Schuur
,
Charles Kuster
,
Yixin Wen
,
Juanzhen Sun
,
Jeff Keeler
,
Zhuming Ying
,
John Cho
,
James Kurdzo
,
Sebastian Torres
,
Chris Curtis
,
David Schvartzman
,
Jami Boettcher
,
Feng Nai
,
Henry Thomas
,
Dusan Zrnić
,
Igor Ivić
,
Djordje Mirković
,
Caleb Fulton
,
Jorge Salazar
,
Guifu Zhang
,
Robert Palmer
,
Mark Yeary
,
Kevin Cooley
,
Michael Istok
, and
Mark Vincent

Abstract

This article summarizes research and risk reduction that will inform acquisition decisions regarding NOAA’s future national operational weather radar network. A key alternative being evaluated is polarimetric phased-array radar (PAR). Research indicates PAR can plausibly achieve fast, adaptive volumetric scanning, with associated benefits for severe-weather warning performance. We assess these benefits using storm observations and analyses, observing system simulation experiments, and real radar-data assimilation studies. Changes in the number and/or locations of radars in the future network could improve coverage at low altitude. Analysis of benefits that might be so realized indicates the possibility for additional improvement in severe-weather and flash-flood warning performance, with associated reduction in casualties. Simulations are used to evaluate techniques for rapid volumetric scanning and assess data quality characteristics of PAR. Finally, we describe progress in developing methods to compensate for polarimetric variable estimate biases introduced by electronic beam-steering. A research-to-operations (R2O) strategy for the PAR alternative for the WSR-88D replacement network is presented.

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Pavlos Kollias
,
Robert Palmer
,
David Bodine
,
Toru Adachi
,
Howie Bluestein
,
John Y. N. Cho
,
Casey Griffin
,
Jana Houser
,
Pierre. E. Kirstetter
,
Matthew R. Kumjian
,
James M. Kurdzo
,
Wen Chau Lee
,
Edward P. Luke
,
Steve Nesbitt
,
Mariko Oue
,
Alan Shapiro
,
Angela Rowe
,
Jorge Salazar
,
Robin Tanamachi
,
Kristofer S. Tuftedal
,
Xuguang Wang
,
Dusan Zrnić
, and
Bernat Puigdomènech Treserras

Abstract

Phased array radars (PARs) are a promising observing technology, at the cusp of being available to the broader meteorological community. PARs offer near-instantaneous sampling of the atmosphere with flexible beam forming, multifunctionality, and low operational and maintenance costs and without mechanical inertia limitations. These PAR features are transformative compared to those offered by our current reflector-based meteorological radars. The integration of PARs into meteorological research has the potential to revolutionize the way we observe the atmosphere. The rate of adoption of PARs in research will depend on many factors, including (i) the need to continue educating the scientific community on the full technical capabilities and trade-offs of PARs through an engaging dialogue with the science and engineering communities and (ii) the need to communicate the breadth of scientific bottlenecks that PARs can overcome in atmospheric measurements and the new research avenues that are now possible using PARs in concert with other measurement systems. The former is the subject of a companion article that focuses on PAR technology while the latter is the objective here.

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