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Atmosphere
Special Issues
Electromagetics and Polarimetric Weather Radar
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Electromagetics and Polarimetric Weather Radar

A special issue of Atmosphere (ISSN 2073-4433). This special issue belongs to the section "Meteorology".

Deadline for manuscript submissions: closed (15 January 2020) | Viewed by 22548

Special Issue Editors

Prof. Dr. Viswanathan Bringi

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Guest Editor
Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO, USA
Interests: polarimetric radar; scattering; microphysics
Dr. Merhala Thurai

E-Mail
Guest Editor
Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO, USA
Interests: rain microphysics; radar rainfall estimates; radiowave propagation

Special Issue Information

Dear Colleagues,

Electromagnetics has played a central role in the development and application of polarimetric weather radars, in particular, the concepts of scattering and propagation of waves and the antenna voltage equation. The modern era of the polarimetric radar began in the early 1970s, driven largely by radio wave propagation interest in the characterization of attenuation and depolarization of EM waves due to rain and ice particles along Earth–satellite links at microwave and millimeter wavelengths. Related advances in accurate dual-polarization antenna feed design, as well as precise reflector manufacturing methods and microwave circuits, driven by stringent Earth station antenna requirements also contributed, in large part, to weather radar polarimetry.

Starting from the early 1980s to mid-1990s, rapid advancements in weather radar polarimetry occurred in the United Kingdom, the United States, Germany, and Italy. Much of this early work involved researchers with strong backgrounds in electromagnetic scattering theory and microwave engineering. Their work led to a wider recognition of the intrinsic value of polarimetry in radar meteorology, which, in the next two decades, led to strong research contributions by meteorologists and non-specialists. This was aided by the ready availability of numerical scattering software tools, reliable and high data quality from polarimetric radars, and advances in modeling of microphysical processes. Currently, the operational deployment of polarimetric, Doppler weather radars by nearly all weather service agencies world-wide has led to research advancements scarcely foreseen by the early pioneers, and continues to grow with the interaction of numerical microphysical models of precipitation growth and evolution, with advanced scattering models and more accurate radar measurements.

This Special Issue, while largely dedicated to the role of electromagnetics in dual-polarization weather radars, has a much broader scope and includes radio wave propagation, scattering models for complex shaped hydrometeors, the polarimetric-basis for retrieval of microphysical parameters and processes, microphysical models and coupled radar forward models, rainfall estimation, winter precipitation estimation, hydrometeor classification, and so on. With the rapid advances in phased array technology, articles describing the polarimetric measurement accuracies or recent measurements from such advanced radars are invited. Articles involving the polarimetric radar studies of non-meteorological phenomena, such as insects and bird migration, are also welcome.

Prof. Dr. Viswanathan Bringi
Dr. Merhala Thurai
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Atmosphere is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Electromagnetic scattering
  • Polarimetric weather radar
  • Quantitative precipitation estimation
  • Microphysical–electromagnetic interaction
  • Radio wave propagation

Published Papers (6 papers)

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Research

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24 pages, 9907 KiB  
Article
Of Fire and Smoke Plumes, Polarimetric Radar Characteristics
by Dusan Zrnic, Pengfei Zhang, Valery Melnikov and Djordje Mirkovic
Atmosphere 2020, 11(4), 363; https://doi.org/10.3390/atmos11040363 - 09 Apr 2020
Cited by 9 | Viewed by 3856
Abstract
Weather surveillance radars routinely detect smoke of various origin. Of particular significance to the meteorological community are wildfires in forests and/or prairies. For example, one responsibility of the National Weather Service in the USA is to forecast fire outlooks as well as to [...] Read more.
Weather surveillance radars routinely detect smoke of various origin. Of particular significance to the meteorological community are wildfires in forests and/or prairies. For example, one responsibility of the National Weather Service in the USA is to forecast fire outlooks as well as to monitor wildfire evolution. Polarimetric variables have enabled relatively easy recognitions of smoke plumes in data fields of weather radars. Presented here are the fields of these variables from smoke plumes caused by grass fire, brush fire, and forest fire. Histograms of polarimetric data from plumes contrast these cases. Most of the data are from the polarimetric Weather Surveillance Radar 1988 Doppler (WSR-88D aka NEXRAD, 10 cm wavelength); hence, the wavelength does not influence these comparisons. Nevertheless, in one case, simultaneous observations of a plume by the operational Terminal Doppler Weather Radar (TDWR, 5 cm wavelength) and a WSR-88D is used to infer backscattering characteristic and, hence, sizes of dominant contributors to the returns. To interpret these measurements, Computational Electromagnetics (CEM) tools are applied. For one wildfire from Oklahoma, radar and satellite (GOES-16, Geostationary Operational Environmental Satellite) images are analyzed. The case demonstrates a potential to forecast fire intensification caused by a very rapid cold front. Finally, we suggest a possible way to extract the smoke plume return from the class of nonmeteorological scatterers. Full article
(This article belongs to the Special Issue Electromagetics and Polarimetric Weather Radar)
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14 pages, 4818 KiB  
Article
Analysis of Raindrop Shapes and Scattering Calculations: The Outer Rain Bands of Tropical Depression Nate
by Merhala Thurai, Sophie Steger, Franz Teschl and Michael Schönhuber
Atmosphere 2020, 11(1), 114; https://doi.org/10.3390/atmos11010114 - 18 Jan 2020
Cited by 7 | Viewed by 3263
Abstract
Tropical storm Nate, which was a powerful hurricane prior to landfall along the US Gulf coast, traversed north and weakened considerably to a tropical depression as it moved near an instrumented site in Hunstville, AL. The outer rain bands lasted 18 h (03:00 [...] Read more.
Tropical storm Nate, which was a powerful hurricane prior to landfall along the US Gulf coast, traversed north and weakened considerably to a tropical depression as it moved near an instrumented site in Hunstville, AL. The outer rain bands lasted 18 h (03:00 to 21:00 UTC on 08 October 2017) and a 2D-video disdrometer (2DVD) captured the event which was shallow at times and indicative of pure warm rain processes. The 2DVD measurements are used for 3D reconstruction of drop shapes (including the rotationally asymmetric drops) and the drop-by-drop scattering matrix has been computed using Computer Simulation Technology integral equation solver for drop sizes >2.5 mm. From the scattering matrix elements, the polarimetric radar observables are simulated by integrating over 1 min consecutive segments of the event. These simulated values are compared with dual-polarized C-band radar data located at 15 km range from the 2DVD site to evaluate the contribution of the asymmetric drop shapes, specifically to differential reflectivity. The drop fall velocities and drop horizontal velocities in terms of magnitude and direction, all being derived from each drop image from two orthogonal cameras of the 2DVD, are also considered. Full article
(This article belongs to the Special Issue Electromagetics and Polarimetric Weather Radar)
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14 pages, 3406 KiB  
Article
Ice Hydrometeor Shape Estimations Using Polarimetric Operational and Research Radar Measurements
by Sergey Y. Matrosov
Atmosphere 2020, 11(1), 97; https://doi.org/10.3390/atmos11010097 - 14 Jan 2020
Cited by 7 | Viewed by 2914
Abstract
A polarimetric radar method to estimate mean shapes of ice hydrometeors was applied to several snowfall and ice cloud events observed by operational and research weather radars. The hydrometeor shape information is described in terms of their aspect ratios, r, which represent [...] Read more.
A polarimetric radar method to estimate mean shapes of ice hydrometeors was applied to several snowfall and ice cloud events observed by operational and research weather radars. The hydrometeor shape information is described in terms of their aspect ratios, r, which represent the ratio of particle minor and major dimensions. The method is based on the relations between depolarization ratio (DR) estimates and aspect ratios. DR values, which are a proxy for circular depolarization ratio, were reconstructed from radar variables of reflectivity factor, Ze, differential reflectivity, ZDR, and copolar correlation coefficient ρhv, which are available from radar systems operating in either simultaneous or alternate transmutation of horizontally and vertically polarized signals. DR-r relations were developed for retrieving aspect ratios and their sensitivity to different assumptions and model uncertainties were discussed. To account for changing particle bulk density, which is a major contributor to the retrieval uncertainty, an approach is suggested to tune the DR-r relations using reflectivity-based estimates of characteristic hydrometeor size. The analyzed events include moderate snowfall observed by an operational S-band weather radar and a precipitating ice cloud observed by a scanning Ka-band cloud radar at an Arctic location. Uncertainties of the retrievals are discussed. Full article
(This article belongs to the Special Issue Electromagetics and Polarimetric Weather Radar)
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15 pages, 7858 KiB  
Article
Analysis of a Precipitation System that Exists above Freezing Level Using a Multi-Parameter Phased Array Weather Radar
by Nobuhiro Takahashi
Atmosphere 2019, 10(12), 755; https://doi.org/10.3390/atmos10120755 - 28 Nov 2019
Cited by 2 | Viewed by 3017
Abstract
An X-band multi-parameter phased array weather radar (MP-PAWR) was developed in 2017. The scan concept of the MP-PAWR is electronic scanning in elevation by combining fan beam transmissions and pencil beam receptions with digital beam-forming techniques and mechanical scanning along the azimuth. The [...] Read more.
An X-band multi-parameter phased array weather radar (MP-PAWR) was developed in 2017. The scan concept of the MP-PAWR is electronic scanning in elevation by combining fan beam transmissions and pencil beam receptions with digital beam-forming techniques and mechanical scanning along the azimuth. The MP-PAWR realized three-dimensional (60 km in radius and 15 km in height) observations without gaps of 30 s. Although the MP-PAWR is supposed to be suitable for observations of rapidly changing convective systems, it can be advantageous for observations of stratiform rainfall because of continuous vertical pointing observations and its ability to apply the Velocity Azimuth Display (VAD) method with a constant radius for a vertical profile of dynamic parameters such as divergence and deformation. In this study, a precipitation system that existed mainly above the freezing level (in this case, it was approximately 5 km in height) observed from 14:00 to 17:00 Japan Standard Time on 6 September 2018 was analyzed using MP-PAWR data. The averaged area of the vertical profile of Z, and the Doppler velocity with fixed elevation showed a stationary structure with time. The average differential reflectivity factor (ZDR) profile with fixed elevation angles showed values that were close to zero and increased with height. Similar characteristics were shown in the average Specific Differential Phase (KDP) profile. Vertical pointing data, especially for Z, ZDR, and Doppler velocity, were utilized when the echo passed over the radar site, and the Doppler velocity showed the acceleration of fall speed below the freezing level. The vertical profile of divergence with a fixed radius was calculated using the VAD method, and the vertical velocity was calculated using the fall speed profile from the vertical pointing data and by assuming the vertical velocity at the cloud base was zero. The results indicate that the updraft region corresponds to higher ZDR and KDP regions. Full article
(This article belongs to the Special Issue Electromagetics and Polarimetric Weather Radar)
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Review

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34 pages, 13076 KiB  
Review
What Polarimetric Weather Radars Offer to Cloud Modelers: Forward Radar Operators and Microphysical/Thermodynamic Retrievals
by Alexander V. Ryzhkov, Jeffrey Snyder, Jacob T. Carlin, Alexander Khain and Mark Pinsky
Atmosphere 2020, 11(4), 362; https://doi.org/10.3390/atmos11040362 - 08 Apr 2020
Cited by 20 | Viewed by 4555
Abstract
The utilization of polarimetric weather radars for optimizing cloud models is a next frontier of research. It is widely understood that inadequacies in microphysical parameterization schemes in numerical weather prediction (NWP) models is a primary cause of forecast uncertainties. Due to its ability [...] Read more.
The utilization of polarimetric weather radars for optimizing cloud models is a next frontier of research. It is widely understood that inadequacies in microphysical parameterization schemes in numerical weather prediction (NWP) models is a primary cause of forecast uncertainties. Due to its ability to distinguish between hydrometeors with different microphysical habits and to identify “polarimetric fingerprints” of various microphysical processes, polarimetric radar emerges as a primary source of needed information. There are two approaches to leverage this information for NWP models: (1) radar microphysical and thermodynamic retrievals and (2) forward radar operators for converting the model outputs into the fields of polarimetric radar variables. In this paper, we will provide an overview of both. Polarimetric measurements can be combined with cloud models of varying complexity, including ones with bulk and spectral bin microphysics, as well as simplified Lagrangian models focused on a particular microphysical process. Combining polarimetric measurements with cloud modeling can reveal the impact of important microphysical agents such as aerosols or supercooled cloud water invisible to the radar on cloud and precipitation formation. Some pertinent results obtained from models with spectral bin microphysics, including the Hebrew University cloud model (HUCM) and 1D models of melting hail and snow coupled with the NSSL forward radar operator, are illustrated in the paper. Full article
(This article belongs to the Special Issue Electromagetics and Polarimetric Weather Radar)
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24 pages, 385 KiB  
Review
Polarization Weather Radar Development from 1970–1995: Personal Reflections
by Viswanathan Bringi and Dusan Zrnic
Atmosphere 2019, 10(11), 714; https://doi.org/10.3390/atmos10110714 - 15 Nov 2019
Cited by 8 | Viewed by 4233
Abstract
The modern era of polarimetric radar begins with radiowave propagation research starting in the early 1970s with applications to measurement and modeling of wave attenuation in rain and depolarization due to ice particles along satellite–earth links. While there is a rich history of [...] Read more.
The modern era of polarimetric radar begins with radiowave propagation research starting in the early 1970s with applications to measurement and modeling of wave attenuation in rain and depolarization due to ice particles along satellite–earth links. While there is a rich history of radar in meteorology after World War II, the impetus provided by radiowave propagation requirements led to high-quality antennas and feeds. Our journey starts by describing the key institutions and personnel responsible for development of weather radar polarimetry. The early period was dominated by circularly polarized radars for propagation research and at S band (frequency near 3 GHz) for hail detection. By the mid to late 70s, a paradigm shift occurred which led to the dominance of linear polarizations with applications to slant path attenuation prediction as well as estimation of rain rates and inferences of precipitation physics. The period from the early 1980s to 1995 can be considered as the “golden” period of rapid research that brought in meteorologists, cloud physicists, and hydrologists. This article describes the evolution of this technology from the vantage point of the authors. Their personal reflections and “behind the scenes” descriptions offer a glimpse into the inner workings at several key institutions which cannot be found elsewhere. Full article
(This article belongs to the Special Issue Electromagetics and Polarimetric Weather Radar)
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