Millimeter-Wavelength Radars: New Frontier in Atmospheric Cloud and Precipitation Research

Kollias, Pavlos; Clothiaux, Eugene E.; Miller, Mark A.; Albrecht, Bruce A.; Stephens, Graeme L.; Ackerman, Thomas P.

doi:10.1175/bams-88-10-1608

Cited by 226 publications

(166 citation statements)

References 64 publications

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“…within the CloudNet and the US ARM (Atmospheric Radiation Measurement) Program, Illingworth et al, 2007;Ackerman and Stokes, 2003;Mather and Voyles, 2013) and from a variety of ship-based and airborne platforms (Kollias et al, 2007). In space, the CloudSat 94 GHz cloud profiling radar has been operating since May 2006 (Stephens et al, 2008).…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

“…Millimetre radars are particularly attractive and effective because of their inherent compactness and portability, their high sensitivity and minimal susceptibility to Bragg scattering and ground clutter (Kollias et al, 2007). In the Rayleigh scattering regime the radar reflectivity factor Z is independent of radar wavelength while the radar backscattering cross section, proportional to λ −4 , is much greater at shorter wavelengths.…”

Section: Radar Scattering Properties At Millimetre Wavelengthsmentioning

confidence: 99%

“…The large sensitivity at shorter wavelengths comes at the price of strong absorption by atmospheric gases and by hydrometeors (Lhermitte, 1990;Kollias et al, 2007). For the EHF range, atmospheric windows (minima in the attenuation spectrum) are located at approximately 35 GHz (K a ), 94 GHz (W), 140 GHz (G), 215 GHz (G) and 342 GHz (see Fig.…”

Section: Gas Attenuationmentioning

confidence: 99%

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G band atmospheric radars: new frontiers in cloud physics

et al. 2014

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Abstract. Clouds and associated precipitation are the largest source of uncertainty in current weather and future climate simulations. Observations of the microphysical, dynamical and radiative processes that act at cloud scales are needed to improve our understanding of clouds. The rapid expansion of ground-based super-sites and the availability of continuous profiling and scanning multi-frequency radar observations at 35 and 94 GHz have significantly improved our ability to probe the internal structure of clouds in high temporal-spatial resolution, and to retrieve quantitative cloud and precipitation properties. However, there are still gaps in our ability to probe clouds due to large uncertainties in the retrievals.The present work discusses the potential of G band (frequency between 110 and 300 GHz) Doppler radars in combination with lower frequencies to further improve the retrievals of microphysical properties. Our results show that, thanks to a larger dynamic range in dual-wavelength reflectivity, dual-wavelength attenuation and dual-wavelength Doppler velocity (with respect to a Rayleigh reference), the inclusion of frequencies in the G band can significantly improve current profiling capabilities in three key areas: boundary layer clouds, cirrus and mid-level ice clouds, and precipitating snow.

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Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

Section: Radar Scattering Properties At Millimetre Wavelengthsmentioning

confidence: 99%

Section: Gas Attenuationmentioning

confidence: 99%

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G band atmospheric radars: new frontiers in cloud physics

et al. 2014

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“…Several examples of research areas in MMW weather radar are the general cloud physics associated with climate-affecting cloud-radiation interaction, the weather modification activities, etc. [20,21]. In Ka-band, 35.2 ∼ 36 GHz of frequency band was allotted for meteorological aids service with other applications such as radiolocation service.…”

Section: Ka-band Radar System Designmentioning

confidence: 99%

Weather Radar Network With Pulse Compression of Arbitrary Nonlinear Waveforms: Ka-Band Test-Bed and Initial Observations

Kim¹

2010

PIER B

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Abstract-Short-wavelength radar networks are expected to complement current long-range weather radar systems. Accordingly, we proposed a configuration for such a network constituting pulse compression radars in order to use frequency resources efficiently and obtain multi-static information. We developed high resolution Ka-band pulse compression weather radar system as a test-bed. Using a commercial direct digital synthesizer (DDS) and field programmable gate array (FPGA) control, we generated linear and arbitrary nonlinear frequency modulated waveforms for low range sidelobes. Further, we completed a high duty factor system with a solid-state power amplifier. In a vertical-pointing mode, we were able to employ the developed radar to detect moderate rainfall up to 15 km. Details of the system design, hardware structure, data acquisition and processing algorithms were described. To validate the performance of the proposed radar system, we conducted several experiments by measuring cloud, snow and rain.

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“…1 Among cloud-detection instruments, millimeter-wavelength radar is widely used to detect the dynamical and structural properties of cirrus clouds. 2,3 To retrieve the macro-and micro-physical properties of clouds from echo information of millimeter-wavelength radar, the interaction between the electromagnetic wave and ice particle must be understood; this is typically computed using electromagnetic scattering theory. There are a variety of numerical algorithms to calculate the scattering properties of non-spherical particles: for example, T-matrix, 4 the finite-difference time domain, 5 the discrete dipole approximation, 6 finite element methods, 7 and the method of moments.…”

Section: Introductionmentioning

confidence: 99%

Radar cross-section measurements of ice particles using vector network analyzer

Wang

Zhang

et al. 2016

AIP Advances

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We carried out radar cross-section (RSC) measurements of ice particles in a microwave anechoic chamber at Nanjing University of Information Science and Technology. We used microwave similarity theory to enlarge the size of particle from the micrometer to millimeter scale and to reduce the testing frequency from 94 GHz to 10 GHz. The microwave similarity theory was validated using the method of moments for single metal sphere, single dielectric sphere, and spherical and non-spherical dielectric particle swarms. The differences between the retrieved and theoretical results at 94 GHz were 0.016117%, 0.0023029%, 0.027627%, and 0.0046053%, respectively. We proposed a device that can measure the RCS of ice particles in the chamber based on the S21 parameter obtained from vector network analyzer. On the basis of the measured S21 parameter of the calibration material (metal plates) and their corresponding theoretical RCS values, the RCS values of a spherical Teflon particle swarm and cuboid candle particle swarm was retrieved at 10 GHz. In this case, the differences between the retrieved and theoretical results were 12.72% and 24.49% for the Teflon particle swarm and cuboid candle swarm, respectively.

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Millimeter-Wavelength Radars: New Frontier in Atmospheric Cloud and Precipitation Research

Abstract: Millimeter-wavelength radars bridge an observational gap in Earth's hydrological cycle by adequately detecting clouds and precipitation, thus offering a unique and more holistic view of the water cycle in action.

Cited by 226 publications

References 64 publications

G band atmospheric radars: new frontiers in cloud physics

G band atmospheric radars: new frontiers in cloud physics

Weather Radar Network With Pulse Compression of Arbitrary Nonlinear Waveforms: Ka-Band Test-Bed and Initial Observations

Radar cross-section measurements of ice particles using vector network analyzer

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