Lightning Investigation with Radar

Williams, Earle; Mazur, Vladislav; Geotis, Spiros G.

doi:10.1007/978-1-935704-15-7_18

Cited by 5 publications

(8 citation statements)

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“…From Table 1, the 36 to 55 dBZ range of reflectivities observed by the 32.8 cm wavelength Profiler falls nicely within the inverse square wavelength dependence presented in Williams et al [1990]. This is surprising because it was expected that the lightning would reflect better at the longer wavelengths [See discussion in Williams et al , 1990; Atlas , 1959]. Nevertheless it is clear that all the echoes at UHF exceed 36 dBZ and are therefore readily detected relative to the typical reflectivities of snow and light to moderate rain at these wavelengths.…”

Section: Related Observationssupporting

confidence: 76%

“…This variability has only permitted Williams et al [1990] to plot histograms of the distribution of volume reflectivity at several wavelengths. From Table 1, the 36 to 55 dBZ range of reflectivities observed by the 32.8 cm wavelength Profiler falls nicely within the inverse square wavelength dependence presented in Williams et al [1990]. This is surprising because it was expected that the lightning would reflect better at the longer wavelengths [See discussion in Williams et al , 1990; Atlas , 1959].…”

Section: Related Observationsmentioning

confidence: 99%

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Radar echoes from lightning and their microphysical environment

Atlas

Williams

2003

Geophysical Research Letters

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A UHF Profiler radar has detected lightning echoes which occurred preferentially in a “balance layer”, the stratum of mean zero Doppler velocity with rising small ice particles and falling graupel and hail, thus providing the conditions for collisional charging and lightning. The results support prior findings of the role of the balance layer in lightning generation. The 32.8 cm Profiler radar is particularly well suited for these observations because the lightning echoes are not masked by the precipitation echoes, thus allowing simultaneous measurement of the microphysical and kinematic properties.

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Section: Related Observationssupporting

confidence: 76%

Section: Related Observationsmentioning

confidence: 99%

Radar echoes from lightning and their microphysical environment

Atlas

Williams

2003

Geophysical Research Letters

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“…1988;Buechler et al 1990;Goodman and Buechler 1990;Orville 1990;Williams et al 1990;Schuur ef al. 1991;Goodman and Raghaven 1993) of the dynamical, microphysical and electrical properties of individual thunderstorms and of mesoscale complexes producing lightning indicate strong correlations between lightning flash-rate f ( s -' ) and other properties of the systems, such as precipitation flux, updraught speed, peak radar reflectivity, total ice and water content of the clouds, and convective available potential energy (CAPE).…”

Section: Introductionmentioning

confidence: 94%

A computational study of the relationships linking lightning frequency and other thundercloud parameters

Baker

Christian

Latham

1995

Quart J Royal Meteoro Soc

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SUMMARYIn an effort to optimize the value of global-scale measurements obtained with the NASA/MSFC satelliteborne Lightning Imaging System (LIS), a simple computational model of thundercloud electrification has been developed, from which it is possible to derive crude relationships between lightning frequency f (which LIS will measure) and cloud parameters such as radar reflectivity Z, precipitation rate P , updraught speed w , cloud radius R, ice-crystal concentration Ni and graupel-pellet concentration N g . Electric field-growth is assumed to occur via the non-inductive charging mechanism, for both Fletcher and Hallett-Mossop types of glaciation mechanisms. A simple criterion is used to distinguish between cloud-to-ground and intracloud lightning discharges. f is found to be especially sensitive to w in situations where, as updraught speed increases, the temperature at balance level, Tbal, of the upper boundary of the charging zone falls. In these circumstances Ni and the sizes of the ice hydrometeors are significantly increased, with a corresponding enhancement of the effectiveness of charge transfer.Over a wide range of conditions, f is found to be roughly proportional to the first power of the parameters R, N,, N g and Z and (in some circumstances) to at least the sixth power of w. The relationship between f and P depends critically on whether or not w and Tbal are strongly linked. Hallett-Mossop glaciation is capable of producing inverted-polarity lightning from thunderclouds; Fletcher glaciation is not.

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“…Studies of radar echoes with the Millstone Hill UHF radar on 440 MHz relied on analog range-time intensity recording [Williams et al, 1989]. In the review of lightning investigations with radar by Williams et al [1990], the wavelength dependence of lightning echoes is accepted to favor the longer wavelengths. The longest radar wavelength applied so far in more recent experiments was 1.95 m [Mazur, 1986].…”

Section: Rc•ti'ger Et Al: Lightning Echoes Observed With Vhf St Radarmentioning

confidence: 99%

“…Larsen and ROttger [ 1987] described the thunderstorm event of June 1978 in some more detail with emphasis on reflectivity due to turbulence and precipitation, and ROttger [1981] pointed out that the spaced antenna method would be most suitable for studying lightning echoes and their environment with the VHF radar interferometer technique. Proposals for future directions in radar studies of lightning were presented in the review by Williams et al [1990], and endeavors to study lightning echoes on lower frequencies were undertaken a few years ago at the middle and upper atmosphere (MU) VHF radar in Japan (operating on 46.5 MHz). To the authors' information, these did not yield suitable results (S. Fukao and T. Sato, personal communication, 1993), since thunderstorms were rare during these radar campaigns.…”

Section: Rc•ti'ger Et Al: Lightning Echoes Observed With Vhf St Radarmentioning

confidence: 99%

Characteristics of lightning echoes observed with VHF ST radar

Röttger¹,

Liu²,

Chen³

et al. 1995

Radio Science

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The development of tropospheric convection was observed with the Chung‐Li VHF stratosphere‐troposphere (ST) radar in Taiwan, Republic of China. Deep convection evolved into thunderstorms during which radar echoes from lightning were recorded with a particular high time resolution program. These lightning echoes usually exist for only several tens to a few hundred milliseconds. To investigate the fine structure in the amplitude and phase of the lightning returns, the necessary time resolution has to be in the order of a few milliseconds. Such time resolutions are for the first time applied with VHF ST radar and the initial results are presented in this paper. Rapid jumps in the phase path were occurring together with sudden amplitude changes. This indicates that the scattering regions change their position, which could be on different branches of the lightning stroke. Large radial velocities of the lightning scattering regions up to several tens of meters per second were observed. Also, strong velocity shears were noticed in these lightning echo regions. Power peaks in Doppler spectra corresponding to velocities of about 300 m s−1 were occasionally detected. It is contemplated that these are caused by Bragg scattering from sound waves resulting from the lightning shock wave. Also a periodic velocity and amplitude modulation of a thin sheet of radar reflectivity was observed which one could attribute to infra‐sound with a frequency of about 6–7 Hz. Preliminary conclusions are drawn finally to confirm that our observations are generally consistent with backscatter from lightning.

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Lightning Investigation with Radar

Cited by 5 publications

References 0 publications

Radar echoes from lightning and their microphysical environment

Radar echoes from lightning and their microphysical environment

A computational study of the relationships linking lightning frequency and other thundercloud parameters

Characteristics of lightning echoes observed with VHF ST radar

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