Polarimetric radar characteristics of storms with and without lightning activity

Mattos, Enrique Vieira; Machado, Luiz A. T.; Williams, Earle; Albrecht, Rachel I.

doi:10.1002/2016jd025142

Cited by 27 publications

(28 citation statements)

References 76 publications

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“…These layers were chosen due to the different physical behaviors related to the thunderstorm electrification process observed by Mattos et al . []. Figure presents the whisker plots for all four thunderstorm layers in the four different lifetimes.…”

Section: Statistical Evaluation Of the 46 Thunderstormsmentioning

confidence: 99%

“…Many works have demonstrated that electric fields in clouds can also influence the orientation of ice crystals with oblate and prolate shapes [Weinheimer and Few, 1987;Metcalf, 1993Metcalf, , 1995Krehbiel et al, 1996;Caylor and Chandrasekar, 1996;Metcalf, 1997;Foster and Hallett, 2002;Ventura et al, 2013;Mattos et al, 2016]. In conditions of strong electric field ice crystals are mostly vertically oriented.…”

Section: Introductionmentioning

confidence: 99%

“…In conditions of strong electric field ice crystals are mostly vertically oriented. When detected by polarimetric radars, these hydrometeors traditionally present negative values for differential propagation phase (Ф DP ) [Caylor and Chandrasekar, 1996;Ryzhkov and Zrnic, 2007;Carey et al, 2009] and negative K DP [Caylor and Chandrasekar, 1996;Carey et al, 2009;Hubbert et al, 2014a;Mattos et al, 2016]. For example, Caylor and Chandrasekar [1996] found that Ф DP and K DP gradually decrease and then abruptly increase after lightning.…”

Section: Introductionmentioning

confidence: 99%

“…The authors documented changes of 5°in Ф DP and a systematic minimum peak in K DP of approximately À0.9°km À1 in the height range 7-14 km just before lightning occurrences. More recently, Mattos et al [2016] documented the polarimetric behavior as a function of the lightning density and observed that negative K DP is observable only in conditions with the strongest lightning frequency. However, the larger unaligned graupel-ice crystals mixture could mask the electrical alignment of ice crystals as indicated by the change in K DP measurements as discussed in previous studies [Marshall et al, 2009;Carey et al, 2009].…”

Section: Introductionmentioning

confidence: 99%

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Electrification life cycle of incipient thunderstorms

et al. 2017

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This work evaluates how clouds evolve to thunderstorms in terms of microphysical characteristics to produce the first intracloud (IC) and cloud‐to‐ground (CG) lightning flashes. Observations of 46 compact isolated thunderstorms during the 2011/2012 spring‐summer in Southeast Brazil with an X‐band polarimetric radar and two‐ and three‐dimensional Lightning Location Systems demonstrated key parameters in a cloud's vertical structure that produce the initial electrification and lightning activity. The majority (98%) of the first CG flashes were preceded (by approximately 6 min) by intracloud (IC) lightning. The most important aspect of the observations going into this paper, which came originally from the visual examination of a large number of thunderstorms, is that an initial positive differential reflectivity (ZDR) (associated with supercooled raindrops) evolved to reduced ZDR (and even negative values) in the cloud layer between 0° and to −15°C before and during the time of the initial lightning, suggesting evolution from supercooled raindrops to frozen particles promoting the formation of conical graupel. An enhanced negative specific differential phase (KDP) (down to −0.5° km−1) in the glaciated layer (above −40°C) was predominantly observed at the time of the first CG flash, indicating that ice crystals, such as plates and columns, were being vertically aligned by a strong electric field. These results demonstrate that the observations of ZDR evolution in the mixed layer and negative KDP in the upper levels of convective cores may provide useful information on thunderstorm vigor and lightning nowcasting.

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Section: Statistical Evaluation Of the 46 Thunderstormsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrification life cycle of incipient thunderstorms

et al. 2017

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“…Also the 75th percentile retains information about the storm even if the convection is relatively shallow, whereas the median must have a storm of at least 6 km depth before showing a signal. Ignoring the data below 2.5 km eliminates the potentially misleading FIGURE 1 The accumulated rainfall from the radar composite on August 31, 2017 from 1200 to 1300, black crosses show the location of lightning strikes intensification of the melting layer (e.g., at 153 km in the top right panel of Figure 2) which contains little information about the microphysics of a thunderstorm (Mattos et al, 2016). It can be seen in Figure 2 that the more convective (1135 and 1140) timestamps have a smaller difference between the entire column method (the black line) and the above the melting layer method (the red line) than the more stratiform timestamp (1130).…”

Section: Storm Trackingmentioning

confidence: 99%

Intensification of single cell storms prior to lightning onset

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Stein

Harrison

et al. 2019

Atmospheric Science Letters

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Single cell storms in the United Kingdom can produce lightning, despite apparently only having developed to towering cumulus rather than cumulonimbus. Such marginal thunderstorms still present severe weather hazards but are difficult to identify and predict and therefore provide a warning. Observations from the Met Office radar mosaic and ATDNet (Arrival Time Difference Network) show that these single cell storms demonstrate a characteristic increase in the area of high reflectivity storm core during the 15 min prior to the first lightning. By using the Met Office Unified Model to investigate reflectivity development in modelled storms, a microphysical explanation for the observed reflectivity increase is identified. During a rapid reflectivity increase, the updraft area at the melting layer, the peak updraft velocity and the storm graupel mass increase. The three quantities examined are linked to each other and to the generation of charge within the storm. The production of graupel is promoted by the increase in updraft area and charge separation is enhanced by the faster peak updraft velocity. This explains some of the physical differences between single cell storms that produce lightning and apparently similar storm systems which do not. It also provides a new basis with which to predict lightning hazard for marginal storms.

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