| Full text | |
| Author(s): |
Mattos, Enrique V.
;
Machado, Luiz A. T.
;
Williams, Earle R.
;
Goodman, Steven J.
;
Blakeslee, Richard J.
;
Bailey, Jeffrey C.
Total Authors: 6
|
| Document type: | Journal article |
| Source: | JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES; v. 122, n. 8, p. 4670-4697, APR 27 2017. |
| Web of Science Citations: | 4 |
| Abstract | |
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 6min) 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 (Z(DR)) (associated with supercooled raindrops) evolved to reduced Z(DR) (and even negative values) in the cloud layer between 0 degrees and to -15 degrees 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 (K-DP) (down to -0.5 degrees km(-1)) in the glaciated layer (above -40 degrees 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 Z(DR) evolution in the mixed layer and negative K-DP in the upper levels of convective cores may provide useful information on thunderstorm vigor and lightning nowcasting. (AU) | |
| FAPESP's process: | 11/13673-8 - Radar and electrical studies of deep convection in Vael do Paraíba during CHUVA |
| Grantee: | Luiz Augusto Toledo Machado |
| Support Opportunities: | Research Grants - Visiting Researcher Grant - International |
| FAPESP's process: | 15/14497-0 - Nowcasting of intense thunderstorms and understanding of the physical processes inside clouds: the SOS-CHUVA (Severe Weather Observation System) |
| Grantee: | Luiz Augusto Toledo Machado |
| Support Opportunities: | Research Program on Global Climate Change - Thematic Grants |
| FAPESP's process: | 09/15235-8 - Cloud processes of the main precipitation systems in Brazil: a contribution to cloud resolving modeling and to the GPM (Global Precipitation Measurement) |
| Grantee: | Luiz Augusto Toledo Machado |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 11/18217-0 - The impact of cloud microphysics on thunderstorms electrification |
| Grantee: | Enrique Vieira Mattos |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 13/04292-6 - Microphysical characteristics of isolated storms before and during the production of the first cloud-to-ground flash |
| Grantee: | Enrique Vieira Mattos |
| Support Opportunities: | Scholarships abroad - Research Internship - Doctorate |