Cloud-to-ground lightning and Mesoscale Convective Systems

Abstract

This work analyzes some of the physical and microphysical properties of Mesoscale Convective Systems (MCS) and cloud-to-ground lightning. Satellite data from the GOES-10 infrared and NOAA-18 and TRMM microwave channels and lightning information from the Brazilian Lightning Detection Network (BrasilDAT) were utilized for the period from 2007 to 2009. Based on an automatic MCS detection method, 720 MCS life cycles were identified during the period and region of study, with a lightning detection efficiency of over 90%. During the diurnal cycle, the electrical activity maximum occurred close to the time of maximum convective cloud fraction and 3 hours after the maximum normalized area expansion rate. The diurnal cycles of both properties are modulated by diurnal heating and thus could be used to monitor the diurnal variability of lightning occurrence. The area growth during the initial phase of the MCS exerted a strong influence on their size-duration, and potential for electrical activity during their life cycle. The average lightning life cycle exhibited a maximum close to MCS maturation, while the maximum of the average lightning density occurred close to the initial MCS life cycle stages. The growth rate of electrical activity during the early stages can indicate the strength of convection and the possible duration of systems with lightning occurrence. The strong condensation processes and mass flux during the growth phase of the systems can provide favorable conditions for cloud electrification and lightning occurrence. A comparison of high microwave frequencies with lightning data showed a strong relationship of the vertically integrated ice content and particle size with lightning occurrence. The polarization difference in the 85 GHZ channel showed that electrical activity increases linearly with polarization reduction, associated with a high value of Pearson's correlation coefficient. This suggests that regions with more intense electrical activity are predominantly located in areas with a high concentration of larger ice particles that are preferentially oriented vertically, due to the existence of intense updrafts and the electric field. These results demonstrate the potential use of thermodynamic, dynamic and microphysical characteristics for analyzing storm severity and as additional information for monitoring of electrical activity over large regions that lack ground-based lightning sensors and for nowcasting.

Observed impact of land uses and soil types on cloud-to-ground lightning in Castilla-Leon (Spain)

“…mountain height), and shows strong seasonal and diurnal patterns related to the timing of the most intense convective storms (Rivas Soriano et al, 2005;Mattos and Machado, 2011). This is clearly seen in Figure 3b, where the relationship between the total (2000-2010) CG flash density and altitude is shown.…”

Polarimetric radar characteristics of storms with and without lightning activity

“…The authors documented that many of the flashes observed in thundersnow were associated with localized high‐ Z H and low‐ Z DR regions, suggesting regions with graupel production indicating that storms with lightning could have larger and more numerous graupel content than storms without lightning. Observations from ground‐based total lightning combined with Doppler and polarimetric radar [ Deierling and Petersen , ], numerical simulations with explicit microphysics [ Calhoun et al ., ], and satellite observations [ Mattos and Machado , ; Matthee and Mecikalski , ] also support this idea, and it is suggested that storms with lightning include better graupel growth conditions due the existence of stronger updrafts, higher supercooled water content, and ice particle mass.…”

Investigating the Ice Water Path in Convective Cloud Life Cycles to Improve Passive Microwave Rainfall Retrievals

“…This new methodology is based on the IWP and D e results from the previous section, cloud life cycle characteristics (inferred with microwave frequencies), and recent studies related to lightning in thunderstorms. Mattos and Machado (2011) found that for D e larger than 1.2 mm (also inferred with the MSPPS algorithm), the lightning probability is higher than for smaller particles. Consequently, greater convection is observed.…”