Radar Reflectivity and Altitude Distributions of Lightning Flashes as a Function of Three Main Storm Types

Abstract

In an effort to improve our knowledge on the horizontal and vertical distribution of lightning initiation and propagation, ~500 multicells (producing a total of 72,619 flashes), 27 mesoscale convective systems (producing 214,417 flashes) and 23 supercells (producing 169,861 flashes) that occurred over northern Alabama and southern Tennessee were analyzed using data from the North Alabama Lightning Mapping Array and the Multi‐Radar Multi‐Sensor suite. From this analysis, two‐dimensional (2‐D) histograms of where flashes initiated and propagated relative to radar reflectivity and altitude were created for each storm type. The peak of the distributions occurred between 8.0 and 10.0 km (−24.0 to −38.5 °C) and between 30 and 35 dBZ for flashes that initiated within multicellular storms. For flashes that initiated within mesoscale convective systems, these peaks were 8.0–9.0 km (−27.1 to −34.6 °C) and 30–35 dBZ, respectively, and for supercells, they were 10.0–12.0 km (−42.6 to −58.1 °C) and 35–40 dBZ, respectively. The 2‐D histograms for the flash propagations were slightly different than for the flash initiations and showed that flashes propagated in lower reflectivities as compared to where they initiated. The 2‐D histograms were also compared to test cases; the root‐mean‐square errors and the Pearson product moment correlation coefficient (R) were calculated with several of the comparisons having R values >0.7 while the root‐mean‐square errors were always ≤0.017 (≤10%), irrespective of storm type. Finally, the mean flash sizes for the multicell, mesoscale convective system, and supercell flashes were 8.3, 9.9, and 7.4 km, respectively.

Lightning Location, NOx Production, and Transport by Anomalous and Normal Polarity Thunderstorms

“…Ultimately, thunderstorm polarity controls the vertical distribution of flashes. In normal polarity thunderstorms, flash initiation is typically between 8 and 10 km versus 5 and 6 km in anomalous polarity thunderstorms (Mecikalski & Carey, , ; Fuchs et al, ; Fuchs & Rutledge, ). Since the lifetime of NO x increases with height, storms that produce more LNO x at upper altitudes may be expected to have a larger impact on tropospheric ozone production compared to thunderstorms that produce more LNO x at lower altitudes, such as anomalous storms.…”

Radar Reflectivity of Lightning Flashes in Stratiform Regions of Mesoscale Convective Systems

“…The areas with highfrequency values in Figure 2b are distributed from 0 to 30 dBZ and 8 to 13 km. The high-frequency areas reported by Mecikalski and Carey (2018b) were within the reflectivity range 15-30 dBZ and an altitude range of 6-11 km. The parameters of the peak bin showed a clear change from those reported by Mecikalski and Carey (2018b).…”

“…This indicates that the main body of most convective lightning flashes spreads within the convective regions. Table 1 lists 254 flashes, which is much less than the number of convective lightning flashes (7,227 flashes) and total lightning flashes considered by Mecikalski and Carey (2018b). The limitations of the network described by Wang et al (2018) might lead to some weak VHF radiation sources being missed.…”

“…The 2-D histogram for the propagation of convective lightning flashes is similar to that of Mecikalski and Carey (2018b), but the distribution of the high-frequency values (>2%) is expanded. The areas with highfrequency values in Figure 2b are distributed from 0 to 30 dBZ and 8 to 13 km.…”

Introduction to the Deep Convective Clouds and Chemistry (DC3) 2012 Studies

“…DeCaria et al () proposed a midlevel (at T = −15 °C) peak distribution for cloud‐to‐ground flashes and a bimodal distribution for intracloud flashes. Analyses of storms in northern Alabama revealed that vertical distributions of intracloud flashes did not have the expected bimodal initiation distribution and that hybrid flashes (i.e., flashes with both intracloud and cloud‐to‐ground components) were consistently larger in size than intracloud or cloud‐to‐ground flashes (Mecikalski & Carey, , ). Mecikalski et al () and Mecikalski and Carey () found that these three types of flashes do not have the same parent distribution and therefore should be treated separately in lightning‐NO x parameterizations.…”