Lightning characteristics relative to radar, altitude and temperature for a multicell, MCS and supercell over northern Alabama

Abstract

Cloud electrification leads to the production of nitrogen oxides (NO x), which has an effect on ozone concentrations. Currently large uncertainties exist regarding the contribution of lightning to the global and local NO x budget, even on a per flash basis. Most lightning NO x (LNO x) models distribute the LNO x at reflectivities (Z) ≥ 20 dBZ in the horizontal, while vertically, a Gaussian distribution function with a peak at-15 °C is used for cloud-to-ground (CG) flashes and a bimodal distribution function with peaks at-15 °C and-45 °C is used for inter-and intracloud (IC) flashes. This research aims to improve our basic understanding of lightning location relative to radar Z as a function of storm and flash type. Using data from the North Alabama Lightning Mapping Array (NALMA) and the Multi-Radar Multi-Sensor data suite, the results from analyzing a multicell storm, mesoscale convective system and supercell storm showed that 29.7%, 15.9% and 6.9% of all flashes initiated in regions where Z < 20 dBZ, respectively. The bimodal lightning initiation distribution for IC flashes was also not observed for any of the three storms. In addition, it is shown that when incorporating the propagation of the flash, the percentage of NALMA lightning sources located in regions where Z < 20 dBZ increases. Finally, when comparing flash types, the results show that Hybrid flashes have consistently larger sizes than IC and CG flashes, while IC and Hybrid flashes tend to have more sources located at Z < 20 dBZ than CG flashes.

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

“…When analyzing a supercellular storm over Oklahoma, DiGangi et al () showed that the peak distribution in the VHF sources occurred between 8 and 10 km, while Zhang et al () found that the majority of flashes initiated between 8 and 12 km for a supercell that occurred in New Mexico. Mecikalski and Carey () found that the peak in the flash initiations as well as the peak in all VHF source locations occurred between 10 and 11 km (−42.5 to −50.6 °C) for supercellular systems, while Stolzenburg et al () specifically showed that the main negative charge region for supercells in their study was located at −22 °C. In addition, both Stolzenburg et al () and Bruning et al () found anywhere between four and eight different charge regions within supercells.…”

“…Prior research has shown that different storm types, such as multicells, mesoscale convective systems (MCSs), and supercells, have different charge structures (a detailed explanation on the differences between these three storm types is given in section ). Mecikalski and Carey () compared one multicell, one MCS, and a supercellular system with four supercells to each other and found that there were differences in where lightning initiated and propagated relative to altitude and reflectivity between these three storm types. Therefore, the research herein aims to improve our knowledge on the horizontal and vertical distribution of lightning initiation and propagation relative to ~500 multicells, 27 MCSs, and 23 supercells and consequently covers a broader range of storms under varying environmental conditions.…”

“…On the other hand, Lang and Rutledge () found the main negative charge region to be located at ~7 km (−16 °C) for an MCS that occurred over the High Plains, while Stolzenburg et al () found this to be located at −16 °C when multiple MCSs were analyzed. Conversely, Ely et al () found the maximum in the lightning very high frequency (VHF) source density (i.e., where flashes propagate) to be between 8 and 12 km (~ −40 °C) for an MCS that occurred over Texas and Hodapp et al () found this to be located between 8 and 13 km for a different MCS that also occurred over Texas, while Mecikalski and Carey () showed a peak in VHF source densities between 7 and 8 km (−22 to −31 °C) for an MCS that occurred over northern Alabama.…”

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.…”

Intracloud Lightning Flashes Initiated at High Altitudes and Dominated by Downward Positive Leaders

“…On the other hand, according to some statistical distributions of the lightning initiation altitude, there is indeed a small portion of lightning flashes initiated at high altitudes of up to 15 km (Fuchs et al, ; Lund et al, ; Mecikalski & Carey, ). However, development characteristics of these high‐altitude flashes and the corresponding charge structures are not clear yet.…”