Comparison of positive and negative compact intracloud discharges

Abstract

[1] Prior studies have found that positive and negative compact intracloud discharges (+CIDs and −CIDs, according to the physics sign convection) occur at distinctly different altitudes, which correspond to different regions in a thunderstorm. On the basis of a large number of CIDs of both polarities recorded by our VLF/LF lightning location network, characteristic differences between +CIDs and −CIDs are discussed in this study. The results reveal that −CID is a more special type of discharge. Compared with +CIDs, −CIDs produce larger electric field changes on average, and they are more isolated from other discharge processes. A locating method based on ionospheric reflection pairs of CIDs is developed, which confirms that −CIDs do occur at higher altitudes. The relationship between CIDs and convective strength is also analyzed. Out of nine storms analyzed in this study, eight produce fewer −CIDs than +CIDs. The percentage of −CIDs seems to increase with the convective strength. Although −CIDs are relatively rare, their occurrences are more temporally compact; that is, a large portion of −CIDs are produced in a very short period. +CIDs also have this characteristic, but it is not as pronounced as that of −CIDs.

ISUAL‐Observed Blue Luminous Events: The Associated Sferics

“…Zhu et al () reported that 10 −NBEs and 67 +NBEs occurred during a 3‐hr observation period, and they found that the derived peak currents of some −NBEs are larger than those of the positive ones. Wu et al () also found that a considerably higher percentage of −NBEs (negative CIDs) than positive ones have large peak values of the normalized electric field changes in the VLF/LF band. The radiation field from a distant and vertical Hertzian dipole is proportional to the time deviation of the vertical current moment (e.g., Nickolaenko & Hayakawa, , p. 69).…”

Joint radio and optical observations of the most radio-powerful intracloud lightning discharges

“…Other authors (Rison et al, 1999;Wu et al, 2011) have shown that occasionally NBEs can initiate otherwise "ordinary" flashes. All of the cases in Fig.…”

“…Another name employed for this unique stroke is "compact intracloud discharge", or CID (see, e.g., Nag et al, 2010). NBEs, and their accompanying VHF pulse, were originally reported in 1980 (Le Vine, 1980) and have been observed by many workers since (e.g., Hamlin et al, 2007;Holden et al, 1995;Jacobson, 2003a, b;Light, 2003, 2012;Jacobson and Heavner, 2005;Jacobson et al, 2007Jacobson et al, , 2011Massey and Holden, 1995;Massey et al, 1998;Nag andRakov, 2009, 2010a, b;Nag et al, 2010;Rison et al, 1999;Smith et al, 1999b;Thomas et al, 2001;Watson and Marshall, 2007;Wu et al, 2011Wu et al, , 2012.…”

Revisiting "Narrow Bipolar Event" intracloud lightning using the FORTE satellite

“…Recently, a ground-based study of NBEs (Nag et al, 2010) observed that out of a total of 157 events, 73 % were isolated. A more extensive survey of 11 876 NBEs in China (Wu et al, 2011) finds that neighbors are very improbable (<2 %) in the 10 ms preceding an NBE, but are sometimes seen (∼12 % for positive-polarity NBEs, ∼4 % for negative-polarity NBEs) in the ten millisec following the NBE. This matter has important implication: Without a prior leader process to ionize the air and prepare a conductive channel, how can a large-scale charge transfer (stroke) occur?…”