Characteristics of Sprite-Producing Positive Cloud-to-Ground Lightning during the 19 July 2000 STEPS Mesoscale Convective Systems

Abstract

During the summer of 2000, the Severe Thunderstorm Electrification and Precipitation Study (STEPS) program deployed a three-dimensional Lightning Mapping Array (LMA) near Goodland, Kansas. Video confirmation of sprites triggered by lightning within storms traversing the LMA domain were coordinated with extremely low frequency (ELF) transient measurements in Rhode Island and North Carolina. Two techniques of estimating changes in vertical charge moment (M q) yielded averages of ϳ800 and ϳ950 C km for 13 sprite-parent positive polarity cloud-to-ground strokes (ϩCGs). Analyses of the LMA's very high frequency (VHF) lightning emissions within the two mesoscale convective systems (MCSs) show that ϩCGs did not produce sprites until the centroid of the maximum density of lightning radiation emissions dropped from the upper part of the storm (7-11.5 km AGL) to much lower altitudes (2-5 km AGL). The average height of charge removal (Z q) from 15 sprite-parent ϩCGs during the late mature phase of one MCS was 4.1 km AGL. Thus, the total charges lowered by spriteparent ϩCGs were on the order of 200 C. The regional 0ЊC isotherm was located at about 4.0 km AGL. This suggests a possible linkage between sprite-parent CGs and melting-layer/brightband charge production mechanisms in MCS stratiform precipitation regions. These cases are supportive of the conceptual MCS spriteproduction models previously proposed by two of the authors (Lyons and Williams).

Transient luminous events above two mesoscale convective systems: Storm structure and evolution

“…[3] As reviewed by Williams and Yair [2006], in order to achieve these large CMC values, the present paradigm for sprite production in warm-season thunderstorms is the discharging of hundreds of C of positive charge within a laterally extensive layer near 0°C in the stratiform region of a mesoscale convective system (MCS) [Houze et al, 1990] by energetic positive CG (+CG) lightning [Marshall and Rust, 1993;Boccippio et al, 1995;Lyons, 1996;Marshall et al, 1996;Williams, 1998;Marshall et al, 2001;Williams, 2001;Lyons et al, 2003]. Such lightning often propagates along cloud base and is called "spider lightning" [Marshall et al, 1989;Mazur et al, 1995Mazur et al, , 1998].…”

“…Assuming CG rate is an approximate measure of convective intensity in MCSs, this suggests that sprite production is not directly correlated with convective intensity. These results are supported by Lyons et al [2003], who noted a significant descent in the altitude of lightning activity before sprite production began as lowlevel discharges associated with the melting layer began to dominate within the stratiform region.…”

“…Another is a midlevel layer near −10 to −15°C [Lang et al, 2004;Carey et al, 2005;Lang and Rutledge, 2008;MacGorman et al, 2008;Lu et al, 2009]. Finally, laterally extensive positive charge near 0°C can be active in lightning Lang and Rutledge, 2008], including sprite-parent lightning [Lyons et al, 2003]. It is this last layer that best fits the current paradigm for sprite-parent lightning.…”

Physical Processes Related to Discharges in Planetary Atmospheres

“…The optical measurements of TLEs (over 10000 events have been recorded) both from the ground (Lyons 2006) and from orbit (e.g., ISUAL on FORMOSAT-2, Mende et al 2006) have resulted in the phenomenological identification of a large number of processes that have been organized into a taxonomy that includes many descriptive and non-descriptive names such as column and carrot sprites, angels, trolls, jets, giant jets, halos, elves, and beads (i.e. Sentman and Wescott 1993;Lyons et al 2003aLyons et al , 2003bLyons 2006;Cummer et al 2006aCummer et al , 2006bAsano et al 2008). The relevant scale lengths range from tens of meters to tens and hundreds of kilometers while the temporal scales range from hundreds of µs to hundreds of ms.…”

Characteristics of lightning flashes generating sprites above storms

“…. [4][5][6][7]. Sprites can also horizontally extend over several tens of km in the form of sprite clusters [3,8,9] and they can even occur over more than ∼100 km in the form of sequential luminous emissions that are called "dancing sprites" [10,11].…”