Cloud-to-Ground Lightning Production in Strongly Forced, Low-Instability Convective Lines Associated with Damaging Wind

Abstract

During 9-11 November 1998 and 9-10 March 2002, two similar convective lines moved across the central and eastern United States. Both convective lines initiated over the southern plains along strong surfacebased cold fronts in moderately unstable environments. Both lines were initially associated with cloud-toground (CG) lightning, as detected by the National Lightning Detection Network, and both events met the criteria to be classified as derechos, producing swaths of widespread damaging wind. After moving into areas of marginal, if any, instability over the upper Midwest, CG lightning production ceased or nearly ceased, although the damaging winds continued. The 9 March 2002 line experienced a second phase of frequent CG lightning farther east over the mid-Atlantic states. Analysis of these two events shows that the production of CG lightning was sensitive to the occurrence and vertical distribution of instability. Periods with frequent CG lightning were associated with sufficient instability within the lower mixed-phase region of the cloud (i.e., the temperature range approximately between Ϫ10°and Ϫ20°C), a lifting condensation level warmer than Ϫ10°C, and an equilibrium level colder than Ϫ20°C. Periods with little or no CG lightning possessed limited, if any, instability in the lower mixed-phase region. The current Storm Prediction Center guidelines for forecasting these convective lines are presented.

The global lightning-induced nitrogen oxides source

“…a small fraction of the annual mean NO 2 column even in the tropics. The computed LNO x column contribution is generally below 20% Boersma et al, 2005;van Noije et al, 2006) with localized fractions of more than 80% in regions with weak surface NO x emissions . Detections of LNO x contributions to the NO 2 column in space-based observations are discussed in Sect.…”

“…The principal sink of tropospheric NO x is oxidation to nitric acid (HNO 3 ) by reaction of NO 2 with OH during the day; during the night, the reaction of NO 2 with O 3 to form NO 3 , the oxidation of NO 2 by NO 3 to form N 2 O 5 , and the subsequent hydrolysis of N 2 O 5 on aerosols contributes considerably to the nitrogen oxides sinks (Dentener and Crutzen, 1993;van Noije et al, 2006). The oxidation products leave the atmosphere by dry or wet deposition ("acid rain") (Logan, 1983).…”

“…The data and the analysis method are described in Richter et al (2005). Figure provided 2002a; Richter and Burrows, 2002;Duncan et al, 2003;Edwards et al, 2003;Kunhikrishnan et al, 2004;Savage et al, 2004;Choi et al, 2005;Irie et al, 2005;Jaeglé et al, 2005;Konovalov et al, 2005;Meyer-Arnek et al, 2005;Ma et al, 2006;van der A et al, 2006;van Noije et al, 2006). Figure 6 illustrates the improvement in spatial resolution provided by SCIAMACHY compared to GOME.…”

“…Any correlation between NO 2 columns and lightning frequency densities is not immediately evident. Different methods of GOME retrievals vary by more than 10% (van Noije et al, 2006). Therefore, accurate LNO x estimates require LNO x column contributions significantly larger than 10%.…”

“…This includes satellite observations of global lightning , satellite observations of NO 2 column distributions , airborne in-situ measurements of NO x abundance near thunderstorms at midlatitudes Huntrieser et al, 2002;Ridley et al, 2004) and over tropical continents, where most lightning occurs (see Sect. 2.4), detailed cloud-resolving model studies (DeCaria et al, 2000;Fehr et al, 2004), and improved global models van Noije et al, 2006). This paper reviews the present knowledge on the global LNO x source rate.…”