Two simultaneous charge structures in thunderstorm convection

Abstract

[1] A pair of simultaneous, horizontally displaced, thunderstorm electric field soundings are used to investigate an existing conceptual model of thunderstorm charge structure. The soundings show that two different vertical charge structures, one in the updraft and one outside the updraft, can exist at the same time inside a storm, as depicted in the existing model. The data suggest that the two charge structures can be relatively close together, since the soundings are separated by only 3 to 8 km horizontally in the convective region of the storm. Horizontal extent of the charge structures is estimated to be at least 4 km  4 km. The differences in the two charge structures are coincident with substantial differences over this same 3 to 8 km horizontal distance in the reflectivity structure, updraft speed, and lightning activity of the convection. The nonupdraft sounding was made through the intense reflectivity core found at middle levels in the convection. Additional electric field complexity and additional charge regions were found in the nonupdraft sounding, and the lightning-related electric field changes tended to be larger in magnitude and more numerous in that sounding than in the updraft sounding.

Regional lightning NO<sub>x</sub> sources during the TROCCINOX experiment

“…The detrainment flux of NO per convective column based on the regional flux divided by the total number of active convective cells gives a production between 0.02 to 0. the production rates deduced from NO x storm budgets. During the STERAO campaign, Skamarock et al (2003) derived a production of about 0.2 kg(N)/s from the observations. A production of 0.058 kg(N)/s/anvil can be deduced from the study of Huntrieser et al (1998) based on the flux of detrained air in the anvil and aircraft observation of NO x mixing ratios in the anvil.…”

“…The estimation is well within the range of current estimates (Price et al, 1997;Lee et al, 1997;Huntrieser et al, 1998) This result should not hide the uncertainties on the number of flash rates simulated by the model. This estimate is below the global production rate calculated by Skamarock et al (2003) 5570 C. Mari et al: Regional lightning NO x sources during the TROCCINOX experiment when multiplying the LiNOx production rate in the 10 July STERAO storm by the storm frequency number following Huntrieser et al (1998). Uncertainties in the LiNOx source are related to the vertical placement of the IC and CG flashes, the number of flashes and NO molecules produced per flash, the initial and lateral boundary NO x profiles and transport parameterization.…”

“…The electrical activity in the thunderstorms is related to the vertical extension of the glaciated region where ice-ice particle rebounding collisions are efficient enough to explain the charging mechanisms (Reynolds et al, 1957;Takahashi, 1978;Saunders, 1992). A growing electrical field then results from the organization of dipolar, tripolar or even more complex charge structures at storm scale (Rust and MacGorman, 2002;Rust and Marshall, 1996;Stolzenburg, 2002;Barthe et al, 2005). The electrical field is broken down by a partial neutralization of the electrical charges.…”

“…Evidences of NO x production by lightning were given by airborne measurements in and near mature thunderstorms. Observations at different latitudes show that NO x can be increased considerably (as much as a few ppbv) in the upper troposphere on small spatial scales (Huntrieser et al, 1998;Dye et al, 2000;Huntrieser et al, 2002;Skamarock et al, 2003) It is still poorly known how much NO x is produced by the storms and how this production relates to cloud parameters like particle phase, updraft strength, cloud top height, or flash rate, which all would be useful for parameterisations of NO x -production. Consequently, estimates of the global NO x production by lightning in thunderstorms still differ by about one order of magnitude, between 1-20 Tg(N)/year (Price et al, 1997;Lee et al, 1997;Huntrieser et al, 1998).…”

Estimation for charge distributions related with individual lightning discharges using VHF broadband digital interferometer

“…They showed the sign reversal on graupel at -11 °C, facilitating the tri-pole charge structure in thunderstorms. Using balloon borne electric field (E-field) measurements launched into summertime thunderstorms in central Oklahoma, Stolzenburg et al (1998Stolzenburg et al ( , 2002 reported that mesoscale convective systems (MCS) are not limited to tri-pole charge structures but may have as many as five stratified charge layers outside the updraft region. However, such in-situ observations cannot depict time evolution of the charge distribution because of their low time resolution.…”