Fractal-based lightning channel length estimation from convex-hull flash areas for DC3 Lightning Mapping Array data

Lightning is the largest natural source of oxides of nitrogen (NOx) in the troposphere. Intensive, coordinated observations of lightning (with VHF Lightning Mapping Arrays) and chemical species (including NOx) during the Deep Convective Clouds and Chemistry (DC3) program in May and June 2012 present an opportunity to constrain with observations estimates of NOx produced per unit of channel length. In a related paper in this session, Thomas et al. present results from a point-to-point connectivity-based and box-covering methods for estimating channel length per flash. This paper compares their results to a simple parameterization that exploits the fractal nature of the lightning channel to calculate the total length from the convex-hull area covered by the flash. We provide theoretical justification for doing so. Flash area is easily calculated as part of any points-to-flashes algorithm, making this method suitable for automated, rapid analysis of flash data in bulk. Initial results of channel length estimation for a case from DC3 will be presented.