Lightning Ground Strikes Analyzed by Singularity and Fractal Techniques: A Mesoscale Convective Complex. Case Study

Abstract

The relationship between thunderstorm dynamics and lightning strike locations, of both polarities, is examined on the Mesoscale Convective Complex that produced a mesocyclone and gust front on 27 May 1987. Two analysis techniques were used. The singularity analysis technique assumes local symmetry to calculate the strength of source/sink (or divergence/convergence) and rotating (or vorticity) singularities using Doppler radar wind data. A well defined gust front was located along with a mesocyclone that developed along the gust front. Both features were detected well in advance of corresponding surface reports. Background convergence was also calculated for low levels using the singularity method and was seen to be highly correlated with the number of negative cloud-to-ground lighting strikes. Upper level divergence was also seen in the form of a jet maximum in the Doppler velocities and also correlated favorably with total cloud-to-ground lightning strikes and low level background convergence. The singularity technique was also able to locate areas of aliased (or folded) velocities within the data set. The second analysis method was a fractal technique. It was found that the distribution of the lighting ground strikes is a fractal. The fractal was observed, however, for negative ground strikes only. A fractal dimension of negative ground strikes of D=1.21 was found within the main core of lightning activity for 30 minute increments. When the analysis was repeated for a five hour interval, the fractal dimension of negative ground strikes was D=1.7. This is the same fractal dimension that was measured for lighting channels using photographs. Very little fractal presence was found for positive ground strikes.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 1990
Accession Number
ADA227649

Entities

People

  • Daniel B. Frashier

Organizations

  • Air Force Institute of Technology

Tags

Communities of Interest

  • Advanced Electronics
  • Energy and Power Technologies
  • Space

DTIC Thesaurus Topics

  • Atmospheric Motion
  • Case Studies
  • Climate Change
  • Convection
  • Data Processing
  • Detection
  • Direction Finding
  • Doppler Radar
  • Environment
  • Geometry
  • Meteorology
  • Mobile Laboratories
  • Radar Beams
  • Surface Analysis
  • Two Dimensional
  • United States
  • Wind Shear

Fields of Study

  • Environmental science

Readers

  • Atmospheric Science/Meteorology
  • Finite Element Method (FEM) for solving Partial Differential Equations (PDEs)
  • Wave Propagation and Nonlinear Chaotic Dynamics.