Cloud-to-ground lightning in Hurricane Andrew

Authors

  • John Molinari,

  • Paul K. Moore,

  • Vincent P. Idone,

  • Ronald W. Henderson,

  • Arsalan B. Saljoughy


Abstract

The spatial and temporal distribution of cloud-to-ground lightning was examined in Hurricane Andrew of 1992. Lightning locations available from the National Lightning Detection Network were superimposed on infrared satellite images to relate lightning activity to hurricane cloud structure. A distinct radial variation occurred in time-averaged flash density, with a weak maximum in the eye wall, a region of near-zero flash density 40 to 100 km from the center, and a steady increase to a large maximum in the outer rainbands 190 km from the center. This radial distribution is consistent with the convective structure of mature hurricanes. Eye wall lightning tended to be episodic, occurring almost exclusively prior to and during periods of intensification of the storm. During these periods, negative flashes occurred several kilometers inward from the highest eye wall cloud tops, in the region of the largest radar reflectivity. Positive eye wall flashes, while small in number, tended to occur directly under the highest cloud tops. The results are suggestive of a normal dipole in sign but outwardly tilted along the sloping eye wall. In general, hurricane flash characteristics resembled those for a background data set of nonhurricane flashes from the same area. The exception occurred for negative flashes in the eye wall, which had a much smaller mean peak current than the background (25.3 kA versus 44.9 kA).

Ancillary