A 10-Year Survey of Tropical Cyclone Inner-Core Lightning Bursts and Their Relationship to Intensity Change

Abstract

Abstract This study seeks to reconcile discrepancies between previous studies analyzing the relationship between lightning and tropical cyclone (TC) intensity change. Inner-core lightning bursts (ICLBs) were identified from 2005 to 2014 in North Atlantic (NA) and eastern North Pacific (ENP) TCs embedded in favorable environments (e.g., vertical wind shear ≤ 10 m s−1; sea surface temperatures ≥ 26.5°C) using data from the World Wide Lightning Location Network (WWLLN) transformed onto a regular grid with 8-km grid spacing to replicate the expected nadir resolution of the Geostationary Lightning Mapper (GLM). Three hypothesized factors that could impact the 24-h intensity change after a burst were tested: 1) prior intensity change, 2) azimuthal burst location, and 3) radial burst location. Most ICLBs occurred in weak TCs (tropical depressions and tropical storms), and most TCs intensified (remained steady) 24 h after burst onset in the NA (ENP). TCs were more likely to intensify 24 h after an ICLB if they were steady or intensifying prior to burst onset. Azimuthally, 75% of the ICLBs initiated downshear, with 92% of downshear bursts occurring in TCs that remained steady or intensified. Of the ICLBs that initiated or rotated upshear, 2–3 times more were associated with TC intensification than weakening, consistent with recent studies finding more symmetric convection in intensifying TCs. The radial burst location relative to the radius of maximum wind (RMW) provided the most promising result: TCs with an ICLB inside (outside) the RMW were associated with intensification (weakening).