Convective Characteristics and GOES-16 GLM Optical Energy in Hurricane Ian (2022)

Tropical cyclone (TC) forecast tracks have greatly improved in recent years; however,
intensity forecasts have struggled to keep up. While recent technological advancements such as
the implementation of GOES Geostationary Lightning Mapper (GLM) data might allow for
better forecasts, there have been conflicting findings on how lightning relates to TC
intensification. When investigating the lightning flash rates, some have found that there is an
increase in flash rates in the inner core during intensification while others have found the
opposite, seeing an increase in the outer bands during TC intensification. Research on lightning
using the GLM has shown that optical energy may be useful in better understanding updrafts in
thunderstorms. Given that GLM lightning characteristics have been linked to updraft and
convective characteristics in land-based thunderstorms, this will be applied to TCs in order to
investigate changes in lightning flash rate and optical energy in the inner core during TC rapid
intensification (RI). GLM data along with airborne Doppler radar measurements allows for
simultaneous measurements of both lightning and convective characteristics, supporting the
analysis of how the two may relate to TC RI. This analysis will be applied to Hurricane Ian
(2022) to help understand changes in lightning optical energy during two periods of RI, one with
very little lightning and one with nearly constant lightning. Radar reflectivity and vertical
velocity are utilized to provide convective characteristics such as ice mass, 350 dBZ volume, and
5+ m/s updraft volume in tail-Doppler radar swaths during the two RI periods. The first RI
period experienced very little lightning and only a slight increase in ice mass and 5+ m/s updraft
volume whereas the second RI period had nearly constant lightning and a larger increase in 30
dBZ volume, ice mass, and 5+ m/s updraft volume above the freezing level. These results
support the hypothesis that updrafts strong enough to lift hydrometeors to levels in which
electrification is possible may be an indication that these updrafts allow for sufficient mass flux
to allow for the TC to rapidly intensify. This would allow for the possibility of GLM lightning
flash optical energy to be utilized as a tool to better understand or predict TC RI.