Abstract
Horizontally-extensive lightning flashes occur frequently in association
with mature and late phases of multicellular thunderstorms, both in
trailing stratiform regions and horizontally-extensive anvils. The
spatial relationship between these flashes and the parent cloud volume
is of importance for space launch operational decision making, and is of
broader scientific interest. Before this question can be accurately
addressed, there is a need to understand the degree to which current
lightning observation systems can depict the spatial extent of these
long flashes. In this ongoing work, we will intercompare the depiction
of horizontally-extensive flashes using several ground-based lightning
locating systems (LLSs) located at Kennedy Space Center (KSC) with
space-based observations observed by the recently-launched Geostationary
Lightning Mapper (GLM) onboard the GOES-16 satellite. Ground-based
datasets include the KSC Lightning Mapping Array (KSCLMA), the
operational narrowband digital interferometer network MERLIN, and the
combined cloud-to-ground and cloud lightning dataset produced by the
U.S. National Lightning Detection Network (NLDN). The KSCLMA system is a
network of VHF time-of-arrival sensors that preferentially report
breakdown processes, and MERLIN is a network of VHF interferometers that
point to the discharges in the horizontal plane. Observations to date
indicate that MERLIN and the KSCSLMA provide similar overall
descriptions of the spatial and temporal extent of these flashes, while
the NLDN does not provide adequate spatial mapping of these flashes. The
KSC LMA system has much better location accuracy, and provides excellent
3-dimensional representation within ~100 km of KSC. It
also has sufficient sensitivity to provide 2-dimensional flash mapping
within ~250 km of KSC. The MERLIN system provides a
more-detailed representation of fast leader propagation (in 2
dimensions) with ~100 km of KSC. Earlier work during the
CHUVA campaign in Brazil with similar systems and the (orbital)
Lightning Imaging System (LIS) has shown that the interferometric data
correlated much better in space and time with the LIS optical
observations. We are currently investigating this relationship at KSC,
where both the LMA and interferometer perform much better than the
systems used during CHUVA.