1. Introduction
Lightning is a spectacular and direct response to strong thundercloud
electric fields, which in turn are generated by intense atmospheric
moist convection and (normally) the onset of active precipitation
processes involving ice particles [Saunders , 2008]. Since
lightning is inherently coupled to storm microphysics and dynamics, it
can be used as a valuable tool to help remotely probe the developmental
state, severity, and evolution of thunderstorms and thunderstorm
complexes [e.g., Yoshida et al. , 2017; Darden et al. ,
2009 and references therein]. Because a lightning discharge produces
lightning nitrogen oxides (LNOx), which in turn affect
greenhouse gas concentrations (such as ozone), lightning also serves as
a key indicator for monitoring long-term climate change
[Williams , 2020], and plays an important role in affecting
air quality forecasts [Koshak et al. , 2014a,b; Koshak et
al. , 2015]. Overall, lightning provides useful information about a
variety of atmospheric processes and offers vital scientific insight
across a broad range of disciplines, such as weather, climate,
atmospheric chemistry, and lightning physics. In addition, lightning
itself is a direct threat to public safety, and also frequently impacts
equipment and infrastructure on the ground.
The Lightning Imaging Sensor (LIS) on the International Space Station
(ISS) plays a special role in improving our understanding of these
complex interrelationships by providing global measurements of total
lightning at high spatial and temporal resolution. This optically based
lightning detection instrument was launched to the ISS in February of
2017, and has successfully operated with limited downtime since then.
The ISS, which is in a low-Earth orbit (LEO) inclined near 55°, has been
increasingly used as a host for a number of Earth-observing instruments
due to its accessibility; ample space, power, and data bandwidth; and
ability to precess through the diurnal cycle.
This paper will describe the ISS LIS instrument and its data products,
document key performance metrics and science results from its first
three years on orbit, discuss applications enabled by near-realtime ISS
LIS data, and point toward new opportunities for cross-platform science
that are enabled by using ISS LIS in conjunction with other
Earth-observing instruments.