Exploring the Scientific Utility of Combined Spaceborne Lidar and
Lightning Observations of Thunderstorms
Abstract
Approximately eight months of co-located spaceborne lidar and lightning
observations were analyzed in a pathfinder study to understand the
advantages and challenges of using these combined observations to
understand thunderstorms. Data from the Lightning Imaging Sensor (LIS)
and the Cloud-Aerosol Transport System (CATS) lidar were used when they
overlapped on the International Space Station during March-October 2017.
Using simple matching criteria, 8246 LIS flashes occurred within 25 km
of the CATS ground track. CATS cloud-top heights near these flashes
showed similar behavior with latitude when compared to a spaceborne
radar-based climatology, but the lidar cloud tops were approximately
2-km higher than 20-dBZ radar echo tops. CATS cloud phase near LIS
flashes was consistent with ice or mixed-phase more than 90% of the
time, showing the value of using lightning observations to validate
lidar-based feature masks. In addition, correlations between a proxy for
LIS flash rate and CATS ice water path, cloud optical depth, and
cloud-top height were low (0.38-0.42) but positive and highly
statistically significant (> 99%), suggesting lidar
retrievals of cloud properties can be meaningfully compared with
lightning observations despite lidar’s known inability to penetrate
deeply into optically thick clouds like thunderstorms. Finally, CATS was
used to help diagnose LIS false alarms due to surface-based glint. The
false alarm rate was approximately 0.1%, which demonstrated the
excellent performance of the surface glint filter in the LIS processing
code. The results suggest that fruitful scientific insights can be
expected from larger combined lidar/lightning datasets.