Characteristics of the Parent Lightning of Sprites Observed in and Around Florida AE31B-3109 Mathieu N. Plaisir1, Amitabh Nag1, Ningyu Liu2, Levi Boggs1, Jason Chiappa1, Kenneth L. Cummins1, 3, William Rison4, Paul Krehbiel4, Hamid K. Rassoul (1) Florida Institute of Technology, (2) University of New Hampshire, (3) University of Arizona, (4) New Mexico Institute of Mining and Technology . • Sprites are a class of transient luminous events (TLEs) that occur in the mesosphere. They are formed Sprites recorded using the Watec 120N+ camera due to the development of a quasi-electrostatic field in the lower ionosphere, produced by the Azimuth=280° removal of a relatively large amount of charge from a thundercloud by a cloud-to-ground discharge. • Understanding the characteristics of sprite-generating lightning remains an important goal in the field of atmospheric electricity. • Between July 2018 and July 2019 we captured 144 sprites using a low-light monochromatic camera, recording at 30 frames per second (fps), located in Melbourne, Florida. • For 93 sprites occurring in 2018, we correlated the sprites with their NLDN-reported parent-CG return stokes. These strokes occurred at distances ranging from 77-554 km from th Introduction Introduction the camera location. Sprite recorded on August 17 2018 at 2:49:38.899 UTC. The parent CG occurred at 2:49:38.692 UTC, the time interval between the stroke time and the sprite time is 207 ms. Note that the time-resolution for this sprite video-camera record was 33 ms.

• th Measurement systems and datasets used: We examined data from the GLM for the August 17 •Watec 120N+ sprite shown above. • Ø Operating at 30 fps The evolution of group energy and group area in 2-ms •Phantom V1210 time-bins reported by the GLM starting 1 or 2 ms prior Ø Operating at 100/3000/5000 fps to the NLDN stroke-time is shown for GLM-groups with •U.S National Lightning Detection Network centroid-locations within 16 km of the NLDN-stroke (NLDN) (ground-strike-point) location. • •GOES-16 Geostationary Lightning Mapper Also shown are the mean group energy and group area (Above) Florida Tech’s optical measurement system. (Below) for 13 sprites. Evolution of a sprite recorded at 3000 fps with an exposure of (GLM) 330 μs on September 29th 2018 at 1:47:32.397 UTC. Group energy for parent- Group area for parent- CG of August 17th sprite CG of August 17th sprite

Map showing locations of sprite-parent CGs CG-to-sprite time difference Δt (ms) N 93 AM (ms) 109 Median (ms) 78 Min (ms) 4.3 Max (ms) 850 Mean group energy for 13 Mean group area for 13 Case Study using GLM Data and Preliminary Results Results and Preliminary Study Case GLMusing Data sprite-parent CGs sprite-parent CGs

Peak current of parent CG strokes Peak current of parent CG strokes Time (s) Negative Positive Total Temporal evolution of average GLM-group-energy and group-area N 86 7 93 for cloud-to-ground and cloud lightning flashes in Florida, reported AM (kA) 138 81 86 by Zhang et al., 2019, AGU Fall Meeting. Note that these are not Median (kA) 102 77 77 necessarily sprite producing flashes. Correlation with NLDN Data Correlation Min (kA) 5.0 9.0 5.0 Max (kA) 294 185 294 (Lu et al. (2017) Summary and Future Work

• We have correlated sprites recorded on video with their parent CG strokes reported by the NLDN. • The median parent-CG peak current was 77 kA for positive and 102 kA for negative strokes. • GLM group energies and areas for times following the parent-CGs will be examined in detail for all recorded sprites to determine if optical signatures of sprites can be clearly distinguished from those of their parent CGs.