Evaluation of the Performance Characteristics of the Lightning Imaging Sensor

The Lightning Imaging Sensor (LIS) that was on board the Tropical Rainfall Measuring Mission (TRMM) satellite captured optical emissions produced by lightning. In this work, we quantify and evaluate the LIS performance characteristics at both the pixel level of LIS events and contiguous clusters of events known as groups during a recent 2-yr period. Differences in the detection threshold among the four quadrants in the LIS pixel array produce small but meaningful differences in their optical characteristics. In particular, one LIS quadrant (Q1, X >= 64; Y >= 64) detects 15%-20% more lightning events than the others because of a lower detection threshold. Sensitivity decreases radially from the center of the LIS array to the edges because of sensor optics. The observed falloff behavior is larger on orbit than was measured during the prelaunch laboratory calibration and is likely linked to changes in cloud scattering pathlength with instrument viewing angle. Also, a two-season comparison with the U.S. National Lightning Detection Network (NLDN) has uncovered a 5-7-km north-south LIS location offset that changes sign because of periodic TRMM yaw maneuvers. LIS groups and flashes that had any temporally and spatially corresponding NLDN reports (i.e., NLDN reported the radio signals from the same group and/or from other groups in the same flash) tended to be spatially larger and last longer (only for flashes) than the overall population of groups/flashes.NASA [80MSFC17M0022]; NASA ROSES-2014 program [NNH14ZDA001N-WEATHER]6 month embargo; published online: 6 June 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

New WMO certified megaflash lightning extremes for flash distance (768 km) and duration (17.01 seconds) recorded from space

Initial global extremes in lightning duration and horizontal distance were established in 2017 (Lang et al. 2017) by an international panel of atmospheric lightning scientists and engineers assembled by the WMO. The subsequent launch of NOAA’s latest GOES-16/17 satellites with their Geostationary Lightning Mappers (GLMs) enabled extreme lightning to be monitored continuously over the western hemisphere up to 55° latitude for the first time. As a result, the former lightning extremes were more than doubled in 2019 to 709 km for distance and 16.730 s for duration (Peterson et al. 2020). Continued detection and analysis of lightning “megaflashes” (Sequin, 2021) has now revealed two flashes that even exceed those 2019 records. As part of the ongoing work of the WMO in detection and documentation of global weather extremes (e.g., El Fadli et al. 2013; Merlone et al. 2010), an international WMO evaluation committee was created to critically adjudicate these two GLM megaflash cases as new records for extreme lightning.We thank S. A. Rutledge and two other reviewers for their valuable comments. M. J. Peterson was supported by the U.S. Department of Energy through the Los Alamos National Laboratory (LANL) Laboratory Directed Research and Development (LDRD) program under project number 20200529ECR. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of U.S. Department of Energy (Contract 89233218CNA000001). T. Logan supported by a NOAA Grant NA16OAR4320115 “Lightning Mapper Array Operation in Oklahoma and the Texas Gulf Coast Region to Aid Preparation for the GOES-R GLM.” I. Kolmasova was supported by GACR Grant 20-09671. S. D. Zhang was supported by a NOAA Grant NNH19ZDA001N-ESROGSS. The participation of J. Montanya in this work is supported by research Grant ESP2017-86263-C4-2-R funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe,” by the “European Union”; and Grants PID2019-109269RB-C42 funded by MCIN/AEI/10.13039/501100011033.Peer ReviewedPostprint (author's final draft

Inter-Comparison of Space- and Ground-Based Observations of Lightning

Lightning observation from space provides a unique way to study the optical properties of lightning flashes. The satellite-based sensors including the Lightning Imaging Sensors (LISs) and Geostationary Lightning Mappers (GLMs) detect optical emissions that are associated with transfer of electrical charge due to lightning, and clusters them into flashes. This work provides an overview of lightning detection from ground- and space-based systems, and presents three research efforts focused on system validation. The first study addressed the performance characteristics of the LIS that was onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. Four different quadrant thresholds in the LIS pixel array caused an approximate 20% variation in the number of detected emissions and the mean energy density. Sensitivity decreased more rapidly along the off-boresight angle than was measured in the pre-launch laboratory calibration. A 5 km periodical location offset in the LIS group centroid is caused by the TRMM yaw maneuvers. In addition, LIS groups/flashes with a temporally and spatially corresponding report by the U.S. National Lightning Detection Network (NLDN) tended to be spatially larger and last longer. Two GLM sensors are deployed on the new GOES East and West satellites. The second study focuses on the performance of these sensors, as part of a NOAA funded validation effort by the GLM Science Team. One of the GLM detection behaviors is difficulty in detecting short and/or small flashes. LIS data with finer resolution and a statistical model were used to investigate possible explanations. The results show that more than half of the light sources were relatively smaller than a GLM pixel size. Short flashes do not have enough time to propagate and develop spatial area large enough or a channel long enough to be detected by GLM. Lightning locating systems (LLSs) inter-comparisons are complicated because the various measurements operate in different frequency ranges, and thus, detect different portions of lightning processes or flashes. The final study compares the LIS with the ground-based U.S. National Lightning Detection Network. Our conventional inter-comparison employed individual reports provided by each LLS, with results that were consistent with previous studies. Future work will include a more-general way to make inter-comparisons based on the physical processes within flashes.Release after 05/08/202

Time Evolution of Satellite‐Based Optical Properties in Lightning Flashes, and its Impact on GLM Flash Detection

The GOES-16 Geostationary Lightning Mapper (GLM) detection efficiency (DE) is studied over a full year (2018/19) in central Florida using the Kennedy Space Center Lightning Mapping Array (KSC LMA). Mean daily flash DE was 73.8%, and detection was highest during nighttime hours. GLM reported 86.5% of the LMA flashes that had coincident cloud-to-ground return strokes reported by the U.S. National Lightning Detection Network. Results also reveal that flash size and duration are critical parameters influencing GLM detection, regardless of the storm type, with 20-40% detection for small and short-duration flashes and greater than 95% detection for very large and long-duration flashes. These findings can be explained by examining the time-evolution of cloud-top optical emissions observed by the Lightning Imaging Sensor (LIS). Statistical simulations based on long-term LIS group area observations indicate that about half of the above-threshold light sources are smaller than a LIS pixel (similar to 4 x 4 km) and are smallest during and just after an initial breakdown in IC flashes. This work also demonstrates that for sources smaller than a GLM pixel, the cloud-top energy detection threshold for GLM is double that for LIS despite GLM's lower energy density threshold. Overall, these findings provide a framework for interpreting GLM performance under varying meteorological conditions, and help explain reports of low flash detection efficiency for storms associated with severe weather, as they typically exhibit high flash rates and resulting small and short-duration flashes. Plain Language Summary The Geostationary Lightning Mapper (GLM) on the GOES-16 satellite is the first of a new generation of satellite-based optical lightning sensor. It is the first satellite sensor to detect the evolution of lightning activity throughout the lifecycle of thunderstorms, and the data products can provide a lead-time for improving severe weather nowcasting such as tornados, strong winds, and large hail. During 2017-2018, GLM detected more than 70% of all lightning flashes in central Florida. The GLM-detected flashes typically last longer and occupy larger areas. Data from the Lightning Imaging Sensor (LIS) and modeling results indicate that longer-duration flashes tend to produce brighter and larger light sources for GLM to detect, whereas shorter-duration flashes tend to produce dimmer and smaller light sources that the GLM might not detect. This finding furthers our understanding of the underlying GLM detection behaviors and will help improve how GLM products are used in severe weather forecasting and other applications.Marshall Space Flight CenterOpen access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]