An interesting case using the GLM occurred over New Mexico from July 2. The time period spans 00Z to 03Z for that day. You can access an animation of the entire period at the following link. (NOTE: The animation is ~76 megabytes. Several still images highlighting key points are shown below.) This shows the GLM 8 km, 1 minute group density (upper left), ABI 11.2 micron IR (upper right), and the composite radar reflectivities from the Albuquerque, El Paso, and Cannon AFB radars. (Apologies to the ABI as only the full disk imagery was archived and therefore only updates every 15 minutes.) No NLDN or Earth Networks data are shown at this time as the data have not been added to the archive as of this writing. A still image from the animation is shown in Figure 1.
Figure 1: A still image from the 00-03Z animation of the GLM 8 km, 1-minute group density (upper left), ABI full disk, 15-minute 11.2 micron IR (upper right), and composite radar reflectivity from Albuquerque, El Paso, and Cannon AFB (lower right) at 0133 UTC on July 2, 2017.
[76 MB] GLM over New Mexico (00-03Z, July 2, 2017)
The main emphasis is using the GLM in data sparse locations. NOAA has a great graphic showing the available WSR-88D coverage across the United States (Figure 2). This example focus on New Mexico and the availability of four radars: Albuquerque (KABX), El Pasa (KEPZ), Holloman AFB (KHDX), and Cannon AFB (KFDX). On this day, it is important to note that the Holloman radar was unavailable.
Figure 2: NOAA graphic showing the NEXRAD coverage in the continental United States below 10,000 Feet above ground level.
Several interesting features stand out during these three hours of data. The first is in northwestern New Mexico and south of the Four Corners region. At 0022 UTC, the GLM detected a small flash. Five flashes occurred between 0022-0041 UTC and with a final flash at 0112 UTC. Figure 3 shows a snap shot at 0036 UTC. Figure 1 shows that this region of New Mexico has no radar coverage below 10,000 feet above ground level. The composite reflectivity from the Albuquerque radar (ABX) hints at some activity at the limit of its range and the ABI observes a small region of cooler cloud tops. Although very little lightning was observed, this can alert forecasters that convectively driven precipitation is occurring where it is otherwise difficult to observe via radar. Also, a small amount of lightning can be observed in the storms in east-central New Mexico as well.
- Figure 3: This is the same as Figure 1, but for 0036 UTC. The yellow circles highlight the area of interest.
A similar case occurred at 0116 UTC (Figure 4) through 0136 UTC. Again, a very weak, isolated cell as observed by the ABI and the El Paso (KEPZ) radar had an initial GLM lightning observation at 0116. The storm never intensified beyond two dozen flashes, but persisted for 20 minutes before dissipating. Also, while the GLM values are quite low, the brighter locations in the group density display highlight some of the stronger cells in the line of storms.
Figure 4: Same as Figure 1, but for 0116 UTC. The yellow circles highlight the area of interest.
We also begin to see the areal extent of the lightning changing by 0152 UTC (Figure 5). Now, the GLM group density observations are beginning to show lightning that is extending behind the main region of convection. This is highlighting that even in a low flash rate environment, lightning can still extent tens of miles away from the convective core.
Figure 5: The same as Figure 1, but for 0152 UTC. The small yellow and black circles highlight the location of the long flash.
The final example showing lightning initiation versus radar observations occurs at 0204 UTC (Figure 6) in central New Mexico. As in Figures 2 and 3, a small lightning flash is observed in a region of weak radar composite reflectivity and cool, but not cold ABI cloud tops. This highlights the initiation of the lightning threat that the radar composite reflectivity may not emphasize in relation to the active lightning associated with the stronger reflectivity regions. The animation shows that this preceded the storm intensifying on radar and overall lightning activity through the end of the animation at ~0300 UTC.
Figure 6: Same as Figure 1, but at 0204 UTC. The small yellow and black circles highlight the region of interest.
NOTE: NOAA’s GOES-16 satellite has not been declared operational and its data are preliminary and undergoing testing. Users receiving these data through any dissemination means (including, but not limited to, PDA and GRB) assume all risk related to their use of GOES-16 data and NOAA disclaims any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose.