GLM is coming: Preparations

Creating demonstration data and products to train forecasters for GLM has presented unique challenges.  Aside from the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS), no other space-based platform had similar capabilities to the GLM.  Furthermore, the OTD and LIS were low-Earth orbiting instruments and would only view a small portion of the Earth for no more than a couple minutes at a time.  This prevented their use as a demonstration data set as forecasters would need to see how total lightning (the combination of intra-cloud and cloud-to-ground) evolved with time.  That put the focus on ground networks, which could observe the entire life cycle of a storm.  The ground networks, unfortunately, lacked the ability to observe total lightning (or the capability was not yet available).  The exception was the ground-based lightning mapping array.

The lightning mapping array (LMA) was developed by New Mexico Tech and evolved out of earlier systems, some of which were tested at Kennedy Space Center.  By operating in the very high frequency end of the electromagnetic spectrum (~80 GHz), the LMAs could observe the entire lightning channel within a cloud.  Primarily designed for lightning research, these would become instrumental in the training activities for the GOES-R Proving Ground and the GLM.  This is because the LMAs were capable of observing total lightning.  Their accuracy was extremely good and they have been used for ground verification for OTD and LIS and will do so again for GLM.  Their primary disadvantage is a very short range; generally no more than 200 km from the center of the network.  Figure 1 shows the physical relationship of total lightning to a storm updraft as well as the lightning jump concept.


Figure 1:  The top two panels show the total lightning density (left) and radar reflectivity at ~20 thousand feet (right) and 1442 UTC.  The radar elevation corresponds to the mixed phase region.  Total lightning is produced by a strong, voluminous updraft extending into the mixed phase region.  This is a non-linear relationship so the strongest updrafts will produce the most lightning.  This physical connection can be harnessed by forecasters as shown in the lower left (total lightning density at 1450 UTC) and right (radar reflectivity at 20 thousand feet at 1452 UTC).  The total lightning shows a “bull’s eye” feature indicating rapid intensification, or lightning jump.  This preceded the radar update at 1452 UTC showing the updraft now extending into the mixed phase region.  This allowed the total lightning to provide additional information on the intensification of this storm and the rapid increase indicates that severe weather is imminent.  Also, the total lightning information shows the spatial extent of the lightning that can be used for safety applications.

The Melbourne, Florida forecast office was the first office to use total lightning data from a local lightning detection and ranging network (very similar to an LMA) in the late 1990s.  This was a combined effort by the forecast office, Massachusetts Institute of Technology (MIT), MIT Lincoln Lab, and NASA Marshall Space Flight Center.  The data became extremely popular with the office and the Lightning Imaging Sensor Demonstration and Display (LISDAD) system was instrumental in investigating the uses of total lightning in real-time.

In 2002, NASA’s Marshall Space Flight Center had installed the research oriented North Alabama Lightning Mapping Array (NALMA).  By March 2003, the NASA SPoRT team, in collaboration with the Huntsville weather forecast office, had made NALMA data available in the National Weather Service display system; AWIPS.  The Huntsville forecast office would then go on to issue its first warning using total lightning data that May.  NASA SPoRT would extend collaborations with a handful of other forecast offices using NALMA as well as the NASA owned Washington D.C. LMA in the late 2000s.

By 2008, the GOES-R Proving Ground was accelerating its efforts with training and hands-on activities, such as the Hazardous Weather Testbed in Norman, Oklahoma.  This required a demonstration product for GLM that could be used in real-time.  The Marshall Space Flight Center had developed the GLM proxy that was derived from NALMA to test data processing algorithms for the GLM.  The drawback was that it could not be run in real-time.  However, in 2009 NASA SPoRT produced the pseudo-GLM (PGLM) product (Figure 2).  It was not an exact replica of future GLM observations, but it represented a reasonable facsimile that allowed for hands-on training that let forecasters better learn about total lightning and its relation to storms intensity and severe weather.


Figure 2:  An example of the pseudo-GLM flash extent density product derived from the Washington D.C. lightning mapping array during the derecho event of 2012.  The radar reflectivity (right) shows a strong line of storms approaching Washington D.C.  The greatest reflectivities (and likely strongest storms) are towards the northeast.  The pseudo-GLM (left) shows that it has update sooner than the radar, but also emphasizes the northeastern end of the line.  In fact, over 110 flashes are observed in two minutes at one location, highlighting the strongest overall storm.  The convection to the southwest is weaker as evidenced by the lack of pseudo-GLM observations.

NASA SPoRT, thanks to funding via the GOES-R visiting scientist program, was able to reach out to each of the other LMAs that were in operation across the country (and one in Canada!).  By 2014, almost a dozen LMAs were collaborating.  This allowed for the PGLM to be produced for numerous locations as well as expand partnerships to over a dozen forecast offices, three center weather service units, and the Aviation Weather Center.  Figure 3 shows the approximate domain and collaborating organization for each available LMA.  Combined, the collaborations between the forecasters, LMA owners, and the testbeds allowed for a wide variety of feedback discussing operational uses and visualization concepts.  Much of this has directly supported my own efforts as the GLM satellite liaison for the ongoing work in the Satellite Foundational Course for GOES-R, preparing for operational applications training, and the 2017 summer assessment.


Figure 3:  The approximate domain of the 11 collaborating lightning mapping arrays that have been used as part of the GLM preparations for the GOES-R Proving Ground.  The numbers correspond to the list at top showing the owners of the collaborative network.

Next up in the “GLM is coming” series is a post describing the GLM instrument itself as we await in initial release of GLM data.

A New Total Lightning Web Display

The SPoRT Center regularly works to display unique data in products, such as total lightning from ground-based lightning mapping arrays (LMAs), in the Weather Service’s display system; AWIPS II.  However, there is occasionally an opportunity to try a different method for specific operational applications.  One of those opportunities came with the Morristown, Tennessee forecast office.  Here, the collaboration was looking for a web-based visualization in order to better collaborate with emergency managers.  Feedback to SPoRT requested the need for a real-time display that could animate the data, auto-update, and allow zooming to a feature that would not reset with an update.  Additionally, there was a need to make this functional on mobile devices.

This has resulted in the test display shown here of the North Alabama Lightning Mapping Array flash extent density from July 1, 2015 from 1:30-4:00 PM (Central).  Like the more traditional display in AWIPS II, this flash extent density highlights the main storm cores where the updraft is intensifying, shows the spatial extent of total lightning, and even highlights several long flashes into the stratiform region behind the main convection, as shown in the still images below.  While the display is just in a development state now, it is demonstrating the potential for how to bring these data to emergency managers and Weather Service forecasters who may be in the field and not in the office, such as for special outdoor events.

Demonstration total lightning web display

The North Alabama Lightning Mapping Array flash extent density animation from 1:30-4:00 PM (Central) on July 1, 2015 in a new demonstration web display.  State and county boundaries are in black, while interstates are blue and major U.S. highways are in red.  (Click for the full resolution image.)

The two images below show a still image from 2:14 PM (Central) of the total lightning flash extent density and the corresponding radar reflectivity.

A still taken from the animation above at 2:14 PM (Central).  The main storm core and stratiform region lightning are highlighted.

A still taken from the animation above at 2:14 PM (Central). The main storm core and stratiform region lightning are highlighted. (Click for the full resolution image.)


The corresponding radar reflectivity at 2:14 PM (Central) for the still image above highlighting the locations of the total lightning features.

The corresponding radar reflectivity at 2:14 PM (Central) for the still image above highlighting the locations of the total lightning features. (Click for the full resolution image.)

Lightning Strikes Aircraft in Flight

The event in this blog post was provided by Amanda Terborg, satellite champion at the Aviation Weather Center.

SPoRT has been coordinating with the Aviation Weather Center (AWC) for a little over a year to incorporate the pseudo-geostationary lightning mapper (PGLM) mosaic demonstration product in operations, derived from ground-based lightning mapping arrays and part of the GOES-R Proving Ground.  This work culminated with the transition from demonstration mode to the AWC’s operations floor in September, thanks to Amanda’s coordination.  Shortly thereafter we received this particular event from October 7th.

On this day, one of the major items of interest was a line of storms moving through Washington D.C. and northern/western Virginia (Fig. 1).  The storms were not creating major disruptions as flights were able to remain ahead of the line or work their way behind the line of storms.  Figure 2 shows the aircraft tracks from 1402 UTC, which corresponds to the radar image in Fig. 1.  Due to the different projection types in N-AWIPs, the primary point of interest is circled in each image.  The major item of note is that there are no National Lightning Detection Network (NLDN) cloud-to-ground strike observations in the entire image.  However, the circled region shows a cluster of 3-4 flashes observed by the PGLM product.  As there are no corresponding NLDN strikes, these are solely intra-cloud flashes.  By observing the flight tracks, the aircraft were flying behind the main line of highest reflectivities.  Although the aircraft were behind the main line, Fig. 2 shows that approximately five aircraft flew into the region where the PGLM flashes were observed.  At around 1400 UTC one of those flights was struck by lightning.  The best news was that, while struck, the aircraft suffered no damage and continued safely on to its destination.


Figure 1: The reflectivity (dBZ) observations from the Sterling, Virginia radar at 1402 UTC. The white circle indicates the region of interest.


Figure 2: The corresponding pseudo-geostationary lightning mapper (PGLM) flash extent density product (filled boxes) and the Aircraft Situation to Display Industry (ASDI) flight tracks and heights (colored lines) at 1402 UTC. The white circle shows the same area of interest as that shown in Fig. 1. Not the observations of PGLM flashes and the lack of cloud-to-ground strike observations from the NLDN.

This example shows one of the major benefits of the future GOES-R Geostationary Lightning Mapper (GLM), as a space-borne instrument capable of observing total lightning (both intra-cloud and cloud-to-ground).  Radar is an excellent tool for helping develop safe flight tracks.  The ability of total lightning to observe intra-cloud flashes, as well as the spatial extent of these flashes, gives aviation planners additional information as to how to route aircraft, particularly in storms that have no cloud-to-ground observations.  This will be very important in data sparse regions were radar and total lightning are currently not available.

Long flash observed by the Colorado Lightning Mapping Array

Earlier this year, SPoRT in collaboration with the GOES-R Proving Ground, New Mexico Tech (developers of LMA technology), and Colorado State University (owner of the Colorado LMA), worked to gain access to the real-time data feed from the Colorado Lightning Mapping Arary.  In addition to helping the GOES-R Proving Ground, SPoRT is helping provide these data to WFOs Boulder and Cheyenne.  As we finalize these efforts the data have been displayed in a Google Earth web page, in addition to New Mexico Tech’s main page.  While observing the lightning in Colorado this afternoon, an interesting flash was observed around 1928 UTC.

First, here is a screen capture of the radar from WFO Boulder’s web page (Figure 1) at 1925 UTC.  We can see a strong cell (circled) southwest of Fort Collins, Colorado.  Of particular note is the low reflectivity values extending eastward towards Greeley, Colorado.


Figure 1: Radar reflectivity at 1925 UTC on 25 July 13 approximately 3 minutes before the long flash initiated.

Switching to the Colorado LMA source density display (Figure 2) at 1927 UTC, we can see some total lightning activity (~21-30 sources).  This is an electrically active storm, but is not undergoing a lightning jump that would indicate severe weather.  Let’s step ahead one more minute.


Figure 3 shows the source densities again, but now for 1928 UTC.  Circled here is a single flash that originated from the storm southwest of Fort Collins, Colorado.  A rough estimate of the distance is ~25 miles.  This demonstrates an important lightning safety feature of total lightning.  These types of observations provide strong visual evidence that flashes are not always confined to the core of the storm.  This is very useful for educating individuals why you should stay indoors for 30 minutes after the last flash, even when the main body of the storm has passed.


Total Lightning in AWIPS II

The NASA SPoRT program has been providing total lightning data to several National Weather Service (NWS) partners since May 2003. This transition, along with training, has helped forecasters in the warning decision making process to enhancing situational awareness. This is made possible by incorporating these unique data in the National Weather Service’s native display environment, AWIPS. This acronym stands for the Advanced Weather Interactive Processing System. The NWS is planning to begin switching to the newer AWIPS II system late this year or early 2010.  SPoRT is working hard to maintain our existing capabilities and to investigate new display abilities within this new environment.

Unlike AWIPS, the new AWIPS II system is more like Google Earth in that a forecaster can pan around the map and zoom in on areas of interest.  The original AWIPS has very rigid viewing levels and does not allow this kind of freedom.  This feature of AWIPS II will allow forecasters to quickly switch between a large overview image to a zoomed image focusing on a specific storm.  SPoRT has created a small demonstration loop showing what total lightning data may look like should the data be made available from six of the existing total lightning networks.  This type of display could be used by the Storm Prediction Center allowing their forecasters to easily interrogate storms across the south where total lightning data are available.  Plans are being made to make these data available for the 2010 Spring Program hosted in Norman, Oklahoma.

This is a test loop of total lightning data displayed in AWIPS II.  The boxes indicate the rough domain covered by each network.  This loop uses data from the North Alabama and Washington D.C. Lightning Mapping Arrays as well as the Kennedy Space Center’s Lightning Detection and Ranging network.  The data in Oklahoma and Texas uses North Alabama data shifted to the other networks to demonstrate the capability of displaying multiple networks in AWIPS II.

This is a test loop of total lightning data displayed in AWIPS II showing the source density product. The boxes indicate the rough domain covered by each network. This loop uses data from the North Alabama and Washington D.C. Lightning Mapping Arrays as well as the Kennedy Space Center’s Lightning Detection and Ranging network. The data in Oklahoma and Texas uses North Alabama data shifted to the other networks to demonstrate the capability of displaying multiple networks in AWIPS II.

Total Lightning Training

The first of two parts in SPoRT’s Total Lightning training has now been posted in the Training section of the SPoRT website.

This training covers the basics of what is meant by total lightning as well as the source density product provided by SPoRT to our partner Weather Forecast Offices. This training also introduces the concept of a lightning jump and how it can be used to enhance severe weather forecasts. Whether you are a forecaster looking for information, or a member of the public interested in the data used by several Weather Service offices, feel free to check this out!

The lightning mapping array can be used to detect electrical activity within thunderstorms.