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Archive for the ‘Lightning Mapping Array’ Category

In late April,  NASA SPoRT and the Albuquerque NWS met with scientists at New Mexico Tech to coordinate the integration of the Langmuir Lab lightning mapping array data into our operations.  According to Bill Rison, Paul Krehbiel, and Ron Thomas, New Mexico Tech’s Lightning Mapping Array (LMA) is a 3-dimensional total lightning location system. The system is patterned after the LDAR (Lightning Detection and Ranging) system developed at NASA’s Kennedy Space Center by Carl Lennon, Launa Maier and colleagues. The LMA measures the time of arrival of 60 MHz RF radiation from a lightning discharge at multiple stations, and locates the sources of the radiation to produce a three-dimensional map of total lightning activity.  The time-of-arrival technique for studying lightning was pioneered by Dave Proctor in South Africa.  The NASA SPoRT core project site details that operationally, total lightning data provide several advantages to forecasters.  First, total lightning data often give a 3-5 minute lead time ahead of the first cloud-to-ground lightning strike.  This improves lightning safety for the National Weather Service’s Terminal Aerodrome Forecasts (TAFs) and Airport Weather Warnings (AWWs).  This safety feature also can be used for incident support of special events. In addition, the total lightning data provides information about the spatial extent of lightning that is not available in the traditional cloud-to-ground data (http://weather.msfc.nasa.gov/sport/lma/).  This data may also be used to evaluate the degree of lightning activity within active wildfire smoke plumes.  The image below is an example of an LMA station at Briggsdale, Colorado taken by New Mexico Tech.  These stations are solar-powered and communications are operated via cell technology.

LMA stations at Briggsdale, Colorado.  Photo available from NM Tech.

Figure 1.  LMA station at Briggsdale, Colorado. Photo available from NM Tech.

After the first collaboration between NWS Albuquerque and NM Tech, forecaster Jennifer Palucki met with Harald Edens in June to install the xLMA and Live LMA software onto our office outreach laptop.  The LMA data that forecasters are evaluating at Albuquerque consists of source densities.  The imagery is available as a contour shaded product and describes the overall extent of sources from a particular thunderstorm or complex of thunderstorms.  The Live LMA software provides the actual point source information that make up the densities available in AWIPS.  The forecaster can actually see the structure of the point sources making up a flash on a 1-minute temporal resolution.  Figure 2 below shows the composite radar reflectivity valid at 0200 UTC July 23, 2014 for a complex of thunderstorms developing southward into the Albuquerque Metro Area.  The associated LMA source density product at 0202 UTC in Figure 3 illustrates the structure of the shaded point sources for the lightning flash.  The graphic shown in Figure 4 details the point sources available with the Live LMA software.  The source densities making up the flash during this 1-minute period stretched as far as 30-km from north to south and 20-km from east to west.  The altitude of the main source region was near 10-km.  The data available in AWIPS also allows the forecaster to slice and dice the data by elevation angle.  Forecasters at the Albuquerque NWS will continue evaluating the LMA products through summer 2014 to offer feedback to NASA SPoRT and NM Tech on its operational application.

 

Figure 2.  Mosaic Composite Reflectivity valid at 0200 UTC July 23, 2014.

Figure 2. Mosaic Composite Reflectivity valid at 0200 UTC July 23, 2014.

 

Figure 3.  Langmuir Lab LMA Source Density product valid at 0202 UTC July 23, 2014.

Figure 3. Langmuir Lab LMA Source Density product valid at 0202 UTC July 23, 2014.

Figure 4.  Live LMA 1-minute point sources valid at 0202 UTC July 23, 2014.

Figure 4. Live LMA 1-minute point sources valid at 0202 UTC July 23, 2014.

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I wanted to point out a couple of operational advantages of total lightning data offered by current LMA networks scattered across parts of the CONUS, but also the advantages forthcoming with the GLM in the future GOES-R era.  While viewing the data today in conjunction with radar and NLDN data, two great examples were noticed.  First, let’s consider the situation where a cell becomes electrically active (intracloud lightning), but never produces a cloud-to-ground strike.  The first image below shows KHTX 0.5 reflectivity overlaid with LMA Flash Extent Density.

Image 1.  KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density valid 1735/1736 UTC 25 June 2014

Image 1. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1735/1736 UTC 25 June 2014

 

Notice the small area of lightning detected by the North Alabama LMA in the central part of the image.  This cell never actually produced a ground strike.  So, using NLDN data alone, a forecaster would not have known that this cell was electrically active, and capable of producing lightning/thunder.  True, CG lightning was never observed by the NLDN network, but this is rather rare.

Next, let’s look at a situation where intra-cloud lightning preceded a CG strike as a cell was approaching an airport location.  Image 2 below, shows a cell that has just become electrically active as it was approaching the Tuscumbia/Muscle Shoals area around 1750 UTC.

Hi

Image 2.  KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1749/1750 UTC 25 June 2014

Notice in the image above that the first lightning detection by the LMA was during the 1749-1750 two-minute interval.  Now, we’ll take a look at an image just a little later, which shows the first incident of cloud to ground lightning as detected by the NLDN.

Image 1. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1735/1736 UTC 25 June 2014

Image 3. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area), including CG strike (small cyan line) as indicated by NLDN  valid 1757/1758 UTC 25 June 2014

The image above (Image 3) shows the first CG strike, indicated by the small cyan line, which was about 7-8 minutes after the first intra-cloud flash.  Notice also that this cell was approaching the Muscle Shoals ASOS to the east, for which the HUN office has airport weather warning responsibilities.  These responsibilities include the issuance of warnings for CG lightning with 5 SM of the airport. So, not only do the total lightning data alert to the presence of lightning when a cell never even produces a CG strike, but intra-cloud flashes will often precede CG strikes.  In fact, research has shown this to be by about 5 to 10 minutes.  Forecasters here at the HUN WFO have been privileged to use these data in operations for over 10 years now.  These and future GLM data will be a boon to operations, allowing for earlier lead times in some warning and forecast situations.

 

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Shortly after arriving for my evening shift today, I was called by a representative from an organization hosting an outdoor event in downtown Huntsville.  She was inquiring about the chances for shower or thunderstorm development into the early evening hours during the outdoor event (movie in the park night).  As I have grown quite accustomed to loading the GOES-R CI and total lightning products to be used for situational awareness, especially during the convective season, I referred to those to help with my assessment…in addition to radar data of course.  The image below shows GOES Visible channel imagery overlaid with GOES-R CI, total lightning data, and NLDN (the latter of which may be hard to see).  The location of Huntsville is labeled, and cloud motion is analyzed in the image.  Notice that the GOES-R CI product indicates generally low probabilities of convection in the area of clouds to the northwest (and upstream) of Huntsville.  The blue colors indicated CI probabilities of around 10-40%.

GOES Vis imagery overlaid with GOES-R CI, Total Lightning, and 15-min NLDN, approx. 2015 UTC June 13, 2014

GOES Vis imagery overlaid with GOES-R CI, Total Lightning, and 15-min NLDN, approx. 2015 UTC June 13, 2014

The next image shows lightning data overlaying the GOES Vis imagery…

GOES Vis imagery overlaid with KHTX 0.5 reflectivity (dZB) ~2015 UTC June 13, 2014

GOES Vis imagery overlaid with KHTX 0.5 reflectivity (dZB) ~2015 UTC June 13, 2014

 

Notice that only a few showers were located to the NW of Huntsville, but the GOES-R CI suggested further development was not likely and the total lightning (available from the North Alabama LMA) suggested these were only showers and thus not electrically active (I had looked over the previous ~20-30 mins).   Notice that lightning activity was relegated mainly to the South and East of the area.  This was a situation in which the GOES-R CI and total lightning data both served to provide a more complete assessment of the situation, allowing for a better forecast for one of our customers.

By the way…my forecast to her?  Well, based on the evidence from the observational imagery/data…I said very small chances for any shower activity, so let the show go on!  No showers ended up impacting the downtown area.

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Total lightning is often useful for situational awareness heading into the heart of the Southeast convective season.  Typically, by late May, nearly all echoes on radar are producing lightning, and data from the North Alabama Lightning Mapping Array (NALMA) help to assess which of the cells require further attention.

This year was a little different.

On several days during the last week of May, a subtle warm layer and large dry layer aloft helped to cap the atmosphere, or at least limit vertical growth, across northern Alabama and southern middle Tennessee.  We observed scattered “thunderstorm” development with 50 dBZ echoes at 0.5 degree elevation–but higher radar tilts yielded very limited vertical structure with these cells (very low reflectivity beyond about 2.4 degrees).  While reviewing data from the NALMA, we realized that total lightning was giving us a clue–few, if any of these cells had any total lightning at all, as you’d expect with such shallow convection.  The stronger cells with greater vertical depth (warranting further interrogation) were the only ones producing any total lightning whatsoever.

So, in this situation, total lightning data still provided situational awareness–but in a slightly different way.  Instead of looking for the storms with the greatest flash rates or source densities (or changes thereof), we were looking for storms with ANY flashes or sources.  However, since then, we’ve been aboard the Mesoscale Convective System train, and we’ve returned to our traditional uses of NALMA data.)

KHTX Radar and North Alabama Lightning Mapping Array (NALMA) Data, valid 2140 UTC 28 May

KHTX Radar and North Alabama Lightning Mapping Array (NALMA) Flash Extent Density Data, valid 2140 UTC 28 May. The image indicates just a handful of cells producing any cloud-to-ground lightning or total lightning, despite appearances of 0.5-degree radar reflectivity.

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Last year, NASA SPoRT submitted a proposal to collaborate with the Operations Proving Ground in Kansas City, Missouri.  The effort is focused on evaluating the Meteogram Moving Trace Tool developed by the Meteorological Development Laboratory (MDL) with support from NASA SPoRT to include total lightning.  One of the top requests from forecasters has been to create a time series plot of total lightning in real-time.  SPoRT first began to develop the total lightning tracking tool for use in AWIPS II to use with total lightning observations from the ground-based lightning mapping arrays.  The effort has now expanded to SPoRT coordinating with MDL’s meteogram tool for AWIPS II.  The advantage of the MDL tool is that it can create time series trends for multiple data sets beyond total lightning (e.g., radar, satellite, models).

This week, the Operations Proving Ground has brought together forecasters, developers, and trainers from multiple organizations to evaluate the use of this tool in several scenarios.  The opportunity for face-to-face discussions, training, and evaluation has been invaluable for the MDL and SPoRT developers to assess how the tool may be used in operations and to fix bugs that are found.  The face-to-face nature has allowed for bugs or requests for new features to be addressed throughout the day and to test the fixes the following day.  The week long evaluation facilitated by the Operations Proving Ground will lead to several improvements to the meteogram trace tool in preparation for its deployment in AWIPS II later this year.

Forecasters evaluating the meteogram trace tool at the Operations Proving Ground in Kansas City, Missouri.

Forecasters evaluating the meteogram trace tool at the Operations Proving Ground in Kansas City, Missouri.

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SPoRT is planning an assessment of Total Lightning products with several existing and new collaborators from WFOs, CWSUs, and National Centers, ranging in locations from southern Florida to New Mexico and Colorado.  From May 15 – July 15, 2014 operational forecasters will evaluate the application of total lightning to support severe storm, public safety, and aviation weather warning responsibilities.  To prepare, SPoRT is holding tele-training sessions with collaborators during the week of April 21 and has provided users several training modules as well as a Total Lightning Quick Guide.  These can be found via SPoRT’s Training Page and on the NOAA LMS.  Experience with total lightning data will prepare users for the GOES-R GLM as well as provide feedback from operations to researchers regarding the types of products users desire.

Total lightning (left) in a source density product form and radar reflectivity near the mixed phase level.  Higher values of total lightning correspond to regions where strong updrafts result in numerous particle collisions and charge separation.

Total lightning (left) in a source density product form and radar reflectivity near the mixed phase level. Higher values of total lightning correspond to regions where strong updrafts result in numerous particle collisions and charge separation. This image is from the NASA/SPoRT Quick Guide Training.

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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.

radar

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

PGLM

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.

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REBLOGED from The GOES-R Proving Ground at the Aviation Weather Center (http://goesrawt.blogspot.com/2013/08/pglm-over-houston-center.html)

At the end of the day yesterday we saw several areas of convection begin to fire along a boundary into eastern TX and western LA. As it further developed it began to impede flight routes not only in the corridor between Dallas and Houston, but also between Houston and the eastern U.S. Figure 1 (Please click on the image to open the animation) shows the radar imagery from 1934 – 2036 Z overlaid with flight routes during that time. Note in particular the airspace between Dallas and Houston as the convection filled in.

rad_2Now check out the PGLM activity in the Houston network for the same time (Figure 2 – Please click on the image to open the animation).

Houston PGLMTowards the beginning of the loop the convective activity between Houston and Dallas was beginning to fill in but flights were still able to shoot the gaps without too much delay. However, the PGLM, while indicating densities of only 10/2 min or less, had flashes in or very near the routes of some of the aircraft. Then, as the convection further strengthened and the PGLM activity increased, air traffic began to divert completely around these areas instead of shooting the gaps.

In the case, you can see the potential utility of the GLM once GOES-R is launched, particularly in the earlier period of convective development. Radar echoes during that time didn’t look particularly intense within the gaps, however the PGLM was showing flashes.

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Last year, SPoRT had the opportunity to expand collaborations with the Aviation Weather Center (AWC) and Storm Prediction Center (SPC) through a GOES-R Visiting Scientist Proposal.  The effort was focused total lightning activities with the National Centers, who have different operational perspectives from a local forecast office.  In addition to providing training on total lightning, SPoRT learned a great deal about the day-to-day operations at each of these locations.  SPoRT works to put products into the end user’s decision support system.  At the National Centers, this is N-AWIPS, which presented an interesting challenge for the GOES-R Geostationary Lightning Mapper (GLM) demonstration data set, the pseudo-GLM.  Unlike a local forecast office, the National Centers needed to be able to see each network at the same time and this need resulted in the PGLM mosaic.  First transitioned in June 2012, the PGLM mosaic has been evaluated informally at AWC and SPC.

Next week, the PGLM will be a participant with the AWC’s Summer Experiment in support of the GOES-R Proving Ground.  In preparation, SPoRT has coordinated with the AWC and SPC GOES-R Satellite Champions to update the display with improved color curves, lightning mapping array range rings, and network status bars as well as producing a training module on the PGLM that is more geared towards the National Centers.  Below is a screen capture of the newest display in N-AWIPS.  SPoRT is currently coordinating with the GOES-R Satellite Champion to transition this product to the Weather Prediction Center / Ocean Prediction Center.  Lastly, generating the mosaic is possible through collaborations that provide the real-time data to SPoRT from several organizations.  There are currently seven collaborating networks.  These are the Colorado Lightning Mapping Array (Colorado State / New Mexico Tech), Houston Lightning Mapping Array (Texas A&M / New Mexico Tech), Langmuir Laboratory Lightning Mapping Array (New Mexico Tech), North Alabama Lightning Mapping Array (NASA), Oklahoma Lightning Mapping Array (University of Oklahoma), Washington D.C. Lightning Mapping Array (NASA), and West Texas Lightning Mapping Array (Texas Tech University).

new_pglm_mosaic2

A screen capture of the pseudo-GLM mosaic product in N-AWIPS for use at the National Centers with the newest color curves, range rings, and network status bars.

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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.

radar_reflectivity_1925_annotated

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.

colma_25jul13_1927_annotated

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.

colma_25jul13_1928_annotated

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