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Mesoscale Lightning Experiment

Space Shuttle Observations of Lightning - Mesoscale Lightning Experiment

Background

Lightning discharge into the stratosphere The present Shuttle lightning observation research program evolved from cooperative research efforts of the Marshall Space Flight Center, State University of New York at Albany, and New Mexico Institute of Mining and Technology at Socorro. These cooperative research programs were conducted to learn more about atmospheric electricity and it's relationship to severe storms and their development. These programs, during the late 1970's and early 1980's, used the NASA Ames U-2 high altitude research aircraft to over-fly developing thunderstorms and or mesoscale thunderstorm complexes. An instrumented pallet, located in the bottom of the U-2 aircraft, provided both optical and electrical signatures from the lightning that were being observed during the over-flights. A CCD TV line-scan camera with a diffraction grating filter provided crude spectral information.

A photo showing a lightning flash and cloud top. This was obtained during a 1980 overflight of a large active thunderstorm in Arkansas, using nadir-viewing VINTEN 70 mm cameras located in the payload bay (Q-bay) of the U-2.

In addition, research flights around thunderstorms were conducted in 1979 using a general aviation aircraft, an instrumented Bellanca Viking , provided by Airborne Research Associates of Weston, Mass. This aircraft, under contract to NASA Marshall Space Flight Center, was used as a test bed to to provide data of the design of a lightweight lightning detection and photographic system that was later flown on the NASA Space Shuttles STS-2, STS-4, and STS-6. This experimental hardware was called Night-time and Daytime Optical Survey of Lightning Experiment (NOSL) and a number of interesting movie sequences were obtained of lightning as seen from the orbiting Shuttle. After this series of Shuttle flights we began to use the payload bay low light level cameras whenever the crewmembers were not using them as part of their normal operations and again some interesting lightning video was collected.

During the late 1980's, after the Space Shuttle Challenger STS-51L disaster (Jan. 28, 1986), a new approach to observe lightning was proposed. This program continued the lightning research program of previous Space Shuttle flights and it was called Mesoscale Lightning Experiment (MLE). The purpose was to observe lightning that was directly under the shuttle as it would be seen by an unmanned orbiting satellite. The data obtained from a number of these Shuttle flights has provided design criteria data that has been incorporated in the design of future sensors for lightning detection and location satellites to be flown in the late 1990's.

Current Efforts

In late 1988 a revised operations plan for MLE was initiated which would use the low light level TV cameras located in the Shuttle' payload bay in a different operational mode. The TV cameras would be operated by the Instrumentation and Communication Operations (INCO'S) personnel located in the Mission Control Center on the ground rather that have the crew to conduct the TV cameras to observe lightning storms that maybe near the limb of the earth. This observation program relieves the crew of the camera operations and allows more observation time to see the large mesoscale storms and their lightning displays. Since the location of the Shuttle is known from it's orbit and due to the low light level sensitivity of the payload bay TV cameras, the star fields and the airglow of the earth can be observed and it is possible to determine the size of the lightning flashes as they are seen. John McKune of NASA Johnson Space Flight Center developed a computer program which he uses in Shuttle pointing operations and it has been used to help us here at MSFC to locating the storm complexes. It also allows one to determine the size of the flashes that are seen in the video images.

During a Shuttle mission STS-34 on October 21, 1989 (Orbit 44) we saw a phenomena that we had not seen before. Although commercial aviation and military pilots had reported that they had seen lightning proceed out the top of thunderstorms and move upward toward the ionosphere,there were no photographic data to prove that this type event had occured. In a number of cases the pilots who saw this type of phenomena and reported it were told that maybe it could happen by the meteorologists who were on duty at the time. Some of these observations were reported in the literature.

During the STS-34 mission, which occured on the night of October 21, 1989, we observed and recorded, using the shuttle's low light level TV cameras, our first vertical like discharge moving out from the top of a thunderstorm that was being illuminated by intra-cloud lightning.

To date our Shuttle observations have captured a total of 19 of the upward vertical like discharges.

Analysis Techniques

Specialized video evaluation software,in conjunction with a Silicon Graphics Iris Indigo Computer, is now being used to digitize the video images for analysis. This equipment allows the researcher to determine the flash rate of the lightning, the size of the flashes, as well as the size of the thunderstorm complexes that are being analyzed.

The analysis capabilities are to be improved in the future as better image enhancement tools become available, state-of-the-art frame grabbers, and/or other software tools become available. We are also planning for the use of CAD/CAM equipment and additional software to provide better mapping tools to display and locate the storm cells with better precision.

Images and Movie Loops

Images

Vertical lightning discharge into the stratosphere
Image and schematic from STS-43, Orbit 55

Montages of other vertical lightning discharges into the stratosphere
These montages contain video images captured by the low light level TV from various space shuttle missions. Time stamps are of the format:
Month Day Year HH:MM:SS.milliseconds Mission/Orbit number , where the time is Universal time (UTC).

MPEG movies

Mpeg movie production courtesy of the Engineering Photo Analysis Group of the MSFC propulsion laboratory.

Storms over Argentina (364,049 bytes)
STS-58 Columbia, with moonlight. This mesoscale convective complex is approximately 930 km across the field of view.

Storms over Mediteranean Sea (6,006,898 bytes)
STS-48, Discovery, low illumination moonlight provides minimal background. Clouds are not seen under this illumination, but the lightning flashes are easily seen. The coast of France is on the left side of the image, and the city of Algiers appears later in the imagery. The average size of the lightning cells is about 35 km and the estimated flash rate for one cell in this system was about 130 flashes per minute.

Nadir view of lightning from STS-52, under no moonlight. (651,031 bytes)
Most of the small flashes seen in this movie are approximately 35 km in diameter.
Stay Tuned ... More to come.

Ground Based Observations of Atmospheric Flashes

Ground based observations by Franz, Nemzek and Winkler reported in Science magazine (1990) that they had observed large luminous discharges above a thunderstorm using a low-light level black and white TV camera system. At 22:14 CST on July 6, 1989 they recorded a twin flash originating in a storm top cloud and discharging into the stratosphere. The active thunderstorm was about 250 km from their site, and below the horizon, so only the upper discharge-like events can be seen.

During the period from 1992 and 1994 Winckler and his associates reported that 150 large discharges were seen over storms in Iowa during 9-10 August 1993.

Ground based research of Lyons and his associates in 1993 reported that he had recorded from his site in Fort Collins Colorado using low-light level black and white TV cameras well in excess of 600 cloud to stratosphere events (CS).

During the period of 1994 Lyons continued his investigations, and on July 11-12 over 40 large sprites were associated with intense cloud flashes.

Images in this section were created from video tapes which were provided by Winkler and Lyons

Recent developments in the study of Atmospheric "Flashes"

Data in this section were developed from a video tape provided by Dave Sentman of the Geophysical Institute, University of Alaska Fairbanks.

Color image of a Red Sprite on July 4, 1994 at 04:00:20 UTC, which reached an altitude of over 85 km, the tendrils beneath the sprite are as low as 60 km. The bright area beneath the sprite is an over-exposure of normal lightning occuring in the top portion of an active thunderstorm complex located in the Texas panhandle. Cloud tops in this complex were about 18 km.

Note the similarities between Sentmans black and white image of a red sprite taken July 4, 1994 at 04:14:19 UTC and this Shuttle-based black and white image observed September 15, 1993 at 01:18:14 UTC. The shuttle was about 1850 km from the target. The shuttle-observed feature appears to have come from a thunderstorm over the edge of the earth's limb. The above-limb portion of this event is approximately 47 km in length. The image that Sentman captured was taken from an aircraft position much closer to the storm complex.

MPEG movie (962363 bytes) sequence of the above red sprite. Note, the sequence is not played back in real-time.

MPEG Black and white version of a red sprite (1593156 bytes) If that is too big ... Smaller version (451581 bytes)

Black and White images of Blue Jets taken by a very wide angle low-light TV camera flying near an active thunderstorm, in eastern Arkansas on July 1 1994.

MPEG movie sequence of Blue Jets, corresponding to the above still frames.

Observations of Sprites and Jets from Langmuir Laboratory, New Mexico*

Mark Stanley, Paul Krehbiel, William Rison, Charles Moore, Marx Brook
Geophysical Research Center, New Mexico Tech., Socorro, NM 87801
and
O.H. Vaughan
Marshall Space Flight Center, NASA, Huntsville, AL 35812

A low light level video camera was used to observe thunderstorms at night during the summer of 1996. The Langmuir Laboratory is situated at 3200 m. elevation in central New Mexico.

Spectacular video observations were obtained of sprites and upward jet phenomenon at relatively close range (75-150 km.) above a large storm over Ruidoso and Carrizozo, New Mexico on the night of July 24/25, 1996. The jets were upward branched from a single vertical channel and had spectacular "fountain" and "flame" or "flare" shapes. The upward development was often detected in sequential video fields, but the flame or flare jets typically appeared in only a single 16 ms field. The inferred development /propagation speed of the latter events was on the order of 10^6 m/s. The flame events exhibited a dense, fine dendritic structure, while the flares and fountains had a smaller number of upward branches, with residual "hot spots" as in subsequent fields. Several higher altitude sprites appeared to be observed at close range and high elevation angle (45 degrees) by the camera.

A black and white movie of very close images of what is probably a Blue Jet taken by a low-light TV camera , during the Langmuir observations. (Sequence not in real time.)

MPEG version (65031 bytes)          Quicktime version (658293 bytes)

*Results of this research were presented at the December 1996 meeting in San Francisco, CA.

Recent Reports On Shuttle Lightning Research

Wescott, E.M., Sentman, D.D., Heavner, M.J., Hampton, D.L., Osborne, D.L., and O.H. Vaughan Jr., 1996, "Blue starters: Brief Upward discharges from an intense Arkansas thunderstorm," Geophysical Research Letters, Vol. 23, No. 16, pp. 2153-2156, August 1, 1996.

Vaughan, Otha H. Jr., 1994, "NASA Shuttle Lightning Research: Observations of Nocturnal Thunderstorms and Lightning Displays as Seen During Recent Space Shuttle Missions," Conference on Optical Spectroscopic Techniques and Instrumentation for Atmospheric and Space Research, SPIE - The International Society for Optical Engineering, Vol. 2266, 25-27 July 1994, San Diego, California.

Boeck, William, Otha H. Vaughan, Jr, Richard Blakeslee, Bernard Vonnegut, Marx Brook, and John McKune, Jr, 1995, "Observations of Lightning in the Stratosphere", Journal of Geophysical Research, Vol. 100, No. D1, pp. 1465-1475, January 20, 1995.

Vaughan, Otha H. Jr., 1994, "Observations of Nocturnal Thunderstorms and Lightning Displays as Seen During Recent Shuttle Missions," Fifth Symposium on Global Change, and the Symposium on Global Electric Circuit, Global Change, and the Meteorological Applications of Lightning Information, American Meteorological Society, Jan. 23-28, Nashville, TN., pp. 355-359.

Vaughan, Otha H. Jr., Richard Blakeslee, William Boeck, Bernard Vonnegut, Marx Brook, and John. McKune Jr., 1992, "A Cloud-to-Space Lightning as Recorded by the Space Shuttle Payload-Bay TV Cameras," Monthly Weather Review, 120 (7), pp. 1459-1461.

Vaughan, Otha H. Jr., 1990, "Mesoscale Lightning Experiment (MLE): A View as Seen from Space During the STS-26 Mission," NASA TM-103513.

Principal Investigator Mesoscale Lightning Experiment (MLE)
Otha H. Vaughan, Jr.
retired from
Earth System Science Division
Space Sciences Lab, NASA/MSFC
Huntsville, AL 35812

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