NSSL scientists will launch instrumented balloons into north Florida thunderstorms as part of an ongoing University of Florida triggered lightning experiment for two weeks beginning July 28. The team hopes to characterize the microphysics and electrical structure of storms in which lightning is triggered and learn more about how lightning works.
NSSL will launch two balloons at a time. One balloon will carry a high-definition video particle imager and a Parsivel disdrometer to measure the number, size, and shape of liquid and frozen water particles, and the other will carry an electric field meter. Both will be tracked by GPS radiosondes which will also measure temperature, pressure, dewpoint and winds.
The University of Oklahoma’s Shared Mobile Atmospheric Research and Teaching Radars (SMART-R) will be making polarimetric observations of the storms. NSSL’s data will be used to help interpret the SMART-R’s polarimetric observations.
Researchers at the University of Florida in Gainesville have had an extensive long-standing program to launch wire-trailing rockets into storm clouds to trigger and study lightning initiation, lightning strikes, and radiation from lightning. This new effort will improve our understanding of lightning produced by thunderstorms, and provide an opportunity to study storms with more tropical characteristics than those observed in the southern Plains.
NSSL’s participation is part of a cooperative agreement with the Defense Advanced Research Projects Agency (DARPA) that sponsors the University of Florida triggered lightning experiment near Gainesville, Fla.
In today’s virtual world, NSSL’s Dave Rust continues to be grounded in reality. With an eye always to the sky, this observational scientist has pioneered creative ways to measure storms for the past 35 years. Dave is retiring at the end of 2010, and we wanted to honor his significant, even revolutionary contributions, to thunderstorm science, especially through observation platforms. From mobile laboratories to instrumented storm-penetrating balloons, Dave’s measurements have contributed much to our present understanding of how storms become charged and produce lightning.
“I have always been in awe of nature,” says Dave as he recalled lying on his front lawn in New Braunfels, Texas, watching the changing shapes of summertime cumulus clouds. He was an only child who loved to study, tinker and build.
Dave has always been good with his hands. Using a homemade set of wooden blocks made by his grandfather, Dave would use wet sand to make structures in his sandbox. He upgraded to a small erector set and came up with simple and then not-so-simple structures. “I used the Erector motor with a gear train to build a carnival ride consisting of four airplanes each suspended from one of four rotor arms,” he says. Dave then created a game using a canon that used rubber bands to launch plastic artillery shells to knock a small figure off the planes as they flew by. In seventh grade shop he learned how to work with leather, making purses and coin holders to sell door-to-door. He took this skill to college, selling crests to his fraternity brothers at Southwestern University in Georgetown, TX.
Dave still tinkers, builds and creates. His most recent project, a high-definition (HD) precipitation imager, built in collaboration with several scientists, technicians and students, records HD video images of precipitation particles in thunderstorms. Carefully fabricated of construction-grade styrofoam to minimize splashed particles falling through the camera’s field of view, the instrument uses six high-intensity LED flashlights to shine brightly enough to show small particle images in dark clouds. An HD camcorder and a GPS tracker are tucked safely in instrument housing away from precipitation. Carried by a large balloon, the HD precipitation imager flies through storms with a radiosonde and electric field meter. Inside storms, these instruments record the size and concentration of raindrops and small hail, along with the corresponding electric field, temperature, location and time. The balloon data will be used in thunderstorm modeling, warn-on-forecast studies, and dual-polarization radar precipitation classification schemes. “I find it extremely gratifying to make a measurement and learn something new,” he says.
It was during graduate school at New Mexico Institute of Mining and Technology in Socorro, N.M. that Dave stumbled into the field of atmospheric electricity. He was measuring radon flow in mountain canyons for his Master’s work, but found something magical about the weather. In his spare time he helped with thunderstorm projects, eventually moving his research into atmospheric electricity. His Ph.D. dissertation became the foundation of his career: the electrical conditions near the bases of thunderclouds using measurements from a tethered balloon.
“Tethered doesn’t work,” Dave says, so he built something that did. As a post doc in Boulder, Colo., Dave used “free-ballooning,” to measure the electric field inside thunderstorms. “I think that probably mobile ballooning would be my biggest career success,” says Dave.
Probably the most important partnership in Dave’s life has been with his wife of almost 45 years, Linda. “Her long term dedication and support is the reason for my enjoyable career, he says. Linda helped fund his graduate degrees, knows how to launch balloons, and has been a team member on field projects. Her first severe storm mission was to hold a radiosonde in the field until it could be tracked – but lightning was striking too close and the mission was aborted. Dave and Linda are hoping to travel more, with trips to Seattle, a Danube River cruise, and possibly Egypt being planned.
Dave is just as passionate about his family as he is about launching balloons into storms. Their two kids are grown up, but both are in the Oklahoma City area. “He always had his hand in their activities.” His two grandsons live close by, and Dave likes to go camping with them and help them with their Cub Scout projects. Retirement will give him more time to spend with them.
Linda tells a story about how she met a young man who was bagging her groceries at the grocery store. As he carried the bags to her car, his eyes eagerly scanned the sky as he said, “thunderstorms this afternoon!” Linda had heard that excited tone before and said, “You need to talk to my husband,” as she gave him Dave’s business card. The grocery bagger did talk to Dave, and ended up being one of the many graduate students Dave has mentored. Those he couldn’t guide in person, he did either through decades of teaching or through his graduate level textbook written with Don MacGorman, “The Electrical Nature of Storms.” A review by a colleague says, “The book is clearly the best compilation of material on storm electricity that exists today.”
Both Dave and Linda are grateful for the wonderful group of people at NSSL and the opportunities he has been given. Dave has a message for his colleagues: “I really appreciate the help and collaboration of the staff at NSSL over three decades. Whatever success I’ve had professionally has been in large part the result of collaborations with, and a tremendous amount of help from, NSSL people.”
NSSL researchers successfully launched two balloon borne prototype instruments into a large thunderstorm complex at the end of October.
The “High Definition Videosonde Particle Imager” (HDVPI), built in NSSL’s machine shop, is designed to capture high-definition images of raindrops. Other instruments attached to the balloon measure the surrounding electrical field and other atmospheric variables.
This microphysical data will be used in thunderstorm modeling, warn-on-forecast studies, and for evaluating and refining radar precipitation classification schemes used by WSR-88D and other polarimetric radars.
The NSSL team has been on standby the month of October to launch the instruments when thunderstorms impact central Oklahoma. Data are also collected simultaneously from the 3-D Oklahoma Lightning Mapping Array (OK-LMA), the National Weather Radar Testbed Phased Array Radar, and the University of Oklahoma Polarimetric Radar for Innovations in Meteorology and Engineering (OU-PRIME) for analysis and comparison.
Researchers will evaluate the quality and relevance of the HD Videosonde observations by comparing them with the microphysical storm structure determined with polarization radars and storm structure with phased array radar.
Researchers believe the HD Videosonde will likely be a useful and potentially important research tool that would contribute to fulfilling aspects of the NOAA/NSSL mission.