Search Results - "Helsdon, John"

On the Triggering Mechanisms of Upward Lightning by Schumann, Carina, Saba, Marcelo M. F., Warner, Tom A., Ferro, Marco A. S., Helsdon, John H., Thomas, Ron, Orville, Richard E.

“…Upward lightning studies took place in Rapid City, South Dakota, USA and S. Paulo, Brazil during the summer thunderstorm seasons from 2011 to 2016. One of the…”
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Observations of bidirectional lightning leader initiation and development near positive leader channels by Warner, Tom A., Saba, Marcelo M. F., Schumann, Carina, Helsdon, John H., Orville, Richard E.

“…Based on the analysis of high‐speed optical and electric field change data, we present three observed cases in which a naturally occurring bidirectional…”
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Upward lightning flashes characteristics from high‐speed videos by Saba, Marcelo M. F., Schumann, Carina, Warner, Tom A., Ferro, Marco Antonio S., Paiva, Amanda Romão, Helsdon, John, Orville, Richard E.

“…One hundred high‐speed video recordings (72 cases in Brazil and 28 cases in USA) of negative upward lightning flashes were analyzed. All upward flashes were…”
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High-speed video and electric field observation of a negative upward leader connecting a downward positive leader in a positive cloud-to-ground flash by Saba, Marcelo M.F., Schumann, Carina, Warner, Tom A., Helsdon, John H., Orville, Richard E.

“…•The leader of a positive lightning flash moves in a stepped fashion or not?•E-field pulses before the flash could be due to the stepping of the leader or…”
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UPLIGHTS: Upward Lightning Triggering Study by Warner, Tom A., Helsdon, John H., Bunkers, Matthew J., Saba, Marcelo M. F., Orville, Richard E.

“…The Upward Lightning Triggering Study (UPLIGHTS) is a three-year National Science Foundation- funded field project that is taking place in Rapid City, South…”
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Bipolar cloud-to-ground lightning flash observations by Saba, Marcelo M. F., Schumann, Carina, Warner, Tom A., Helsdon Jr, John H., Schulz, Wolfgang, Orville, Richard E.

“…Bipolar lightning is usually defined as a lightning flash where the current waveform exhibits a polarity reversal. There are very few reported cases of…”
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An examination of thunderstorm-charging mechanisms using a two-dimensional storm electrification model by Helsdon, John H., Wojcik, William A., Farley, Richard D.

“…The early, prelightning, electrification of a storm resulting from noninductive (NI) charging involving graupel, cloud ice/snow, and supercooled cloud water in…”
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Numerical modeling of lightning-produced NOx using an explicit lightning scheme: 1. Two-dimensional simulation as a "proof of concept" by Zhang, Xingjun, Helsdon Jr, John H., Farley, Richard D.

“…We use the two‐dimensional (2D) version of our Storm Electrification Model to test its potential for studying lightning‐produced NOx. We assume that NO…”
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Hydrometeor charges observed below an electrified cloud using a new instrument by Mo, Qixu, Detwiler, Andrew G., Helsdon, John, Winn, W. P., Aulich, G., Murray, W. Clifton

“…Investigation of charges on particles in thunderstorms was conducted during the Severe Thunderstorm Electrification and Precipitation Study. In the case…”
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Comment on “On the roles of deep convective clouds in tropospheric chemistry” by Chien Wang and Ronald G. Prinn by Helsdon Jr, John H.

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An examination of the convective charging hypothesis: Charge structure, electric fields, and Maxwell currents by Helsdon Jr, John H., Gattaleeradapan, Sirin, Farley, Richard D., Waits, C. Christopher

“…An examination of the convective charging hypothesis is undertaken using our three‐dimensional (3D) storm electrification model (SEM). In an attempt to cover…”
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Aircraft observations of a lightning channel in STEPS by Warner, Tom A., Helsdon Jr, John H., Detwiler, Andrew G.

“…We analyze a portion of an intracloud lightning channel that was captured on video by an instrumented aircraft and mapped three‐dimensionally by a ground‐based…”
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The Severe Thunderstorm Electrification and Precipitation Study by Lang, Timothy J., Miller, L. Jay, Weisman, Morris, Rutledge, Steven A., Barker, Llyle J., Bringi, V. N., Chandrasekar, V., Detwiler, Andrew, Doesken, Nolan, Helsdon, John, Knight, Charles, Krehbiel, Paul, Lyons, Walter A., MacGorman, Don, Rasmussen, Erik, Rison, William, Rust, W. David, Thomas, Ronald J.

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Aircraft observations of the creation of lower positive charges in thunderstorms by Mo, Qixu, Helsdon Jr, John H., Winn, William P.

“…The existence of lower positive charges in the so‐called tripole thundercloud model has been confirmed by in situ measurements from balloons and by remote…”
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Numerical modeling of lightning-produced NOx using an explicit lightning scheme: 2. Three-dimensional simulation and expanded chemistry by Zhang, Xingjun, Helsdon Jr, John H., Farley, Richard D.

“…We continue the development of a modeling system for the investigation of lightning‐produced NOx at the process level by including the chemistry aspects used…”
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Numerical modeling of lightning-produced NO x using an explicit lightning scheme: 1. Two-dimensional simulation as a “proof of concept” by Zhang, Xingjun, Helsdon, John H., Farley, Richard D.

“…We use the two‐dimensional (2D) version of our Storm Electrification Model to test its potential for studying lightning‐produced NO x . We assume that NO…”
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Numerical modeling of lightning-produced NO x using an explicit lightning scheme: 2. Three-dimensional simulation and expanded chemistry by Zhang, Xingjun, Helsdon, John H., Farley, Richard D.

“…We continue the development of a modeling system for the investigation of lightning‐produced NO x at the process level by including the chemistry aspects used…”
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THE SEVERE THUNDERSTORM ELECTRIFICATION AND PRECIPITATION STUDY by Lang, Timothy J., Miller, L. Jay, Weisman, Morris, Rutledge, Steven A., Barker, Llyle J., Bringi, V. N., Chandrasekar, V., Detwiler, Andrew, Doesken, Nolan, Helsdon, John, Knight, Charles, Krehbiel, Paul, Lyons, Walter A., MacGorman, Don, Rasmussen, Erik, Rison, William, Rust, W. David, Thomas, Ronald J.

“…During May–July 2000, the Severe Thunderstorm Electrification and Precipitation Study (STEPS) occurred in the High Plains, near the Colorado–Kansas border…”
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The North Dakota Thunderstorm Project: A Cooperative Study of High Plains Thunderstorms by Boe, Bruce A., Stith, Jeffrey L., Smith, Paul L., Hirsch, John H., Helsdon, John H., Detwiler, Andrew G., Orville, Harold D., Martner, Brooks E., Reinking, Roger F., Meitín, Rebecca J., Brown, Rodger A.

“…The North Dakota Thunderstorm Project was conducted in the Bismarck, North Dakota, area from 12 June through 22 July 1989. The project deployed Doppler radars,…”
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Comment on: On the roles of deep convective clouds in tropospheric chemistry. Authors' reply by HELSDON, John H, CHIEN WANG, PRINN, Ronald G

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