TY - JOUR
T1 - Characteristics of upward-connecting-leader current leading to attachment in downward negative cloud-to-ground lightning strokes
AU - Nag, Amitabh
AU - Cummins, Kenneth L.
AU - Plaisir, Mathieu N.
AU - Brown, Robert G.
AU - Wilson, Jennifer G.
AU - Crawford, David E.
AU - Noggle, R. Carl
AU - Rassoul, Hamid K.
N1 - Funding Information:
The authors would like to acknowledge funding from the U.S. National Science Foundation Award 1934066 and U.S. Air Force contract FA252117P0079 . We thank two anonymous reviewers for their thoughtful comments on the paper. Data used in this paper is available by contacting the first author ( [email protected] ).
Publisher Copyright:
© 2023
PY - 2023/10
Y1 - 2023/10
N2 - We analyzed currents associated with upward connecting leaders (UCLs) initiated from the Kennedy Space Center Industrial Area Tower in two negative cloud-to-ground strokes that struck the tower. One stroke was also recorded using a high-speed video camera located 760 m from the KSC IAT. The NLDN-reported peak currents for the two strokes were − 31.7 and − 98.5 kA. During the UCL development phase the current waveforms exhibited a monotonically (quasi-exponentially) increasing “background” current overlaid with 10-μs scale pulses with a median amplitude of 51.1 A. The UCL current durations for the two strokes were 1039 and 449 μs, respectively. During the pre-attachment processes (UCL and slow front) the total negative charge effectively transferred to ground were 70.2 and 55 mC, respectively. For the stroke captured on high-speed video, the average line-charge-density for the 109-m long UCL was found to be 0.5 mC/m. The average UCL 2-D speed was 2.4 × 105 m/s, and it was observed to accelerate toward the downward leader prior to attachment. We observed that UCL-pulse amplitudes are larger, background currents are higher, and interpulse intervals are shorter at later times during UCLs, which can be attributed to the intensification of the local electric field due to the approaching downward negative leader. The median positive charge injected into the UCL by a pulse was 297 μC. The UCL associated with the higher peak-current stroke produced the highest injected pulse-charge values about three times sooner during its development, likely due to the 2–2.7 times faster average downward leader vertical speeds.
AB - We analyzed currents associated with upward connecting leaders (UCLs) initiated from the Kennedy Space Center Industrial Area Tower in two negative cloud-to-ground strokes that struck the tower. One stroke was also recorded using a high-speed video camera located 760 m from the KSC IAT. The NLDN-reported peak currents for the two strokes were − 31.7 and − 98.5 kA. During the UCL development phase the current waveforms exhibited a monotonically (quasi-exponentially) increasing “background” current overlaid with 10-μs scale pulses with a median amplitude of 51.1 A. The UCL current durations for the two strokes were 1039 and 449 μs, respectively. During the pre-attachment processes (UCL and slow front) the total negative charge effectively transferred to ground were 70.2 and 55 mC, respectively. For the stroke captured on high-speed video, the average line-charge-density for the 109-m long UCL was found to be 0.5 mC/m. The average UCL 2-D speed was 2.4 × 105 m/s, and it was observed to accelerate toward the downward leader prior to attachment. We observed that UCL-pulse amplitudes are larger, background currents are higher, and interpulse intervals are shorter at later times during UCLs, which can be attributed to the intensification of the local electric field due to the approaching downward negative leader. The median positive charge injected into the UCL by a pulse was 297 μC. The UCL associated with the higher peak-current stroke produced the highest injected pulse-charge values about three times sooner during its development, likely due to the 2–2.7 times faster average downward leader vertical speeds.
KW - Attachment processes
KW - Charge transferred to ground
KW - Cloud-to-ground lightning
KW - Current measurements
KW - Upward connecting leaders
KW - Upward positive leaders
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U2 - 10.1016/j.atmosres.2023.106943
DO - 10.1016/j.atmosres.2023.106943
M3 - Article
AN - SCOPUS:85167575373
SN - 0169-8095
VL - 294
JO - Atmospheric Research
JF - Atmospheric Research
M1 - 106943
ER -