Open AccessFirst versus subsequent return‐stroke current and field peaks in negative cloud‐to‐ground lightning discharges
Author(s) -
Nag Amitabh,
Rakov Vladimir A.,
Schulz Wolfgang,
Saba Marcelo M. F.,
Thottappillil Rajeev,
Biagi Christopher J.,
Oliveira Filho Alcides,
Kafri Ahmad,
Theethayi Nelson,
Gotschl Thomas
Publication year - 2008
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007jd009729
Subject(s) - lightning (connector) , peak current , stroke (engine) , lightning detection , electric field , physics , meteorology , environmental science , thunderstorm , power (physics) , electrode , quantum mechanics , electrochemistry , thermodynamics
We examine relative magnitudes of electric field peaks of first and subsequent return strokes in negative cloud‐to‐ground lightning flashes recorded in Florida, Austria, Brazil, and Sweden. On average, the electric field peak of the first stroke is appreciably, 1.7 to 2.4 times, larger than the field peak of the subsequent stroke (except for studies in Austria where the ratio varies from 1.0 to 2.3, depending on methodology and instrumentation). Similar results were previously reported from electric field studies in Florida, Sweden, and Sri Lanka. For comparison, directly measured peak currents for first strokes are, on average, a factor of 2.3 to 2.5 larger than those for subsequent strokes. There are some discrepancies between first versus subsequent stroke intensities reported from different studies based on data reported by lightning locating systems (LLS). The ratio of LLS‐reported peak currents for first and subsequent strokes confirmed by video records is 1.7 to 2.1 in Brazil, while in the United States (Arizona, Texas, Oklahoma, and the Great Plains) it varies from 1.1 to 1.6, depending on methodology used. The smaller ratios derived from the LLS studies are likely to be due to poor detection of relatively small subsequent strokes. The smaller values in Austria are possibly related (at least in part) to the higher percentage (about 50% versus 24–38% in other studies) of flashes with at least one subsequent stroke greater than the first. The effects of excluding single‐stroke flashes or subsequent strokes in newly formed channels appear to be relatively small.