@InProceedings{SaraivaCaAlPiZeBu:2014:EsReLe,
author = "Saraiva, Ant{\^o}nio Carlos V. and Campos, Leandro Zanella de
Souza and Alves, J{\'e}ferson and Pinto Jr., Osmar and Zepka,
Gisele dos Santos and Buzato, Tiago Santos",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de
Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas
Espaciais (INPE)} and {Instituto Nacional de Pesquisas Espaciais
(INPE)} and {Instituto Nacional de Pesquisas Espaciais (INPE)}",
title = "Estimates of recoil leaders peak currents based on high-speed
video observations",
booktitle = "Proceedings...",
year = "2014",
organization = "International Lightning Detection Conference, 23. (ILDC); and
International Lightning Meteorology Conference, 5 (ILMC).",
publisher = "Vaisala",
note = "Informa{\c{c}}{\~o}es Adicionais: During the summer season of
2012, a network of high-speed cameras, called RAMMER network,
recorded two bipolar flashes produced by a thunderstorm that
occurred on March 13th. Data from BrasilDAT network provided
location and peak current information for the events. Additional
RAW data from the sensors, allowed more detailed analyses. Both
bipolar flashes presented multiple negative return strokes, and
there was intense recoil leader activity bellow cloud base. The
objective of this work is the evaluation of the peak currents of
those recoil leaders. The bipolar nature of these flashes allowed
a unique way to calibrate the camera luminosity with the stroke
peak currents estimated by the local lightning location system
(LLS). Recoil leaders are commonly visible below cloud base during
positive flashes development, but have not yet been observed
during negative flashes in a similar fashion. The bipolar flashes
observed had one positive return stroke and multiple negative
return strokes that were used in the calibration process. In order
to evaluate the recoil leaders peak current, the luminosity levels
of each video were calibrated using the unsaturated pixel
brightness levels during the negative return strokes and the data
from the BrasilDAT LLS. The same high-speed camera used during the
observation campaign was tested in laboratory to determine its
CMOS sensor response curve. Through a scatter diagram of
luminosity (estimated from the pixel intensity values) versus
estimated peak current (provided by the BrasilDAT network), it was
shown that both physical quantities are related. The calibrated
pixel values were used to create equations to calculate the recoil
leader peak currents. A total of 281 recoil leaders were
identified, 191 in flash #1 and 90 in flash #2. Results show that
recoil leader estimates are closely related to previous
observations of cloud discharges by LLS. The geometric mean value
was 1.06 kA, with a maximum of 7.7 kA. Less than 14% presented
peak.",
keywords = "atmospheric electricity, recoil leaders, high-speed video
observations, lightning.",
abstract = "During the summer season of 2012, a network of high-speed cameras,
called RAMMER network, recorded two bipolar flashes produced by a
thunderstorm that occurred on March 13th. Data from BrasilDAT
network provided location and peak current information for the
events. Additional RAW data from the sensors, allowed more
detailed analyses. Both bipolar flashes presented multiple
negative return strokes, and there was intense recoil leader
activity bellow cloud base. The objective of this work is the
evaluation of the peak currents of those recoil leaders. The
bipolar nature of these flashes allowed a unique way to calibrate
the camera luminosity with the stroke peak currents estimated by
the local lightning location system (LLS). Recoil leaders are
commonly visible below cloud base during positive flashes
development, but have not yet been observed during negative
flashes in a similar fashion. The bipolar flashes observed had one
positive return stroke and multiple negative return strokes that
were used in the calibration process. In order to evaluate the
recoil leaders peak current, the luminosity levels of each video
were calibrated using the unsaturated pixel brightness levels
during the negative return strokes and the data from the BrasilDAT
LLS. The same high-speed camera used during the observation
campaign was tested in laboratory to determine its CMOS sensor
response curve. Through a scatter diagram of luminosity (estimated
from the pixel intensity values) versus estimated peak current
(provided by the BrasilDAT network), it was shown that both
physical quantities are related. The calibrated pixel values were
used to create equations to calculate the recoil leader peak
currents. A total of 281 recoil leaders were identified, 191 in
flash #1 and 90 in flash #2. Results show that recoil leader
estimates are closely related to previous observations of cloud
discharges by LLS. The geometric mean value was 1.06 kA, with a
maximum of 7.7 kA. Less than 14% presented peak currents
comparable to weak return strokes (> 2 kA).",
conference-location = "Tucson",
conference-year = "mar. 18-19, 2014 / mar. 20-21, 2014",
label = "lattes: 4161737266837399 2 SaraivaCaAlPiZeBu:2014:EsReLe",
language = "en",
targetfile = "Saraiva et al-Estimates of recoil leader peak currents based on
high-speed video observations-2014-ILDC-ILMC.pdf",
url = "http://www.vaisala.com/en/events/ildcilmc/Documents/2014%20ILDC-ILMC%20Agenda.pdf",
volume = "1",
urlaccessdate = "28 mar. 2024"
}