TY - JOUR
T1 - Lightning channel length and flash energy determined from moments of the flash area distribution
AU - Bruning, Eric C.
AU - Thomas, Ronald J.
N1 - Funding Information:
The Deep Convective Clouds and Chemistry Experiment (DC3) is sponsored by the US National Science Foundation (NSF), the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), and the Deutsches Zentrum fur Luft-und Raumfahrt (DLR). This investigation was supported by NSF-1063966. The authors wish to acknowledge the rest of the PIs in the Colorado domain for availability of data during DC3. Data used in this study may be downloaded from the DC3 data archive at http://data.eol.ucar.edu/master_list/? project=DC3. We are grateful for the astute remarks of the reviewers of this study. These helped us clarify our findings.
Publisher Copyright:
© 2015. American Geophysical Union. All Rights Reserved.
PY - 2015
Y1 - 2015
N2 - A widely used approach in observational and modeling studies of NOx produced by lightning is to relate NOx production to the number of flashes, without regard for the distribution of lightning flash sizes. Recent studies have begun to consider channel length and flash size, which is now observable with VHF Lightning Mapping Array data. This study uses a capacitor model for flash energy based on the flash coverage area, which defines a size scale. This flash area is then filled with channel using a fractal method and compared to other methods that estimate length directly from the VHF source locations. In the presence of instrument measurement errors, area- and fractal-based estimates are shown to be more stable estimators of flash length than connect-the-dots approaches and therefore are better suited for comparison to NOx production. A geometric interpretation of using vertical profiles of VHF source density to weight the altitude distribution of total channel length is developed. An example of the time series of moments of the lightning flash size distribution is shown for an example case, and some meteorological interpretation is given.
AB - A widely used approach in observational and modeling studies of NOx produced by lightning is to relate NOx production to the number of flashes, without regard for the distribution of lightning flash sizes. Recent studies have begun to consider channel length and flash size, which is now observable with VHF Lightning Mapping Array data. This study uses a capacitor model for flash energy based on the flash coverage area, which defines a size scale. This flash area is then filled with channel using a fractal method and compared to other methods that estimate length directly from the VHF source locations. In the presence of instrument measurement errors, area- and fractal-based estimates are shown to be more stable estimators of flash length than connect-the-dots approaches and therefore are better suited for comparison to NOx production. A geometric interpretation of using vertical profiles of VHF source density to weight the altitude distribution of total channel length is developed. An example of the time series of moments of the lightning flash size distribution is shown for an example case, and some meteorological interpretation is given.
KW - Flash rate, energy, and channel length can be determined as moments of the flash area distribution
KW - Moments of the flash area distribution covary differently with thundercloud life cycle stage
KW - Specifying channel length as a fractal helps produce stable estimates of lightning channel length
UR - http://www.scopus.com/inward/record.url?scp=84943453713&partnerID=8YFLogxK
U2 - 10.1002/2015JD023766
DO - 10.1002/2015JD023766
M3 - Article
AN - SCOPUS:84943453713
VL - 120
SP - 8925
EP - 8940
JO - Journal of Geophysical Research
JF - Journal of Geophysical Research
SN - 0148-0227
IS - 17
ER -