investigating lightning cessation at ksc
DESCRIPTION
Investigating Lightning Cessation at KSC. Holly A. Melvin Henry E. Fuelberg Florida State University GOES-R GLM Workshop September 2009. Purpose. Better understand electrical activity at the end of a storm Gain insight into forecasting the last flash of a storm. 20 km. 20 km. - PowerPoint PPT PresentationTRANSCRIPT
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Investigating Lightning Cessation at KSC
Holly A. MelvinHenry E. Fuelberg
Florida State University
GOES-R GLM WorkshopSeptember 2009
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Purpose• Better understand electrical activity at the end
of a storm• Gain insight into forecasting the last flash of a
storm
Vertical cross-section of 1-min LDAR total lightning source density at 2246 UTC 9 Aug 2005, during the peak rate of core lightning
Vertical cross-section of 1-min LDAR total lightning source density at 2326 UTC 9 Aug 2005, the last IC lightning flash of the storm
20 km20 km
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Methodology
– Consolidate LDAR sources into flashes using a modified version of NASA’s flash creation algorithm (Nelson, 2002)
– Match CGLSS/NLDN flashes to LDAR flashes using McNamara’s algorithm (2002)
– Separate matched flashes into IC sources, CG sources, IC initiation sources, CG initiation sources, and CG strike location data for further analysis
– Use WDSS-II software (Lakshmanan et al., 2006) to identify and track storms and their associated lightning and radar characteristics
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Storm Cell Tracking• Using the WDSS-II K-Means clustering algorithm:
– Identify storms based on VIL density– Set clustering thresholds low enough to track storms through lightning cessation– Clustering small, isolated, weakening cells presents a major challenge!
WDSS-II Derived Lightning Parameters
WDSS-II Derived Radar parameters
1-min VILMA of IC LDAR initiation points
Max reflectivity at 0°C/-10°C/-20°C
1-min VILMA of CG LDAR initiation points
Avg reflectivity at 0°C/-10°C/-20°C
1-min VILMA of all CG LDAR sources Layer Avg reflectivity between 0°C and -20°C
1-min VILMA of all IC LDAR sources Vertically Integrated Liquid (VIL)
1-min Multiplicity/Peak current for +, -, and all CG strikes
Height of the 30 dBZ above -10°C
1-min Density for +, -, and all CG strikes
Height of the 50 dBZ above -10°C
1-min Height of the Max LMA of IC and/or CG initiation points
Precipitation rates and 5-min, 10-min, and 15-min accumulations
VIL Density and associated storm clusters on 1 Sep 2005
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Different Styles of Cessation
Analyzed 106 storms
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Abrupt Cessation
Max dBZ
Hail Reports
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Time Series of Reflectivityand Source Density
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Gradual Cessation
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Time Series of Reflectivityand Source Density
OO
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Outlier
20 minO
O
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Another Outlier
OO9 min
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Trying to Put it all TogetherComposites
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Initiation Heights in Normalized Time
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Initiation HeightsCG vs IC Flashes
CG IC
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Multiplicity Peak Current
Multiplicity and Peak Currents
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Max Reflectivity
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Reflectivity Data Being Analyzed
Much More Work RemainsDetailed Statistical Studies