Spatial, Temporal, and Electrical Characteristics of Lightning in Reported Lightning-Initiated Wildfire Events.

Christopher J Schultz,Christopher R Hain,Jordan R Bell,Nicholas J Nauslar,J Brent Wachter

doi:10.3390/fire2020018

Christopher J Schultz, Christopher R Hain + Show 3 more

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https://doi.org/10.3390/fire2020018

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Abstract

Analysis was performed to determine if a lightning flash could be associated with every reported lightning-initiated wildfire that grew to at least 4 km2. In total, 905 lightning-initiated wildfires within CONUS between 2012 and 2015 were analyzed. Fixed and fire radius search methods showed that 81–88% of wildfires had a corresponding lightning flash within a 14 day period prior to the report date. The two methods showed that 52–60% of lightning-initiated wildfire were reported on the same day as the closest lightning flash. The fire radius method indicated the most promising spatial results, where the median distance between the closest lightning and the wildfire start location was 0.83 km, followed by a 75th percentile of 1.6 km, and a 95th percentile of 5.86 km. Ninety percent of the closest lightning flashes to wildfires were negative polarity. Maximum flash densities were less than 0.41 flashes km2 for the 24 hour period at the fire start location. The majority of lightning-initiated holdover events were observed in the Western CONUS, with a peak density in north-central Idaho. A twelve day holdover event from New Mexico was also discussed; outlining the opportunities and limitations of using lightning data to characterize wildfires.

Highlights

Lightning-caused wildfires represent 16% of all wildfires in the last 21 years within the ContinentalUnited States (CONUS) but they are responsible for 56% of the total acreage burned [1]
The association of lightning to lightning initiated wildfires fell to 83% (757/905)
The results show that 90% (613/681) of lightning time to the wildfire start location were analyzed (Figure 5)

Summary

Introduction

Lightning-caused wildfires represent 16% of all wildfires in the last 21 years within the ContinentalUnited States (CONUS) but they are responsible for 56% of the total acreage burned [1]. Much like severe thunderstorm reports [2,3], wildfire reports can have spatial and temporal offsets, which provide challenges to developing new tools for real-time fire detection. Lightning is one way to assess these offsets due to precise spatial and temporal detection technology which pinpoints lightning occurrence. Very few studies have examined in detail spatial and temporal offsets between lightning-initiated fire reports in wildfire databases and ground-based lightning data [4,5,6,7]. The majority of wildfire reports at Kennedy Space Center came within 2 days of lightning occurrence [4]. A three day holdover criterion has been used previously to assign lightning strokes to wildfires in Australia [5].

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