Long return intervals lead to fuel accumulations that burn with greater intensity and produce more severe effects. The timing and location of lightning has a direct effect on seasonality and an indirect effect on fire return interval, as less frequent lightning ignitions result in longer intervals between fires. A fire regime is defined according to attributes such as seasonality, fire return interval, size, spatial complexity, intensity, severity, and fire type. Information about the temporal and spatial distributions of lightning and the factors that affect those distributions is critical for predicting the occurrence of wildland fires and for understanding fire regimes.įire ecologists use fire regimes to describe the complex pattern of fire effects over long time periods, multiple fire events, and numerous ecosystem properties (Sugihara et al. These variations are influenced by geography, topography, and large-scale weather patterns. In addition, lightning strike characteristics such as polarity, maximum peak current, and number of return strokes vary over time and space. Although lightning strikes are pervasive, their temporal and spatial distributions vary across the state and have differential effects on lightning fire ignitions. Lightning strikes are an important source of ignition for wildland fires in California and throughout the western US. The role fire plays in an ecosystem is dependent on the simultaneous occurrence of an ignition source, sufficient fuel to carry the fire, and weather conditions conducive for burning. Understanding the variation in lightning strike distributions provides insight into the role of fire in different bioregions of the state and aids in the prediction of wildland fire occurrence. Weather patterns associated with lightning included strengthened high pressure cells stationed over the western United States that deploy moist monsoonlike air masses and promote rising motions, especially over mountain features. Strike polarity varied by month, and mean peak positive current, mean peak negative current, and number of return strokes per strike varied by bioregion. The number of strikes increased with elevation. Although there were significant differences in the number and density of strikes among bioregions, the annual, monthly, and hourly patterns were similar. We analyzed 16 years of lightning strike data obtained from the National Lightning Detection Network to determine how the distribution of lightning strikes was affected by geography, topography, and large-scale weather patterns. Links to detailed dataset information, descriptions of field campaigns and satellite measurements, and access to the Lightning Primer, a beginner's guide to lightning are provided above.The temporal and spatial distribution of lightning strikes varies across California and has a differential effect on lightning fire ignitions. The data collected are routinely shared with scientists around the globe, resulting in numerous advancements in the field of Atmospheric Science. Instruments of various types have been designed, constructed, and deployed as ground-based, airborne, and space-based sensors capable of lightning detection and characterization, to study the electrical behavior of thunderstorms. The primary objectives of lightning study include determining the relationship between the electrical characteristics of storms and precipitation, convection, and severe weather. Multiple ground and airborne instruments viewed severe weather at the same time as GLM. For example, the newGeostationary Lightning Mapper ( GLM) instrument on the Geostationary Operational Environmental Satellite ( GOES)-16 is being validated using data from a GOES-R field campaign that took place in 2017. There are new instruments and different instruments viewing the same events allowing for assessment of instrument measurement characteristics and capabilities. Lightning continues to be studied by scientists and engineers who use a variety of instruments. We now have a better understanding of why lightning occurs and where, what lightning patterns exist over the globe, and what lightning tells us about atmospheric convection. Lightning research has come a long way in the past few decades.
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