Highlights of a New Ground-Based, Hourly Global Lightning Climatology
Virts, Katrina S. ; Wallace, John M. ; Hutchins, Michael L. ; Holzworth, Robert H.
The seasonally and diurnally varying frequency of lightning flashes provides a measure of the frequency of occurrence of intense convection and, as such, is useful in describing the Earth's climate. Here we present a few highlights of a global lightning climatology based on data from the ground-based World Wide Lightning Location Network (WWLLN), for which global observations began in 2004. Because WWLLN monitors global lightning continuously, it samples ~100 times as many lightning strokes/flashes per year as the Tropical Rainfall Measuring Mission's (TRMM) Lightning Imaging Sensor (LIS). Using WWLLN data it is possible to generate a global lightning climatology that captures seasonal variations, including those associated with the midlatitude storm tracks, and resolves the diurnal cycle, thereby illuminating the interplay between sea breezes, mountain-valley wind systems, and remotely forced gravity waves in touching off thunderstorms in a wide variety of geographical settings. The text of the paper shows a few samples of regional, WWLLN-based seasonal (the midlatitude storm tracks and the Mediterranean) and diurnal (the Maritime Continent, the central Andes, and equatorial Africa) climatologies, and the online supplement presents animations of the global seasonal cycle and of the diurnal cycle for the latter regions.
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