Initial Geostationary Lightning Mapper Observations

Abstract

The Geostationary Lightning Mapper (GLM) continuously observes lightning throughout a near‐hemispheric field of view, capturing spatiotemporal variability on unprecedented scales. This study documents GLM lightning distributions during the initial 9 months in the operational Geostationary Operational Environmental Satellite‐East position (December 2017 to August 2018). Spatial maps, summary statistics, and time series illustrate seasonal, regional, and diurnal lightning patterns. Lightning activity shifts from south to north during the study period with most lightning over land (83%). The average GLM flash extends over a 454‐km2 area, lasts 301 ms, produces 262 fJ of optical energy, and consists of 16.4 (42.2) groups (events). On average, GLM flashes over the oceans are larger (570 km2), of longer duration (345 ms), and brighter (420 fJ) than flashes over land (431 km2, 293 ms, and 230 fJ). The baseline values and early insights reported herein aim to guide the early development and application of GLM observations.

First Observations of Gigantic Jets From Geostationary Orbit

“…Table 1 shows the GJ signatures exhibit longer maximum series and flash durations, larger maximum event and flash optical energies, and smaller maximum group distances when compared with other flashes detected by GLM. The mean flash area of the GJ signatures and other flashes was about the same, but the mean flash area reported by Rudlosky et al (2018) was about one half of these values. The mean for GJs is nearly ten times larger than that of the other flashes.…”

“…The mean for GJs is nearly ten times larger than that of the other flashes. The discrepancy may be a result of the relatively small sample size of the flashes from 19 August 2017 (≈600,000) compared to the flashes presented in Rudlosky et al, 2018Rudlosky et al, (2018≈237,000,000). The mean maximum group distance for the GJ flashes is about one half the values for other flashes detected on that day.…”

“…GLM detections are organized into event, group, and flash features (Goodman et al, 2013;Rudlosky et al, 2018). These features describe the recorded lightning signals on temporal and spatial scales ranging from 1 pixel within 2 ms to tens to hundreds of pixels over multiple seconds.…”

“…The most pronounced difference between the GJ and the other flashes is the maximum series duration. The study of Rudlosky et al (2018) documented the GLM lightning distributions during the initial 9 months in the operational GOES-East position (December 2017 to August 2018). The GJ flashes also exhibit about 2 times greater maximum flash optical energy.…”

“…GJs have also been observed by space-based instruments including the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) onboard the FORMOSAT-2 satellite (Chen et al, 2008). However, with the establishment of geosynchronous instrumentation such as the Geostationary Lightning Mapper (GLM; Rudlosky et al, 2018), new opportunities are available to detect and observe TLEs and GJs. ISUAL was designed to provide a limb view of the Earth's surface around local midnight, and its instrument consists of an ICCD imager, a six-channel spectrophotometer, and a dual-band array photometer.…”