Multispectral Optical Diagnostics of Lightning from Space

Abstract

We present spectroscopic diagnostic methods that allow us to estimate the gas and the electron temperature in emerged lightning stroke channels (from thunderclouds) observed by the photometers and cameras of the Atmosphere Space Interaction Monitor (ASIM). We identify the species (molecules, atoms and ions) producing light emission in different wavelengths, and how the blue (337 ± 2 nm), red (777.4 ± 2.5 nm) and ultraviolet (180–230 nm) optical emissions captured by ASIM photometers change as a function of the temperature in the lightning stroke channel. We find good agreement between the light curves of the emerged lightning observed by ASIM and the synthetic ones obtained from calculated spectra. Our results suggest that (i) early stage (high temperature > 20,000 K) emerged lightning strokes at high altitude can contribute to the optical signals measured by the PH2 photometer (180–230 nm), (ii) intermediate stage (mid temperatures, 6000–21,000 K) emerged lightning strokes can produce 777.4 nm near-infrared radiation (observable by PH3) exhibiting higher intensity than PH1 observable N2 SPS between ∼6000 K and ∼8000 K, and than ion optical emissions (336.734 nm and 337.714 nm) between ∼16,000 K and ∼21,000 K, (iii) from ∼16,000 K to 35,000 K, neutral oxygen 777.4 nm radiation and ion emissions at 336.734 nm and 337.714 nm can be simultaneoulsy observed but 777.4 nm dominates only between ∼16,000 K and ∼21,000 K, (iv) the availability of detections with a narrow 0.5 nm gap filtered photometer (336.75–337.25 nm), with the same or better sensitivity than PH1 in ASIM-MMIA but with a central wavelength at exactly 337.0 nm (the strongest N2 SPS transition), would give access to the late stage of lightning strokes (emerged or not) when temperatures are between 8000 K and 5000 K (or lower for a photometer with better sensitivity than PH1 in ASIM-MMIA) when the production of nitrogen oxides (NOx) and hydroxyl radicals (OH) maximizes.

On the Role of Continuing Currents in Lightning‐Induced Fire Ignition

“…The algorithm that cluster groups into flashes estimates the coordinates of each flash as the centroid of the groups weighted by their energy. The optical signature of lightning measured by GLM is usually scattered and reflected by clouds above the lightning channel (Montanyà et al., 2021; Pérez‐Invernón, Gordillo‐Vázquez, et al., 2022), causing the illumination of a large area of clouds. Flashes with CC observed by GLM and confirmed with ELF sensors (Montanyà et al., 2021, 2022) showed that the illuminated area can extend further than 0.5° from the location of the grounding‐point of the flash.…”

“…We used lightning data over CONUS between 15 May 2018 and 31 August 2018 provided by the GLM, aboard the Geostationary Operational Environmental Satellite‐16 (GOES‐16) (Goodman et al., 2013) since 2017 and aboard the GOES‐17 since 2018. The GLM is a Charge‐Coupled Device imager with narrow spectral band filters centered on the atomic oxygen line 777.4 nm that are usually associated with lightning (Kieu et al., 2021; Orville, 1968; Pérez‐Invernón, Gordillo‐Vázquez, et al., 2022). The GLM can provide continuous measurements of the optical signal emitted by lightning in the Americas, some parts of the Pacific Ocean and the Atlantic Ocean.…”

“…Flashes with CC observed by GLM and confirmed with ELF sensors (Montanyà et al., 2021, 2022) showed that the illuminated area can extend further than 0.5° from the location of the grounding‐point of the flash. Nevertheless, the activity of the groups is more frequent and intense near the point where the lightning strikes the ground (Montanyà et al., 2021; Pérez‐Invernón, Gordillo‐Vázquez, et al., 2022), suggesting that taking the position of the flash as the centroid of the groups weighted by their energy is appropriate to search for lightning candidates for wildfires when dealing with lightning with CC. On the other hand, using the position of individual groups to determine the best candidate group has the disadvantage that the vast majority of pulses detected by GLM corresponds to Intra‐Cloud (IC) pulses.…”

Simulating asteroid impacts and meteor events by high-power lasers: from the laboratory to spaceborne missions

“…Notably, spectral records of plasma sources emitting radiation in the atmosphere do not include only natural meteors, but also fireball or airglow surrounding artificial objects entering the atmosphere (Loehle et al, 2021), atmospheric electricity (Pérez-Invernón et al, 2022), rocket launches (Qian et al, 2005) or explosions of manmade objects (Zhang et al, 2018) and interplanetary bodies (Svettsov, 1998;Ferus et al, 2019). The application potential of spaceborne spectroscopy of plasma provided by a hyperspectral camera and supported by laboratory laser-based experiments includes:…”