Meteosat Third Generation Lightning Imager for the continuous monitoring of lighting from space

The Meteosat Third Generation (MTG) Lightning Imager (LI) is the first geostationary optical lightning detector imaging Europe, Africa, and a large fraction of the Atlantic Ocean. Launched on board of the MTG-I1 satellite on 13 December 2022, LI will perform the detection from space of optical pulses produced by lightning. Optical pulses at cloud tops are produced by the photons emitted by lightning electric discharges within or below clouds that reach cloud tops after multiple scattering. The LI senses this cloud-top light within a 1.9 nm wide band centred on 777 nm, with a 4.5 km resolution at sub-satellite point, and 1 kHz acquisition frequency.

The LI instrument consists of four cameras (optical channels), covering a total of 84% of visible disk with continuous lightning data. The field of view of the LI fully covers Europe and Africa. In addition, the eastern and southern parts of the Atlantic Ocean, eastern part of South America and north western part of the Indian Ocean are also covered.

The operationally disseminated LI data (expected in early 2024) will consist of point data and accumulated data. The most important point data products for severe storm monitoring and tracking are the lightning groups (LGR) and lightning flashes (LFL), containing the times, latitudes, longitudes and optical radiance information of observed lightning groups and flashes. The lightning group product is similar to strokes/pulses produced by ground-based lightning location systems while the LI flash product is similar to flashes produced by ground-based systems.

In addition to point data, three accumulated data products, Accumulated Flashes (AF), Accumulated Flash Area (AFA) and Accumulated Flash Radiance (AFR) will be disseminated. All accumulated products provide users with information about the full accumulated spatial extent of the observed optical pulses. This is achieved by integrating over 30 sec pixels-based lightning detections composing the Level 2 flashes (also available in LFL as point data). This type of data will allow users to monitor features like long horizontal lightning channels in the stratiform regions of Mesoscale Convective Systems. Finally, all accumulated products are provided to users on the Flexible Combined Imager (FCI) 2 km grid, making it easy to combine LI and FCI products for more advanced severe weather monitoring products.

The presentation will give a brief overview of the LI System to introduce examples of LI data complemented by some early Commissioning results.