Visualizing the geometry of lightning detected by MTG’s Lightning Imager

The Lightning Imager (LI) instrument aboard the first Meteosat Third Generation (MTG) satellite provides valuable data for detecting and monitoring convective storms by capturing localized pulses of visible light emitted by lightning. These detections have a spatial resolution of approximately 10 km and occur at a high temporal resolution of 1 kHz, or one detection per millisecond.

Following a sophisticated filtering process developed at EUMETST to eliminate false positives, lightning detections are identified as pixels that illuminate for at least 1 millisecond. These are then grouped based on spatial proximity into “groups,” which are subsequently combined into “flashes”, composite lightning events lasting at least 1 ms. Each group is assigned a central location, weighted by the intensity of radiation detected at each contributing pixel or event. This method allows for an effective spatial resolution finer than the nominal 10 km.

At ESSL, we have developed a visualization technique in which individual lightning groups are connected by line segments. The algorithm begins with the most centrally located group from the first time step of a flash. It then progressively links the nearest groups to the existing network, one millisecond at a time. This sequential process builds a branching, dendritic structure that resembles the complex geometry of actual lightning strikes. While the resemblance to real lightning structures cannot be quantitatively verified, notably large and long-duration flashes tend to appear in regions where such events are commonly observed by ground-based systems or Lightning Mapping Arrays (LMAs) such as stratiform precipitation areas of mesoscale convective systems.

We will show examples of this visualization and explore its potential utility in forecasting and warning operations. We will also share insights from its use atg the EUMETSAT–ESSL Testbeds.