Repeatable Velocity Fine Structure of Lightning K‐Leaders From a Single VHF Interferometer Made Three‐Dimensional

Abstract

Abstract K‐processes re‐illuminate lightning channels at speeds of order 10 7 m s −1 , but measuring their three‐dimensional (3‐D) propagation velocity has required multi‐station systems available at few sites. An error‐isomorphism range inversion upgrades a single very‐high‐frequency interferometer (INTF) into a 3‐D imager: Lightning Mapping Array (LMA) sources are back‐projected so that both data sets carry the same systematic bias, and Gaussian process regression extends the sparse LMA ranges to all INTF sources. Applied to three K‐leaders in a Florida cloud‐to‐ground flash, the method reconstructs the channel far more densely than the LMA and yields time‐resolved 3‐D velocities. The three leaders retrace one unbranched channel and reproduce the same velocity sequence, re‐intensifying after deep deceleration, their first maxima falling within 25 μs at 2.7–3.1 × 10 7 m s −1 , indicating that branch junctions are not necessary for organized velocity variation.