D Region Electron Density Derived From Sprite Observations

Four upward propagating streamers in two carrot sprites over northwest Texas were recorded at 100,000 frames per second at 07:46:35 UT, 2 June 2019, from the Langmuir Laboratory near Socorro, New Mexico. The streamers reached velocities of 50-80 x 10(6) m/s with accelerations up to 25 x 10(10) m/s/s. The upward motion ended with the top of the streamers near 90 km altitude. At this time, the streamers reached maximum brightness. The streamer head then dissolved and the brightness decayed exponentially with time constants between 0.078 and 0.097 ms. We interpret the dissolution and decay to be the result of interaction with the bottom of the ionosphere. Assuming the decay to be dictated by electric field relaxation, the ambient D region electron density would be 10(7) to 10(8) m(-3). The analysis suggests that sprite observations can provide multipoint measurements of the D region ionosphere impacted by powerful lightning capable of triggering sprites.