2026/06/25 by Magnus F Ivarsen, Kaili Song, Jean-Pierre St-Maurice +1 · 1 voice
Physics and Astronomy · #physics.space-ph #astro-ph.IM #physics.geo-ph
arxiv published 2026/06/25 · arxiv updated 2026/06/29
We treat coherent radar echoes from aurorae as a finite point process and measure its structure factor S(k) from pairwise echo separations. Backscatter requires electron drifts to exceed the ion-acoustic speed, making the echoes a threshold (excursion-set) sample of the ionospheric electric field, and |S-1| is that field's spectrum, to leading order. We test this against in-situ observations: in co-moving frames, the radar spectrum is scale-free with a spectral index near -5/3, matching the in-situ indices. The auroral electric field is thus imaged by its excursion set, a point process of Farley-Buneman threshold exceedances.