Electron energy and electric field estimates in sprites derived from ionized and neutral N2 emissions

[1] During the EXL98 aircraft mission, sprites and blue jets were observed by narrow band cameras that measure the N2+ 1NG (0,1) band at 4278A and the N2 2PG (0,0) band at 3370A. We discuss the observations (∼1km resolution), instrumental and atmospheric corrections, and altitude profiles of ionized (1NG) and neutral (2PG) emission observed during a specific sprite. The ratio of ionized-to-neutral emission indicates a relative enhancement of ion emission below 55km. Characteristic electron energies (ECh) and electric fields (E) are derived from these emission ratios using excitation rates computed from a model that solves the Boltzmann equation as a function of electric field. Up to 55km E follows the breakdown field (Ek) and ECh is ∼2.2eV. Above 55km E drops below Ek and ECh drops to ∼1.75eV near 60km.

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