Electron energy deposition in the middle atmosphere

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Abstract
Spectra of locally precipitating 36‐ to 317‐keV electrons obtained by instrumentation on the S3‐2 satellite are used to calculate energy deposition profiles as a function of latitude, longitude, and altitude. In the 70‐ to 90‐km altitude, mid‐latitude ionization due to these precipitating energetic electrons can be comparable to that due to direct solar H Lyman α. At night, the electrons produce ionization more than an order of magnitude greater than that expected from scattered H Lyman α. Maximum precipitation rates in the region of the South Atlantic Anomaly are of the order of 10−2 erg/cm² s with a spectrum of the form j(E) = 1.34 × 105 E−2.27 (keV). Southern hemisphere precipitation dominates that in the north for 1.1 < L < 6 except for regions of low local surface field in the northern hemisphere. Above L = 6, local time effects dominate; i.e., longitudinal effects due to the asymmetric magnetic field which are strong features below L = 6 disappear and are replaced by high‐latitude precipitation events which are local time features.