On the origin and spatial extent of high-latitudeFregion irregularities

摘要: Further evidence is presented that structured soft-electron precipitation an important source of large-scale (λ ≳ 10 km ) F region ionization irregularities in the high-latitude ionosphere. We show large amplitude, 20-km to 80-km plasma exists both dayside and nightside auroral oval. In latter case, layer has been observed convect into through field view Chatanika radar. Here, a companion paper, we hypothesize this soft electron primary structure convection acts distribute irregular throughout polar Indeed, at production scale (20–80 km), can easily with negligible decay from classical or anomalous diffusion, including effects conducting E region. Our convection/decay model also explains following features published irregularity data: (1) The steep gradient intensity equatorward edge nighttime magnetospheric zone. (2) existence cap. (3) reduction central (4) dawn-dusk asymmetry boundary On other hand, if theory applied 100-m structure, diffusion should rapidly limit area within few degrees zone, prediction not upheld by experimental data. Thus, instabilities must operate on structures produce intermediate (100 m < λ km) power law spectra. Calculations instability growth rate its generalized form, which includes field-aligned currents (the current convective instability), shows occur. universal drift then these features. suggest maintains shorter expense more rapid cascade-like process. Enhanced, turbulent reduce significantly lifetime but larger structures, therefore still transit