Кустов, А. В. О пороговом электрическом поле для возникновения авроральных неоднородностей с длиной волны около одного метра / А. Кустов, М. Успенский, И. Кангас ; Акад. Наук СССР, Кол. фил. им С. М. Кирова, Поляр. геофиз. ин-т. – Препр. ПГИ-87-06-60. - Апатиты : [б. и.], 1988.

missed the radiophysical aspects related. Let’s describe qualitatively only one. Due to the electrojet microstructure the patches, where the drift velocity is decreased (the electron density is increased), but E-field is ever the threshold, ’collect" the largest volume cross- sections. The same is right when all is opposite viz the patches with high drift velocities (low electron densities) collect the small cross-sections. After inherent averaging in the unit scatter volume the measured mean drift velocity will be decreased. Similar to the soft threshold the mentioned effects in the irregularity drift velocity measurements are difficult to be excluded Now we apply the description to RHS of Fig.3 assuming the dashed area covers regions where electron densities are increased (the E- fields are decreased). If the mean E-field is moderate-to-strong then the dashed area covers regions of the increased signals. From the white area the signal exsists but it is weak. However in a case of a nearly threshold E-field the signature can be changed. Now the dashed area is a region where the irregulariities (scattering) are absent. Hence, the single place where it exists is the white area. The latter situation is very similar to a distribution of echoes near the auroral arcs (Kustov et al ., 1979). The auroral backscatter were detected from regions in the vicinity of an arc but never was found evidently from the inside parts of the arc itself. As regarding the soft E-field threshold, F “ we will define it arbitrary at the level -20 dB under the "stable” EDFA magnitude 3 X . Then it is 13-16 «V/m. When E > 16 mV/m the EDFA growth becomes fast. However the limited data statistics leaves details of this EDFA transfer zone for future studies. In the present study and in our earlier paper by Nielsen et al. (1987) we have obtained that the EDFA is a function of the electric field when it varies in the range (1 - 2)E“ . One can suggest this to be a result of the unresolved microstructure effect discussed in the point c) i. e. the graduel filling of the scattering volume with irregularities. Hence, it follows the large scale ionospheric patches unresolved by radar can create substantial difficulties for the Ionospheric electrojet diagnostics i.e. the irregularity properties, by means of radar auroral backscatter technique. This conclusion has a particular importance for a low/moderate electric field. One question of the topic Is the Influence of neutral wina on 25