On the dependence of radar aurora amplitude on ionospheric electron density

Radar aurora amplitudes have been correlated with mean electron density measurements by means of ionosondes during two geophysically widely different events. A similar, roughly linear relationship was found between the two quantities in both cases. On the other hand, the amplitude seems to be almost independent of the ambient electric field, once it is well above the instability threshold.           ARK: https://n2t.net/ark:/88439/y093977 Permalink: https://geophysicsjournal.com/article/189 &nbsp

Spatial variations of ionospheric conductivity and radar auroral amplitude in the eastward electrojet region during pre-substorm conditions

The dependence of auroral backscatter amplitude on different ionospheric parameters (conductivity, current density, electric field) is studied by means of data recorded by STARE (Scandinavian Twin Auroral Radar Experiment), the two-dimensional Scandinavian Magnetometer Array (SMA), and auroral all-sky cameras. The observations were made on 16 March 1978 during pre-substorm conditions in the region of the eastward polar electrojet. The paper shows that in this event the auroral backscatter amplitudes in the 140 MHz frequency band were controlled mainly by spatial variations in the electron density or conductivity inside the back-scatter volume. To a certain extent also a linear relationship between backscatter amplitude and ionospheric current density was found but it is regarded as a special case of a more general relationship between electron density and backscatter amplitude. A stable discontinuity in the Hall conductivity over the most equatorward auroral arc was deduced from the data: On the equatorward side the conductivity was 3-5 times higher than on the nearby poleward side. Our conclusions are discussed in the light of some previously published results on the same subject.           ARK: https://n2t.net/ark:/88439/y000016 Permalink: https://geophysicsjournal.com/article/262 &nbsp

Conjugacy of Auroral Oval

Results of statistical studies so far made hitherto on the auroral ovals in the northern and southern hemispheres are reviewed. Then, a same analysis method is applied on both northern and southern optical auroras to identify the auroral ovals as a function of magnetic activities. The result shows that a good geomagnetically conjugate relationship of the auroral oval is established. In the end, the configurations of the northern auroral oval at different universal times for different magnetic activities are projected along the real magnetic field lines onto the southern hemisphere surface

Experimental data on electric field and electron density dependence of auroral E-region drift turbulence and radar backscatter

Haldoupis et al. (1982), Uspensky et al. (1983) and Starkov et al. (1983) have recently found that the 140 MHz backscatter amplitude in the auroral ionosphere depends mainly on the mean electron density (height-integrated conductivity) in the E–layer. A similar relationship for the 46 MHz band was also found by Leinonen et al. (in press, 1983). In principle, this can be explained by only a slight dependence of the relative level of E-region drift turbulence < (∆N/ N)2 > in the auroral ionosphere on ionospheric parameters, viz. electric field and mean electron density.  However, up to now, quantitative evidence for such a backscatter amplitude — electron density relationship is restricted to the few events which have so far been analyzed. Therefore, the aim of this short note is to add some more data to that data set. Furthermore, we will compare measurements made in the evening and morning sectors, where the conditions for irregularity excitation might be different.           ARK: https://n2t.net/ark:/88439/y063050 Permalink: https://geophysicsjournal.com/article/196 &nbsp