Large polarization electric fields associated with midlatitude sporadicE

摘要: Recent 50 MHz E region coherent backscatter observations and in situ rocket measurements established the existence of enhanced electric fields midlatitude ionosphere that can become at times sufficiently large to excite Farley-Buneman instability. To understand origin these fields, we present a simple quantitative model relates local polarization process acting inside spatially confined, nighttime sporadic layers dense ionization. By including effects field-aligned currents current continuity equation estimate necessary conditions on relative horizontal layer extent ratio integrated Pedersen conductivities above for generation both zonal meridional fields. We show account elevated several millivolts per meter, which are implied often from Doppler during unstable midlatitude. The much more effective strongly elongated Es under action an ambient field. In this case, may be capable exciting plasma waves sustained. stringent requirements with sharp boundaries, low ionospheric relation those inside, relatively would explain why type 1 echoes so rare backscatter.