Interferometer studies of equatorial F region irregularities and drifts

A radar interferometer technique developed at Jicamarca, Peru and first used to study electrojet irregularities has now been used successfully to study plasma turbulence in the equatorial F region. Our first results have shown that the most ‘turbulent’ echoes appear to come from a region that extends for tens of kilometers in altitude but for only a kilometer or less in the east‐west direction. This slab may very well be the wall of a depleted region, a plasma ‘bubble’. Sometimes the irregularities can be tracked as they move eastward or westward. Velocity profiles for the evening period obtained in this way show a strong shear, with westward velocities at the lowest altitudes observed and eastward velocities above. A plausible explanation for this shear is that the westward drifts are driven by electric fields produced by westward E region winds and mapped up along magnetic field lines, while at higher heights, where the electron density is greater, the drifts are controlled by the F region dynamo driven by eastward winds.