Rocket and incoherent scatter radar common-volume electron measurements of the equatorial lower ionosphere

A coordinated rocket and radar investigation has enabled the comparison of electron density measurements in essentially a common volume of the equatorial lower ionosphere. The rocket instrumentation included a Faraday rotation experiment, uniquely adapted for measuring electrons at low latitude, and fixed-bias Langmuir probes. The ALTAIR tracking radar was configured in an incoherent scatter mode. For the 75-92 km region, we note very good agreement between Faraday rotation and radar electron density measurements. Langmuir probe current measurements, calibrated to the Faraday rotation data, provided information about fine-scale electron density vertical structure and extended the rocket-radar comparisons of electron density to 130 km. Good overall agreement was also observed at higher altitudes, with evidence of electron density layering - including sporadic E - detected by both measurement techniques. The outcomes from our study support this unique Faraday rotation approach and the IS radar for measuring electron density in the equatorial lower ionosphere.