Electron density and temperature measurements obtained in the DEOS campaign Original Research Article

In the DEOS campaign (Dynamics of the Equatorial ionosphere Over SHAR) electron densities and temperatures have been measured with impedance and Langmuir probes. Three rocket flights have been performed in the evening equatorial ionosphere, shortly before and during equatorial spread-F (ESF). In the first flight, an undisturbed evening ionosphere was encountered and the resulting density profiles are compared with a profile obtained from ionosonde observations during the flight and with predictions from the IRI-95 model. In the second flight, which was launched under ESF conditions, large plasma bubbles were detected during the upleg. Both instruments resolve the large scale features as well as the intermediate scale fluctuations inside the plasma bubbles and agree well in the absolute densities measured. The temperature profiles show a strong reduction of the electron temperature in the depleted region, as compared with the ambient plasma. A temperature profile taken under unperturbed conditions is presented and compared with current models.