Atomic oxygen number densities in the mesosphere–lower thermosphere region measured by solid electrolyte sensors on WADIS-2

摘要

Absolute profiles of atomic oxygen number densities with high verticalresolution have been determined in the mesosphere–lower thermosphere (MLT) region from in situmeasurements by several rocket-borne solid electrolyte sensors. Theamperometric sensors were operated in both controlled and uncontrolled modesand with various orientations on the foredeck and aft deck of the payload.Calibration was based on mass spectrometry in a molecular beam containingatomic oxygen produced in a microwave discharge. The sensor signal isproportional to the number flux onto the electrodes, and the mass flow rate inthe molecular beam was additionally measured to derive this quantity from thespectrometer reading. Numerical simulations provided aerodynamic correctionfactors to derive the atmospheric number density of atomic oxygen from thesensor data. The flight results indicate a preferable orientation of theelectrode surface perpendicular to the rocket axis. While unstable during theupleg, the density profiles measured by these sensors show an excellentagreement with the atmospheric models and photometer results during thedownleg of the trajectory. The high spatial resolution of the measurementsallows for the identification of small-scale variations in the atomic oxygenconcentration.