Abstract
Abstract. Absolute profiles of atomic oxygen number densities with high vertical resolution have been determined in the mesosphere–lower thermosphere (MLT) region from in situ measurements by several rocket-borne solid electrolyte sensors. The amperometric sensors were operated in both controlled and uncontrolled modes and with various orientations on the foredeck and aft deck of the payload. Calibration was based on mass spectrometry in a molecular beam containing atomic oxygen produced in a microwave discharge. The sensor signal is proportional to the number flux onto the electrodes, and the mass flow rate in the molecular beam was additionally measured to derive this quantity from the spectrometer reading. Numerical simulations provided aerodynamic correction factors to derive the atmospheric number density of atomic oxygen from the sensor data. The flight results indicate a preferable orientation of the electrode surface perpendicular to the rocket axis. While unstable during the upleg, the density profiles measured by these sensors show an excellent agreement with the atmospheric models and photometer results during the downleg of the trajectory. The high spatial resolution of the measurements allows for the identification of small-scale variations in the atomic oxygen concentration.
Highlights
The mesosphere–lower thermosphere (MLT) is a region of Earth’s atmosphere governed by a complex interplay of numerous fundamental processes that affect the energy budget at altitudes between 70 and 110 km
This paper presents the measurements of atomic oxygen number densities on WADIS-2 with FIPEX solid electrolyte sensors
While this paper focuses on the technical aspects of the FIPEX measurements, it is accompanied by two publications that deal with the interpretation of the results in the atmospheric–physical context: a paper by Strelnikov et al analyzes waves and turbulence in the rocket data of neutrals, ions, electrons and atomic oxygen (Strelnikov et al, 2019), and a paper by Grygalashvyly et al examines the excitation mechanism of O2 based on the simultaneous measurement of atomic oxygen by both FIPEX and photometers (Grygalashvyly et al, 2019)
Summary
The mesosphere–lower thermosphere (MLT) is a region of Earth’s atmosphere governed by a complex interplay of numerous fundamental processes that affect the energy budget at altitudes between 70 and 110 km. M. Eberhart et al.: Atomic oxygen densities measured by solid electrolyte sensors on WADIS-2 atmospheric temperature distribution (Lindzen, 1981). Apart from its important role as a carrier of chemical energy, atomic oxygen is involved in the most relevant heat sink in the MLT: the radiant emission of carbon dioxide in the infrared 15 μm band Measurement of this radiation is fundamental for most satellite-based methods for the determination of atmospheric temperature profiles. The project WADIS (WAve propagation and DISsipation in the middle atmosphere: energy budget and distribution of trace constituents), initiated by the IAP (Leibniz Institute of Atmospheric Physics at the University of Rostock) and the IRS (Institute of Space Systems at the University of Stuttgart), investigated both dynamical and chemical processes in the MLT and their interaction based on simultaneous rocket-borne in situ measurements. While this paper focuses on the technical aspects of the FIPEX measurements, it is accompanied by two publications that deal with the interpretation of the results in the atmospheric–physical context: a paper by Strelnikov et al analyzes waves and turbulence in the rocket data of neutrals, ions, electrons and atomic oxygen (Strelnikov et al, 2019), and a paper by Grygalashvyly et al examines the excitation mechanism of O2 based on the simultaneous measurement of atomic oxygen by both FIPEX and photometers (Grygalashvyly et al, 2019)
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