Measurement of atomic oxygen in the middle atmosphere using solid electrolyte sensors and catalytic probes

M Eberhart,S Löhle,S Fasoulas,T Binder,A Steinbeck

doi:10.5194/amt-8-3701-2015

M Eberhart, S Löhle + Show 3 more

Open Access

https://doi.org/10.5194/amt-8-3701-2015

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Abstract

Abstract. The middle- and upper-atmospheric energy budget is largely dominated by reactions involving atomic oxygen (O). Modeling of these processes requires detailed knowledge about the distribution of this oxygen species. Understanding the mutual contributions of atomic oxygen and wave motions to the atmospheric heating is the main goal of the rocket project WADIS (WAve propagation and DISsipation in the middle atmosphere). It includes, amongst others, our instruments for the measurement of atomic oxygen that have both been developed with the aim of resolving density variations on small vertical scales along the trajectory. In this paper the instrument based on catalytic effects (PHLUX: Pyrometric Heat Flux Experiment) is introduced briefly. The experiment employing solid electrolyte sensors (FIPEX: Flux φ(Phi) Probe Experiment) is presented in detail. These sensors were laboratory calibrated using a microwave plasma as a source of atomic oxygen in combination with mass spectrometer reference measurements. The spectrometer was in turn calibrated for O with a method based on methane. In order to get insight into the horizontal variability, the rocket payload had instrument decks at both ends. Each housed several sensor heads measuring during both the up- and downleg of the trajectory. The WADIS project comprises two rocket flights during different geophysical conditions. Results from WADIS-1 are presented, which was successfully launched in June 2013 from the Andøya Space Center, Norway. FIPEX data were sampled at 100 Hz and yield atomic oxygen density profiles with a vertical resolution better than 9 m. This allows density variations to be studied on very small spatial scales. Numerical simulations of the flow field around the rocket were done at several points of the trajectory to assess the influence of aerodynamic effects on the measurement results. Density profiles peak at 3 × 1010 cm−3 at altitudes of 93.6 and 96 km for the up- and downleg, respectively.

Highlights

Atomic oxygen (O) is a highly reactive species and a key element in a number of atmospheric processes
In the following the results from the FIPEX measurements before and after aerodynamic correction are given
Emphasis is placed on the atomic oxygen density profiles; values for molecular oxygen, obtained from the platinum cathode sensors, are presented briefly

Summary

Introduction

Atomic oxygen (O) is a highly reactive species and a key element in a number of atmospheric processes. At high altitudes it is one of the major constituents of Earth’s atmosphere and may cause erosion to exposed parts of spacecraft, especially on solar panels of satellites and the International Space Station (Reddy, 1995). Atomic oxygen is involved in the most important heat sink in the MLT, the radiation of CO2 in the 15 μm band, where the population of the relevant energy levels depends mainly on collisions with O (e.g., Mlynczak, 1996). In the past decades numerous experiments with a number of different measure-

Results

Discussion

Conclusion