München 2019 – wissenschaftliches Programm
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UP: Fachverband Umweltphysik
UP 8: Physics of the middle atmosphere
UP 8.1: Vortrag
Donnerstag, 21. März 2019, 11:00–11:20, HS 22
Chemiluminescent potassium emission in the Earth’s atmosphere — •Stefan Noll1,2, John M. C. Plane3, Wuhu Feng3, Bastian Proxauf4, Stefan Kimeswenger5,6, and Wolfgang Kausch5 — 1Universität Augsburg, Germany — 2DLR, Weßling-Oberpfaffenhofen, Germany — 3University of Leeds, UK — 4MPI für Sonnensystemforschung, Göttingen, Germany — 5Universität Innsbruck, Austria — 6UCN, Antofagasta, Chile
The evaporation of cosmic dust particles entering the Earth’s atmosphere at high speeds leads to the formation of metal layers in the mesopause region at around 90 km. The alkali metal potassium (K) can be observed via the K(D1) line at 769.9 nm, which can be stimulated by sunlight, lasers, and chemical reactions. The latter mechanism is particularly useful for studying the underlying chemistry. However, as the related weak nighttime emission is difficult to observe, only a rough mean intensity has been measured, so far. With about 2,300 high-resolution spectra from the astronomical echelle spectrograph UVES at Cerro Paranal in Chile taken between 2000 and 2015, we have been able to study K nightglow in much more detail. Nighttime, seasonal, and long-term variations have been investigated for the first time. Moreover, we have simulated the K emission with the Whole Atmosphere Climate Community Model (WACCM) in order to estimate the efficiency of the chemiluminescent emission process. Overall, the variability and quantum yield are surprisingly different from the corresponding results for the better studied nightglow emission of sodium, another light alkali metal.