Greifswald 2024 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 1: Atmospheric Trace Gases and Aerosols

UP 1.1: Hauptvortrag

Montag, 26. Februar 2024, 11:00–11:30, ELP 6: HS 4

Atmospheric impact of energetic particle precipitation from the lower thermosphere to the surface — •Miriam Sinnhuber — Karlsruher Institut für Technologie

Energetic charged particles - protons, electrons and heavier ions with energies from tens of keV to hundreds of MeV - precipitate into the atmosphere at high latitudes, guided by the Earth's magnetic field. They originate from the sun, accelerated in the solar corona during flares or coronal mass ejection events, or from the terrestrial magnetosphere, accelerated during geomagnetic storms or auroral substorms by variations in the high-speed solar wind. In the atmosphere, they interact with the most abundant species by collision reactions, starting a chain of chemical-dynamical coupling mechanism. The first step is atmospheric ionization and the formation of radicals of the NOx and HOx families mainly in the mesosphere and lower thermosphere, and subsequent ozone loss. NOx can be transported into the stratosphere during polar winter, and contribute significantly to ozone loss at the top of the ozone layer. Radiative feedbacks in turn affect atmospheric dynamics possibly even down to tropospheric weather systems. This so-called geomagnetic forcing of the climate system is modulated by the quasi-continuous solar wind and sporadic solar eruptions and varies over the 11-year solar cycle; since CMIP6, it is also recommended as part of the solar forcing of the climate system. In this presentation, an overview of the state of the art will be provided, focusing on the 11-year variability as well as on the impact of extreme solar events.

Keywords: solar variability; geomagnetic forcing; middle atmosphere